Abortion

Williams Obstetrics

Chapter 9 Abortion

OBGY R1 Lee Eun Suk

Abortion

Spontaneous abortiono Pathology

o Etiology

o Fetal Factors

o Maternal Factors

o Paternal Factors

o Categories of Spontaneous Abortion

Induced abortiono History of abortion

o Indications

o Elective (Voluntary) Abortion

Presumption of ovulation after abortion

Abortion

Termination of pregnancy, either spontaneously or intentionally

Pregnancy 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 miscarriage

Pathology o Hemorrhage into the decidua basinalis, followed by necrosis of tissues adjacent to the bleeding

o If early, the ovum detaches, stimulating uterine contractions

that result in its ovulation

o Gestational sac is opened , fluid surrounding a small macerated

fetus or alternatively no fetus is visible → blighted ovum


Pathology

o In later abortion, the retained fetus may undergo maceration

The skull bones collapse, the abdomen distends with blood-

stained fluid, and the internal organs degenerate

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

o When amnionic fluid is absorbed, the fetus may become compressed and desiccated → fetal compressus

o The fetus become so dry and compressed that it resembles parchment - a fetus papyraceous


Etiology

o More than 80 percent of abortions occur in the first 12 weeks of pregnancy

o At least half result from chromosomal anomalies

o After the first trimester, both the abortion rate & the incidence of chromosomal anomalies decrease

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Etiology

o The risk of spontaneous abortion increases with parity as well as with maternal and paternal age

o The frequency of abortion increases from 12 percent in women younger than 20 years to 26 percent in those older than 40 years

o If a woman conceives within 3 months following a term birth

→ incidence of abortion ↑

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Etiology

o The exact mechanism responsible for abortion are not apparent

o 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

o 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

o Early spontaneous abortion commonly display a developmental abnormality of the zygote, embryo, early fetus, or placenta

o 1000 spontaneous abortions analyzed by Hertig and Sheldon

Half demonstrated degenerated or absent embryos, that is,

blighted ova

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Aneuploid abortion

o 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

o Jacobs and Hassold (1980)

95 percent of chromosomal abnormalities

d/t maternal gametogenesis error

5 percent → d/t paternal error

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Aneuploid abortion - Autosomal trisomy

o The most frequently identified chromosomal anomaly associated with first-trimester abortions

o 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

o Autosomes 13, 16, 18, 21, and 22 – most commom


Monosomy X

o The second frequent chromosomal abnormality

o Usually results in abortion

o Much less frequently in liveborn female infant (Turner syndrome)

Triploidy

o Associated with hydropic placental (molar) degeneration

o Incomplete (partial) hydatidiform moles may contain triploidy or trisomy for only chromosome 16


Tetraploid abortuses

o Rarely are liveborn and most often are aborted early in gestation

Chromosomal structural abnormalities

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


Euploid abortion

o Abort later in gestational than aneuploid

o Three fourths of aneuploid abortions occurred before8 weeks

o Euploid abortions peak at about 13 weeks

o The incidence of euploid abortions increased dramatically after maternal age exceeded 35 years

Spontaneous abortion – Maternal factors

Infections

o Uncommon causes of abortion in human

Listeria monocytogenes

Clamydia trachomatis

Mycoplasma hominis

Ureaplasma urealyticum

Toxoplasma gondii


Chronic debilitating diseases

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

o Celiac sprue

Cause both male and female infertility and recurrent abortions


Endocrine abnormalities

o Hypothyroidism

Iodine deficiency associated with excessive miscarriages

Thyroid autoantibodies → incidence of abortion↑

o Diabetes mellitus

The rates of spontaneous abortion & major congenital malformations

Poor glucose control → incidence of abortion↑

o Progesterone deficiency

Luteal phase defect

Insufficient progesterone secretion by the corpus luteum or placenta

Poor glucose control → incidence of abortion↑


Nutritiono Dietary deficiency of any one nutrients → not important cause

Drug use and environmental factor o Tobacco

↑ Risk for euploid abortion

More than 14 cigarettes a day → the risk twofold greater ↑

o Alcohol

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 ↑

o Caffeine

At least 5 cups of coffee per day → slightly increased risk of abortion


Drug use and environmental factor

o Radiation

In sufficient doses → abortifacient

o Contraceptives

When intrauterine devices fail to prevent pregnancy → abortion↑

o Environmental toxins

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


Immunological factors – autoimmune factorso Recurrent pregnancy loss patients : 15%

