Abortion & Miscarriage

Abortion (miscarriage) is the termination of pregnancy before the fetus attains viability, conventionally taken as 20 weeks of gestation or fetal weight < 500 g (WHO uses 22 weeks/500 g). It is the commonest complication of early pregnancy and a guaranteed source of direct recall questions in NEET PG — both for the clinical classification and the MTP Act provisions.

Definition & basic terminology

• Abortion / miscarriage — expulsion or extraction of the products of conception (POC) before viability. The lay-friendly term "miscarriage" is preferred for spontaneous loss; "abortion" now often implies induced. For exams the words are used interchangeably for spontaneous loss.
• Early abortion — before 12 completed weeks (first trimester); late abortion — 12 to 20 weeks.
• Spontaneous abortion — occurs naturally; induced abortion — deliberate termination (medical/surgical).
• Viability cut-off — 20 weeks / 500 g in India (Indian textbooks, e.g. Dutta); the WHO threshold is 22 weeks / 500 g. Either may appear, but Indian texts favour 20 weeks.

High-yield: Spontaneous abortion occurs in ~15% of clinically recognised pregnancies. The single most common cause of spontaneous (especially first-trimester) abortion is chromosomal abnormality, most often autosomal trisomy (trisomy 16 being the commonest single trisomy).

Etiology of spontaneous abortion

Causes are conventionally split by trimester. First-trimester loss is dominated by fetal (genetic) factors; second-trimester loss is dominated by maternal/anatomical factors.

Category	Examples
Genetic (commonest in 1st trimester)	Autosomal trisomy (esp. trisomy 16), monosomy X (45,X / Turner), triploidy, polyploidy
Endocrine	Luteal phase defect, uncontrolled diabetes, thyroid dysfunction, PCOS
Anatomical (commonest in 2nd trimester)	Cervical incompetence, uterine septum, bicornuate uterus, submucous fibroid, Asherman syndrome
Infective	TORCH, syphilis, listeria, malaria, bacterial vaginosis
Immunological	Antiphospholipid antibody syndrome (APLA), SLE
Maternal/medical	Severe anaemia, hypertension, cyanotic heart disease, trauma
Environmental	Smoking, alcohol, irradiation, lead, anaesthetic gases

High-yield: Cervical incompetence is the classic cause of recurrent painless, mid-trimester abortion with progressive cervical dilatation and expulsion of a live fetus. Antiphospholipid antibody syndrome (APLA) is the most important treatable cause of recurrent abortion.

Clinical types — the core classification

This table is the single most examined concept of the chapter. Memorise the cervical-os status and uterine size for each.

Type	Bleeding	Pain	Internal os	Uterus size	POC passed	Outcome
Threatened	Slight	Mild/absent	Closed	= dates	No	Pregnancy may continue (~⅔ continue)
Inevitable	Moderate→heavy	Yes (cramping)	Open	= dates	No (yet)	Abortion unavoidable
Incomplete	Heavy	Yes	Open	< dates	Partial	Some POC retained
Complete	Decreasing	Subsides	Closed	< dates	All POC	Resolved
Missed	Slight/brown	Absent	Closed	< dates	No (dead)	Retained dead fetus
Septic	Offensive	Yes + fever	Open/closed	Variable	±	Infected; sepsis

Stepwise natural history of an abortion: Threatened → (if it progresses) → Inevitable → (partial expulsion) → Incomplete → (full expulsion) → Complete. A threatened abortion may also resolve and the pregnancy continue normally.

Threatened abortion

Slight vaginal bleeding with a closed internal os and a viable intrauterine pregnancy. The uterus corresponds to the period of amenorrhoea. Management is largely expectant: rest, reassurance, avoid heavy work, no proven benefit of routine progesterone (though it is widely used). Confirm fetal viability with USG.

Inevitable abortion

Bleeding with painful uterine contractions and a dilated (open) internal os; the pregnancy cannot be salvaged. Management: if < 12 weeks and stable, surgical evacuation (suction/curettage); if heavy bleeding, resuscitate and evacuate. After 12 weeks, allow expulsion of fetus then evacuate placenta.

Incomplete abortion

Part of the POC is expelled, part retained (commonly placental tissue). Continued bleeding and cramping, open os, uterus smaller than dates. Suction evacuation / D&E is the treatment of choice; medical management with misoprostol is an option for stable patients.

Complete abortion

The entire conceptus is expelled (more typical before 8 weeks or after 16 weeks, when fetus and placenta come away together). Bleeding and pain subside, os closes, uterus involutes. USG shows an empty uterus with endometrial thickness < 15 mm — no intervention needed.

Missed abortion (early fetal demise / "silent miscarriage")

The fetus dies but is retained for weeks. Symptoms of pregnancy regress, the uterus stops growing or shrinks, and there is no/brown discharge. Older texts describe a carneous (fleshy) mole (Breus mole) — a blood-clot–surrounded retained ovum. Diagnosis is by USG.

