A missed abortion (also called missed miscarriage or early embryonic demise) is a nonviable intrauterine pregnancy in which the embryo or fetus has died but has not been expelled from the uterus. The patient is typically asymptomatic or has minimal symptoms, and the diagnosis is made by transvaginal ultrasound showing absence of fetal cardiac activity in a previously documented pregnancy. Approximately 15% of all clinically recognized pregnancies end in miscarriage, with ~50% attributable to fetal chromosomal abnormalities. [1-3]
1. History
- LMP, gestational age, and pregnancy dating method (ultrasound vs. LMP)
- Prior ultrasound findings (documented fetal cardiac activity, gestational sac size, CRL)
- Vaginal bleeding: onset, volume, color, clots, tissue passage
- Cramping or pelvic pain: location, severity, timing
- Loss of pregnancy symptoms (resolution of nausea, breast tenderness)
- Prior β-hCG levels and trend
- Contraceptive history, fertility treatments, IVF
- History of prior miscarriages, ectopic pregnancies, or uterine procedures
2. Alarm Features
- Heavy vaginal hemorrhage with hemodynamic instability (tachycardia, hypotension, syncope)
- Fever, chills, purulent vaginal discharge → concern for septic abortion [4]
- Severe or worsening abdominal/pelvic pain → rule out ectopic pregnancy, uterine perforation
- Signs of DIC: petechiae, mucosal bleeding, oozing from IV sites (rare, more associated with prolonged retained fetal demise) [5]
- Refractory hypotension with exaggerated leukocytosis → consider clostridial infection [4][6]
3. Medications
- Medical management (ACOG-recommended protocol): [2]
- Mifepristone 200 mg PO → 24 hours later → Misoprostol 800 mcg vaginally (repeat dose as needed, no earlier than 3 hours, typically within 7 days)
- Combination mifepristone + misoprostol is superior to misoprostol alone (RR 1.25 for complete expulsion) [2][7]
- Pain management: NSAIDs (ibuprofen 600–800 mg q6h), acetaminophen, or opioids as needed
- Rh(D) immune globulin: Administer within 72 hours in Rh-negative, unsensitized patients; 50 mcg dose is adequate in the first trimester (300 mcg if lower dose unavailable) [2][8]
- Contraindicated: Methotrexate (used for ectopic, not for missed abortion); avoid misoprostol in patients with known allergy to prostaglandins
- Antibiotic prophylaxis: Single preoperative dose of doxycycline 200 mg recommended before surgical evacuation [2]
4. Diet
- No specific dietary triggers or restrictions
- Encourage adequate hydration, especially if experiencing bleeding or diarrhea from misoprostol
- Avoid alcohol during active management
5. Review of Systems
- GYN: Vaginal bleeding, tissue passage, pelvic pain, vaginal discharge
- GI: Nausea/vomiting (loss may suggest declining hCG), diarrhea (misoprostol side effect)
- Constitutional: Fever, chills, fatigue, lightheadedness, syncope
- Psych: Anxiety, depression, grief — screen for emotional distress
- Heme: Easy bruising, prolonged bleeding (DIC screen)
6. Collateral History and Family History
- Partner involvement and emotional support
- History of recurrent pregnancy loss in patient or first-degree relatives
- Family history of chromosomal abnormalities, thrombophilias, or autoimmune disease
- Social context: domestic violence screening, substance use, support system
7. Risk Factors
- Advanced maternal age: Risk rises from ~12% (age 20–29) to 40% (age 40) to 65% (age ≥45) [2-3]
- Prior miscarriage: risk increases ~10% per additional loss (42% after ≥3 losses) [3]
- Obesity (BMI >24–25 kg/m²) [3][9]
- Paternal age >40 years [3]
- Chromosomal abnormalities (~50% of all early losses) [2][10]
- Smoking, alcohol, high caffeine intake [3]
- Uterine anomalies (septate uterus), fibroids
- Poorly controlled diabetes, thyroid disease, antiphospholipid syndrome [3]
