Abortion

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Chapter 7 Abortion

INTRODUCTION

Description: Abortion is the loss or failure of early pregnancy in several forms: complete, incomplete, inevitable, missed, septic, and threatened. A complete abortion is the termination of a pregnancy before the age of viability, typically defined as occurring at less than 20 weeks from the first day of the last normal menstrual period or involving a fetus of weight less than 500 g. Most complete abortions generally occur before 6 weeks or after 14 weeks of gestation. An incomplete abortion is the spontaneous passage of some, but not all, of the products of conception, associated with uniform pregnancy loss. A pregnancy in which rupture of the membranes and/or cervical dilation takes place during the first half of pregnancy is labeled an inevitable abortion. Uterine contractions typically follow, ending in spontaneous loss of the pregnancy for most patients. A missed abortion is the retention of a failed intrauterine pregnancy for an extended period; however, with ultrasound studies, this can often be detected significantly sooner than it could be on clinical grounds alone. A septic abortion is a variant of an incomplete abortion in which infection of the uterus and its contents has occurred. A threatened abortion is a pregnancy that is at risk for some reason. Most often, this applies to any pregnancy in which vaginal bleeding or uterine cramping takes place but no cervical changes have occurred.
Prevalence: Estimates for the frequency of complete abortions are as high as 50% to 60% of all conceptions and between 10% and 15% of known pregnancies. Of pregnant women hospitalized for bleeding, 60% have an incomplete abortion. Less than 2% of fetal losses are missed abortions. Septic abortions occur in 0.4 to 0.6 of 100,000 spontaneous pregnancy losses. Threatened abortions occur in 30% to 40% of pregnant women.
Predominant Age: Reproductive.
Genetics: Some chromosomal abnormalities are associated with reduced or absent fertility and increased risk of fetal loss (e.g., translocations).

ETIOLOGY AND PATHOGENESIS

Causes: Endocrine abnormalities (25% to 50%)—hyperandrogenism, in utero diethylstilbestrol (DES) exposure, luteal phase defect, thyroid disease. Genetic factors (10% to 70%)—balanced translocation/carrier state, nondisjunction, trisomy (40% to 50%, trisomy 16 most common, any possible except trisomy 1), monosomy X (15% to 25%), triploidy (15%), tetraploidy (5%). Reproductive tract abnormalities (6% to 12%)—abnormality of placentation, bicornuate or unicornuate uterus, incompetent cervix, intrauterine adhesions (Asherman’s syndrome), in utero diethylstilbestrol exposure, leiomyomata uteri (submucous), septate uterus. Infection—Mycoplasma hominis, syphilis, toxoplasmosis, Ureaplasma ureolyticus, possibly chlamydia and herpes. Systemic disease—chronic cardiovascular disease, chronic renal disease, diabetes mellitus, systemic lupus erythematosus/lupus anticoagulant. Environmental factors—alcohol, anesthetic gases, drug use, radiation, smoking, toxins. Other factors—advanced maternal age, delayed fertilization (old egg), trauma.
Risk Factors: Increasing parity, increasing maternal age, increasing paternal age, a short interval between pregnancies, excessive caffeine consumption (≥6 cups of coffee per day). Retention of tissue after pregnancy loss increases the risk of a septic abortion.

CLINICAL CHARACTERISTICS

Signs and Symptoms

• General—vaginal bleeding (may be bright red to dark in color)

• Abdominal cramping (generally rhythmic, accompanied by pelvic or low back pressure)
• Passage of tissue (complete and incomplete abortion)
• Cervical dilation (typical of all types of abortion except missed and threatened)
• Cervical dilation with tissue visible at the cervical os (diagnostic of either incomplete or inevitable abortion)

• Missed abortion—decreased or minimal uterine growth early in pregnancy

• Vaginal bleeding that changes to a dark-brown discharge that continues
• Loss of early symptoms of pregnancy, such as breast fullness or morning sickness
• Disseminated intravascular coagulopathy (DIC) can occur when an intrauterine fetal demise in the second trimester has been retained beyond 6 weeks after the death of the fetus (rare)

• Septic abortion—severe hemorrhage (vaginal)

• Midline lower abdominal pain
• Uterine and perimetric tenderness
• Bacteremia
• Septic shock
• Renal failure

• Threatened abortion—implantation bleeding

• Cervical polyps, cervicitis
• Other causes of lower abdominal discomfort (e.g., urinary tract infection, constipation)

DIAGNOSTIC APPROACH

Differential Diagnosis

• Ectopic pregnancy
• Cervical polyps, cervicitis
• Molar pregnancy
• Possibility of trauma, including perforation of the uterus or vagina, when sepsis is present

Associated Conditions: Thirty percent of patients treated by sharp curettage for missed abortion form intrauterine adhesions. Septic abortion is associated with septic shock, ascending infection (myometritis, pelvic inflammatory disease), disseminated intravascular coagulopathy, and renal failure.

