Williams Obstetrics

Chapter 9 Abortion

OBGY R1 Lee Eun Suk

Abortion

Spontaneous abortion

Pathology Etiology Fetal Factors Maternal Factors Paternal Factors Categories of Spontaneous Abortion History of abortion Indications Elective (Voluntary) Abortion

Induced abortion

Presumption of ovulation after abortion

Abortion

Termination of pregnancy, either spontaneously or intentionallyPregnancy termination prior to 20 weeks gestation or less than 500-g birthweight Definition vary according to state laws for reporting abortions, fetal deaths, and neonatal deaths

Spontaneous abortion

Abortion occurring without medical or mechanical means to empty the uterus is referred to as spontaneous Another widely used term is miscarriagePathology

Hemorrhage into the decidua basinalis, followed by necrosis of tissues adjacent to the bleeding If early, the ovum detaches, stimulating uterine contractions that result in its ovulation Gestational sac is opened , fluid surrounding a small macerated fetus or alternatively no fetus is visible blighted ovum

Spontaneous abortion

Pathology

In later abortion, the retained fetus may undergo maceration

The skull bones collapse, the abdomen distends with bloodstained fluid, and the internal organs degenerate

The skin softens and peels off in utero or at the slightest tough

When amnionic fluid is absorbed, the fetus may become compressed and desiccated fetal compressus The fetus become so dry and compressed that it resembles parchment - a fetus papyraceous

Spontaneous abortion

Etiology

More than 80 percent of abortions occur in the first 12 weeks of pregnancy At least half result from chromosomal anomalies After the first trimester, both the abortion rate & the incidence of chromosomal anomalies decrease

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Spontaneous abortion

Etiology

The risk of spontaneous abortion increases with parity as well as with maternal and paternal age The frequency of abortion increases from 12 percent in women younger than 20 years to 26 percent in those older than 40 years If a woman conceives within 3 months following a term birth incidence of abortion

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Spontaneous abortion

Etiology

The exact mechanism responsible for abortion are not apparent In the first 3 months of pregnancy

Death of the embryo or fetus nearly always precedes spontaneous expulsion of the ovum Finding of the cause of early abortion involves ascertaining the cause of fetal death

In subsequent months

The fetus frequently does not die before expulsion

Other explanations for its expulsion should be sought

Spontaneous abortion - Fetal factors

Abnormal zygotic development

Early spontaneous abortion commonly display a developmental abnormality of the zygote, embryo, early fetus, or placenta 1000 spontaneous abortions analyzed by Hertig and Sheldon

Half demonstrated degenerated or absent embryos, that is, blighted ova

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Spontaneous abortion - Fetal factors

Aneuploid abortion

Approximately 50 to 60 percent of embryos and early fetuses that are spontaneously aborted contain chromosomal abnor-malities accounting for most of early pregnancy wastage Jacobs and Hassold (1980)

95 percent of chromosomal abnormalities

d/t maternal gametogenesis error

5 percent d/t paternal error

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Spontaneous abortion - Fetal factors

Aneuploid abortion - Autosomal trisomy

The most frequently identified chromosomal anomaly associated with first-trimester abortions Most trisomies result from isolated nondisjunction , balanced structural chromosomal rearrangements are present in one partner in 2 to 4 percent of couples with a history of recurrent abortions Autosomes 13, 16, 18, 21, and 22 most commom

Spontaneous abortion - Fetal factors

Monosomy X

The second frequent chromosomal abnormality Usually results in abortion Much less frequently in liveborn female infant (Turner syndrome)

Triploidy

Associated with hydropic placental (molar) degeneration Incomplete (partial) hydatidiform moles may contain triploidy or trisomy for only chromosome 16

Spontaneous abortion - Fetal factors

Tetraploid abortuses

Rarely are liveborn and most often are aborted early in gestation

Chromosomal structural abnormalities

Identified only since the development of banding techniques, infrequently cause abortion

Spontaneous abortion - Fetal factors

Euploid abortion

Abort later in gestational than aneuploid Three fourths of aneuploid abortions occurred before8 weeks Euploid abortions peak at about 13 weeks The incidence of euploid abortions increased dramatically after maternal age exceeded 35 years

