Abdominal Pain in Pregnancy Diagnoses and Imaging

8/12/2019 Abdominal Pain in Pregnancy Diagnoses and Imaging

1/17

WS14 AJR:194, June 2010

AJR Integrative Imaging

LIFELONG LEARNING

FOR RADIOLOGY

Abdominal Pain in Pregnancy: Diagnoses and ImagingUnique to PregnancyReviewCourtney A. Woodfield1, Elizabeth Lazarus1, Karen C. Chen1,2, William W. Mayo-Smith1

Keywords: abdominal pain, CT, MRI, ul trasound, womens imaging

DOI:10.2214/AJR.07.7139

Received November 14, 200 8; accepted after revision November 4, 2009.

1Department of Diagnostic Imaging, The Warren Alpert Medical School of Brown University, Women and Infants Hospital, Rhode Island Hospital, 593 Eddy St., Providence, RI 02903.Address correspondence to C. A. Woodfield ([email protected]).

2Present address: Department of Radiology, University of California at San Diego, San Diego, CA.

WEBThis is a Web exclusive article.

AJR2010;194:WS14WS30 0361803X/10/1946WS14 American Roentgen Ray Society

ObjectiveAbdominal pain during pregnancy can be caused by a wide

variety of diseases including disorders of the obstetric, gyne-

cologic, gastrointestinal, hepatobiliary, genitourinary, and

vascular systems. Some causes are unique to pregnancy, are

exacerbated by pregnancy, or require an altered imaging al-

gorithm for diagnosis during pregnancy. The educational ob-

jectives of this review article are for the participant to exer-

cise, self-assess, and improve his or her understanding of the

imaging evaluation of abdominal pain during pregnancy.

Conclusion

This article reviews the causes of abdominal pain that

are unique to pregnancy as well as some of the more com-

mon and severe causes of abdominal pain in which the im-

aging workup differs in the pregnant population. The rela-

tive advantages of using ultrasound, CT, and MRI to help

establish the cause of the pain are also reviewed.

Introduction

A wide variety of diseases, including disorders of the ob-

stetric, gynecologic, gastrointestinal, hepatobiliary, genito-

urinary, and vascular systems, can present as abdominal

pain during pregnancy [13] (Table 1). The clinical diagno-

sis of an intraabdominal disease in pregnant women is oftenobscured by concurrent maternal physiologic and anatomic

changes [3, 4]. Guarding in the setting of peritonitis may

not occur because of the loss of elasticity in the abdominal

wall musculature [2]. Leukocytosis in pregnancy is less use-

ful in clinical evaluation because WBC count is typically

elevated in pregnancy, ranging from 6,00016,000 cells/L

during the rst and second trimesters to 2030,000 cells/L

at the end of the third trimester [3]. Ureteral compression

and displacement of intraabdominal organs, including the

appendix, by the gravid uterus may also confound the clin-

ical presentation [2].

A delay in the diagnosis of many of the causes of ab-

dominal pain can be threatening to both the mother andthe fetus [3, 5]. Imaging can clarify a confusing clinical pic-

ture and expedite diagnosis. Ultrasound is widely used as

the initial diagnostic imaging technique during pregnancy

because of its availability, portability, and lack of ionizing

radiation. Ultrasound often can elucidate the cause of ab-

dominal pain, particularly if pain is due to an obstetric and

gynecologic abnormality. However, evaluation of the bowel,

pancreas, ureters, and mesenteric vasculature may be lim-

ited on ultrasound because of patient body habitus, a small

eld of view, and the presence of overlying structures. Air

within the bowel can particularly limit evaluation of the

mesenteric vessels, pancreas, and bowel.

MRI is also a useful technique for imaging pregnant patients

given the lack of ionizing radiation. Several recent studies have

shown that MRI is valuable in evaluating abdominal pain dur-

ing pregnancy, especially in the diagnosis of appendicitis,

which is the most common cause of an acute abdomen in preg-

nancy [68]. To date, no deleterious effects to the developing

fetus exposed to MRI have been reported. Therefore, no spe-

cic consideration for MRI during the rst, second, or third

trimester has been recommended [9]. The use of MRI for the

evaluation of abdominal pain during pregnancy may be de-

pendent on institutional availability and radiologist experience.

A recent guidance document for safe MR practices from the

American College of Radiology (ACR) does not recommend

the routine use of gadolinium during pregnancy [9]. Gadolini-um-based MR contrast agents are known to pass through the

placenta to the fetal circulation. The contrast material is then

excreted by the fetal kidneys into the amniotic uid where the

agent can remain for an indeterminate amount of time. To

date, no large, well-controlled studies have been performed to

document the presence or absence of adverse fetal effects re-

sulting from maternal gadolinium administration. Therefore,

the potential risks to the fetus remain unknown [9].

Examinations using ionizing radiationin particular,

CTcan also accurately diagnose many causes of abdomi-

nal pain during pregnancy. A riskbenet analysis is par-

ticularly warranted before performing an examination in-

volving ionizing radiation on a pregnant or potentiallypregnant patient. However, most diagnostic imaging stud-


2/17

AJR:194, June 2010 WS15

Abdominal Pain in Pregnancy

ies utilizing ionizing radiation do not expose the fetus to a

radiation dose high enough to result in developmental or

neurologic decits. Therefore, ionizing radiation examina-

tions can still be offered to pregnant women when the study

is in the best health interest of the mother and the patient

understands the minimal and unknown risks to the fetus

[10]. For example, CT remains the most reliable technique

for depicting obstructing urinary tract calculi in pregnant

women [11]. Based on our experience with a low-dose renal

calculus protocol (160 mA and 140 kVp on a 16-MDCT

scanner), the mean radiation dose delivered to the female

pelvis is 16 mGy and to the fetus, 47.2 mGy and 8.511.7

mGy at 0 and 3 months of gestation, respectively [12]. This

dose is below the recommended 50-mGy (5-rad) maternal

dose limit for avoiding deterministic radiation effects (i.e.,

effects that have a radiation threshold below which they

should not occur) such as fetal teratogenesis [13]. There is

no known maternal radiation limit for fetal stochastic ef-

fects (i.e., effects that can occur regardless of radiation

dose) such as carcinogenesis; therefore, radiation levels

should be kept as low as reasonably achievable (ALARA)for all ionizing radiation studies [13].

Similar to gadolinium-based MR contrast agents, iodinat-

ed IV contrast agents have been shown to cross the placenta

to the fetal circulation and ultimately to be excreted into the

amniotic uid. No teratogenic fetal effects from a single in

utero exposure to iodinated contrast material at diagnostic

doses have been reported. However, there have also been no

published large, well-controlled studies investigating poten-

tial teratogenic effects from iodinated contrast agents. In

early reports, investigators described transient congenital

hypothyroidism after amniofetography using iodinated con-

trast material [14]. However, more recent small studies of

pregnant patients receiving iodinated contrast material aspart of a CT protocol did not show any effect on thyroid

function [15]. Similar to its recommendations with regard to

gadolinium-based contrast agents, the ACR recommends IV

iodinated contrast administration during pregnancy only

when it is deemed necessary for prompt and accurate evalua-

tion of the pregnant patients medical condition [16].

This review focuses on the causes of abdominal pain that

are unique to pregnancy as well as some of the more com-

mon and severe causes of abdominal pain in which the im-

aging workup differs in the pregnant population compared

with the nonpregnant population. This article also explores

the relative advantages of using different imaging tech-

niques including ultrasound, CT, and MRI to help establishthe cause of the pain.

Obstetric CausesDuring the rst trimester of pregnancy, common causes

of abdominal and pelvic pain include early pregnancy fail-

ure and ectopic pregnancy. During the second and third tri-

mesters, causes of pain include preterm labor and the less

common, but more severe, complications of placental

abruption and uterine rupture.

Early Pregnancy Failure

Spontaneous abortion occurs in approximately 1012%

of known rst trimester pregnancies. Although the patient

may be asymptomatic, spontaneous abortion commonly re-

sults in pain and vaginal bleeding [17].

Ultrasound is the initial diagnostic test of choice for a

rst trimester patient with pain and bleeding. Ultrasound

can conrm early pregnancy failure with high specicity if

no fetal cardiac activity is detected by the time the embryo

measures 5 mm in length or if the pregnancy is known to be

6.5 weeks without an embryo with a heartbeat [18].