o 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


Immunological factors – autoimmune factors

o Therapy of antiphopholipid antibody syndrome

: low dose aspirin, prednisone, heparin, intravenous Ig

→ affect both immune & coagulation system

→ counteract the adverse action of antibodies


Immunological factors – alloimmune factors

o Allogeneity

Genetic dissimilarities between animals of the same species

Human fetus is allogenic transplant tolerated by mother

o Several test for diagnosis of alloimmune factors

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


Inherited thrombophiliao Many studies of aggregated thrombophilias

→ excessive recurrent abortions

Laparotomyo Surgery performed during early pregnancy

→ no evidence of tncreased abortion

o Peritonitis increases the likelihood of abortion

Physical trauma

o Major abdominal trauma → abortion↑


Uterine defects – acquired uterine defectso 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

o 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


Uterine defects – acquired uterine defects

o Diagnosis of uterine synechiae

Hysterosalpingogram → characteristic multiple filling defects

Hysteroscopy → most accurate & direct diagnosis

o Treatment of uterine synechiae

Lysis of adhesions via hysteroscopy

Prevention of adherence : IUD

Promotion of endometrial proliferation

: Continuous high-dose estrogen (60-90 days)


Uterine defects – developmental uterine defects Consequence of abnormal mullerian duct formation or fusion

Spontaneously

Induced by in utero exposure to DES (diethylstilbestrol)


o 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

Diagnosis in nonpregnant women

Hysterography

Pull-through techniques of inflated Foley catheter balloons

Acceptance without resistance at the internal os of specifically sized cervical dilators

The use of transvaginal ultrasound in pregnant women

Cervical length - shortening

Funneling


o Incompetent cervix – Etiology Previous trauma to the cervix

Dilatation & curettage

Conization

Cauterization

Abnormal cervical development Exposure to DES in utero


o 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


o 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


o Incompetent cervix – Cerclage procedures Types of operations commonly used

McDonald Modified Shirodkar

→ 85~90% success rate


o 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


o 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

o Little is known in the genesis of spontaneous abortiono Chromosomal translocations in sperm can lead to abortion

Categories of spontaneous abortion

o Threatened abortiono Inevitable abortion o Complete or incomplete abortion o Missed abortion o Recurrent abortion

Threatened abortion

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

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

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

o Prognosis Approximately ½ will abort

Risk of preterm delivery, low birthweight, perinatal death↑

Risk of malformed infant does not appear to be increased


o 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

o 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

Threatened abortion


Threatened abortion

o Treatment : slight bleeding persists for weeks Vaginal sonography

Serial serum quantitative hCG

Serum progesterone

→ can help ascertain if the fetus is alive & its location

o 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


Threatened abortion

o 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


Inevitable abortion

o 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


o Complete abortion Following complete detachment & expulsion of the conceptus

The internal cervical os closes

o 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

Complete or incomplete abortion


o 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

Missed abortion


o Definition : Three or more consecutive spontaneous abortionso Clinical investigation of recurrent miscarriage

Parental cytogenetic analysis

Lupus anticoagulant & anticardiolipin antibodies assays

o Postconceptional evaluation Serial monitoring of Я–hCG from missed mens period

Я–hCG>1500mIU/ml → USG

Maternal serum α-fetoprotein assessment (GA16-18wks)

Amniocentesis → fetal karyotype

o Prognosis Depends on potential underlying etiology & number of prior losses

Recurrent abortion


INDUCED ABORTION

o The medical or surgical termination of pregnancy before the time of fetal viability

o Therapeutic abortion Termination of pregnancy before of fetal viability for the purpose

of saving the life of the mother

Induced abortion

Induced abortion

Indication

o 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

o Pregnancy resulted from rape or incest

o Continuation of pregnancy is likely to result in the birth of child with severe physical deformities

or mental retardation

Induced abortion

Elective (voluntary) abortion

o 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

o Continued pregnancy with its risks & parental responsibilities

o Continued pregnancy with its risks & its responsibilities of arranged adoption

o The choice of abortion with its risks

Surgical techniques for abortion

Dilatation and curettage

o Performed first by dilating the cervix & evacuating the product of conception Mechanically scraping out of the contents (sharp curettage)

