Introduction
Spontaneous abortion (miscarriage) is loss of a pregnancy before viability, usually defined as before 20–22 weeks or a fetus under 500 g. About 10–20% of clinically recognised pregnancies miscarry, 80% in the first trimester.
Clinical types
Ultrasound criteria for a failed pregnancy
- Crown–rump length ≥ 7 mm with no heartbeat, or mean sac diameter ≥ 25 mm with no embryo (repeat the scan if in doubt).
Management principles
- Assess bleeding and haemodynamics first; resuscitate if needed.
- Exclude ectopic pregnancy.
- Options: expectant, medical (misoprostol 800 µg vaginally, with mifepristone 200 mg 24–48 h earlier for missed miscarriage), or surgical (manual vacuum aspiration or suction curettage).
- Anti-D for RhD-negative women having surgical management or bleeding after 12 weeks.
Recurrent miscarriage
Two or three consecutive losses (definitions vary) affect 1–2% of couples. Investigate: parental karyotypes, antiphospholipid antibodies, uterine anatomy (3D ultrasound), thyroid function and diabetes. Antiphospholipid syndrome is treated with low-dose aspirin plus heparin; cervical insufficiency with a cerclage.
The state of the cervical os separates the types: closed os means threatened, complete or missed; open os means inevitable or incomplete.