Abortion, Spontaneous

Key Features

Essentials of Diagnosis

• Intrauterine pregnancy < 20 weeks

• Low or falling levels of human chorionic gonadotropin (hCG)

• Bleeding or midline cramping pain, or both

• Open cervical os

• Complete or partial expulsion of products of conception

General Considerations

• Defined as termination of gestation prior to the 20th week of pregnancy

• 75% of cases occur before the 16th week, with 75% of these before the 8th week

• Almost 20% of clinically recognized pregnancies terminate in spontaneous abortion

• More than 60% of cases result from chromosomal defects

• About 15% of cases are associated with

  • Maternal trauma

  • Infection

  • Dietary deficiency

  • Diabetes mellitus

  • Hypothyroidism

  • The lupus anticoagulant-anticardiolipin-antiphospholipid antibody syndrome

  • Anatomic malformations

  • There is no evidence that psychic stimuli such as severe fright, grief, anger, or anxiety can induce termination

• There is no evidence that electromagnetic fields are associated with an increased risk of termination

• It is important to distinguish women with incompetent cervix from more typical early abortion, premature labor, or rupture of the membranes

Demographics

• Predisposing factors

  • History of incompetent cervix

  • Cervical conization or surgery

  • Cervical injury

  • Diethylstilbestrol exposure

  • Anatomic abnormalities of the cervix

Clinical Findings

Symptoms and Signs

• Incompetent cervix

  • Classically presents as "silent" cervical dilation (without contractions) between weeks 16 and 28

• Threatened abortion

  • Bleeding or cramping without termination

  • The cervix is not dilated

• Inevitable abortion

  • The cervix is dilated and membranes may be ruptured

  • Passage of products of conception has not occurred but is considered inevitable

• Complete abortion

  • The products of conception are completely expelled

  • Pain ceases, but spotting may persist

  • Cervical os is closed

• Incomplete abortion

  • Some portion of the products of conception remains in the uterus

  • Cramps are usually mild; bleeding is persistent and often excessive

• Missed abortion

  • The pregnancy has ceased to develop, but the conception has not been expelled

  • There may be brownish vaginal discharge but no active bleeding

  • Symptoms of pregnancy disappear

Differential Diagnosis

• Ectopic pregnancy

• Hydatidiform mole

• Incompetent cervix

• Anovular bleeding in a nonpregnant women

• Menses or menorrhagia

• Cervical neoplasm or lesion

Diagnosis

Laboratory Tests

• Falling levels of hCG

• Complete blood count should be obtained if bleeding is heavy

• Rh type should be determined and Rho(D) Ig given if the type is Rh negative

• All recovered tissue should be preserved and assessed by a pathologist

Imaging Studies

• Transvaginal ultrasound can identify the gestational sac 5–6 weeks from the last menstrual period, a fetal pole at 6 weeks, and fetal cardiac activity at 6–7 weeks

• Diagnostic criteria of early pregnancy loss

  • Crown-rump length of 7 mm or more and no heartbeat

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