Vacuum aspiration (suction curettage)

Both

o Before 14 weeks, D&C or vacuum aspiration should be performed

o After 16 weeks, dilatation & evacuation (D&E) is performed Wide cervical dilatation

Mechanical destruction & evacuation of fetal parts


Dilatation and curettageo Hygroscopic dilators

: swell slowly & dilate cervix → cervical trauma can be minimized

o 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


Technique for dilatation & curettage

o Remove laminaria → Uterus is sounded carefully to

Identify the status of the internal os

Confirm uterus size & position

o Further dilation of cervix with Hegar dilator


Complications : uterine perforationo 2 important determinants

Skill of the physician

Position of the uterus (retroverted)

o Small defects by uterine sound or narrow dilator

→ often heal without complication

o Suction & sharp curettage

→ Considerable intra-abdominal damage risk↑

→ Laparotomy to examine abdominal content (safest action)

o Other complications – cervical incompetence or uterine synechiae


Menstrual aspiration

o Aspiration of endometrial cavity using a flexible cannula and syringe within 1-3 weeks after failure

to menstruate

o 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


Laparotomy

o Abdominal hysterotomy or hysterectomy

o Indications

Significant uterine disease

Failure of medical induction during the 2nd trimester

Medical induction of abortion

Early abortion

o Outpatient medical abortion is an acceptable alternative to surgical abortion in women with

pregnancies of less than 49 days’ gestation

(ACOG, 2001b)

o Three medications for early medical abortion

Antiprogestin mifeprostone

Antimetabolite methotrexate

Prostaglandin misoprostol

Medical induction of abortion _

2nd trimester abortion


Oxytocin

o Successful induction of 2nd trimester abortion is possible with high doses of oxytocin administered

in small volumes of IV fluids

o Satisfactory alternatives to PG E2 for midtrimester abortion

o Laminaria tents inserted the night before Chance of successful induction is greatly enhanced


Prostaglandins

o Used extensively to terminate pregnancies, especially in the 2nd T PG E1, E2, F2α

o 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


Intra-amnionic hyperosmotic solutionso 20-25% saline or 30-40% urea injected into amnionic sac

→ stimulate uterine contraction & cervical dilatation

o Action mechanism : prostaglandin mediated ?

o 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


Antiprogesterone RU 486o Oral agent used alone in combination with oral PG to effect abortions in early gestation

o High receptor affinity for progesterone binding site

→ Block progesterone action

o Abortion rate

Single 600mg dose prior 6 weeks → 85%

Addition of oral, vaginal or injected PG → over 95%

o If given within 72 hours

Also highly effective as emergency postcoital contraception

Progressively less effective after 72 hours

o Side effects

Nausea, vomiting, & gastrointestinal cramping

Major risk → hemorrhage is a risk if abortion is incomplete


Epostane

o 3Я-hydroxysteroid dehydrogenase inhibitor

→ blocks the synthesis of endogenous progesterone

o Frequent side effect – nausea

o Hemorrhage is a risk if abortion is incomplete

Consequences of elective abortion

Maternal mortality

o 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


Impact on future pregnancies

o Fertility : not altered by an elective abortion

o Vacuum aspiration for a first pregnancy

: Do not increase the incidence of

2nd trimester spontaneous abortions

Preterm delivery

Ectopic pregnancy

LBW infants


Impact on future pregnancies

o Dilatations & curettage for a first pregnancy

: Increased risks for

Ectopic pregnancy

2nd trimester spontaneous abortions

LBW infants

o Multiple elective abortion : Not increased the incidence of preterm delivery & LBW infants

Placenta previa

→ increased following multiple sharp curettage abortion procedures


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

o Ovulation may resume as early 2 weeks after an abortiono Therefore, if pregnancy is to be prevented,

effective contraception should be initiated soon after abortion

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Abortion