Workup and Evaluation

Laboratory: Administer a pregnancy test (if pregnancy has not been confirmed). If serial determinations of quantitative β-human chorionic gonadotropin (β-hCG) do not show at least a 66% increase every 48 hours, the outlook for the pregnancy is poor. Perform complete blood count (if blood loss has been excessive). Serial determinations of serum β-hCG may be used to confirm pregnancy loss but are not required for diagnosis.
Imaging: Ultrasonography of the uterus may be used to confirm loss of intrauterine contents, the absence of a fetal pole, or failure to grow.
Special Tests: None indicated.
Diagnostic Procedures: If significant cervical dilation is identified by speculum and bimanual examination or if tissue is seen at the cervix, the diagnosis of inevitable or incomplete abortion is established.

Pathologic Findings

Products of conception (including chorionic villi); in a missed abortion there is the absence of a fetal pole.

MANAGEMENT AND THERAPY

Nonpharmacologic

General Measures: Support and evaluation are helpful; analgesia if required. Rh-negative mothers should be treated with Rh immune globulin after completion of the abortion. Because ovulation may occur as early as 2 weeks after an abortion, a discussion of contraception is warranted.
Specific Measures: When there is a complete abortion, immediate considerations include control of bleeding, prevention of infection, pain relief (if needed), and emotional support. Ensuring that all the products of the conception have been expelled from the uterus controls bleeding. Although most patients with an incomplete or inevitable abortion spontaneously pass the remaining tissue (complete abortion), bleeding, cramping, and the risk of infection associated with expectant management generally require surgical evacuation. If retained tissue is present or cannot be ruled out, curettage must be performed promptly. When a missed abortion is diagnosed, evacuation of the uterus can be accomplished either through dilation and evacuation or through medical therapies such as prostaglandin suppositories or mifepristone (RU-486), based on the stage of the pregnancy and other considerations. Septic abortion requires immediate and aggressive management. Broad-spectrum parenteral antibiotics, fluid therapy, and prompt evacuation of the uterus are indicated. Emergency evacuation of the uterine contents is mandatory because of the significant threat they represent. When the diagnosis of threatened abortion is made, intervention should be minimal, even when bleeding is accompanied by low abdominal pain and cramping. If there is no evidence of cervical change, the patient can be reassured and encouraged to continue normal activities. If significant pain or bleeding persists, especially bleeding leading to hemodynamic alterations, evacuation of the uterus should be carried out.
Diet: No specific dietary changes are indicated unless immediate surgical therapy is being considered; in that case, nothing should be taken by mouth.
Activity: Generally there is no restriction. When sepsis is present, bed rest is initially required while therapy is instituted. After evacuation is accomplished and fever is reduced, the patient may return to normal activity. Although frequently recommended, a short period of bed rest has no documented benefit for patients with a threatened abortion.
Patient Education: Reassurance; American College of Obstetricians and Gynecologists Patient Education Pamphlet AP038 (Bleeding During Pregnancy), AP090 (Early Pregnancy Loss: Miscarriage, Ectopic Pregnancy, and Molar Pregnancy), AP062 (Dilation and Curettage [D&C]), and AB012 (Planning Your Pregnancy).

Drug(s) of Choice

To hasten the expulsion of tissue and reduce bleeding—oxytocin 10 to 20 units/L IV fluids or methylergonovine maleate (Methergine) 0.2 mg IM may be used.
Septic abortion—aggressive fluid therapy, antibiotic therapy (ampicillin 1 to 2 g IV followed by 500 mg IV every 4 to 6 hours, ampicillin/sulbactam 1.5 to 3 g IV every 6 hours, or clindamycin 600 mg IV or IM every 6 hours and gentamicin 80 mg IM every 8 hours).
Contraindications: Undiagnosed vaginal bleeding.
Precautions: Methergine should be used with care in patients with hypertension.
Interactions: Vasoconstrictors and ergot alkaloids.

Alternative Drugs

Prostaglandin E2, mifepristone (RU-486). For septic abortion, other broad-spectrum antibiotics, singly or in combination, are available.

FOLLOW-UP

Patient Monitoring: Anticipate normal return of menstrual function in 4 to 6 weeks and offer contraceptive counseling. Patients with septic abortions must be monitored for the possibility of septic shock.
Prevention/Avoidance: None. Septic abortions may be prevented by the prompt evacuation of the uterus for patients with incomplete or inevitable abortions. Data on the risk of sepsis for patients with missed abortions are lacking; therefore, expectant, medical, or surgical managements are all acceptable.
Possible Complications: Infection (myometritis, pelvic inflammatory disease) may occur. Removal of the products of conception, combined with vaginal rest (no tampons, douches, or intercourse), provides adequate protection against infection for most patients.
Expected Outcome: The risk of pregnancy loss subsequent to a spontaneous abortion increases slightly, although much of this increase may be due to selection for those with factors that preclude successful pregnancy. For those with an inevitable abortion who do not spontaneously lose the pregnancy, infection or bleeding often ensue, requiring evacuation of the uterus. Missed abortions may spontaneously abort, progressing through incomplete to complete stages, or they may be evacuated. After the pregnancy has terminated (spontaneous abortion or surgical evacuation of products of conception), normal menses return in 4 to 6 weeks. With aggressive antibiotic treatment and prompt evacuation of the uterus, the outcome should be good for patients with a septic abortion. Among patients with a threatened abortion, one half go on to lose the pregnancy in a spontaneous abortion. (The risk of failure is greater in those who bleed for 3 or more days.) For those who carry the fetus to viability there is a greater risk for preterm delivery and low fetal birth weight and a higher incidence of perinatal mortality. There does not, however, appear to be a higher incidence of congenital malformations in these newborns.