TABLE 1: Causes of Abdominal Pain in PregnantWomen by Organ System

Organ System Cause

Obstetric Abortion

Ectopic pregnancy

Preterm labor

Placental abruption

Uterine rupture

Gynecologic Adnexal mass or ovarian cyst

Adnexal torsion

Uterine leiomyoma

Endometriosis

Pelvic inflammatory disease

Gastrointestinal Appendici tis

Inflammatory bowel disease

Intestinal obstruction

Gastroesophageal reflux

Peptic ulcer disease

Hepatobiliary HELLP syndrome

Acute fatty liver of pregnancy

Cholelithiasis or choledocholithiasis

Acute cholecystitis

Acute pancreatitis

Hepatitis

Genitourinary Hydronephrosis of pregnancy

Urolithiasis

Pyelonephritis

Cystitis

Vascular Gonadal vein thrombosis

Mesenteric vein thrombosis

Gonadal vein syndrome

Aneurysm rupture

Vasculitis

NoteHELLP = hemolysis, elevated liver enzymes, low platelet count.


3/17

Woodfield et al.

WS16 AJR:194, June 2010

Additional sonographic ndings such as abnormal gesta-

tional sac size or shape and embryonic bradycardia may be

suggestive of a poor outcome but are not denitive for early

pregnancy failure. Large gestational sacs without a yolk sac or

an embryo are worrisome. The most widely accepted dis-

criminatory sizes of the gestational sac using endovaginal

ultrasound are an 8-mm mean sac diameter by which a yolksac must be visualized and a 16-mm mean sac diameter by

which an embryo must be visualized for the pregnancy to be

considered normal [19, 20]. However, a range of higher dis-

criminatory values has been reported in the literature, with

mean sac diameter values up to 13 mm for visualization of the

yolk sac and 18 mm for visualization of the embryo proposed

before considering a pregnancy abnormal [1921]. Given this

range of values, use of the discriminatory sac size is limited.

Worrisome ndings on ultrasound also include slow embry-

onic cardiac activity, irregular gestational sac, and low posi-

tion of the gestational sac [22]. Embryonic heartbeat rates

below 80 beats per minute (bpm) at 6.06.2 weeks or below

100 bpm at 6.37.0 weeks menstrual age are associated witha very high rate of early pregnancy failure [23].

When the ultrasound examination either shows worri-

some features or is inconclusive, such as in cases with an

embryo smaller than 5 mm without a heartbeat, follow-up

ultrasound is indicated. Follow-up ultrasound is typically

performed 57 days later to allow measurable growth. Cor-

relating sonographic ndings with maternal serum level of

-HCG can also help indicate whether early pregnancy fail-

ure has occurred. A gestational sac is expected to be visible

when the -HCG level is above 2,000 mIU/mL (third inter-

national reference preparation) and the embryo when the

-HCG level is above 10,800 mIU/mL [24].

Ectopic Pregnancy

Ectopic pregnancy, which remains the most frequent ob-

stetric cause of death in pregnancy, often presents with ab-

dominal or pelvic pain in the rst trimester [25]. The inci-

dence of ectopic pregnancy has been increasing steadily

since 1970. This increased incidence correlates with an in-

crease in the prevalence of risk factors for ectopic pregnan-

cy including sexually transmitted diseases and assisted re-

productive techniques [26, 27]. Ultrasound plays an

instrumental role in ruling out an ectopic pregnancy if it

Fig. 1Tubal ectopic pregnancy in woman 8 weeks pregnant who presentedwith right-sided pelvic pain. Gray-scale transvaginal ultrasound image revealsextrauterine gestational sac (arrows) with yolk sac (arrowhead) between rightovary (O) and uterus (UT).

A

Fig. 2Interstitial ectopic pregnancy.A,Woman 7 weeks pregnant who presented with abdominal pain. Gray-scale transvaginal ultrasound image shows eccentric intrauterine gestational sac (arrows)containing yolk sac and embryo. Endometrium (arrowheads) extends up to, but does not surround, gestational sac; these findings are consistent with intersti tial pregnancy.B,Woman 8 weeks pregnant who presented with abdominal pain. Coronal T2-weighted single-shot fast spin-echo MR image also shows eccentric intrauterinegestational sac (arrows) that is not surrounded by endometrium (arrowheads).

B


4/17

AJR:194, June 2010 WS17


can conrm an intrauterine pregnancy. Heterotopic preg-

nancy, a coexistent ectopic and intrauterine pregnancy, is

rare (1 in 7,000) in the general population. However, the

incidence of heterotopic pregnancy is higher after in vitro

fertilization, approaching 1% in some studies [28, 29].

In a small percentage of cases, ultrasound may conclusive-

ly diagnose ectopic pregnancy if it shows an extrauterinegestational sac with a yolk sac or embryo (Fig. 1). More com-

monly, ultrasound reveals ndings that are only suggestive of

an ectopic pregnancynotably, an adnexal mass and pelvic

free uid. An adnexal mass is the most common sonographic

nding in ectopic pregnancy, occurring in 6584% of cases

[3032]. The adnexal mass can have a variety of appearanc-

es, including appearing to be a saclike ring, solid, or complex.

A small amount of pelvic free uid can be seen in normal

pregnancies, but a moderate to large amount of pelvic uid,

particularly if in association with an adnexal mass, signi-

cantly increases the risk for ectopic pregnancies. The pres-

ence of uid-containing echoes, correlating with hemoperito-

neum, carries a 93% positive predictive value for ectopicpregnancy [33]. Occasionally ultrasound ndings may ap-

pear normal in the setting of ectopic pregnancy.

MRI can be used as a problem-solving technique for the

less common nontubal forms of ectopic pregnancies when

sonography is indeterminate. With its multiplanar capabili-

ties, MRI can help to conrm a suspected cervical ectopic

pregnancy or cesarean section scar ectopic pregnancy before

treatment. In addition, MRI can help differentiate between

eccentric implantation in the endometrium versus an inter-

stitial ectopic pregnancy (Fig. 2). An interstitial ectopic preg-

nancy on MRI will appear as a gestational sac centered in the

cornual aspect of the uterine wall and will be separated from

the endometrium by an intact junctional zone [34] (Fig. 2).

Placental Abruption

Symptoms of placental abruption are variable but often

include vaginal bleeding and abdominal or pelvic pain. Pla-

cental abruption is dened as in utero separation of the pla-

centa from the myometrium and accounts for 1025% of

prenatal deaths [35]. In most cases, ultrasound does not show

any signs of abruption because the hemorrhage resulting

from placental separation can pass through the cervical os.

Sonographic ndings suggestive of placental abruption,

when they are visible, are usually due to hematomas. Visual-

ization of a hematoma is clinically important because thesepregnancies have a worse prognosis [35]. The most common

location of hematomas in this setting is subchorionic (i.e.,

between the uterine wall and chorionic membrane) [36]. Ret-

roplacental (behind the placenta) and preplacental (in front

of the placenta) hematomas are less common. The sono-

graphic appearance of a hematoma varies with its acuity.

Acute hematomas are hyperechoic to isoechoic (Fig. 3). Ini-

tially, the only nding of an acute or subacute hematoma on

ultrasound may be an abnormally thickened placenta. In

these cases, T1-weighted MRI may be used to help distin-guish high-signal hematomas from the lower-T1-signal-in-

tensity placenta [37]. Hematomas more than 12 weeks in

age appear progressively more hypoechoic [36].

Preterm Labor

Preterm labor is dened as uterine contractions strong

enough to cause cervical dilatation and effacement between

20 and 37 weeks gestation. The abdominal pain that ac-

companies these contractions is often clinically distinguish-

able, so imaging is typically not indicated for diagnosis.

However, ultrasound evaluation of cervical length is the

most sensitive predictor of preterm birth. The shorter the

cervical length measures, the higher the risk of preterm

birth. Also, the earlier a shortened cervical length is found,

the higher the risk of preterm birth. A normal cervical

length is more than 30 mm between 14 and 30 gestational

weeks [3840]. Cervical funneling is also associated with an

increased risk of preterm labor. Funneling occurs when the

internal os is open proximally and gradually narrows, ap-

proximating the appearance of a cone. If funneling is pres-

ent, the cervical length is almost always shortened. How-

ever, the presence of funneling in a patient with a normal

cervical length does not increase the risk of preterm birth.

