Ultrasound roundsSample Journal Club Presentation

Clinical case

31 y/o female presents to the emergency department

6 hour history of abdominal pain.

The pain was of sudden onset, has been constant, 6/10 in severity, and it is well-localized to the RLQ.  

Vital Signs:

HR 98, RR 16, 116/72, T 37.0, sats 99% on room air

Clinical Case

Hx:

She has had no urinary symptoms, no N/V, and she denies any recent febrile illness.

Her last bowel motion was earlier today and was “normal”.

She “is pretty sure” her LMP was 6 weeks ago. She denies any vaginal discharge or bleeding, and she has no known history of STI.

She is not using any contraception.

Clinical case

On examination:

She appears fairly comfortable. No acute distress.

She winces slightly when you palpate the RLQ, but there is no evidence of peritonitis. You don’t appreciate any masses.

A pelvic exam is negative for any CMT or palpable adnexal masses.

labs

Nurse informs you that the urine is beta-hCG positive

Subsequent quantitative results:

Beta-hCG 1200 mIU/mL

CBC – Hgb 121, WBC 9, plts 156

G&S – A+, Ab screen negative

What now?

Time for some ultrasound!!

Transabdominal OB EDE:

- curved array probe

- bladder full to provide optimum acoustic window

- Advantage: More convenient and improved patient comfort, easily comprehensible spatial orientation

TA OB ede 1

(1)Place the probe in the longitudinal plane in the midline, just above the pubic symphysis.

(2) Identify the bladder and juxtaposed uterus.

(3)Center the uterus by adjusting the depth, and heeling the probe cephalad or caudad.

(4)Sweep through the uterus and the endometrial stripe.

(5)Rotate the probe 90° counterclockwise and sweep through the uterus in the transverse plane.

TV OB EDE 1

Endocavitary probe, usually 5.0-7.5 MHz.

No need for acoustic windows.

Higher frequency = better axial resolution.

Use sterile gel, and avoid air bubbles in the cover tip.

TV OB EDE 1

(1) Insert the probe in the vagina in the sagittal plane.

(2) Identify the bladder.

(3) Identify the uterus and center it on the screen.

(4) Sweep through the uterus and the endometrial stripe.

(5) Rotate the probe and sweep through the uterus in the coronal plane.

OB ede 1

Criteria for confirming an IUP:

(1) Bladder-uterine juxtaposition

(2) Myometrial mantle > 5mm

(3) Decidual Reaction (strongly echogenic white lining)

(4) Gestational Sac (anechoic fluid collection within the decidual reaction)

(5) Yolk Sac within the Gestational Sac

***The conclusion drawn from this scan is binary: either IUP or NDIUP, there is no middle ground.

Clinical case (reassess)

You complete the TA + TV OB EDE on the patient.

You visualize a full bladder with good vesico-uterine juxtaposition.

You visualize the uterus, including the endometrial stripe, in all of the pertinent views.

There is no identifiable decidual reaction, no gestational sac, and no evidence any yolk sac.

You document NDIUP in the patient’s chart.

Practice points

Is our patient appropriate for an urgent surgical/OB consult?

Does the magnitude of the quantitative beta-hCG level help us with our diagnosis? Does it influence our management plan?

literature

Doubilet, Peter et al.

Further Evidence Against the Reliability of the Human Chorionic Gonadotropin Discriminatory Level

Where: Brigham and Women’s Hospital, USA

When: January 1, 2000 through December 31, 2010

What: retrospective analysis reviewed charts from women who had been found to have a positive Beta with a NDIUP sought correlations between beta-levels and subsequent pregnancy outcomes.

subjects

PATIENTS: women who met the following criteria…

(1) Serum β-hCG testing and transvaginal sonography were performed on the same day;

(2) β-hCG was positive and sonography showed no intrauterine fluid collection;

(3) a live intrauterine pregnancy was subsequently documented on a follow-up sonogram showing embryonic or fetal cardiac activity.

Scans – 1st TM

First-trimester outcomes:

(1) “live” if there was either a live birth or a second- or third-trimester scan showing cardiac activity.

(2) “demise” if there was a first-trimester scan showing spontaneous demise or a note in the medical record documenting a miscarriage.

(3) “uncertain” if neither of these criteria were met.

Term outcomes

Final pregnancy outcomes:

(1)“liveborn” if a live baby was delivered after 25 weeks’ gestation

(2) “demise” if there was a spontaneous pregnancy loss at any gestational age

(3) “uncertain” if neither of these criteria were met.

results

202 patients met the inclusion criteria:

162 had β-hCG levels below 1000 mIU/mL

19 had levels of 1000 to 1499 mIU/mL

12 had levels of 1500 to 1999 mIU/mL

9 had levels > 2000 mIU/mL.

results

First-trimester:

174 (89.7%) of the women had a live pregnancy at the end of the 1st trimester

18 (10.3%) had a spontaneous 1st-trimester pregnancy loss

Term Outcomes:

Of 158 cases with known final pregnancy outcomes, 135 (85.4%) were live born.

Conclusions??

