What is the significance of the human chorionic gonadotropin value in ectopic pregnancy?

Surgical and pathology data were analyzed with the quantitative serum hCG values from 131 patients with tubal pregnancies. The hCG value correlated with both the size and contents of the eccyesis. Patients with ruptured tubal pregnancies had significantly greater serum hCG levels than did those with intact tubal gestations. Isthmic tubal pregnancies were associated with more frequent rupture and larger amounts of hemoperitoneum than were pregnancies in the ampullary segment of the tube. Tubal rupture with hCG values below 100 mIU/mL occurred in two isthmic pregnancies but in no ampullary pregnancies. With serum hCG levels below 300 mIU/mL, significant hemorrhage did not occur unless the tube was ruptured. Half of the patients had hCG levels sufficient to use a vaginal sonographic hCG discriminatory zone to assist in the diagnosis. A maximum of 15% of tubal pregnancies may be diagnosed by ultrasonographic detection of adnexal cardiac activity. A serum hCG assay sensitive to 10 mIU/mL will detect nearly all tubal pregnancies. The hCG level frequently has diagnostic value when used in conjunction with vaginal sonography. At hCG levels of 100 mIU/mL or less, tubal rupture is very unlikely for ampullary, but not for isthmic, tubal pregnancies.