Uterine RuptureUterine rupture is a rare, catastrophic event that often

presents with severe abdominal pain. Predisposing factors

include previous uterine surgery, including cesarean deliver-

ies and myomectomy, and congenital uterine malforma-

tions. Uterine rupture can occur during labor or before de-

livery such as in cases of interstitial ectopic pregnancies

that rupture [41]. Only a very short time interval for suc-

cessful intervention exists once uterine rupture has oc-

curred, so imaging in this setting may consume valuable

Fig. 3Placental abruption in woman 20 weeks pregnant who presented withabdominal pain and vaginal bleeding. Gray-scale transabdominal ultrasoundimage shows isoechoic collection in retroplacental location (arrows),representing acute retroplacental hematoma secondary to placental abruption.Normal placenta (arrowheads) is seen.


5/17


6/17

AJR:194, June 2010 WS19


nate for torsion, MRI may better show ovarian edema result-

ing from early or intermittent ovarian torsion [45] (Fig. 6).

Leiomyomas

Uterine leiomyomas are commonly encountered during

pregnancy, with 1 in 500 pregnant women hospitalized for a

leiomyoma-related complication [44]. Approximately half ofall leiomyomas grow during pregnancy, mainly in the rst

trimester because of rising estrogen levels [51]. Abdominal

pain and uterine contractions can result from necrosis and

degeneration of leiomyomas secondary to rapid growth.

Red degeneration is the most common type of degenera-

tion during pregnancy and occurs when a leiomyoma out-

grows its blood supply with resulting hemorrhage. Such leio-

myomas can appear on ultrasound as circumscribed masseswith cystic spaces or heterogeneous echogenicity [51, 52]

A

Fig. 6Degenerated fibroid in woman 17 weeks pregnant who presented with right-sided abdominal pain.A andB,Transverse (A) and sagittal (B) transabdominal ultrasound images show exophytic fibroid (straightarrows) extending from right lateral aspect of uterus. Innerhypoechoic region with low-level echoes (arrowheads) represents cystic degeneration secondary to necrosis. Intrauterine fetal head (curved arrow, A)is seen.

B

AFig. 5Ovarian torsion in woman 11 weeks pregnant who presented with 2 days of lower abdominal and pelvic pain.A,Transverse gray-scale transabdominal ultrasound image through pelvis shows cystic and solid midl ine mass (arrows). Separate normal right ovar y was seentransvaginally (not shown). Separate left ovary was not seen on transabdominal or transvaginal ultrasound. MRI was performed for further evaluation 1 hour later.B,Coronal T2-weighted fast spin-echo MR shows enlarged, partially necrotic left ovary ( black arrows) and cystic mass arising from left ovary (white arrow) with fewseptations in inferior aspect of mass (arrowhead). Left ovary and mass were surgically removed later that day. Pathology results were torsed, necrotic left ovary withmucinous cystadenocarcinoma of left ovary serving as lead point mass.

B


7/17

Woodfield et al.

WS20 AJR:194, June 2010

(Fig. 7). Ultrasound can further conrm a degenerating leio-

myoma as the source of pain if the patient experiences pain

when the probe is directly placed over the leiomyoma [44].

On MRI, red degeneration of a leiomyoma manifests as pe-

ripheral or diffuse high signal intensity on T1-weighted im-ages and corresponding variable signal intensity with or

without a low-signal-intensity rim on T2-weighted images

[48]. Leiomyomas are also the most common solid adnexal

masses in pregnancy [45]. Exophytic leiomyomas have the

potential to torse during pregnancy, causing pain due to loss

of blood supply and rapid necrosis.

Gastrointestinal CausesGastrointestinal causes of pain during pregnancy include

appendicitis and other inammatory, infectious, and obstruc-

tive processes of the bowel. These diseases are neither unique

to nor more common in pregnancy but can be more difcult

to diagnose during pregnancy. The approach to imaging thebowel of a pregnant patient also differs from that of a non-

pregnant patient because ultrasound and MRI are typically

preferred over techniques that impart ionizing radiation such

as radiography and CT.

Appendicitis

Appendicitis is the most common nonobstetric reason for

emergency surgery during pregnancy, occurring in approxi-

mately 1 in 1,500 deliveries [53]. Early diagnosis is important

because a 66% increased incidence of appendiceal perfora-

tion during pregnancywith a resulting increased rate of

fetal loss and maternal mortalityhas been reported with

surgical delays greater than 24 hours from the time of symp-tom onset [53]. Clinically diagnosing appendicitis during

Fig. 8Acute appendicitis in 25-year-old pregnant woman who presented withright lower quadrant pain. Sagittal gray-scale ultrasound image shows blind-ending, dilated, tubular structure (arrows) in right lower quadrant containingovoid echogenic structure (arrowhead) with posterior acoustic shadowing. Acuteappendicitis with appendicolith was diagnosed at surgery.

A

Fig. 7Ovarian edema in woman 13 weeks pregnant who presented with right lower quadrant pain.A,Transvaginal ultrasound image with spectral Doppler shows mildly enlarged right ovar y (volume = 16.1 cm3) with arterial flow.B,Axial T2-weighted single-shot fast spin-echo image from MR examination performed same day as ultrasound ( A) shows increased signal intensity of central ovarianstroma (black arrow) and peripheral displacement of subcentimeter physiologic ovarian fol licles (whitearrows); these findings are consistent with ovarian edema.Surgery confirmed right ovarian edema due to compression of right adnexal vessels between enlarging uterus and anterior pelvic wall.

B


8/17

AJR:194, June 2010 WS21


pregnancy is difcult because of multiple factors including,

rst, the variable appendiceal position (the appendix is grad-

ually displaced upward during pregnancy); second, limited

physical examination of the gravid abdomen; and, third, the

nonspecicity of symptoms such as nausea, vomiting, guard-

ing, and leukocytosis during pregnancy [2, 3, 54].

The primary options for imaging pregnant patients withsuspected appendicitis are ultrasound, MRI, and CT. Ultra-

sound is usually the rst imaging technique of choice because

of its availability, lack of ionizing radiation, and lack of need

for IV contrast material. The sonographic criteria for diag-

nosing appendicitis in pregnant patients are the same as in

nonpregnant patients: visualization of a dilated (> 67 mm

in diameter), aperistaltic, noncompressible, and blind-ending

tubular structure arising from the cecum. The outer diame-

ters of both a normal appendix and an inamed appendix

are known to vary on ultrasound, with reported normal ap-

pendix diameters ranging from 2 to 13 mm and inamed ap-

pendix diameters from 6 to 30 mm [55]. Therefore, an appen-

dix with a diameter of between 6 and 7 mm withoutadditional features of acute inammation may be considered

indeterminate for appendicitis [56]. Associated ndings, such

as appendiceal wall thickening (> 2 mm), appendicoliths, and

surrounding hyperechoic inamed fat, or hypoechoic uid

may also be seen sonographically (Fig. 8). However, ultra-

sound of the appendix is a highly operator-dependent ex-

amination that can be further limited by the pregnant body

habitus. Sensitivities ranging from 50% to 100%, specici-

ties ranging from 33% to 92%, accuracies ranging from 73%

to 93%, and negative predictive values ranging from 64% to

88% have been reported for the sonographic diagnosis of ap-

pendicitis in the general adult population [5762]. In addi-

tion, an elevated or retrocecal appendix may be difcult to

nd sonographically and a ruptured appendix may have non-

specic ndings on ultrasound. Therefore, a negative ultra-

sound examination does not exclude the possibility of ap-pendicitis and if there remains high clinical suspicion for

appendicitis (persistent right lower quadrant pain of uncer-

tain cause), additional imaging should be considered [63].

When available, MRI is the next preferred examination

for evaluating the appendix in pregnancy also because of its

lack of ionizing radiation. Recent studies have shown that

MRI can reliably diagnose acute appendicitis during preg-

nancy with 100% sensitivity and 94% specicity [7, 64].

MR examinations for appendicitis in pregnancy at our in-

stitution include an oral contrast preparation (300 mL of

barium sulfate [Readi-CAT 2, E-Z-EM] and 300 mL of fer-

umoxsil [GastroMARK, AMAG Pharmaceuticals]) started

2 hours before the examination. These agents are used be-cause they are the oral contrast preparations already avail-

able in our department for other CT (barium sulfate) and

MR (ferumoxsil) examinations, and this specic negative

oral contrast preparation has been previously described in

the literature as a means of limiting bowel susceptibility

artifact and conrming appendiceal patency [7].