- Night shift work, persistent stress, air pollution exposure [3]
8. Differential Diagnosis
- Ectopic pregnancy — cannot-miss; always rule out before initiating treatment if no prior confirmed IUP [2][11]
- Threatened abortion — viable IUP with vaginal bleeding; fetal cardiac activity present
- Inevitable/incomplete abortion — open cervical os, partial tissue passage
- Anembryonic pregnancy (blighted ovum) — gestational sac without embryo (MSD ≥25 mm) [12-13]
- Gestational trophoblastic disease (molar pregnancy) — "snowstorm" ultrasound, markedly elevated β-hCG [2]
- Normal early pregnancy — critical to avoid premature diagnosis; if CRL <7 mm without cardiac activity, repeat ultrasound in 7–10 days [13]
9. Past Medical History
- Prior miscarriages, ectopic pregnancies, molar pregnancies
- Uterine surgery (D&C, myomectomy, cesarean section) — risk of Asherman syndrome
- Autoimmune conditions (antiphospholipid syndrome, lupus)
- Endocrine disorders (PCOS, thyroid disease, diabetes)
- Thrombophilias
- History of cervical procedures (LEEP, cone biopsy)
10. Physical Exam
- Vitals: Heart rate, blood pressure (assess hemodynamic stability), temperature
- Abdominal exam: Tenderness, peritoneal signs (concerning for ectopic rupture or sepsis)
- Speculum exam: Quantify bleeding, assess for tissue at cervical os, purulent discharge
- Bimanual exam: Cervical os open vs. closed (typically closed in missed abortion), uterine size relative to dates, adnexal masses/tenderness, cervical motion tenderness
- Expected findings: Closed os, uterus may be smaller than expected for dates, minimal to no active bleeding
11. Lab Studies
- Quantitative β-hCG: Establishes baseline; serial levels if diagnosis uncertain (should decline or plateau in nonviable pregnancy) [2][11]
- CBC: Hemoglobin/hematocrit for hemorrhage assessment; WBC for infection
- Blood type and Rh: Essential for Rh immunoglobulin decision [2][8]
- Serum progesterone: Low levels (<5 ng/mL) support nonviability [12]
- Coagulation studies (PT/INR, fibrinogen, D-dimer): If concern for DIC or prolonged retained products [5]
- Blood cultures, lactate: If septic abortion suspected [6]
- Recurrent loss workup (antiphospholipid antibodies, karyotype, thyroid) is not indicated after a single loss — consider after ≥2 consecutive losses [2]
12. Imaging
- First-line: Transvaginal ultrasound (TVUS) — gold standard for diagnosis [12-13]
- Definitive diagnostic criteria (Society of Radiologists in Ultrasound / ACOG): [12-13]
- CRL ≥7 mm with no cardiac activity
- Mean sac diameter (MSD) ≥25 mm with no embryo
- Gestational sac with yolk sac but no embryo with cardiac activity ≥11 days after initial scan
- Gestational sac without yolk sac and no embryo with cardiac activity ≥14 days after initial scan
- Suggestive but NOT diagnostic: CRL <7 mm without cardiac activity, MSD 16–24 mm without embryo, slow fetal heart rate (<100 bpm at 5–7 weeks), enlarged yolk sac (>7 mm), subchorionic hemorrhage [2][13]
- When findings are indeterminate, repeat TVUS in 7–10 days before initiating treatment [2][13]
The following figure illustrates the definitive ultrasound criteria for diagnosing pregnancy failure:
13. Special Tests
- Point-of-care ultrasound (POCUS): Useful in ED for rapid assessment of IUP, free fluid
- β-hCG discriminatory zone: 1,500–3,000 mIU/mL — above this level, an IUP should be visible on TVUS; failure to visualize raises concern for ectopic or pregnancy loss [11][13]
- No validated scoring system specific to missed abortion; clinical diagnosis is ultrasound-based
14. ECG
- Not routinely indicated
- Obtain if hemodynamically unstable, significant hemorrhage, or pre-procedural assessment for surgical management under anesthesia
