Obstetric Topic 16. Spontaneous abortion

I. Definition and Causes

Definition

• Spontaneous abortion / miscarriage: non-induced pregnancy loss before viability.
• Hungarian/Semmelweis exam cutoff: before GW24; many international sources use before 20 weeks.
• Early abortion: before 12 weeks; late abortion: 12-24 weeks.
• Frequency: about 10-15% of clinically recognized pregnancies; most occur in 1st trimester.
• Recurrent pregnancy loss: usually ≥2 clinical losses for evaluation; classic exam definition is ≥3 consecutive losses.

Etiology

1. Fetal: chromosomal abnormalities, congenital anomalies.
2. Maternal anatomical: uterine septum, fibroid, adhesions, cervical insufficiency.
3. Maternal endocrine/systemic: uncontrolled diabetes, thyroid disease, hypertension, renal disease, SLE.
4. Infection: TORCH, syphilis, mycoplasma, listeria.
5. Hematologic/immune: antiphospholipid syndrome, thrombophilia.
6. Environmental: smoking, alcohol, drugs, radiation, trauma, domestic violence.

II. Classification

Types of Miscarriage

• Threatened abortion: bleeding ± mild pain, closed cervix, no POC expelled, US shows living fetus.
• Inevitable abortion: heavy bleeding/cramps, dilated cervix, no POC expelled yet, pregnancy unlikely to continue.
• Incomplete abortion: heavy bleeding, dilated cervix, partial POC expulsion, retained POC on US.
• Complete abortion: bleeding and pain stop, cervix closed, all POC expelled, empty uterine cavity.
• Missed abortion: embryo/fetus dead, cervix closed, POC retained, often little/no bleeding.
• Septic abortion: infected retained POC → fever, uterine tenderness, foul discharge, sepsis risk.

Complications

• Hemorrhage and shock.
• Endometritis, sepsis.
• DIC: retained dead tissue/abruption/sepsis → thromboplastin release.
• Asherman syndrome: intrauterine adhesions after D&C/infection.
• Rh alloimmunization in Rh-negative patients.

III. Diagnosis

Work-Up

• Assess stability first: BP, pulse, bleeding amount, pain, fever.
• Pelvic/speculum exam: bleeding source, cervical os open/closed, visible POC, uterine size, infection signs.
• Labs: β-hCG trend, CBC/Hb, blood group and Rh(D), coagulation tests if heavy bleeding/sepsis/missed prolonged loss.
• Ultrasound: intrauterine pregnancy, fetal cardiac activity, empty sac, retained POC, ectopic/molar differential.
• Nonviability on TVUS: CRL ≥7 mm with no heartbeat or mean sac diameter ≥25 mm with no embryo; repeat scan if uncertain.

IV. Management

Threatened Abortion

• Expectant management: reassurance, observation, return if bleeding/pain worsens.
• No proven benefit from strict bed rest.
• Progesterone may be considered in early bleeding with previous miscarriage, depending local protocol.

Inevitable / Incomplete / Missed Abortion

• Unstable, septic, heavy bleeding or severe anemia → urgent surgical evacuation + resuscitation.
• Stable patient: expectant, medical or surgical management according to gestational age, symptoms and preference.
• Medical: misoprostol; mifepristone before misoprostol improves success where available.
• Surgical: suction curettage/D&C mainly in 1st trimester; D&E or induction methods later.
• Give analgesia and clear follow-up instructions.

Complete Abortion

• No evacuation if bleeding stopped, patient stable and US confirms empty cavity.
• Follow-up: symptoms, ultrasound or β-hCG until complete resolution if uncertain.

Rh and Follow-Up

• Rh-negative unsensitized patient: give anti-D after later first-trimester loss, surgical evacuation, heavy bleeding or later pregnancy loss according to local protocol.
• Septic abortion: broad-spectrum antibiotics + evacuation after stabilization.
• After loss: offer emotional support and contraception if desired.
• Recurrent loss work-up: uterine anatomy, APS, thyroid/diabetes and genetic factors as indicated.