The MR examination then consists of the following se-

quences: axial, sagittal, and coronal T2-weighted single-shot

fast spin echo (SSFSE), axial T1-weighted dual gradient-echo,

A

Fig. 9Acute appendicitis in 30-year-old pregnant woman who presented with right lower quadrant pain. Ultrasound findings were normal.A andB,Axial (A) and sagittal (B) T2-weighted single-shot fast spin-echo MR images reveal dilated (1.2 cm) appendix with high-T2-signal-intensity luminal contents(straightarrows) due to fluid and adjacent periappendiceal fat stranding and fluid (arrowheads); these findings are indicative of periappendiceal inflammation. Low-signal-intensity oral contrast material fills cecum (curved arrow, B). Acute appendicitis without perforation was diagnosed at surgery.

B


9/17

Woodfield et al.

WS22 AJR:194, June 2010

axial true fast imaging with steady-state precession (FISP),

and axial STIR. The multiplanar T2-weighted SSFSE images

allow imaging of the bowel in a relatively motionless state and

help to conrm the location of the appendix in more than one

plane. The axial T1-weighted gradient-echo images are ob-

tained to help conrm appendiceal patency by showing bloom-

ing artifact from air or oral contrast material in the appendix

lumen from out-of-phase to in-phase imaging. The axial true

FISP images also help differentiate high-signal-intensity ad-nexal vessels from the lower signal intensity of a normal ap-

pendix, and the axial STIR sequence is used to highlight any

periappendiceal edema or uid associated with appendicitis.

The largest study to date of MRI for appendicitis in preg-

nant patients has described the following criteria for diag-

nosing acute appendicitis in this population: an appendix

diameter of > 7 mm with high-T2-signal-intensity luminal

contents, appendiceal wall thickening (> 2 mm), or periap-

pendiceal fat stranding and uid [7] (Fig. 9). An appendix

with high-T2-signal-intensity luminal contents and a diam-

eter of between 6 and 7 mm on MRI without associated

wall thickening or periappendiceal inammatory changesmay be considered indeterminate for appendicitis and war-

rants close clinical follow-up [7, 65].

Appendicitis can also be readily diagnosed on CT using the

same criteria in pregnant patients as in nonpregnant patients

[12]. CT is generally performed if MRI is unavailable or if

the patient has contraindications to MRI to prevent a delay

in the diagnosis and treatment of a possible appendicitis.

Sensitivities ranging from 72% to 100%, specicities ranging

from 83% to 99%, accuracies ranging from 78% to 98%, and

negative predictive values ranging from 64% to 99% have

been reported for the CT diagnosis of appendicitis in the gen-

eral adult population [58, 59, 61, 62, 66].

Infectious Diseases and Inflammatory Bowel Disease

Infection and inammation of the bowel are additional po-

tential causes of acute abdominal pain during pregnancy. In-

ammatory bowel disease has a peak incidence in women of

Fig. 11Hepatic rupture in 28-year-old recently postpartum woman with HELLP(hemolysis, elevated liver enzymes, low platelet count) syndrome and abdominalpain. Axial enhanced CT image reveals high-attenuation (52-HU) perihepaticmaterial (arrows) diagnostic of hemoperitoneum, which was secondary tohepatic rupture. Note lower-attenuation (8-HU) small bilateral pleural effusions(arrowheads).

A

Fig. 10Small-bowel obstruction in 31-year-old pregnant woman who presented with abdominal pain and distention. Patient has history of gastric bypass surgery.A,Transverse gray-scale ultrasound image of left abdomen shows dilated loop of bowel (arrows).B,Subsequent axial enhanced CT image through abdomen reveals multiple dilated loops of small bowel with airfluid levels (arrows) and superior mesenteric veinthrombus (arrowhead). Small-bowel obs truction due to inter nal hernia was diagnosed at surgery. Hypercoagulabilit y due to pregnancy was implicated as cause ofsuperior mesenteric vein thrombus.

B


10/17

AJR:194, June 2010 WS23


reproductive age. Disease activity is largely independent of

pregnancy; however, activity during pregnancy is associated

with increased fetal loss rate and fetal growth retardation [3].

Ultrasound is often the rst imaging study chosen for evaluat-

ing localized or generalized abdominal pain during pregnancy

and may reveal a thick-walled segment of bowel in the setting

of active infection or inammation [67]. However, cross-sec-

tional imaging is commonly required to evaluate the entire

extent of disease as well as any associated complications such

as bowel obstruction, stulas, or abscess formation.

Both MRI and CT can show the presence, extent, and

complications of infectious and inammatory bowel diseases.

MR examinations without or with an oral preparation (MRenterography) using T2-weighted SSFSE images can readily

depict thick-walled segments of small and large bowel and

associated complications in pregnant patients and nonpreg-

nant patients [65, 68]. Similar to CT, ndings of Crohns dis-

ease on MRI include segmental bowel wall thickening and

small-bowel involvement. Additional ndings such as bowel

stenosis with prestenotic dilatation, brofatty proliferation,

increased vascularity of the vasa recta, and mesenteric ade-

nopathy may also be readily depicted on both CT and MRI

[69]. The role of MRI in evaluating ulcerative colitis is less

established, but MRI can reportedly show the continuous co-

lonic wall thickening and loss of haustral folds characteristic

of ulcerative colitis [70].

Bowel Obstruction

Bowel obstruction is a third gastrointestinal emergency

that can arise during pregnancy with an incidence of 1 in

2,500 deliveries. Maternal mortality associated with bowel

obstruction is as high as 6% and is most commonly second-

ary to adhesions [71]. Pregnant patients more commonly

present with bowel obstruction in the third trimester perhaps

because of increased mass effect of the enlarging gravid uter-us on the large and small bowel with resulting bowel displace-

ment [72]. Clinically diagnosing bowel obstruction in a preg-

nant patient can be difcult because the gravid uterus limits

physical examination and because some of the symptoms of

bowel obstruction (abdominal pain, nausea, vomiting) are

also common symptoms of pregnancy. However, the onset of

such symptoms after the rst trimester should raise the pos-

sibility of other gastrointestinal abnormalities or diseases

such as intestinal obstruction [2].

A

C

Fig. 12Gallstone pancreatitis in 27-year-old pregnant woman who presented

with right upper quadrant and epigastric pain. Patient had undergonelaparoscopic cholecystectomy 2 years earlier.A,Coronal thick-slab MR cholangiopancreatography image illustrates mi lddilatation of intrahepatic bile ducts (arrowheads) and moderate dilation ofcommon bile duct (arrow).Band C, Axial T2-weighted single-shot fast spin-echo MR images through levelof distal common bile duct (B) and pancreas (C) reveal dependent filling defectin distal common bile duct (arrowhead, B) and small amount of retroperitonealand peripancreatic fluid (arrows, C). This fluid was believed to be secondary togallstone-related pancreatitis because patient had elevated serum amylase (1,321U/L) and lipase (1,015 U/L) levels. Subsequent ERCP with stone extraction resultedin resolution of patients abdominal pain and normalization of serum amylaseand lipase levels. Common duct s tone is not visible on coronal t hick-slab MRcholangiopancreatography image because of volume averaging with high-signal-intensity bile.

B


11/17

Woodfield et al.

WS24 AJR:194, June 2010

Ultrasound is again often the rst imaging study of

choice for evaluating generalized abdominal pain in preg-

nancy and may show dilated loops of bowel with uid levels

and aperistalsis with long-standing or high-grade obstruc-

tion, but ultrasound does not reliably depict the point or

cause of bowel obstruction. Therefore, cross-sectional im-

aging with MRI or CT is again often required for furthercharacterization (Fig. 10). Similar to imaging bowel inam-

mation or infection, MR studies for bowel obstruction can

be performed with the use of multiplanar T2-weighted

SSFSE imaging and may be performed with or without oral

contrast preparation [73]. If MRI cannot be performed ex-

peditiously or expertise in MR interpretation is not readily

available, CT may be performed because the risk of delayed

diagnosis and treatment of a potential bowel obstruction

may pose a greater risk to the fetus than radiation exposure

from a diagnostic examination.

