ultrasound screening in the 1st and 2nd trimester

Last reviewed 01/2018

Ultrasonography can be used for the following:

  • diagnosis of pregnancy
  • abortion
  • ectopic pregnancy
  • hydatidiform mole
  • multiple pregnancy
  • dating a pregnancy
  • detection of congenital abnormality
  • guidance of invasive procedures

Notes (1):

  • pregnant women should be offered an early ultrasound scan between 10 weeks 0 days and 13 weeks 6 days to determine gestational age and to detect multiple pregnancies. This will ensure consistency of gestational age assessment and reduce the incidence of induction of labour for prolonged pregnancy
  • crown-rump length measurement should be used to determine gestational age. If the crown-rump length is above 84 mm, the gestational age should be estimated using head circumference


  1. NICE (2008). Antenatal care