- Monitor for tachycardia as a sign of hemorrhage
15. Assessment
A missed abortion is a first-trimester nonviable pregnancy with retained products of conception and a closed cervical os. The hallmark is an asymptomatic or minimally symptomatic patient with ultrasound-confirmed embryonic/fetal demise. Key considerations:
- Confirm diagnosis with strict ultrasound criteria to avoid terminating a viable pregnancy [2][12]
- Severity stratification: hemodynamically stable (majority) vs. unstable (hemorrhage, sepsis)
- Complications to consider: infection/septic abortion, hemorrhage, retained products, DIC (rare), Asherman syndrome (post-surgical), psychological impact [4-5]
16. Treatment Plan
Three equally acceptable options; patient preference should guide management in the absence of complications: [2][12]
Expectant management: [2]
- Appropriate for first trimester; success rate ~80% over up to 8 weeks
- Less effective for missed abortion than for incomplete abortion
- Counsel regarding moderate-to-heavy bleeding, cramping, and need for possible surgical intervention
Medical management (preferred when patient wants to avoid surgery): [2]
- Mifepristone 200 mg PO → 24 hours later → Misoprostol 800 mcg vaginally
- Repeat misoprostol dose if no response (no earlier than 3 hours, typically within 7 days)
- Complete expulsion rate: 83% with combination vs. 76% with misoprostol alone at 7 days [7][15]
- Prescribe pain medications; administer RhIg if Rh-negative [2][8]
Surgical management: [12][16]
- Suction aspiration (manual vacuum aspiration or electric) with cervical preparation — ranked most effective method overall (SUCRA 92.7%) [16]
- Indicated urgently for: hemorrhage, infection, hemodynamic instability, failed medical/expectant management
- Preoperative doxycycline 200 mg recommended [2]
- IUD can be placed immediately post-procedure if desired [2]
17. Disposition
- Discharge (majority): Hemodynamically stable, no signs of infection, reliable follow-up, understands return precautions
- Observation: Moderate bleeding requiring monitoring, awaiting ultrasound confirmation, initiating medical management
- Admission criteria: Hemodynamic instability, hemorrhage requiring transfusion, septic abortion, need for emergent surgical evacuation, suspected DIC [5-6]
- Specialist consultation: OB/GYN for surgical management, failed medical management, suspected ectopic, septic abortion, or diagnostic uncertainty
18. Follow Up / Return Precautions
- Follow-up ultrasound within 7–14 days to confirm complete expulsion (absence of gestational sac; endometrial thickness <30 mm is commonly used but not mandatory) [2]
- Serial β-hCG can substitute if ultrasound unavailable [2]
- Return immediately for: Soaking >1 pad/hour for ≥2 hours, fever >100.4°F (38°C), severe abdominal pain, foul-smelling discharge, dizziness/syncope
- Counsel that bleeding may last 1–2 weeks; cramping is expected
- Emotional support: Acknowledge grief; offer counseling resources; screen for depression/anxiety at follow-up [12]
- Contraception: Ovulation can resume within 2 weeks; discuss contraception if desired
- Future fertility: Reassure that ~80% of women give birth within 5 years of a miscarriage; no evidence that management method affects subsequent pregnancy rates [12]
- Recurrent loss workup: Not recommended after a single loss; consider after ≥2 consecutive losses (antiphospholipid antibodies, karyotype, thyroid function, uterine evaluation) [2]
References
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3. Operative Hysteroscopy vs Vacuum Aspiration for Incomplete Spontaneous Abortion: A Randomized Clinical Trial. — Huchon C, Drioueche H, Koskas M, et al. The Journal of the American Medical Association. 2023.
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