High-yield: A serious complication of prolonged missed abortion (retention > 4 weeks) is disseminated intravascular coagulation (DIC) due to release of thromboplastin. Always check coagulation profile / fibrinogen before evacuating a long-standing missed abortion.

Septic abortion

Any abortion complicated by infection of the genital tract (temperature ≥ 38°C, offensive discharge, lower abdominal pain/tenderness). Usually follows unsafe/illegal induced abortion or incomplete abortion. Common organisms: E. coli, Bacteroides, anaerobic streptococci, Clostridium perfringens (gas gangrene), C. tetani.

Grading of septic abortion:

• Grade I — infection localised to the uterus.
• Grade II — spread to parametrium, tubes, ovaries, pelvic peritoneum.
• Grade III — generalised peritonitis, septicaemia, endotoxic shock, acute renal failure.

Management: triple antibiotics (ampicillin + gentamicin + metronidazole), IV fluids, evacuation of the uterus once antibiotic levels achieved (usually within hours if bleeding heavy), tetanus prophylaxis, and surgery (colpotomy/laparotomy) for collections or bowel injury.

Recurrent (habitual) abortion

Definition: three or more consecutive spontaneous abortions (ACOG/clinically, evaluation is begun after two consecutive losses). Affects ~1% of couples.

Trimester	Typical cause	Hallmark
First-trimester recurrent	Genetic (balanced translocation), APLA, endocrine (LPD, thyroid, DM), PCOS	Often early, with pain & bleeding
Second-trimester recurrent	Cervical incompetence, uterine anomalies (septate uterus)	Painless cervical dilatation, live fetus expelled

• Investigations: parental karyotyping, APLA panel (lupus anticoagulant, anticardiolipin, anti-β2-glycoprotein I), TSH/HbA1c, pelvic USG/hysteroscopy/HSG for uterine anomalies.
• Cervical incompetence Rx: cervical cerclage — McDonald (purse-string, commonest) or Shirodkar suture, placed at 14–16 weeks, removed at ~37 weeks or at onset of labour.
• APLA Rx: low-dose aspirin + heparin (LMWH) throughout pregnancy — the classic high-yield answer.

High-yield: The most common anatomical cause of recurrent miscarriage is a septate uterus (best treated by hysteroscopic septal resection). The most common treatable cause overall is APLA syndrome.

Investigations & investigation of choice

• Transvaginal ultrasound (TVS) is the single most useful investigation — confirms location (rules out ectopic), viability, and type of abortion.
• USG criteria for non-viability (early pregnancy failure):
  • Crown-rump length (CRL) ≥ 7 mm with no cardiac activity.
  • Mean gestational sac diameter (MSD) ≥ 25 mm with no embryo (yolk sac/fetal pole).
  • No embryo with heartbeat ≥ 2 weeks after a scan showing a gestational sac without a yolk sac, or ≥ 11 days after a sac with a yolk sac.
• Serum β-hCG: discriminatory zone — a normal IUP should be seen on TVS once β-hCG > 1500–2000 mIU/mL. In a viable IUP β-hCG roughly doubles every 48 hours; a sub-optimal rise suggests failing pregnancy or ectopic.
• Blood group & Rh typing — to plan anti-D.
• CBC, coagulation profile (especially in missed/septic abortion).

High-yield: Remember the magic numbers — CRL ≥ 7 mm, no FHR and MSD ≥ 25 mm, empty sac = early pregnancy failure (miscarriage). These exact cut-offs are frequently asked.

Management overview

General approach: Assess haemodynamic stability → confirm diagnosis on TVS → decide expectant vs medical vs surgical → give anti-D to all Rh-negative women → counsel.

Modality	Best for	Agent / procedure
Expectant	Threatened; some incomplete/missed (stable, < 12 wk)	Watchful waiting
Medical	Missed/incomplete abortion, stable patient	Mifepristone then misoprostol; misoprostol alone also used
Surgical	Heavy bleeding, sepsis, failed medical, patient choice	Suction evacuation (MVA) < 12 wk; D&E later

• Drug of choice for medical evacuation: Mifepristone (anti-progesterone) 200 mg followed 24–48 h later by Misoprostol (PGE1 analogue) 800 µg. Misoprostol acts as a cervical ripener and uterotonic.
• Anti-D immunoglobulin (e.g. 50 µg < 12 weeks, 300 µg later) to all Rh-negative, non-sensitised women after any abortion.
• Ergometrine / oxytocin for uterine atony bleeding after evacuation.

The MTP Act — high-yield legal facts

The Medical Termination of Pregnancy (MTP) Act, 1971, amended in 2021, governs legal induced abortion in India.

Gestation	Approval needed
Up to 20 weeks	Opinion of one registered medical practitioner (RMP)
20 to 24 weeks	Opinion of two RMPs (only for special categories of women)
Beyond 24 weeks	Only if substantial fetal abnormality diagnosed by a State Medical Board (no upper limit)

Permissible grounds for MTP:

1. Risk to the life of the pregnant woman or grave injury to physical or mental health.
2. Substantial risk of serious fetal abnormality ("eugenic").
3. Pregnancy caused by rape (presumed to cause grave mental injury).
4. Contraceptive failure — now extended to any woman and her partner (earlier only married woman).

