What are the differences between incomplete abortion and missed abortion and what are the recommended management options (surgical evacuation, medical misoprostol therapy, or expectant management) for each?

Incomplete vs Missed Abortion: Key Differences and Management

Definitions and Diagnostic Criteria

Incomplete abortion involves partial expulsion of conception products with an open cervix, while missed abortion (embryonic/fetal demise) involves confirmed fetal death with retained products and a closed cervix—these are fundamentally different clinical entities requiring distinct management approaches. 1

Incomplete Abortion

• Characterized by partial expulsion of products of conception with vaginal bleeding and an open or dilating cervix 1
• Ultrasound shows retained intrauterine tissue with variable amounts of debris 1
• Patient typically presents with ongoing bleeding and cramping 1

Missed Abortion (Embryonic/Fetal Demise)

• Confirmed by crown-rump length ≥7 mm without cardiac activity, mean sac diameter ≥25 mm without embryo, or absence of embryo ≥14 days after initial gestational sac visualization 1
• Cervix remains closed with minimal or no bleeding 1, 2
• Use term "embryonic/fetal demise" rather than outdated terms like "blighted ovum" 1
• Fetal demise specifically applies at ≥11 weeks gestation 1

Management of Incomplete Abortion

Surgical Evacuation (Preferred for Active Bleeding)

Surgical evacuation via vacuum aspiration is the gold standard for incomplete abortion with moderate-to-severe bleeding, offering the lowest complication rates. 1, 3

• Complication rates with surgical evacuation: hemorrhage 9.1%, infection 1.3%, retained tissue requiring repeat procedure 1.3% 1
• Vacuum aspiration superior to sharp curettage: less blood loss (-17 mls), less pain (RR 0.74), shorter procedure duration (-1.2 minutes) 3
• Perform urgently without delay in patients with profuse bleeding 1

Medical Management with Misoprostol

• Dosing: Misoprostol 600-800 mcg vaginally achieves 91.5% success rate in first trimester 1, 4
• Vaginal route superior to oral: higher success rate (RR 0.85), shorter induction-to-expulsion interval, greater patient satisfaction, fewer side effects 5
• Higher complication rates than surgical: hemorrhage 28.3%, infection 23.9%, retained tissue 17.4% 1
• Appropriate for hemodynamically stable patients without profuse bleeding 6

Expectant Management

• May be considered for stable patients with minimal bleeding and small amounts of retained tissue 7
• Requires close follow-up and patient understanding of warning signs 7
• Not appropriate for moderate-to-severe bleeding 1

Management of Missed Abortion

Expectant management is absolutely contraindicated in missed abortion—active evacuation is required due to increased risks of intrauterine infection, coagulopathy, and maternal sepsis with prolonged retention. 1

Gestational Age-Based Approach

<9 Weeks Gestation

• Medical management: Mifepristone 200 mg orally followed by misoprostol 800 mcg vaginally/buccally achieves 80% success rate 1
• Combination therapy more effective than misoprostol alone 1
• Surgical option: Vacuum aspiration remains highly effective 1

9-12 Weeks Gestation

• Surgical evacuation preferred due to higher success rates at this gestational age 1
• Medical management still possible but with lower efficacy 1

>12 Weeks Gestation

• Dilation and evacuation (D&E) is the procedure of choice 1
• Medical induction may be considered but carries higher maternal morbidity 1

Critical Warning Signs Requiring Urgent Intervention

Do not wait for fever to diagnose infection—clinical symptoms may be subtle in early pregnancy. 1

• Maternal tachycardia, purulent cervical discharge, uterine tenderness indicate infection 1
• If infection suspected: initiate broad-spectrum antibiotics immediately and proceed with urgent surgical evacuation 1
• Intraamniotic infection occurs in 38% with expectant management vs 13% with active evacuation 1

Essential Preventive Measures

Rh Immunoprophylaxis

All Rh-negative women with incomplete or missed abortion must receive anti-D immunoglobulin. 1, 2

• Dose: 50 mcg for first trimester losses 1
• Fetomaternal hemorrhage occurs in 32% of spontaneous abortions 1, 2
• Administer regardless of management method chosen 1

Comparative Outcomes: Key Decision Points

When to Choose Surgical Over Medical Management

• Profuse or ongoing bleeding (surgical has 9.1% vs 28.3% hemorrhage risk) 1
• Patient preference for definitive single-visit treatment 8
• Gestational age >9 weeks (higher surgical success rates) 1
• Signs of infection (requires urgent surgical evacuation) 1

When Medical Management is Appropriate

• Hemodynamically stable patient 6
• Gestational age <9 weeks 1
• Patient desires home-based care 1
• No signs of infection 1
• Patient accepts 5.3% risk of requiring subsequent surgical intervention 6

Common Pitfalls to Avoid

• Delaying treatment in missed abortion waiting for spontaneous expulsion—this increases infection and coagulopathy risk 1
• Waiting for fever before treating suspected infection—initiate antibiotics and evacuate based on clinical signs alone 1
• Using sharp curettage instead of vacuum aspiration—vacuum aspiration has superior safety profile 3
• Failing to provide Rh immunoprophylaxis—32% of spontaneous abortions involve fetomaternal hemorrhage 1
• Choosing expectant management for missed abortion—maternal morbidity rate 60.2% vs 33% with active management 1

Post-Treatment Care

• Provide contraceptive counseling immediately—ovulation resumes within 2-4 weeks 1
• Combined hormonal contraceptives or implants can start immediately without waiting for menses 1
• No backup contraception needed if started within 7 days of abortion 1
• Clinical follow-up to confirm complete evacuation and rule out complications 1