Spontaneous abortion Maternal factors

Infections

Uncommon causes of abortion in human

Listeria monocytogenes Clamydia trachomatis Mycoplasma hominis Ureaplasma urealyticum Toxoplasma gondii

Spontaneous abortion Maternal factors

Chronic debilitating diseases

In early pregnancy, fetuses seldom abort secondary to chronic wasting disease such as tuberculosis or carcinomatosis Celiac sprue

Cause both male and female infertility and recurrent abortions

Spontaneous abortion Maternal factors

Endocrine abnormalities

Hypothyroidism

Iodine deficiency associated with excessive miscarriages Thyroid autoantibodies incidence of abortion

Diabetes mellitus

The rates of spontaneous abortion & major congenital malformations Poor glucose control incidence of abortion

Progesterone deficiency

Luteal phase defect Insufficient progesterone secretion by the corpus luteum or placenta Poor glucose control incidence of abortion

Spontaneous abortion Maternal factors

Nutrition

Dietary deficiency of any one nutrients not important cause

Drug use and environmental factor

Tobacco

Risk for euploid abortion More than 14 cigarettes a day the risk twofold greater Spontaneous abortion & fetal anomalies result from frequent alcohol use during the first 8 weeks of pregnancy Drinking twice a week abortion rates doubled Drinking daily abortion rates tripled At least 5 cups of coffee per day slightly increased risk of abortion

Alcohol

Caffeine

Spontaneous abortion Maternal factors

Drug use and environmental factor

Radiation

In sufficient doses abortifacient When intrauterine devices fail to prevent pregnancy abortion Anesthetic gases : exact fetal risk of chronic maternal exposure is unknown Arsenic, lead, formaldehyde, benzene, ethylene oxide abortifacient Video display terminal & accompanying electromagnetic fields short waves & ultrasound do not increase the risk of abortion

Contraceptives

Environmental toxins

Spontaneous abortion Maternal factors

Immunological factors autoimmune factors

Recurrent pregnancy loss patients : 15% Antiphospholipid antibody : most significant

LCA (lupus anticoagulant), ACA (anticardiolipin Ab) Reduce prostacyclin production facilitating thromboxane dominant milieu thrombosis Prostacyclin : produced by vascular endothelial cell potent vasodilator & inhibit platelet aggregation Thromboxane A2 : produced by platelets vasoconstrictor & platelet aggregator Strong association with

Decidual vasculopathy , placental infarction, fetal growth restriction Early-onset preeclampsia, recurrent abortion, fetal death

Spontaneous abortion Maternal factors

Immunological factors autoimmune factors

Therapy of antiphopholipid antibody syndrome : low dose aspirin, prednisone, heparin, intravenous Ig affect both immune & coagulation system counteract the adverse action of antibodies

Spontaneous abortion Maternal factors

Immunological factors alloimmune factors

Allogeneity

Genetic dissimilarities between animals of the same species Human fetus is allogenic transplant tolerated by mother Maternal & paternal HLA comparison Maternal serum test for blocking antibodies : blocking antibodies to paternal antigens : ig G origin Maternal serum test for antipaternal antibodies : cytotoxic antibodies to paternal leukocyte

Several test for diagnosis of alloimmune factors

Spontaneous abortion Maternal factors

Inherited thrombophilia

Many studies of aggregated thrombophilias excessive recurrent abortions

Laparotomy

Surgery performed during early pregnancy no evidence of tncreased abortion Peritonitis increases the likelihood of abortion

Physical trauma

Major abdominal trauma abortion

Spontaneous abortion Maternal factors

Uterine defects acquired uterine defects

Uterine leiomyoma : usually do not cause abortion

Placental implantation over or in contact with myoma placental abruption, abortion, preterm labor location is more important than size

Uterine synechiae (Asherman syndrome)

Partial or complete obliteration of the uterine cavity by adherence of uterine wall Cause : destruction of large areas of endometrium by curettage insufficient endometrium to support implantation & menstruation recurrent abortion, amenorrhea, hypomenorrhea

Spontaneous abortion Maternal factors

Uterine defects acquired uterine defects

Diagnosis of uterine synechiae

Hysterosalpingogram characteristic multiple filling defects Hysteroscopy most accurate & direct diagnosis