Hepatobiliary Causes

Two hepatic complications unique to pregnancy that canpresent with acute abdominal pain are HELLP (hemolysis,

elevated liver enzymes, low platelet count) syndrome and

acute fatty liver of pregnancy (AFLP). Although pancrea-

titis is not unique to pregnancy, the approach to imaging

pregnant patients with pancreatitis differs from that of the

nonpregnant patient.

HELLP Syndrome

HELLP syndrome is a rare but serious condition that

most commonly presents in the late third trimester or early

postpartum period in association with severe preeclampsia

or eclampsia. It is estimated that up to 1028% of pre-

eclampsia pregnancies are associated with some degree ofHELLP syndrome [3]. Patients with HELLP syndrome

variably present with hemolytic anemia, thrombocytope-

nia (< 100,000/mm3), and liver function test abnormalities

(elevated lactate dehydrogenase level, > 600 U/L; elevated

bilirubin level, > 1.2 mg/dL; or elevated aspartate amino-

transferase level, > 70 U/L) [2]. The deposition of intravas-

cular brin deposits in the liver with HELLP syndrome re-

sults in various hepatic manifestations ranging from

hepatic congestion and edema to hepatic necrosis, hemor-

rhage, and rupture, which can require emergent cesarean

delivery, exploratory laparotomy, or hepatic embolization

[74]. The clinical presentation of HELLP syndrome is vari-

able and nonspecic. Patients most commonly present with

abdominal pain and nausea. Patients with severe complica-

tions of hepatic rupture and hemorrhage may present with

abdominal pain that radiates to the right upper quadrant

or right shoulder and with hypovolemic shock [3].

The main role of imaging in patients with clinically diag-

nosed HELLP syndrome is to identify the hepatic compli-

cations. Ultrasound, CT, or MRI can be used to assess the

presence and extent of hepatic injury. The selected imaging

technique will depend on availability, patient stability, and

whether the patient is postpartum. Ultrasound can show

intra- and extrahepatic hematomas and uid collections.

CT and MR examinations can further reveal the extent of

hepatic damage and can help distinguish among hepatic

edema, necrosis, and hemorrhage [74] (Fig. 11).

Acute Fatty Liver of Pregnancy

AFLP is also a rare but serious hepatic complication unique

to pregnancy that can be fatal. It is characterized by micro-

vascular fatty inltration of the liver and can result in both

hepatic and renal failure. Patients also typically present in the

late third trimester or early postpartum period with symp-

toms of abdominal pain, vomiting, and jaundice. Similar to

HELLP syndrome, management of AFLP centers on prompt

delivery and supportive care [3]. AFLP can be difcult to dif-

ferentiate from HELLP syndrome and preeclampsia or ec-

lampsia clinically. However, histologically HELLP syndrome

and AFLP can be readily differentiated because HELLP syn-

drome is characterized by periportal hemorrhage, sinusoidalbrin deposition, and occasional periportal necrosis, whereas

AFLP is characterized by microvesicular fatty inltration

with occasional necrosis and inammation [2].

Imaging with ultrasound, CT, or MRI may also help distin-

guish between HELLP syndrome and AFLP as well as depict

the extent of hepatic complications. However, in the early

stages of AFLP the liver may appear normal [75]. The imag-

ing of patients with suspected AFLP will depend on technique

availability, patient stability, and pregnancy status. Ultra-

sound is often the rst technique of choice for pregnant and

unstable patients and can reveal diffuse increased heterogene-

ity and echogenicity of the hepatic echotexture. If the patient

is postpartum, CT is often the rst imaging study of choiceand may reveal diffuse decreased hepatic attenuation. The

role of MRI for diagnosing AFLP has not been determined,

but MR examinations performed with T1-weighted dual gra-

dient-echo in-phase and out-of-phase sequences can readily

depict hepatic steatosis by showing loss of hepatic signal in-

tensity from in-phase to out-of-phase images.

Pancreatitis

Pancreatitis is a rare cause of abdominal pain during preg-

nancy, occurring in 0.11% of pregnancies and occurring most

commonly in the third trimester [3]. In pregnancy, gallstones

are the most common cause of pancreatitis because pregnancy

promotes the formation of sludge and stones within the gall-

bladder due to increased cholesterol synthesis, bile stasis, and

decreased gallbladder contraction. In addition, higher levels of

maternal estrogen in the third trimester can increase triglycer-

ide synthesis and, in some cases, can induce pancreatitis sec-

ondary to hypertriglyceridemia. Increased intraabdominal

pressure on the bile ducts in the third trimester has also been

proposed as a potential reason for the reported increased inci-

dence of pancreatitis in the third trimester [4, 76].


12/17

AJR:194, June 2010 WS25


In the nonpregnant population, contrast-enhanced CT is

usually the study of choice for evaluating complications ofpancreatitis. However, during pregnancy ultrasound can

rst be used to search for the cause and complications of

pancreatitis including choledocholithiasis and pseudocyst

formation. If ultrasound is normal or indeterminate, MRI

with multiplanar T2-weighted SSFSE and axial T1-weight-

ed sequences and MR cholangiopancreatography (MRCP)

with heavily T2-weighted sequences can be performed to

conrm the diagnosis of pancreatitis and to search for

causes and complications of pancreatitis (Fig. 12). Screen-

ing the biliary tree for possible stones with MRCP can also

help avoid or guide a more invasive ERCP procedure, thusminimizing maternal and fetal risk and exposure to ionizing

radiation [13].

Genitourinary CausesUrinary tract causes of pain during pregnancy include

physiologic and obstructive hydronephrosis and infectious

causes such as cystitis and pyelonephritis, which do not usually

require imaging for diagnosis and treatment. The incidence of

urolithiasis is not increased during pregnancy. However, the

A

C

Fig. 13Obstructive hydronephrosis in 23-year-old pregnant woman whopresented with left flank pain.A,Sagittal gray-scale ultrasound image of left kidney shows mild hydronephrosis(arrow).B,Transverse color Doppler ultrasound image through bladder shows rightureteral jet (arrow) but absence of left ureteral jet. Neither left ureteral calculusnor dilatation of left ureter was seen sonographically.C,Subsequent unenhanced CT image reveals 2-mm calculus (arrow) at leftureterovesical junction.

B


13/17

Woodfield et al.

WS26 AJR:194, June 2010

approach to imaging urolithiasis and the need to differentiate

between physiologic and obstructive hydronephrosis differs

between pregnant and nonpregnant patients.

Hydronephrosis

Obstructive hydronephrosis typically presents in the sec-

ond or third trimester and is most commonly caused by uri-

nary tract calculi [13]. Urolithiasis is reportedly detected in

1 in 90 to 1 in 3,800 pregnancies and occurs more commonly

in multipara pregnancies with equal involvement of the

right and left sides [2]. Hospitalization for pain manage-

ment is often required for pregnant patients with symptom-

atic urolithiasis, although 7080% of all obstructive calculi

will spontaneously pass with conservative management [2].

Potential complications of urolithiasis include pyelonephri-

tis and premature labor induced by renal colic with or with-

out concomitant infection.

Physiologic dilatation of the collecting system, which oc-

curs in up to 90% of pregnant patients, can mimic obstructive

hydronephrosis clinically and can delay accurate diagnosis

[2]. Physiologic hydronephrosis is usually asymptomatic, but

it can present with abdominal pain and functional ureteral

obstruction [77]. Physiologic dilatation of the renal pelvis

and ureter, the major pitfall in the assessment of urolithiasis

in pregnant patients, is due to the combination of hormone-

related relaxation of the ureters during pregnancy and ex-

trinsic compression of the ureters by the growing uterus and

engorged ovarian veins against the iliopsoas muscle [2]. It is

A

C

Fig. 14Obstructive hydronephrosis in 31-year-old pregnant woman whopresented with right flank pain.

A,Sagittal gray-scale ultrasound image of right kidney shows mild hydronephrosis(arrow). No right-sided perinephric fluid, calculus, ureteral dilatation, or ureteraljet is seen. Subsequent MR examination of abdomen and pelvis was performed1 day later to further differentiate between obstructive versus physiologic righthydronephrosis.B andC,Coronal T2-weighted single-shot fast spin-echo MR images throughabdomen illustrate moderate right perinephric fluid (arrows, B) and mild righthydroureteronephrosis (arrows, C) with abrupt termination of dilated rightureter at level of pelvic rim (arrowhead, C); these findings are suggestive ofobstructive right hydroureteronephrosis. Ureteral calculus was not visible on MRexamination. Patient subsequently passed 3-mm calculus.

