Beta human chorionic gonadotropin levels in cul-de-sac blood of patients with ectopic pregnancies.

hCG levels in cul-de-sac and peripheral blood in patients with ectopic pregnancies were studied. hCG levels were significantly higher in the cul-de-sac blood than in peripheral blood (P less than 0.01). The high hCG level in the cul-de-sac blood was not due to interference by proteolytic enzymes in cul-de-sac blood since the protease inhibitors, aprotinin and phenylmethylsulfony fluoride, did not alter the RIA results from cul-de-sac samples, nor did Con-A chromatography of the samples. Assay of cul-de-sac blood samples for hCG may increase the sensitivity of diagnosing ectopic pregnancies.