Overview
Miscarriage (Early Pregnancy Loss)
Topic Overview
Summary
Miscarriage is spontaneous pregnancy loss before 24 weeks gestation (most occur in the first trimester). It affects 15-25% of recognised pregnancies. Classification depends on ultrasound findings and clinical presentation: threatened, inevitable, incomplete, complete, missed, or septic. Management may be expectant, medical (misoprostol), or surgical (MVA/ERPC). Emotional support is essential. Rhesus-negative women require anti-D if over 12 weeks or if surgical management.
Key Facts
- Definition: Pregnancy loss before 24 weeks (UK definition)
- Incidence: 15-25% of recognised pregnancies
- Types: Threatened, inevitable, incomplete, complete, missed, septic
- Diagnosis: Transvaginal ultrasound (TVUSS)
- Management: Expectant, medical (misoprostol), or surgical
- Anti-D: Required if RhD-negative and over 12 weeks or surgical management
Clinical Pearls
Always exclude ectopic pregnancy first — measure β-hCG and USS
An "empty sac" on USS needs repeat scan in 7-14 days before diagnosing missed miscarriage
Septic miscarriage is a life-threatening emergency
Why This Matters Clinically
Miscarriage is common and distressing. Accurate diagnosis, appropriate management, and sensitive communication are essential. Ectopic pregnancy must always be excluded.
Visual Summary
Visual assets to be added:
- Types of miscarriage diagram
- TVUSS findings comparison
- Miscarriage management algorithm
- Anti-D guidance flowchart
Epidemiology
Incidence
- 15-25% of clinically recognised pregnancies
- Over 80% occur in first 12 weeks
- True rate higher (many before missed period)
Risk Factors
| Factor | Notes |
|---|---|
| Maternal age | Over 35: 20-25%; over 40: 40-50% |
| Previous miscarriage | Increases risk |
| Chromosomal abnormality | Cause in 50-60% |
| Smoking | |
| Alcohol | Heavy use |
| Obesity | |
| Uterine abnormality | Fibroids, septum |
| Antiphospholipid syndrome | Recurrent miscarriage |
Pathophysiology
Causes
- Chromosomal abnormalities (50-60%) — most common
- Uterine abnormalities
- Thrombophilia (antiphospholipid syndrome)
- Hormonal (thyroid, diabetes)
- Infection
- Unknown
Mechanism
- Abnormal embryo development
- Failed implantation
- Placental insufficiency
- Leads to pregnancy loss and expulsion
Clinical Presentation
Symptoms
Types of Miscarriage
| Type | Cervix | Bleeding | Products | USS Finding |
|---|---|---|---|---|
| Threatened | Closed | Light | None passed | Viable intrauterine pregnancy |
| Inevitable | Open | Heavy | Not yet | May still see sac |
| Incomplete | Open | Heavy | Some passed | Retained products |
| Complete | Closed | Settling | All passed | Empty uterus |
| Missed | Closed | Light/none | None | Non-viable pregnancy (no heartbeat) |
| Septic | May be open | Variable | Variable | Products ± infection |
Red Flags
| Finding | Significance |
|---|---|
| Haemodynamic instability | Life-threatening haemorrhage |
| Fever + miscarriage | Septic miscarriage |
| Severe pain | Consider ectopic |
| Products at os | Remove to stop bleeding |
Vaginal bleeding (light to heavy)
Common presentation.
Abdominal/pelvic cramping
Common presentation.
Passage of tissue
Common presentation.
Loss of pregnancy symptoms
Common presentation.