B


14/17

AJR:194, June 2010 WS27


more commonly seen on the right ureter because of relative

protection of the left ureter by the sigmoid colon.

Ultrasound is usually the rst imaging technique of

choice for evaluating hydronephrosis and urolithiasis dur-

ing pregnancy with reported sensitivities for renal and ure-

teral calculi ranging between 34% and 95% [78, 79]. Ultra-

sound may directly show calculi or reveal secondary ndingsof acute obstruction such as hydronephrosis with peri-

nephric uid or an absent ureteral jet. The absence of the

ureteral jet on the suspected side of obstruction is reported

to have a sensitivity of 100% and a specicity of 91% for

the diagnosis of obstructive hydronephrosis and indicates

complete obstruction [80] (Fig. 13). However, an absent

ureteral jet has also been reported in approximately 15% of

asymptomatic pregnant women [81]. To decrease false-pos-

itive results of absent ureteral jets, patients can be imaged

in the contralateral decubitus position (i.e., left posterior

oblique to visualize the right ureteral jet) to decrease gravid

uterus mass effect on the bladder and ureter. Transvaginal

ultrasound and transverse images through the bladder canalso facilitate detection of distal ureteral calculi.

Using Doppler ultrasound, the intrarenal resistive index

(RI) can be calculated. This value may aid in differentiating

between physiologic hydronephrosis and pathologic hydro-

nephrosis because normal pregnancy does not usually affect

the intrarenal RI; an elevated RI (> 0.70) should be consid-

ered abnormal. The elevation in the RI usually occurs within

6 hours after acute obstruction of the collecting system. The

RI as a test for diagnosing obstructive hydronephrosis in

pregnancy has a reported sensitivity, specicity, and accura-

cy of 45%, 91%, and 87%, respectively. However, a differ-

ence of 0.40 or greater between the RIs of the normal kidney

and the abnormal kidney (RI) is reportedly a better indica-tion of obstruction in the kidney with the higher RI [82].

The sensitivity, specicity, and accuracy of RI for diagnos-

ing acute unilateral ureteral obstruction in pregnant women

are reported to be 95%, 100%, and 99%, respectively [82].

Ultrasound has the advantages of being portable and

noninvasive and not exposing the pregnant patient to ion-

izing radiation or IV contrast material. However, maternal

body wall acoustics, the gravid uterus, and overlying bowel

gas often limit visualization of the ureter. Therefore, a nor-

mal or indeterminate renal ultrasound examination may

require additional imaging if there is strong clinical suspi-

cion for urolithiasis.

Further imaging options may depend on the stage of ges-

tation. To limit radiation exposure to the developing fetus,

some authors have suggested a limited IV urography ex-

amination consisting of a scout lm, 10-minute lm, and

minimal number of additional lms if the patient is less

than 24 weeks gestation and a low-dose CT examination

using a low-dose renal calculus protocol if the patient is

greater than 24 weeks gestation [83]. The high sensitivity

(> 95%) and specicity (> 98%) of CT for detecting urinary

tract calculi as small as 12 mm make CT typically the rst

imaging technique of choice in nonpregnant patients and

the second imaging technique of choice in pregnant pa-

tients for diagnosing urolithiasis [13].

MR urography (MRU) with T2-weighted imaging has also

been reported to have a high sensitivity for the detection of

urinary tract dilatation and for the identication of the siteof obstruction. MRU can also help differentiate between

physiologic hydronephrosis and obstructive hydronephrosis

[84]. Features of obstructive hydronephrosis with MRI in-

clude renal enlargement, perinephric uid, and an abrupt

change in the caliber of the ureter above or below the uterus

(Fig. 14). In contrast, physiologic hydronephrosis on MRU is

characterized by gradual, smooth tapering of the mid ureter

due to extrinsic compression between the gravid uterus and

iliopsoas muscle [84] (Fig. 15). MRI is also particularly help-

ful in revealing complications of pyelonephritis. However, it

remains a useful second-line examination largely because of

its limited ability in detecting small calculi and characteriz-

ing the exact size and shape of calculi.

Vascular CausesVascular causes of abdominal pain that have a higher inci-

dence in pregnancy include venous thromboembolic disease,

gonadal vein dilatation, and splenic artery aneurysm rupture.

Venous Thromboembolic Disease

Both venous stasis and hypercoagulability place preg-

nant patients at increased risk for venous thrombosis. Ve-

nous stasis begins in the rst trimester and peaks around 36

weeks of gestation and is likely due to a combination of

progesterone-induced venodilation, pelvic venous compres-

sion by the gravid uterus, and pulsatile compression of theleft iliac vein by the right iliac artery [85]. The hypercoagu-

lable state of pregnancy results from the fact that the he-

mostatic system is progressively activated to prepare the

patient for the hemostatic challenge of delivery.

Most venous thromboembolic events occur in the lower

extremities. However, pregnant patients are also at in-

creased risk for pelvic, hepatic (Budd-Chiari syndrome),

mesenteric, and gonadal venous thrombi. Mesenteric ve-

nous thrombosis is particularly ominous because it can re-

sult in bowel infarction and because it is difcult to diag-

nose given that patients typically present with insidious

onset of poorly localized abdominal pain and nonspecic

ndings on physical examination [3]. Color Doppler ultra-

sound can diagnose hepatic thrombosis or occlusion, but

the role of ultrasound for the diagnosis of pelvic, mesen-

teric, and gonadal venous thrombosis is limited. MRI or

contrast-enhanced CT can diagnose abdominal and pelvic

venous thrombosis (Fig. 10B). In the pregnant patient, de-

pending on institution experience and MR availability, MR

venography (MRV) may be the preferred imaging test be-

cause MRV avoids the use of radiation and can be per-


15/17

Woodfield et al.

WS28 AJR:194, June 2010

formed without the use of IV contrast material. Both time-

of-ight and true FISP MR sequences can detect ow and

depict thrombus in abdominal and pelvic vessels. However,

unenhanced sequences can be limited by ow signal arti-

facts [86]. Treatment of thromboembolic disease during

pregnancy requires systemic anticoagulation therapy.

Gonadal Vein Syndrome

Enlargement of the right gonadal vein in the late second

and third trimesters of pregnancy has also been reported as

a potential cause of abdominal pain [65]. Dilatation of the

gonadal vein itself or the resulting extrinsic compression of

the ureter by the enlarged gonadal vein has been referred to

as right ovarian vein syndrome [65]. Rarely, subsequent

rupture of the dilated right ovarian vein during pregnancy

has been described [87]. Right ovarian vein dilatation is like-

ly a diagnosis of exclusion when it is the only nding on ul-

trasound, MRI, or CT to account for a pregnant patients

right-sided pain (Fig. 16).

Splenic Artery Aneurysm

Pregnancy is a major risk factor for the rupture of a splenic

artery aneurysm, particularly in the third trimester or during

labor. It has been theorized that hormonal changes during

pregnancy alter the elastic properties of the arterial wall [88].

Splenic artery aneurysms are usually asymptomatic but can

occasionally present as vague epigastric or left upper quadrant

pain. If a splenic artery aneurysm ruptures, it can be a cata-

strophic event associated with both maternal and fetal mor-

tality. Therefore, if a splenic artery aneurysm is detected inci-

dentally in a woman of child-bearing age, elective treatmentwith splenectomy, artery resection, aneurysm exclusion, or

aneurysm embolization is recommended even if the patient is

asymptomatic [3, 89]. Splenic artery aneurysms can be de-

tected on abdominal ultrasound, CT, or MRI.

References 1. Firstenberg MS, Malangoni MA. Gastrointestinal surgery during pregnancy.

Gastroenterol Clin North Am1998; 27:7388

2. Mayer IE, Hussain H. Abdominal pain in pregnancy. Gastroenterol Clin North

Fig. 15Physiologic hydronephrosis in 22-year-old pregnant woman whopresented with persistent right flank pain radiating inferiorly. Sagittal T2-weighted single-shot fast spin-echo MR image through abdomen and pelvisshows mild dilatation of right ureter with gradual, smooth tapering of distal ureter(arrow) between posterior gravid uterus and iliopsoas muscle. These findings

are consistent with physiologic hydronephrosis, which is normal finding ofpregnancy that can cause abdominal pain and can be confused with obstruct ivehydronephrosis.