Take home message:

There was no significant relationship between initial β-hCG level and either first-trimester outcome or final pregnancy outcome (p> .05)

Interesting findings:

The highest β-hCG was 6567 mIU/mL, and the highest value that preceded a liveborn term baby was 4336 mIU/mL.

Discussion

“discriminatory zone”

Term coined by Kadar et al. in 1981

Seminal paper assessing the visibility of a normal intrauterine pregnancy on sonography in relation to the hCG level

TA OB scans only

No normal IUP visualized with levels <6000

They concluded that “absence of a gestational sac above this level signifies ectopic pregnancy”

discussion

“discriminatory zone” since decreased with improved U/S resolution

Since Kadar’s paper, many hospitals in the U.S. began to employ protocols based on these thresholds

This paper sought to debunk this practice

Critical appraisal

Evidence of selection bias?

Sampling bias – inherent given the inclusion criteria

Study design was retrospective and non-randomized

Participant attrition

Unclear prevalence given unknown total population from which the study sample was obtained.

Critical appraisal

Who was performing the scans?

Scans were generally performed by a sonographer and interpreted by a sonologist who subspecializes in sonography or emergency radiology

Sonologist was most often in the scanning room for at least part of the transvaginal examination

For all cases stored images and video clips were reviewed by the sonologist

Proficiency/competency not objectively disclosed/tested

Critical appraisal

How were the scans performed?

Both transabdominal and transvaginal imaging performed, the latter using broadband transducers with frequencies of 5-9 MHz

Images and video clips of the entire uterus and both adnexal regions were stored

Largely meeting standard of care

Lacks detail re: prep/views and IUP criteria used

Critical appraisal

Indeterminates?

These were OB scans so only IUP vs NDIUP

Study selected NDIUPs only in patient’s with β-hCG < than or > than the apparent “discriminatory zone” of 1000-2000

Definition of NDIUP “no intrauterine fluid collection”

Unclear how many 1st trimester scans in total were performed during the study period or how many were confirmed IUPs – NO DENOMINATOR

Critical appraisal

Quality assurance process?

No formal QA process documented, although…For cases with β-hCG > 2000 mIU/mL stored images and clips were reviewed to assess the quality of the scan and determine whether the endometrium had been well seen

Of the 9 patients with β- hCG > 2000 mIU/mL…All scans were “adequate and complete”, and none had fibroids or other anatomic features that interfered with visualization of the endometrium

Criteria for determining a “adequate” or “complete” scan was not explicitly defined

Critical appraisal

What was the gold standard?

For 1st trimester scans: follow-up imaging (either repeat 1st or 2nd/3rd trimester scans) documenting fetal cardiac activity/miscarriage in medical records

For final pregnancy outcomes: birth records or medical records documenting spontaneous loss at any gestational age

Relationship between initial β- hCG level and 1st trimester and final pregnancy outcomes assessed using the Fisher exact test and logistic regression

**Unclear if laparoscopies performed to rule out ectopics

Critical appraisal

Blinding?

No intentional blinding of sonographers to the patients’ examination or with regards to the gold standard

Follow-up?

Not formalized – observational study only

28 of the study cases “uncertain” 1st trimester outcome

Of the remaining 174: 156 (89.7%) alive at the end of 1st trimester, and 18 (10.3%) had a spontaneous 1st trimester pregnancy loss

Critical appraisal

Limitations?

Observational study only

Lack of statistical rigor in design/methods

EDE definition of IUP vs NDIUP not utilized

Wide threshold for “discriminatory zone” with small sample sizes in higher β-hCG subgroups (>1000) – poorly powered

Patients were asymptomatic

Practice differences between Canada and U.S. with regards to management/policies

Critical appraisal

What could have been done differently?....

Attempt a prospective study with formalized follow-up scans

Ensure standardized methods of scanning/QA protocols, and documentation of gold standards, GA

Characterize the “denominator” to assess for prevalence of missed early IUPs givenβ-hCG above the “discriminatory zone” with an empty uterus on initial scan

Perform analysis on individual subgroups

Recruit larger sample sizes

Critical appraisal

Will this impact our practice?

Less likely to manage as an ectopic empirically given a discrete β-hCG value above the “discriminatory zone” within the 1st trimester and no intrauterine collection on formal TVUS as many can progress to live birth

References

1. Doubilet PM, Benson CB. Further evidence against the reliability of the human chorionic gonadotropin discriminatory level. J Ultrasound Med 2011; 30:1637–1642.

2. Gilovich T. Too much from too little: the misinterpretation of incomplete and unrepresentative data. In: How We Know What Isn’t So: The Fallibility of Human Reason in Everyday Life. New York, NY: The Free Press; 1991:29–48.

3. Kadar N, Bohrer M, Kemman E, Shelden R. The discriminatory hCG zone for endovaginal sonography: a prospective, randomized study. Fertil Steril 1994; 61:1016–1020.

4. Kadar N, DeVore G, Romero R. Discriminatory hCG zone: its use in the sonographic evaluation for ectopic pregnancy. Obstet Gynecol 1981; 58:156–161.