Key 2021 amendment points (frequently tested):

• Upper limit raised from 20 → 24 weeks for special categories (survivors of rape/incest, minors, differently-abled, fetal malformation, change in marital status, etc.).
• No upper gestational limit when a State Medical Board diagnoses substantial fetal abnormality.
• Confidentiality of the woman's identity is mandatory.
• The opinion of the woman alone is sufficient; consent of the husband is NOT required (only the woman's written consent; guardian's consent if minor or mentally ill).

High-yield: Below 20 weeks → one doctor; 20–24 weeks → two doctors; beyond 24 weeks → only for fetal abnormality via State Medical Board. Consent of the woman ALONE (≥ 18 yrs) suffices; partner consent is not required.

Complications

• Haemorrhage and shock (especially inevitable/incomplete).
• Sepsis — leading to septic shock, septic pelvic thrombophlebitis.
• DIC — missed abortion, septic abortion, amniotic-fluid related.
• Uterine perforation / cervical injury during surgical evacuation; bowel/bladder injury.
• Acute renal failure in septic abortion (clostridial / endotoxic).
• Retained POC → continued bleeding, infection.
• Asherman syndrome (intrauterine adhesions) and cervical incompetence from repeated/aggressive curettage — late sequelae causing secondary infertility and future recurrent loss.
• Rh isoimmunisation in Rh-negative women not given anti-D.

Key differential diagnoses

A woman with first-trimester bleeding ± pain — always exclude:

Condition	Distinguishing feature
Ectopic pregnancy	Amenorrhoea + pain + bleeding; empty uterus with β-hCG above discriminatory zone; adnexal mass, cervical motion tenderness; collapse if ruptured
Hydatidiform mole	Uterus larger than dates, very high β-hCG, "snowstorm" / bunch-of-grapes USG, hyperemesis, early pre-eclampsia, theca-lutein cysts, grape-like vesicles per vaginum
Implantation bleed	Scanty, self-limiting; viable IUP on USG
Cervical/local lesion	Polyp, erosion, carcinoma — speculum & Pap
DUB / non-pregnant cause	Negative pregnancy test

High-yield: First-trimester bleeding + empty uterus + β-hCG > discriminatory zone = ectopic until proven otherwise. Never anchor on "abortion" without ruling out ectopic and molar pregnancy.

Eponyms & named terms

• Carneous / Breus mole — retained missed abortion surrounded by laminated blood clot.
• McDonald & Shirodkar — cervical cerclage techniques for incompetent os.
• Asherman syndrome — intrauterine synechiae after vigorous curettage.
• Discriminatory zone — β-hCG threshold (1500–2000 mIU/mL) above which an IUP should be visible on TVS.

Recently asked / exam angle

• Direct one-liners on os status (closed in threatened/missed/complete; open in inevitable/incomplete).
• MTP Act limits post-2021 amendment — "Beyond 24 weeks termination allowed only for…?" → substantial fetal abnormality via State Medical Board; "20–24 weeks needs opinion of how many doctors?" → two.
• USG cut-offs for early pregnancy failure (CRL ≥ 7 mm no FHR; MSD ≥ 25 mm empty).
• Commonest cause of spontaneous abortion → autosomal trisomy (trisomy 16).
• Recurrent mid-trimester painless loss → cervical incompetence; treatment → cerclage at 14–16 weeks.
• Treatable cause of recurrent abortion → APLA → aspirin + heparin.
• Drug regimen for medical abortion → mifepristone + misoprostol; misoprostol mechanism (PGE1).
• Missed abortion + prolonged retention → DIC / hypofibrinogenaemia.
• Septic abortion grading and organism (Clostridium perfringens → gas gangrene, ARF).

Rapid revision

1. Abortion = pregnancy loss before 20 weeks / 500 g (India); WHO 22 weeks.
2. Commonest cause of spontaneous abortion = chromosomal (autosomal trisomy, trisomy 16).
3. Os closed → threatened, missed, complete; os open → inevitable, incomplete.
4. Threatened abortion = slight bleed + closed os + viable fetus → expectant management.
5. Incomplete abortion → suction evacuation is treatment of choice.
6. Missed abortion retained > 4 weeks → risk of DIC; check fibrinogen.
7. USG early pregnancy failure: CRL ≥ 7 mm no FHR or MSD ≥ 25 mm empty sac.
8. Recurrent abortion = ≥ 3 consecutive losses; evaluate after 2.
9. Painless mid-trimester loss = cervical incompetence → cerclage at 14–16 weeks (McDonald/Shirodkar).
10. APLA = treatable recurrent abortion → low-dose aspirin + LMWH.
11. Medical abortion = mifepristone 200 mg + misoprostol 800 µg; misoprostol = PGE1.
12. MTP Act: ≤ 20 wk → 1 doctor; 20–24 wk → 2 doctors; > 24 wk → fetal abnormality + State Medical Board; woman's consent alone suffices, anti-D for all Rh-negative women.