Fig. 16Gonadal vein syndrome in 27-year-old pregnant woman who present edwith right-sided abdominal pain. Axial time-of-flight MR image shows patent butdilated gonadal veins, with dilatation of right ( long arrow) being greater than left(short arrow) vein. Given that no ot her reason for abdominal pain was evidenton MR examination or clinically, patients pain was attributed to dilatation of

right gonadal vein. Also note patency but compression of inferior vena cava(arrowhead) by gravid uterus.


16/17

AJR:194, June 2010 WS29


Am1998; 27:136

3. Cappell MS, Friedel D. Abdominal pain during pregnancy. Gastroenterol Clin

North Am2003; 32:158

4. Sharp HT. The acute abdomen during pregnancy. Clin Obstet Gynecol2002;

45:405413

5. Melnick DM, Wahl WL, Dalton VK. Management of general surgical prob-

lems in the pregnant patient.Am J Surg2004; 187:170180

6. Oto A, Ernst RD, Shah R, et al. Right lower quadrant pain and suspected ap-

pendicitis in pregnant women: evaluation with MR imaging: initial experience.

Radiology2005; 234:445451

7. Pedrosa I, Levine D, Eyvazzadeh AD, Siewert B, Ngo L, Rofsky NM. MR

imaging of acute appendicitis in pregnancy.Radiology2006; 238:891899

8. Birchard KR, Brown MA, Hyslop WB, Firat Z, Semelka RC. MRI of acute

abdominal and pelvic pain in pregnant patients.AJR2005; 184:452458

9. Kanal E, Barkovich AJ, Bell C, et al.; ACR Blue Ribbon Panel on MR Safety. ACR

guidance document for safe MR practices: 2007.AJR2007; 188:14471474

10. American College of Radiology Website. ACR practice guideline for imaging

pregnant or potentially pregnant adolescents and women with ionizing radia-

tion. www.acr.org/SecondaryMainMenuCategories/quality_safety/guidelines/

dx/Pregnancy.aspx. Published 2008. Accessed on February 21, 2010

11. Sudah M, Vanninen RL, Partanen K, et al. Patients with acute flank pain: com-

parison of MR urography with unenhanced helical CT. Radiology 2002;

223:98105

12. Lazarus E, Mayo-Smith WW, Mainiero MB, Spencer PK. CT in the evaluation ofnontraumatic abdominal pain in pregnant women.Radiology2007; 244:784790

13. Patel SJ, Reede DL, Katz DS, Subramaniam R, Amorosa JK. Imaging the preg-

nant patient for nonobstetric conditions: algorithms and radiation dose consid-

erations.RadioGraphics2007; 27:17051722

14. Rodesch F, Camus M, Ermans AM, Dodion J, Delange F. Adverse effect of

amniofetography on fetal thyroid function. Am J Obstet Gynecol 1976;

126:723726

15. Atwell TD, Lteif AN, Brown DL, et al. Neonatal thyroid function after admin-

istration of IV iodinated contrast agent to 21 pregnant patients. AJR 2008;

191:268271

16. American College of Radiology Website. Manual on contrast media. www.acr.

org/SecondaryMainMenuCategories/qualitysafety/contrast_manual.aspx. Pub-

lished 2008. Accessed February 22, 2010

17. Wilcox AJ, Weinberg CR, OConner JF, et al. Incidence of early loss of preg-

nancy.N Engl J Med1988; 319:189194

18. Laing FC, Frates MC, Benson CB. Ultrasound evaluation during the first tri-

mester of pregnancy. In: Callen PW, ed. Ultrasonography in obstetrics and

gynecology, 5th ed. Philadelphia, PA: Saunders, 2008:181224

19. Rowling SE, Langer JE, Coleman BG, et al. Sonography during early preg-

nancy: dependence of threshold and discriminatory values on transvaginal

transducer frequency.AJR1999; 172:983988

20. Levi CS, Lyons EA, Lindsay DJ. Early diagnosis of nonviable pregnancy with

endovaginal US.Radiology1988; 167:383385

21. Rowling SE, Coleman BG, Langer JE, et al. First-trimester US parameters of

failed pregnancy.Radiology1997; 203:211217

22. Nyberg DA, Laing FC, Filly RA. Threatened abortion: sonographic distinction

of normal and abnormal gestation sacs.Radiology1986; 158:397400

23. Doubilet PM, Benson CB. Embryonic heart rate in the early first trimester:

what rate is normal?J Ultrasound Med1995; 14:431434

24. Bree RL, Edwards M, Bhm-Velz M, Beyler S, Roberts J, Mendelson EB.

Transvaginal sonography in the evaluation of normal early pregnancy: correla-tion with HCG level.AJR1989; 153:75

25. Centers for Disease Control and Prevention (CDC). Current Trends Ectopic

Pregnancy: United States, 19901992.MMWR1995; 44:4648

26. Maymon R, Shulman A. Controversies and problems in the current manage-

ment of tubal pregnancy.Hum Reprod Update1996; 2:541551

27. Clayton HB, Schieve LA, Peterson HB, et al. Ectopic pregnancy risk with as-

sisted reproductive technology procedures. Obstet Gynecol 2006; 107:595

604

28. Fernandez H, Gervaise A. Ectopic pregnancies after infertility treatment: mod-

ern diagnosis and therapeutic strategy.Hum Reprod Update2004; 10:503513

29. Goldman GA, Fisch B, Ovadia J, Tadir Y. Heterotopic pregnancy after assisted

reproductive technologies. Obstet Gynecol Surv1992; 47:217221

30. Brown DL, Doubilet PM. Transvaginal sonography for diagnosing ectopic

pregnancy: positivity criteria and performance characteristics. J Ultrasound

Med1994; 13:259266

31. Nyberg DA, Mack LA, Jeffrey RB Jr, Laing FC. Endovaginal sonographic evalu-

ation of ectopic pregnancy: a prospective study.AJR1987; 149:11811186

32. Cacciatore B. Can the status of tubal pregnancy be predicted with transvaginal

sonography? A prospective comparison of sonographic, surgical, and serumhCG findings.Radiology1990; 177:481484

33. Nyberg DA, Hughes MP, Mack LA, Wang KY. Extrauterine findings of ectopic

pregnancy at transvaginal US: importance of echogenic fluid.Radiology1991;

178:823826

34. Jung SE, Byun JY, Lee JM, et al. MR imaging of maternal diseases in preg-

nancy.AJR2001; 177:12931300

35. Nyberg DA, Mach LA, Benedetti TJ, Cyr DR, Schuman WP. Placental abrup-

tion and placental hemorrhage: correlation of sonographic findings with fetal

outcome.Radiology1987; 164:357361

36. Nyberg DA, Cyr DR, Mack LA, Wilson DA, Shuman WP. Sonographic spec-

trum of placental abruption.AJR1987; 148:161164

37. Trop I, Levine D. Hemorrhage during pregnancy: sonography and MR imag-

ing.AJR2001; 176:607615

38. Iams JD, Goldenberg RL, Meis PJ, et al. The length of the cervix and the risk

of spontaneous premature delivery: National Institute of Child Health and Hu-man Development Maternal Fetal Medicine Unit Network.N Engl J Med1996;