Treatment of uterine synechiae

Lysis of adhesions via hysteroscopy Prevention of adherence : IUD Promotion of endometrial proliferation : Continuous high-dose estrogen (60-90 days)

Spontaneous abortion Maternal factors

Uterine defects developmental uterine defects

Consequence of abnormal mullerian duct formation or fusion

Spontaneously Induced by in utero exposure to DES (diethylstilbestrol)

Spontaneous abortion Maternal factors

Incompetent cervix

Painless dilatation of cervix in the 2nd or early in the 3rd trimester prolapse & ballooning of membranes into vagina rupture of membrane & expulsion of immature fetus

Unless effectively treated, tends to repeat in each pregnancy Hysterography Pull-through techniques of inflated Foley catheter balloons Acceptance without resistance at the internal os of specifically sized cervical dilators Cervical length - shortening Funneling

Diagnosis in nonpregnant women

The use of transvaginal ultrasound in pregnant women

Spontaneous abortion Maternal factors

Incompetent cervix Etiology

Previous trauma to the cervix

Dilatation & curettage Conization Cauterization

Abnormal cervical development

Exposure to DES in utero

Spontaneous abortion Maternal factors

Incompetent cervix Treatment

The operation is performed to surgically

Reinforcement of weak cervix by some type of purse string suture ( Cerclage )

Prophylactic surgery : generally performed between 12 & 16weeks

Should be delayed until after 14 weeks gestation Early abortion due to other factors will be completed

The more advanced the pregnancy, the more likely the risk that surgical intervention stimulate preterm labor or membrane rupture

Usually do not perform after about 23 weeks

Spontaneous abortion Maternal factors

Incompetent cervix Preoperative evaluation

Sonography : Confirm living fetus & exclude major fetal anomalies Cervical cytology Cultures for gonorrhea, chlamydia, group B streptococci

Obvious cervical infections treatment is given For at least a week before & after surgery sexual intercourse should be restricted

Spontaneous abortion Maternal factors

Incompetent cervix Cerclage procedures

Types of operations commonly used

McDonald Modified Shirodkar 85~90% success rate

Spontaneous abortion Maternal factors

Incompetent cervix Transabdominal cerclage

Requries laparotomy for

Placement of cerclage at uterine isthmus level Cerclage removal, delivery, or both

Indications

Anatomical defects of cervix Failed transvaginal cerclage

Spontaneous abortion Maternal factors

Incompetent cervix Complications

High incidence when performed much after 20 weeks

Membranes ruptures Chorioamnionitis Intrauterine infection

Urgent removal of suture

Operation fails Signs of imminent abortion or delivery

Spontaneous abortion Paternal factors

Little is known in the genesis of spontaneous abortionChromosomal translocations in sperm can lead to abortion

Categories of spontaneous abortion

Threatened abortionInevitable abortion

Complete or incomplete abortionMissed abortion

Recurrent abortion

Categories of spontaneous abortion

Threatened abortion

Definition

Any bloody vaginal discharge or bleeding during 1st half of pregnancy

Bleeding is frequently slight, but may persist for days or weeks

Frequency

Extremely common (one out of four or five pregnant women)

Prognosis

Approximately will abort Risk of preterm delivery, low birthweight, perinatal death Risk of malformed infant does not appear to be increased

Categories of spontaneous abortion

Threatened abortion

Symptoms

Usually bleeding begins first Cramping abdominal pain follows a few hours to several days later Presence of bleeding & pain Poor prognosis for pregnancy continuation

Treatment

Bed rest & acetaminophen-based analgesia Progesterone (IM) or synthetic progestational agent (PO or IM)

Lack of evidence of effectiveness Often results in no more than a missed abortion

D-negative women with threatened abortion

Probably should receive anti-D immunoglobulin

Categories of spontaneous abortion

Threatened abortion

Treatment : slight bleeding persists for weeks

Vaginal sonography Serial serum quantitative hCG Serum progesterone can help ascertain if the fetus is alive & its location

Vaginal sonography

Gestational sac(+) & hCG < 1000mIU/ml gestation is not likely to survive If any doubt(+), check the serum hCG level at intervals of 48hrs if not increase more than 65%, almost always hopeless

