The use of ultrasound in threatened abortion.

One hundred and twenty-seven pregnancies complicated by painless vaginal bleeding before 20 weeks of gestation were scanned. In the 51 cases where pregnancy continued the scan was normal in 80%. In an additional 10% the only abnormalities were either a low placental implantation or a twin pregnancy, one sac of which was blighted. In another 6% the initial scan was difficult to interpret and a repeat scan was normal. In the remaining 2% an error was made. In the 76 cases where the pregnancy did not continue the scan was abnormal in 83%, there was a low placental implantation but no other abnormality in 4% and in an additional 6.5% a repeat scan was abnormal after an initial normal scan. In the remaining five cases there was one error, abortion occurred probably for obstetrical reasons in three and there was one twin pregnancy where only one sac was abnormal but both were aborted. Ectopic pregnancy was diagnosed in only 33% of cases while molar pregnancy was diagnosed in 75% and in the one which ultrasound failed to diagnose the appearances suggested abortion was inevitable.