334:567572

39. Hibbard JU, Tart M, Moawad AH. Cervical length at 1622 weeks gestation

and risk for preterm delivery. Obstet Gynecol2000; 96:972978

40. Murakawa H, Utumi T, Hasegawa I, Tanaka K, Fuzimori R. Evaluation of

threatened preterm delivery by transvaginal ultrasonographic measurement of

cervical length. Obstet Gynecol1993; 82:829832

41. Rooholamini SA, Au AH, Hansen GC, et al. Imaging of pregnancy-related

complications.RadioGraphics1993; 13:753770

42. Schmeler KM, Mayo-Smith WW, Peipert JF, et al. Adnexal masses in pregnancy:

surgery compared with observation. Obstet Gynecol2005; 105:10981103

43. Chang HC, Bhatt S, Dogra VS. Pearls and pitfalls in diagnosis of ovarian tor-

sion.RadioGraphics2008; 28:13551368

44. Eyvazzadeh AD, Levine D. Imaging of pelvic pain in the first trimester of preg-

nancy.Radiol Clin North Am2006; 44:863877

45. Chiang G, Levine D. Imaging of adnexal masses in pregnancy. J Ultrasound

Med2004; 23:805819

46. Bromley B, Benaccerraf B. Adnexal masses during pregnancy: accuracy of

sonographic diagnosis and outcome.J Ultrasound Med1997; 16:447452

47. Ribic-Pucelj M, Kobal B, Peternelj-Marinsek S. Surgical treatment of adnexal

masses in pregnancy: indications, surgical approach and pregnancy outcome.J

Reprod Med2007; 52:273279

48. Smorgick N, Pansky M, Feingold M, et al. The clinical characteristics and

sonographic findings of maternal ovarian torsion in pregnancy. Fertil Steril

2009; 92:19831987; Epub Nov. 5, 2008

49. Stark JE, Siegel MJ. Ovarian torsion in prepubertal and pubertal girls: sono-

graphic findings.AJR1994; 163:14791482

50. Rosado WM Jr, Trambert MA, Gosink BB, Pretorius DH. Adnexal torsion:

diagnosis by using Doppler sonography.AJR1992; 159:12511253

51. Lev-Toaff AS, Coleman BG, Arger PH, et al. Leiomyomas in pregnancy: sono-

graphic study.Radiology1987; 164:37538052. Kawakami S, Togashi K, Konishi I, et al. Red degeneration of uterine leiomy-

oma: MR appearance.J Comput Assist Tomogr1994; 18:925928

53. Tamir IL, Bongard FS, Klein SR. Acute appendicitis in the pregnant patient.

Am J Surg1990; 160:571576

54. Oto A, Srinivasan PN, Ernst RD, et al. Revisiting MRI for appendix location

during pregnancy.AJR2006; 186:883887

55. Rettenbacher T, Hollerweger A, Macheiner P, et al. Outer diameter of the ver-

miform appendix as a sign of acute appendicitis: evaluation at US. Radiology

2001; 218:757762

56. Jeffrey RB, Jain KA, Nghiem HV. Sonographic diagnosis of acute appendicitis:


17/17

Woodfield et al.

WS30 AJR:194 June 2010

interpretive pitfalls.AJR1994; 162:5559

57. Lim HK, Bae SH, Seo GS. Diagnosis of acute appendicitis in pregnant women:

value of sonography.AJR1992; 159:539542

58. Wise SW, Labuski MR, Kasales CJ, et al. Comparative assessment of CT and

sonographic techniques for appendiceal imaging.AJR2001; 176:933941

59. Johansson EP, Rydh A, Riklund KA. Ultrasound, computed tomography, and labo-

ratory findings in the diagnosis of appendicitis.Acta Radiol2007; 48:267273

60. Israel GM, Malguria N, McCarthy S, Copel J, Weinreb J. MRI vs ultrasound

for suspected appendicitis during pregnancy. J Magn Reson Imaging 2008;

28:428433

61. Poortman P, Lohle PN, Schoemaker CM, et al. Comparison of CT and sonog-

raphy in the diagnosis of acute appendicitis: a blinded prospective study. AJR

2003; 181:13551359

62. Gaitini D, Beck-Razi N, Mor-Yosef D, et al. Diagnosing acute appendicitis in

adults: accuracy of color Doppler sonography and MDCT compared with sur-

gery and clinical follow-up.AJR2008; 190:13001306

63. Mourad J, Elliott JP, Erickson L, Lisboa L. Appendicitis in pregnancy: new

information that contradicts long-held clinical beliefs. Am J Obstet Gynecol

2000; 182:10271029

64. Cobben LP, Groot I, Haans L, Blickman JG, Puylaert J. MRI for clinically

suspected appendicitis during pregnancy.AJR2004; 183:671675

65. Pedrosa I, Zeikus EA, Levine D, et al. MR imaging of acute right lower quad-

rant pain in pregnant patients and nonpregnant patients.RadioGraphics2007;

27:72175366. Raman SS, Lu DS, Kadell BM, Vodopich DJ, Sayre J, Cryer H. Accuracy of

nonfocused helical CT for the diagnosis of acute appendicitis: a 5-year review.

AJR2002; 178:13191325

67. Worlicek H, Lutz H, Heyder N, Matek W. Ultrasound findings in Crohns disease

and ulcerative colitis: a prospective study.J Clin Ultrasound1987; 15:153163

68. Haggett PJ, Moore NR, Shearman JD, Travis SP, Jewell DP, Mortensen NJ.

Pelvic and perineal complications of Crohns disease: assessment using mag-

netic resonance imaging. Gut1995; 36:407410

69. Furukawa A, Saotome T, Yamasaki M, et al. Cross-sectional imaging in Crohn

disease.RadioGraphics2004; 24:689702

70. Maccioni F, Colaiacomo MC, Parlanti S. Ulcerative colitis: value of MR imag-

ing.Abdom Imaging2005; 30:584592

71. Perdue PW, Johnson HW Jr, Stafford PW. Intestinal obstruction complicating

pregnancy.Am J Surg1992; 164:384388

72. Davis MR, Bohon CJ. Intestinal obstruction in pregnancy. Clin Obstet Gynecol

1983; 26:832842

73. Regan F, Beall DP, Bohlman ME, Khazan R, Sufi A, Schaefer DC. Fast MR im-

aging and the detection of small-bowel obstruction.AJR1998; 170:14651469

74. Nunes JO, Turner MA, Fulcher AS. Abdominal imaging features of HELLP

syndrome: a 10-year retrospective review.AJR2005; 185:12051210

75. Castro MA, Ouzounian JG, Colletti PM, Shaw KJ, Stein SM, Goodwin TM.

Radiologic studies in acute fatty liver of pregnancy: a review of the literature

and 19 new cases.J Reprod Med1996; 41:839843

76. Bzowej NH. Gastrointestinal complications of pregnancy. In: Grendell JH,

Friedman SL, McQuaid KR, eds. Current diagnosis & treatment in gastroen-

terology. New York, NY: McGraw-Hill, 2003:183185

77. Puskar D, Balagovic I, Filipovic A, et al. Symptomatic physiologic hydronephrosis in

pregnancy: incidence, complications and treatment.Eur Urol2001; 39:260263

78. Parulkar BG, Hopkins TB, Wollin MR, Howard PJ, Lal A. Renal colic during

pregnancy: a case for conservative treatment.J Urol1998; 159:365368

79. Stothers L, Lee LM. Renal colic in pregnancy. J Urol1992; 148:13831387

80. Deyoe LA, Cronan JJ, Breslaw BH, Ridlen MS. New techniques of ultrasound

and color Doppler in the prospective evaluation of acute renal obstruction: do

they replace the intravenous urogram?Abdom Imaging1995; 20:5863

81. Wachsberg RH. Unilateral absence of ureteral jets in the third trimester of preg-

nancy: pitfall in color Doppler US diagnosis of urinary obstruction.Radiology

1998; 209:279281

82. Shokeir AA, Mahran MR, Abdulmaaboud M. Renal colic in pregnant women:

role of renal resistive index. Urology2000; 55:34434783. Fielding JR, Washburn D. Imaging the pregnant patient: a uniform approach. J

Womens Imaging2005; 7:1621

84. Spencer JA, Chahal R, Kelly A, Taylor K, Eardley I, Lloyd SN. Evaluation of

painful hydronephrosis in pregnancy: magnetic resonance urographic patterns in

physiologic dilatation versus calculus obstruction.J Urol2004; 171:256260

85. Greer IA. Thrombosis in pregnancy: maternal and fetal issues.Lancet1999;

353:12581265

86. Nagayama M, Watanabe Y, Okumura A, Amoh Y, Nakashita S, Dodo Y. Fast

MR imaging in obstetrics.RadioGraphics2002; 22:563580

87. Renuka T, Dhaliwal LK, Gupta I. Hemorrhage from ruptured utero-ovarian

veins during pregnancy.Int J Gynaecol Obstet1998; 60:167168

88. Stanley JC, Fry WJ. Pathogenesis and clinical significance of splenic artery

aneurysms. Surgery1974; 76:898909

89. Parangi S, Levine D, Henry A, Isakovich N, Pories S. Surgical gastrointestinal

disorders during pregnancy.Am J Surg2007; 193:223232

F O R Y O U R I N F O R M A T I O N

The readers attention is directed to the Self-Assessment-Module for this article,

which appears on page S42.

Date post:	03-Jun-2018
Category:	Documents
Upload:	quester1515
View:	221 times
Download:	0 times

Abdominal Pain in Pregnancy Diagnoses and Imaging

Documents