Serum progesterone value < 5 ng/ml dead conceptus

Categories of spontaneous abortion

Threatened abortion

Treatment : after death of conceptus

Uterus should be emptied examination of all passed tissue whether the abortion is complete

Ectopic pregnancy should be considered if gestational sac or fetus are not identified

Categories of spontaneous abortion

Inevitable abortion

Gross rupture of membrane,evidenced by leaking amnionic fluid, in the presence of cervical dilatation, but no tissue passed during 1st half of pregnancy

Placenta (in whole or in part) is retained in the uterus Uterine contractions begin promptly or infection develops The gush of fluid is accompanied by bleeding, pain, or fever, abortion should be considered inevitable

Categories of spontaneous abortion

Complete or incomplete abortion

Complete abortion

Following complete detachment & expulsion of the conceptus The internal cervical os closes

Incomplete abortion

Expulsion of some but not all of the products of conception during 1st half of pregnancy The internal cervical os remains open & allows passage of blood The fetus & placenta may remain entirely in utero or may partially extrude through the dilated os Remove retained tissue without delay

Categories of spontaneous abortion

Missed abortion

Retention of dead products of conception in utero for several weeks

Many women have no symptoms except persistent amenorrhea Uterus remain stationary in size, but mammary changes usually regress uterus become smaller

Most terminates spontaneously Serious coagulation defect occasionally develop after prolonged retention of fetus

Categories of spontaneous abortion

Recurrent abortion

Definition : Three or more consecutive spontaneous abortionsClinical investigation of recurrent miscarriage

Parental cytogenetic analysis Lupus anticoagulant & anticardiolipin antibodies assays Serial monitoring of hCG from missed mens period

Postconceptional evaluation

hCG>1500mIU/ml USG

Maternal serum -fetoprotein assessment (GA16-18wks) Amniocentesis fetal karyotype Depends on potential underlying etiology & number of prior losses

Prognosis

INDUCED ABORTION

Induced abortion

The medical or surgical termination of pregnancy before the time of fetal viabilityTherapeutic abortion

Termination of pregnancy before of fetal viability for the purpose of saving the life of the mother

Induced abortion

Indication

Continuation of pregnancy may threaten the life of women or seriously impair her health

Persistent heart disease after cardiac decompensation Advanced hypertensive vascular disease Invasive carcinoma of the cervix

Pregnancy resulted from rape or incest Continuation of pregnancy is likely to result in the birth of child with severe physical deformities or mental retardation

Induced abortion

Elective (voluntary) abortion

Interruption of pregnancy before viability at the request of the women, but not for reasons of impaired maternal health or fetal disease

Counseling before elective abortion

Continued pregnancy with its risks & parental responsibilities Continued pregnancy with its risks & its responsibilities of arranged adoption The choice of abortion with its risks

Surgical techniques for abortion

Dilatation and curettage

Performed first by dilating the cervix & evacuating the product of conception

Mechanically scraping out of the contents (sharp curettage) Vacuum aspiration (suction curettage) Both

Before 14 weeks, D&C or vacuum aspiration should be performed After 16 weeks, dilatation & evacuation (D&E) is performed

Wide cervical dilatation Mechanical destruction & evacuation of fetal parts

Surgical techniques for abortion

Dilatation and curettage

Hygroscopic dilators : swell slowly & dilate cervix cervical trauma can be minimized Laminaria tents : stem of brown seaweed ( Laminaria digitata or japonica) drawing water from proteoglycan complexes of cervix dissociation allow the cervix to soften & dilate

Insertion technique : tip rests just at the level of internal os Usually after 4-6hours, laminaria dilate the cervix sufficiently to allow easier mechanical dilation & curettage May cause cramping pain easily managed with 60 mg codeine every 3-4 hours

Surgical techniques for abortion

Technique for dilatation & curettage

Remove laminaria Uterus is sounded carefully to

Identify the status of the internal os Confirm uterus size & position

Further dilation of cervix with Hegar dilator

Surgical techniques for abortion

Complications : uterine perforation

2 important determinants

Skill of the physician Position of the uterus (retroverted)

