Abortion (obstetric)
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Abortion (Obstetric)
In obstetrics, abortion refers to the termination of pregnancy — either spontaneous or induced — before the fetus reaches viability (generally before 20–24 weeks of gestation or a fetal weight < 500 g). The term "miscarriage" is commonly used interchangeably with spontaneous abortion.
Classification
By Cause
| Type | Description |
|---|---|
| Spontaneous | Unintentional loss of pregnancy (miscarriage) |
| Induced/Elective | Deliberate termination using medical or surgical methods |
| Therapeutic | Induced abortion for maternal or fetal medical indications |
By Clinical Presentation (Spontaneous)
| Type | Cervical Os | Products of Conception | Bleeding | Key Features |
|---|---|---|---|---|
| Threatened | Closed | In utero | Present | Pregnancy may continue; fetal heartbeat usually present |
| Inevitable | Open | In utero | Present + cramping | Cannot be prevented; miscarriage will occur |
| Incomplete | Open | Partially expelled | Heavy | Some tissue retained in uterus |
| Complete | Closed | Fully expelled | Diminishing | All POC passed; uterus empty on USS |
| Missed (Silent) | Closed | Retained | None/minimal | Fetal demise without expulsion; embryonic/gestational sac present |
| Septic | Variable | May be retained | Variable | Signs of infection (fever, uterine tenderness, offensive discharge) |
| Recurrent | — | — | — | ≥3 consecutive spontaneous abortions; affects ~1% of couples |
Epidemiology
- Spontaneous abortion occurs in approximately 15–20% of all clinically recognized pregnancies (Medication Management for Early Pregnancy Loss, p. 2).
- The majority (>80%) occur in the first trimester.
- Recurrent pregnancy loss affects ~1% of couples trying to conceive.
Etiology & Risk Factors
First-Trimester Loss
- Chromosomal/genetic abnormalities (~50–60% of cases) — most common cause; trisomies, monosomy X, polyploidy
- Advanced maternal age
- Uterine anomalies (fibroids, septum, Asherman's syndrome)
- Endocrine disorders (uncontrolled diabetes, thyroid disease, hyperprolactinaemia)
- Thrombophilias (antiphospholipid syndrome — especially in recurrent loss)
- Infections (Listeria, Toxoplasma, CMV, Rubella)
- Smoking, alcohol, cocaine use
- Obesity
Second-Trimester Loss
- Cervical incompetence/insufficiency
- Uterine anomalies
- Placental abruption
- Infection
- Chromosomal abnormalities (less common than first trimester)
Clinical Features
| Symptom | Notes |
|---|---|
| Vaginal bleeding | Cardinal symptom; ranges from spotting to heavy haemorrhage |
| Lower abdominal/pelvic cramping | Colicky; may indicate inevitable or incomplete abortion |
| Passage of tissue | Confirms expulsion of POC |
| Absence of fetal movement | In later presentations |
| Cervical dilation on exam | Indicates inevitable/incomplete abortion |
| Signs of infection | Fever, tachycardia, tender uterus, purulent discharge — septic abortion |
Diagnosis
Investigations
- Serum β-hCG: Serial measurements every 48 hours — a rise of <53% or a falling trend is suspicious for non-viable pregnancy; should approximately double every 48h in viable early pregnancy.
- Transvaginal ultrasound (TVUSS): Primary diagnostic tool
- Empty gestational sac (mean sac diameter ≥25 mm) without embryo → anembryonic pregnancy
- Crown-rump length ≥7 mm without cardiac activity → missed abortion
- Absent fetal heart activity
- Full blood count: Assess for anaemia
- Blood group and Rh factor: Anti-D prophylaxis required in Rh-negative patients
- Cervical swabs: If septic abortion suspected
- In recurrent pregnancy loss: thrombophilia screen, karyotyping (both partners), uterine cavity assessment (hysteroscopy/sonohysterography), thyroid/endocrine workup
Management
General Principles
A patient-centred approach is recommended. Three management strategies are available and all are safe and effective; patients offered their preferred option have higher satisfaction and better outcomes (Medication Management for Early Pregnancy Loss, p. 2).
1. Expectant Management
- Suitable for: incomplete abortion, missed abortion (haemodynamically stable patient with no infection)
- Allow spontaneous passage of POC
- Success rate: ~50–80% within 2 weeks for missed abortion; higher for incomplete
- Monitor β-hCG to confirm resolution
- Patient must have 24-hour access to emergency care
2. Medical Management
- Misoprostol (prostaglandin E₁ analogue): sublingual, buccal, or vaginal; causes uterine contractions and cervical softening
- Mifepristone + misoprostol (combined regimen): more effective than misoprostol alone for missed/anembryonic pregnancy
- Mifepristone 200 mg orally, followed 24–48 hours later by misoprostol 800 µg vaginally/buccally
- Success rate >80% within 2 weeks (Abortion Care, p. 17; Medication Management for Early Pregnancy Loss, p. 2)
- Side effects: cramping, nausea, vomiting, diarrhoea, fever
- Follow-up USS or β-hCG to confirm complete evacuation
3. Surgical/Procedural Management
- Uterine aspiration (manual vacuum aspiration [MVA] or electric vacuum aspiration [EVA]): preferred surgical method; safe and highly effective (>95%)
- Sharp curettage (D&C): less preferred due to risk of intrauterine adhesions (Asherman's syndrome); generally reserved where aspiration not available
- Indications for urgent surgical management:
- Heavy haemorrhage / haemodynamic instability
- Suspected or confirmed intrauterine infection (septic abortion)
- Patient preference when other methods have failed
Septic Abortion
- Medical emergency
- Broad-spectrum IV antibiotics (e.g. metronidazole + cephalosporin ± gentamicin)
- Prompt uterine evacuation (after stabilisation and antibiotics initiated)
- ICU support if septic shock
Rh-Negative Patients
- Anti-D immunoglobulin (Rh prophylaxis) should be given to all Rh(D)-negative women undergoing surgical evacuation or where gestational age is ≥10 weeks (local guidelines vary on threshold).
Complications
| Complication | Notes |
|---|---|
| Haemorrhage | Most common; may require transfusion or emergency evacuation |
| Infection / Sepsis | Especially post-procedure or retained POC |
| Retained products of conception (RPOC) | May require repeat evacuation |
| Uterine perforation | Rare surgical complication |
| Cervical injury | From instrumentation |
| Intrauterine adhesions (Asherman's) | Associated with D&C, especially repeated procedures |
| Psychological sequelae | Grief, depression, anxiety, PTSD — counselling should be offered |
| Cervical incompetence | Risk for future pregnancies after multiple procedures |
| Isoimmunisation | If Rh prophylaxis omitted in Rh-negative patients |
Prognosis & Counselling
- After a single spontaneous abortion, >80% of women will have a successful subsequent pregnancy.
- After 3 consecutive losses, the risk of another is ~40–45% without intervention; systematic investigation and treatment of underlying causes improves outcomes significantly.
- Women should be offered psychological support and counselling; grief is a normal response.
- Pregnancy can usually be attempted again after one normal menstrual cycle following a first-trimester loss.
Sources: Abortion Care (WHO, p. 17); Medication Management for Early Pregnancy Loss (p. 2); supplemented with standard obstetric clinical knowledge (Williams Obstetrics; RCOG/ACOG guidelines).
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