Threatened miscarriage (or threatened abortion) is mainly a clinical term, used when a pregnant woman in first 20 weeks of gestation presents with spotting, mild abdominal pain and contractions, with a closed cervical os.
It occurs in 20-25% of pregnancies and is associated with an increased rate of fetal loss (15-50%, compared to 2-7%).
Cervix is closed, and there is a live intrauterine gestation.
In many cases, the ultrasound will be either completely normal, or with a subchorionic haemorrhage.
Some features suggestive of a poor outcome:
- fetal bradycardia: <80-90 bpm
- small mean gestational sac diameter
- large and calcified yolk sac of more than 7 mm
- small or irregular gestational sac: MSD/CRL <5 mm
- large subchorionic haemorrhage more than 2/3 of gestational sac
- expanded amnion sign (an abnormally large amniotic cavity)
- absent or poor decidual reaction
Treatment and prognosis
Threatened miscarriage can go on to become any of:
First trimester of pregnancy
- ultrasound findings in early pregnancy
- confirming intrauterine gestation
- pregnancy of unknown location (PUL)
first trimester vaginal bleeding
- ectopic pregnancy
failed early pregnancy
- pregnancy of uncertain viability (PUV)
- anembryonic pregnancy
- yolk sac abnormalities
- gestational trophoblastic disease
- subchorionic haemorrhage
- demise of a twin
- implantation bleeding
- aneuploidy testing