EARLY PREGNANCY COMPLICATIONSSPONTANEOUS ABORTION potx

295

SPONTANEOUS ABORTION

Spontaneous abortion (miscarriage) is the termination of pregnancy

before completion of the 20th gestational week. The term applies to

both live and stillborn fetuses weighing 500 g. However, a fetus

need not be identified if other products of conception are present

(e.g., placenta or membranes). Familiarity with the local legal def￾inition is mandatory because there is considerable state to state

variation.

Loss of pregnancy is very common. Recent estimates are that

only 62.5% of pregnancies result in live births, 21.9% end in legal

abortions, 13.8% have spontaneous abortions, 1.3% are ectopic ges￾tations, and 0.5% end in fetal deaths. Other estimates place spon￾taneous abortion at 15%–40%. The earlier in gestation, the more

likely is spontaneous abortion. About 75% occur before 16 weeks,

and approximately 60% occur before 12 weeks. A major difficulty

in detailing exact numbers is the variability of methods for preg￾nancy diagnosis. For example, a serum beta-subunit hCG determi￾nation will detect very early pregnancies (and thus more losses) than

the available standard urine pregnancy tests. At least 80% of all

pregnancies terminate spontaneously before the woman or physi￾cian is aware of the pregnancy (subclinical or undiagnosed spon￾taneous abortion). Table 10-1 estimates the losses with in vitro fer￾tilization (which would be included in the subclinical category).

Mortality is rare (0.7 per 100,000) with spontaneous abortion,

but risk factors include: women age
35 years, races other than

white, and abortion in the second trimester. Direct causes of deaths

include: infection (
59%), hemorrhage (18%), embolism (13%),

complications from anesthesia (5%), and other (5%). Disseminated

intravascular coagulation complicates many of the cases proceed￾ing to death.

10

EARLY PREGNANCY

COMPLICATIONS

CHAPTER

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BENSON & PERNOLL’S

296 HANDBOOK OF OBSTETRICS AND GYNECOLOGY

ABORTION DEFINITIONS

Many different variables apply to abortion, and a number of defi￾nitions are required. It is assumed that all definitions refer to spon￾taneous abortion, if not otherwise specified.

Early abortion occurs 12th gestational week.

Late abortion occurs between 12 and 20 weeks gestation.

Threatened abortion refers to intrauterine bleeding 20th week

of completed gestation, with or without uterine contraction, without

cervical dilatation, and without expulsion of the products of con￾ception (POC). Moreover, ultrasound must reveal the fetus to show

signs of life (e.g., heartbeat or motion). In threatened abortion, the

previable gestation is in jeopardy, but the pregnancy continues.

Inevitable abortion is intrauterine bleeding before the 20th

completed gestational week, with continued cervical dilatation but

without expulsion of the POC. In inevitable abortion, momentary

evacuation of part or all of the conceptus is likely. Abortion is con￾sidered inevitable with two or more of the following:

● Moderate effacement of the cervix ● Cervical dilatation
3 cm ● Rupture of the membranes ● Bleeding for
7 days ● Persistence of cramps despite narcotic analgesics ● Signs of termination of pregnancy (e.g., absent mastalgia)

Incomplete abortion is the expulsion of some but not all of the

POC 20th completed gestational week.

Complete abortion is expulsion of all the POC 20th completed

gestational week. When the entire conceptus has been expelled, pain

ceases, but slight spotting persists for a few days.

TABLE 10-1

IN VITRO FERTILIZATION LOSSES

● 16% of fertilized ova do not divide ● 15% of fertilized ova are lost before implantation (first

gestational week) ● 27% are lost during implantation (second gestational

week) ● 10.5% are lost following the first missed menses ● Total loss is 68.5%

Missed abortion is death of the embryo or fetus 20th com￾pleted gestational week, but the POC are retained in utero for 8

weeks. Symptoms of pregnancy disappear, and there may be a

brownish vaginal discharge but no free bleeding. Pain and tender￾ness are absent, the cervix is semifirm and closed or only slightly

patulous, the uterus becomes smaller and irregularly softened, and

the adnexa are normal. Fetal death at 18–26 weeks followed by

missed labor and retention for
6 weeks may be associated with

maternal fibrinogen depletion (dead fetus syndrome). Consider ad￾ministration of cryoprecipitate to prevent hemorrhage from hy￾pofibrinogenemia before evacuation of the uterus (Fig. 10-1).

CHAPTER 10

EARLY PREGNANCY COMPLICATIONS 297

FIGURE 10-1. Top. Complete abortion. At right, product of complete abor￾tion. Bottom. Incomplete abortion. At right, product of incomplete abortion.