Clinical overview
Miscarriage — the spontaneous loss of a pregnancy before 24 weeks (UK/SA definition) or 20 weeks (US definition) — is the most common complication of early pregnancy. It affects approximately 15–20% of clinically recognised pregnancies; if biochemical losses are included, the figure rises to 30–40%. For the individual woman it is rarely "common" — it is loss, grief, and uncertainty. The registrar's job is therefore part medical (resuscitation when needed, accurate diagnosis, safe evacuation), part counselling (validating loss, navigating future fertility), and part systemic (recognising recurrent miscarriage that needs workup, distinguishing miscarriage from ectopic, knowing when to refer).
The chapter covers definitions, classification by type, assessment, ultrasound diagnostic criteria, the three management options (expectant, medical, surgical), counselling, anti-D in Rh-negative women, and indications for recurrent miscarriage workup. The South African context — limited early pregnancy unit access in some districts, anti-D supply considerations, integration with the Choice on Termination of Pregnancy Act services — is woven through.
Core knowledge
Definitions and classification
Classification turns on cervical status, viability, retained tissue, and whether products have passed.
- Threatened miscarriage: vaginal bleeding before 24 weeks with a closed cervix; viable pregnancy on ultrasound.
- Inevitable miscarriage: bleeding + cramping with open cervix; pregnancy not yet expelled.
- Incomplete miscarriage: some products passed, some retained; open cervix; ongoing bleeding.
- Complete miscarriage: all products passed; closed cervix; uterus empty on ultrasound.
- Missed (delayed) miscarriage: non-viable pregnancy retained in utero without symptoms; diagnosed on ultrasound.
- Septic miscarriage: any of the above complicated by infection; usually associated with unsafe termination, retained products, or instrumentation.
- Recurrent miscarriage: ≥3 consecutive losses (UK historical) or ≥2 losses (newer ESHRE/ASRM definitions, especially with maternal age ≥35).
- Biochemical pregnancy: β-hCG positive but pregnancy never visualised on ultrasound.
Aetiology
The cause is most often identified only in recurrent loss; for single losses ~50–60% are due to chromosomal abnormalities of the conceptus (especially trisomy 16). Other causes:
- Chromosomal — trisomies (16 most common), monosomy X (45,X — usually first trimester loss), triploidy, structural abnormalities, parental balanced translocations.
- Maternal anatomical — septate uterus, fibroids (submucosal especially), intrauterine adhesions (Asherman's), cervical insufficiency (more common in second trimester loss).
- Endocrine — uncontrolled diabetes (especially in first trimester), thyroid disease, prolactinoma, severe PCOS.
- Thrombophilic — antiphospholipid syndrome (most evidence-based; lupus anticoagulant, anticardiolipin antibodies, anti-β2-glycoprotein I); inherited thrombophilias less consistently associated.
- Infectious — uncommonly causal in sporadic loss; syphilis, parvovirus B19, TORCH; bacterial vaginosis associated with second trimester loss.
- Immunological — beyond APS, evidence weak.
- Environmental — smoking, heavy alcohol, cocaine, lead, mercury.
- Maternal age — major risk factor. Loss rate ~10% at age 20, rising to ~50% at age 40+, ~80% at age 45+.
Pathophysiology of bleeding and pain
In early miscarriage:
- Trophoblastic separation from decidua → exposed maternal vessels → bleeding.
- Uterine contractions to expel non-viable tissue → suprapubic cramping.
- Cervical dilatation → sacral referred pain.
Septic miscarriage
A medical emergency. Usually polymicrobial — Gram-negatives (E. coli, Klebsiella), anaerobes (Bacteroides), Group A streptococcus, Clostridium perfringens (rare, devastating). Presents with fever, foul discharge, uterine tenderness, sepsis. Risk highest after unsafe termination — see termination-of-pregnancy. Septic shock progresses rapidly; multi-organ failure within hours. Mortality remains a major issue globally.
