Pregnancy-specific beta-1 glycoprotein in ectopic pregnancy

PSBG and hCG were estimated by radioimmunoassays in the serum of 19 consecutive patients undergoing abdominal surgery for suspected ectopic pregnancy. Ectopic pregnancy was verified at operation in 14 cases, and the other five patients had a hemorrhagic cyst of the corpus luteum. Demonstrable PSBG and hCG were found in all patients with ectopic pregnancy. One of them had taken bromocriptine for infertility, and in serial blood samples taken during the luteal phase both PSBG and hCG were identified on day 24 of the fertile cycle. One of the five patients with a hemorrhagic cyst of the corpus luteum showed detectable PSBG and hCG in several serum samples taken before operation. This patient had experienced legal abortion 3 months ago, and the presence of PSBG and hCG in her serum may represent prolonged trophoblastic activity after pregnancy. Our results show that PSBG appears in the serum very early in pregnancy. However, some obscure positive results may be encountered, and this must be appreciated when these markers are applied for clinical use. Since the PSBG and hCG tests are likely to have different sources of error, PSBG estimation may become a useful adjunct to the hCG test in the detection of trophoblastic activity in suspected ectopic pregnancy.