Small defects by uterine sound or narrow dilator often heal without complication Suction & sharp curettage Considerable intra-abdominal damage risk Laparotomy to examine abdominal content (safest action)Other complications cervical incompetence or uterine synechiae

Surgical techniques for abortion

Menstrual aspiration

Aspiration of endometrial cavity using a flexible cannula and syringe within 1-3 weeks after failure to menstruate Several points at early stage of gestation

Woman not being pregnant Implanted zygote may be missed by the curette Failure to recognize an ectopic pregnancy Infrequently, a uterus can be perforated

Surgical techniques for abortion

Laparotomy

Abdominal hysterotomy or hysterectomy Indications

Significant uterine disease Failure of medical induction during the 2nd trimester

Medical induction of abortion

Early abortion

Outpatient medical abortion is an acceptable alternative to surgical abortion in women with pregnancies of less than 49 days gestation (ACOG, 2001b) Three medications for early medical abortion Antiprogestin mifeprostone Antimetabolite methotrexate Prostaglandin misoprostol

Medical induction of abortion _

2nd trimester abortion

Medical induction of abortion

Oxytocin

Successful induction of 2nd trimester abortion is possible with high doses of oxytocin administered in small volumes of IV fluids Satisfactory alternatives to PG E2 for midtrimester abortion Laminaria tents inserted the night before

Chance of successful induction is greatly enhanced

Medical induction of abortion

Prostaglandins

Used extensively to terminate pregnancies, especially in the 2nd T

PG E1, E2, F2

Technique : Can act effectively on the cervix & uterus (86~95% effectiveness)

Vaginal prostaglandin E2 suppository & prostaglandin E1 (misoprostol) As a gel through a catheter into the cervical canal & lowermost uterus Injection into the amnionic sac by amniocentesis Parenteral injection Oral ingestion

Medical induction of abortion

Intra-amnionic hyperosmotic solutions

20-25% saline or 30-40% urea injected into amnionic sac stimulate uterine contraction & cervical dilatation Action mechanism : prostaglandin mediated ? Complications of hypertonic saline

Death Hyperosmolar crisis (early into maternal circulation) Cardiac failure Septic shock Peritonitis Hemorrhage DIC Water intoxication

Hyperosmotic urea : less likely to be toxic

Medical induction of abortion

Antiprogesterone RU 486

Oral agent used alone in combination with oral PG to effect abortions in early gestation High receptor affinity for progesterone binding site Block progesterone action Abortion rate

Single 600mg dose prior 6 weeks 85% Addition of oral, vaginal or injected PG over 95% Also highly effective as emergency postcoital contraception Progressively less effective after 72 hours Nausea, vomiting, & gastrointestinal cramping Major risk hemorrhage is a risk if abortion is incomplete

If given within 72 hours

Side effects

Medical induction of abortion

Epostane

3-hydroxysteroid dehydrogenase inhibitor blocks the synthesis of endogenous progesterone Frequent side effect nausea Hemorrhage is a risk if abortion is incomplete

Consequences of elective abortion

Maternal mortality

Legally induced abortion

Relative safe during the first 2 months of pregnancy ( 0.6/100,000 procedures) Doubled for each 2 weeks of delay after 8 weeks gestation

Consequences of elective abortion

Impact on future pregnancies

Fertility : not altered by an elective abortion

Vacuum aspiration for a first pregnancy : Do not increase the incidence of 2nd trimester spontaneous abortions Preterm delivery Ectopic pregnancy LBW infants

Consequences of elective abortion

Impact on future pregnancies

Dilatations & curettage for a first pregnancy : Increased risks for

Ectopic pregnancy 2nd trimester spontaneous abortions LBW infants

Multiple elective abortion :

Not increased the incidence of preterm delivery & LBW infants Placenta previa increased following multiple sharp curettage abortion procedures

Consequences of elective abortion

Septic abortion

Most often associated with criminal abortion Metritis is usual outcome, but parametritis, peritonitis, endocarditis, and septicemia may all occur Management

Prompt evacuation of products of conception Broad-spectrum IV antimicrobials

Resumption of ovulation after abortion

Ovulation may resume as early 2 weeks after an abortionTherefore, if pregnancy is to be prevented, effective contraception should be initiated soon after abortion