Assessment
History
- Gestational age (LMP, dating scan).
- Bleeding: amount, clots, products passed, duration.
- Pain: site, character, severity.
- Last viable confirmation (positive β-hCG, ultrasound).
- Previous miscarriages, ectopics, terminations.
- Mode of conception (spontaneous, IVF — heterotopic risk).
- General health, fever, malaise, recent symptoms.
- For Rh-negative women: confirm status.
- Allergies, medications.
- Social: support network, partner, mood.
Examination
- Vitals — tachycardia, hypotension, fever.
- Abdominal: tenderness, peritonism.
- Speculum: assess cervix open or closed, products at the os (remove gently with sponge forceps, send for histology), bleeding source.
- Bimanual: uterine size (compared to dates), tenderness, adnexal masses, cervical motion tenderness.
Investigations
- Urine or serum β-hCG.
- FBC, U&E, group-and-save (cross-match if heavy bleeding), CRP, coagulation if heavy.
- Blood group + Rhesus status.
- Endocervical swabs (especially if septic).
- Blood cultures + lactate if septic.
- HIV test (always offered).
- Transvaginal ultrasound is the cornerstone:
Ultrasound diagnostic criteria for non-viable pregnancy (RCOG/ESHRE)
Either:
- Crown-rump length (CRL) ≥7 mm with no fetal heart activity, OR
- Mean gestational sac diameter (MSD) ≥25 mm with no embryo visible.
If borderline, repeat scan in 7–14 days before confirming non-viability — never act on a single borderline scan.
Pregnancy of unknown location (PUL): positive β-hCG with no IUP and no clear ectopic on TVS. Serial β-hCG (48-hour interval) interpretation:
- Rising appropriately (>53% in 48 h) — likely early IUP; repeat scan when β-hCG >1500.
- Plateau or suboptimal rise — likely failing pregnancy or ectopic; manage as ectopic until proven otherwise.
- Falling (>50% drop in 48 h) — likely failing pregnancy; continue serial until <5 IU/L.
Management
Threatened miscarriage
- Reassurance.
- No bed rest (no evidence of benefit).
- No prophylactic progesterone routinely (PRISM trial: small benefit only in women with previous miscarriage + current bleeding).
- Repeat scan in 1–2 weeks.
Inevitable / incomplete / missed miscarriage — three management options
1. Expectant management
- Suitable for: stable patient, no infection, willing to wait.
- ~50% success at 2 weeks; ~70% by 6 weeks for incomplete miscarriage; lower for missed.
- Counsel: may pass tissue at home; expect 7–14 days of bleeding; come back if heavy bleeding, fever, foul discharge.
- Repeat scan at 2 weeks.
2. Medical management
- Misoprostol 800 mcg vaginally (some protocols use 600 mcg sublingually), repeat after 24–48 h if needed.
- For missed miscarriage: consider adding mifepristone 200 mg 24–48 h before misoprostol (MIST trial: better completion rate with combination).
- Expect cramping, heavy bleeding, passage of tissue within hours.
- Provide adequate analgesia (NSAIDs, opioids if needed).
- Anti-emetic (misoprostol commonly causes nausea, sometimes diarrhoea, transient fever).
- Review at 2 weeks with ultrasound or urine pregnancy test.
3. Surgical management
- Manual vacuum aspiration (MVA) — outpatient, local anaesthesia, very effective for incomplete miscarriage <12 weeks; minimal infrastructure; central to SA TOP and incomplete miscarriage services.
- Suction curettage under general anaesthesia — for larger pregnancies, failed medical management, septic miscarriage, heavy bleeding, patient preference.
- Antibiotic prophylaxis (doxycycline 100 mg PO 12-hourly × 5 days) where infection risk; mandatory in suspected septic miscarriage.
- Complications: perforation (~0.5%), retained products (<5%), infection, Asherman's (especially after septic or repeated curettage).
