Miscarriage loosely refers to loss of pregnancy in the first half a pregnancy: before 20 weeks in New Zealand, after 20 weeks it is termed stillbirth.1 Miscarriage is very common; RANCOG reports the lifetime risk is in the region of 25%. The term spontaneous abortion is synonymous with miscarriage.
Classification of miscarriage (by timing and symptoms)
Missed miscarriage
When a foetus is found to be dead incidentally this is known as a missed miscarriage. It is often only picked up at routine antenatal clinic visits as it is classically asymptomatic with no expulsion of pregnancy tissue. The cervical os is closed
Threatened miscarriage
This is the term typically given to any vaginal bleeding, or more accurately, pregnancy associated bleeding per vaginam. The os remains closed and a viable pregnancy present by imaging.
Incomplete miscarriage
Refers to the partial loss of pregnancy tissue before 20 weeks gestation. It is associated with moderate to severe vaginal bleeding and associated pelvic pain which is often ongoing. The cervical os is typically open.
Complete miscarriage
The passage of all pregnancy tissue is associated with bleeding and pain, often the products of conception are frankly visible. At the completion of the miscarriage, that is, when all tissue is expelled, the pain should rapidly subside, ongoing pain and bleeding my suggest incomplete miscarriage as above. The os is typically closed.
Treatment of miscarriage
Threatened miscarriage
In patients with a history of miscarriage, vaginal progesterone (400mg, micronised) should be offered. If a foetal heartbeat is confirmed, progesterone should be continued until 16 weeks.
Conservative
Advise on the expected course and observe. Often the miscarriage will complete without medical intervention.
Medical
The typical regimen is:
- Mifepristone 200mg, followed 48hr later by;
- Misoprostol 800mg bucally.
- With the addition of simple analgesia.
Surgical
This can be offered at any stage, though often preferred to medical management at later gestations.
Termination of pregnancy
Medical abortion in the first trimester is simply a matter of inducing miscarriage. Usually this is done with medicines or surgically, as with uterine evacuation.
The dosing for medical termination of pregnancy is the same as that for the treatment of miscarriage. This is because the medications, mifepristone and misoprostol, causes failure of placentation and uterine contraction.
Further reading
- Ectopic pregnancy and miscarriage: diagnosis and initial management. NG126. National Institute for Healthcare and Excellence; 2019.
Footnotes
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Births, Deaths, Marriages, and Relationships Registration Act 2021. Dec 15, 2021. ↩