Miscarriage
Definition
Epidemiology
Risk Factors
Aetiology
Pathogenesis
Minute haemorrhage in endometrium --> embryo detach --> uterine contraction
(<8/40) --> whole embryo expelled --> uterine bleeding --> blighted ovum
(8-14/40) --> defective foetus expelled, placenta remains --> huge haemorrhage
(14-22/40) --> foetus expelled then placenta --> less bleeding, more pain (like mini labour)
- Abortion = Expulsion of foetus before it reaches viability
- Terminology: Abortion = induced abortion, miscarriage = spontaneous abortion
- WHO def of viability: 22/40 or >500g = ability to survive outside uterus
- Tasmania = 24/40
Epidemiology
- M/C commonly 6-10/40
- 10-20% of population
- 95% PV bleeding <20/40 (others: ectopic preg, hydatidiform mole, cervical ca, everted cervical epithelium, endocervical polyp)
Risk Factors
- Maternal age (>30y, higher >35y)
- Paternal age (>40y; but lesser risk than maternal age)
- Gravidity (more = higher risk)
Aetiology
- 20% Implantation (N = 8-10d after ovulation; poorer outcome if implanted later)
- 70% Ovofoetal (0-10/40; failed development/ malformation)
- 10% Maternal (11-22/40; systemic disease (SLE, inf), uterine anomaly (submucous tumour, cervical incompetence), smoking)
Pathogenesis
Minute haemorrhage in endometrium --> embryo detach --> uterine contraction
(<8/40) --> whole embryo expelled --> uterine bleeding --> blighted ovum
(8-14/40) --> defective foetus expelled, placenta remains --> huge haemorrhage
(14-22/40) --> foetus expelled then placenta --> less bleeding, more pain (like mini labour)
Clinical Features
Threatened M/C
Bleeding: Yes
Pain (contractions): Yes/ No
Cervix: Closed
US: N foetus with beating heart (98%)/ empty sac/ missed or incomplete M/C
Rx: Reassure + D/C/ Continue monitoring
Inevitable M/C
Bleeding: Yes
Pain (contractions): Yes
Cervix: Open + sac showing
US: To determine if everything is expelled
Rx: Admit. Wait till complete M/C. If incomplete (ie >10mm tissue/clots), curettage or misoprostol. Monitor for shock (vasovagal/ haemorrhagic)
Complete M/C
Bleeding: Yes (<12/40, products of conception will be expelled)
Pain: Yes but stopped
Abdo: small uterus
Cervix: Open/ closed
US: Empty uterus
Rx: Products of conception - pathological check for chorionic villus. Seen = D/C. If not seen/ no specimen, serial B-HCG (should decrease. If not = ectopic pregnancy)
Incomplete M/C
Bleeding: Yes (>12/40, products of conception present, only fetus passed)
Pain: Yes
Abdo: Uterus smaller than gestation age but products of conception still present
Cervix: Open
US: Products of conception present
Rx: Medical/ surgical evacuation
NOTE: Bleeding varies, can be severe enough to cause hypovolaemic shock
Missed M/C
Bleeding: Yes
Pain: No
Cervix: Closed
Pregnancy sx stop
No foetal HR; US: arrested growth
Rx: Wait for spontaneous M/C/ If >12-14/40 gestational size or >28d after dx, surg evacuation due risk of haemorrhage
Source
Llewellyn-Jones Fundamentals of Obsterics and Gynaecology 9th Ed 2010
UpToDate 2013