Clinical Examination
General
- Vital signs (tachycardia, hypotension if significant bleeding)
- Pallor
Abdominal
- Suprapubic tenderness
- Peritonism (consider ectopic)
Speculum
- Assess bleeding
- Products at cervical os
- Cervical appearance
Bimanual
- Cervical os open or closed
- Uterine size
- Adnexal tenderness/mass (ectopic)
Investigations
Urine
- Pregnancy test (confirm pregnancy)
Blood Tests
| Test | Purpose |
|---|---|
| β-hCG | Quantitative; helps diagnose pregnancy of unknown location |
| FBC | Anaemia |
| Group & Save/Crossmatch | If significant bleeding |
| Rhesus status | For anti-D decision |
Imaging
| Modality | Findings |
|---|---|
| Transvaginal USS (TVUSS) | Gold standard; confirms intrauterine pregnancy, viability |
USS Criteria for Miscarriage
| Finding | Diagnosis |
|---|---|
| CRL ≥7mm, no heartbeat | Missed miscarriage |
| Mean sac diameter ≥25mm, no embryo | Empty sac/anembryonic |
| If uncertain | Repeat USS in 7-14 days |
Classification & Staging
By Type
| Type | Definition |
|---|---|
| Threatened | Bleeding, closed os, viable pregnancy |
| Inevitable | Open os, pregnancy will be lost |
| Incomplete | Retained products |
| Complete | All products passed |
| Missed | Non-viable but not expelled |
| Septic | Miscarriage with infection |
Recurrent Miscarriage
- 3 or more consecutive losses
- Requires investigation
Management
Threatened Miscarriage
- Reassurance
- Repeat USS in 7-14 days
- No proven treatment
Confirmed Miscarriage — Options
1. Expectant Management:
- Allow natural expulsion
- Suitable for many women
- May take 1-2 weeks
- Follow-up USS to confirm complete
2. Medical Management:
- Misoprostol (vaginal or oral)
- Dose: 800 mcg PV or 600 mcg SL
- May need repeat dose
- Follow-up to confirm complete
3. Surgical Management (MVA or ERPC):
- Manual vacuum aspiration (MVA) under local
- Evacuation of retained products (ERPC) under GA
- Indicated if heavy bleeding, patient preference, incomplete after medical
Specific Situations
Products at Os:
- Remove with ring forceps — stops bleeding
Septic Miscarriage:
- IV antibiotics (broad-spectrum — gentamicin + metronidazole + amoxicillin)
- Urgent surgical evacuation
- Resuscitation
Anti-D Prophylaxis
| Indication | Anti-D |
|---|---|
| Under 12 weeks, expectant/medical | Not required |
| Under 12 weeks, surgical | Required |
| Over 12 weeks | Required (all management types) |
| Any ectopic | Required if RhD-negative |
Emotional Support
- Sensitive communication
- Offer follow-up
- Miscarriage Association resources
- Consider psychological support
Complications
Of Miscarriage
- Heavy bleeding requiring transfusion
- Infection (septic miscarriage)
- Retained products
Of Management
- Incomplete procedure
- Uterine perforation (surgical)
- Infection
- Asherman's syndrome (rare)
Prognosis & Outcomes
Future Pregnancy
- 85% will have successful subsequent pregnancy
- Risk increases with recurrent miscarriage
Recurrent Miscarriage
- 3 or more: Investigate (antiphospholipid, thrombophilia, uterine abnormalities)
Evidence & Guidelines
Key Guidelines
- NICE NG126: Ectopic Pregnancy and Miscarriage
- RCOG Green-Top Guideline on Early Pregnancy Loss
Key Evidence
- Expectant management is as effective as medical/surgical for most
- Misoprostol is effective for medical management
Patient & Family Information
What is Miscarriage?
Miscarriage is when a pregnancy ends by itself before 24 weeks. It is very common — about 1 in 4 pregnancies end this way.
Symptoms
- Vaginal bleeding
- Cramping pain
- Passing tissue
Treatment Options
- Wait for it to happen naturally
- Medication to help it happen
- A small procedure to remove the pregnancy tissue
Emotional Support
- It is normal to grieve
- Support is available
- Most women go on to have successful pregnancies
Resources
References
Primary Guidelines
- NICE. Ectopic Pregnancy and Miscarriage: Diagnosis and Initial Management (NG126). 2019. nice.org.uk
Key Reviews
- Bourne T, et al. Early pregnancy loss. Nat Rev Dis Primers. 2016;2:16102. PMID: 28103269
- RCOG. Green-Top Guideline No. 25: Management of Early Pregnancy Loss. 2006.