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MISCELLANEOUS

Other Notes: When losses are caused by aneuploidy or polyploidy, they tend to happen earlier in gestation (75% before 8 weeks) and are more likely to recur in subsequent pregnancies. Abnormal development, including the zygote, embryo, fetus, or placenta, is common. Expulsion of the pregnancy is almost always preceded by the death of the embryo or fetus. For threatened abortion, intercourse is usually proscribed for 2 to 3 weeks, or longer, although this probably provides more psychological support than medical effect. Progesterone therapy for threatened abortions is of no benefit and may potentially result in virilization of a fetus or a missed abortion. It should not be used. Incomplete abortions are more common after the 10th week of gestation, when fetal and placental tissues tend to be passed separately.
ICD-9-CM Codes: 634.9 (Complete abortion), 637.9 (Incomplete abortion), 634.7 (Inevitable abortion), 632 (Missed abortion), 634.0, 635.0 (Septic abortion following legal termination of pregnancy), 636.0 (Septic abortion following illegal termination of pregnancy), 640.0 (Threatened abortion).

REFERENCES

Level II

Batzofin JH, Fielding WI, Friedman EA. Effect of vaginal bleeding in early pregnancy on outcome. Obstet Gynecol. 1984;63:515.

Boklage CE. Survival probability of human conceptions from fertilization to term. Int J Fertil. 1990;35:75.

Bromley B, Harlow BL, Laboda LA, Benacerraf BR. Small sac size in the first trimester: a predictor of poor fetal outcome. Radiology. 1991;178:375.

Funderburk SJ, Guthrie D, Meldrum D. Outcome of pregnancies complicated by early vaginal bleeding. Br J Obstet Gynecol. 1980;87:100.

Hakim-Elahie E, Tovell HM, Burnhill MS. Complications of first-trimester abortions: a report of 170,000 cases. Obstet Gynecol. 1990;76:129.

Johannisson E, Oberholzer M, Swahn ML, Bygdeman M. Vascular changes in the human endometrium following the administration of the progesterone antagonist RU 486. Contraception. 1989;39:103.

Mackenzie WE, Holmes DS, Newton JR. Spontaneous abortion rate in ultrasonographically viable pregnancies. Obstet Gynecol. 1988;71:81.

Schaff EA, Stadalius LS, Eisinger SH, Franks P. Vaginal misoprostol administered at home after mifepristone (RU486) for abortion. J Fam Pract. 1997;44:353.

Swahn ML, Bygdeman M. The effect of the antiprogestin RU 486 on uterine contractility and sensitivity to prostaglandin and oxytocin. Br J Obstet Gynaecol. 1988;95:126.

Thom DH, Nelson LM, Vaughan TL. Spontaneous abortion and subsequent adverse birth outcomes. Am J Obstet Gynecol. 1992;166:111.

Warburton D, Fraser FC. Spontaneous abortion risks in man: data from reproductive histories collected in a medical genetics unit. Am J Human Genet. 1964;16:1.

Level III

American College of Obstetricians and Gynecologists. Medical management of abortion. ACOG Clinical management guidelines for obstetricians and gynecologists, Number 67. Washington, DC: ACOG, 2005.

Chen BA, Creinin MD. Contemporary management of early pregnancy failure. Clin Obstet Gynecol. 2007;50:67.

Goldstein SR. Embryonic death in early pregnancy: a new look at the first trimester. Obstet Gynecol. 1994;84:294.

Hogue CJR. Impact of abortion on subsequent fecundity. Clin Obstet Gynecol. 1986;13:95.

Katz VL. Spontaneous and recurrent abortion, (CH16). In: Katz VL, Lentz GM, Lobo RA, et al, editors. Comprehensive Gynecology. 5th ed. Philadelphia: Mosby/Elsevier; 2007:359.

Kripke C. Expectant management vs. surgical treatment for miscarriage. Am Fam Physician. 2006;74:1125.

Poland BJ, Miller JR, Jones DC, Trimble BK. Reproductive counseling in patients who have had a spontaneous abortion. Am J Obstet Gynecol. 1977;127:685.

Smith RP. Gynecology in Primary Care. Baltimore: Williams & Wilkins, 1997;99.

Stubblefield PG, Grimes DA. Septic abortion. N Engl J Med. 1994;331:310.

Tang OS, Ho PC. Clinical applications of mifepristone. Gynecol Endocrinol. 2006;22:655.

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