Subchorionic haemorrhage

Last revised by Chirag Udhani on 17 Oct 2022

Subchorionic haemorrhage occurs when there is perigestational haemorrhage and blood collects between the uterine wall and the chorionic membrane in pregnancy. It is a frequent cause of first and second trimester bleeding.

It typically occurs within the first 20 weeks of gestation. When seen in the first 10-14 days of gestation, they are also termed implantational bleeds.

  • crescentic collection with elevation of the chorionic membrane
  • depending on the time elapsed since bleeding, the collection will have variable echotexture
    • acute: hyperechoic and may be difficult to differentiate from the adjacent chorion
    • subacute-chronic: decreasing echogenicity with time
  • in almost all cases there is an extension of the haematoma towards the margin of the placenta 3

In early pregnancy, a subchorionic haemorrhage is considered small if it is <20% of the size of the sac, medium-sized if it is 20-50% 9, and large if it is >50-66% of the size of the gestational sac 5.

Large haematomas by size (>30-50%) and volume (>50 mL) worsen the patient's prognosis 9.

Fetal outcome is dependent on the size of the haematoma, maternal age, and gestational age 2. In most cases, the haematoma gradually decreases in size on follow-up and can resolve over 1-2 weeks 9. A subchorionic haemorrhage places the gestation at increased risk of:

If the collection extends to the internal os and/or there is dilatation of the internal cervical os, this is an indication of extremely poor prognosis, almost always leads to impending miscarriage

General imaging differential considerations include:

ADVERTISEMENT: Supporters see fewer/no ads

Updating… Please wait.

 Unable to process the form. Check for errors and try again.

 Thank you for updating your details.