Septic miscarriage
- Resuscitation: A-B-C, IV access, fluids, oxygen.
- Blood cultures + IV broad-spectrum antibiotics within 1 hour (SA NDoH STG: ampicillin + gentamicin + metronidazole; or ceftriaxone + metronidazole).
- Urgent surgical evacuation of retained products (definitive source control).
- Multidisciplinary: anaesthesia, ICU, possibly haematology if DIC.
- Hysterectomy may be needed in severe cases (clostridial sepsis, uncontrolled bleeding, uterine necrosis).
Anti-D prophylaxis
Rh-negative women with any miscarriage ≥12 weeks: anti-D 1500 IU IM within 72 hours. For first-trimester miscarriage, anti-D is given if there is heavy bleeding, surgical management, or instrumentation. NICE and RCOG guidance has evolved; default to giving when in doubt and per local protocol. See rh-isoimmunisation.
Recurrent miscarriage workup
After 2–3 consecutive losses (criteria vary; offer earlier if maternal age ≥35):
- Antiphospholipid syndrome screen: lupus anticoagulant, anticardiolipin IgG/IgM, anti-β2-glycoprotein I IgG/IgM (twice, 12 weeks apart).
- Parental karyotype (if products of conception had abnormality, or otherwise unexplained).
- Pelvic ultrasound (uterine anomaly, fibroids) ± saline-infusion sonography or hysteroscopy.
- Thyroid function and HbA1c.
- TSH/TPO antibodies if known thyroid disease.
- Inherited thrombophilia screen (controversial; reserve for personal/family VTE).
- Lifestyle counselling: smoking, alcohol, weight, drugs.
Treatment depends on findings:
- Confirmed APS: low-dose aspirin + prophylactic LMWH from positive pregnancy test.
- Uterine septum: hysteroscopic septum resection.
- Antiphospholipid syndrome without recurrent loss but documented: per haematology guidance.
Counselling
- Sensitive language: "loss," not "failed pregnancy." Avoid "abortion" (medically correct but emotionally loaded for many patients).
- Validate grief; acknowledge anniversary effects; offer follow-up.
- Future pregnancy: most women conceive again; no need to wait beyond next cycle for conception attempts (WHO guidance has shifted from 6 months to no waiting period).
- Risk of recurrence: after one miscarriage ~15%, after two ~30%, after three ~40%.
- Bereavement resources where available.
- Address partner — they grieve too.
Red flags / pitfalls
- Missing ectopic in PUL — treat as ectopic until disproven by appropriate serial β-hCG and imaging.
- Anti-D omission — check Rh status on every miscarriage.
- Inadequate analgesia during medical management.
- Sending home a septic miscarriage on oral antibiotics — admit, IV, surgical evacuation.
- Performing evacuation in unstable patient — resuscitate first.
- Not offering all three management options — patient choice matters; success rates similar.
- Not arranging follow-up — 2-week scan or urine pregnancy test crucial.
- Inadequate counselling around recurrent loss — vague reassurance does harm.
- Forgetting HIV test — SA practice always.
- Not addressing partner / mental health — refer for bereavement support.
Evidence anchors
- NICE NG126 — Ectopic Pregnancy and Miscarriage: Diagnosis and Initial Management (2019).
- RCOG Green-top Guideline No. 17 — Recurrent Miscarriage.
- ESHRE Guideline on Recurrent Pregnancy Loss (2022).
- South African National Department of Health Maternity Care Guidelines (latest edition) — early pregnancy loss management.
- Coomarasamy A, et al. PRISM trial — progesterone in threatened miscarriage. NEJM 2019.
- Schreiber CA, et al. Mifepristone pretreatment for the medical management of early pregnancy loss (MIST). NEJM 2018.
- WHO Technical Updates on Safe Abortion Care (2022).
- South African Choice on Termination of Pregnancy Act, 1996 (Act 92 of 1996) — for context where TOP services intersect with miscarriage management.