Radioimmunoassay of human chorionic gonadotropin beta-subunit as an early diagnostic test in ectopic pregnancy.

Serum HCG-beta has been assayed in 100 cases of ectopic pregnancy. Results above 10 IU/l were considered positive. Positive values were found in 97 cases, of which 23 were within the range of a normal pregnancy, one was above and 73 below the normal range. In the 3 cases with a negative HCG-beta value, devitalized ectopic pregnancies were found at operation. The routine urine pregnancy test was negative in 53, positive in 29 and not performed in 18 cases.