Ectopic pregnancy. Six atypical cases.

Improved methods for detecting ectopic pregnancy, including pelvic ultrasound and radioimmunoassay of the beta subunit of human chorionic gonadotropin, have increased the physician's ability to make an early and specific diagnosis. An algorithm presented in this article decreases the chance of misdiagnosis and often defines unusual cases that previously may have been overlooked, such as concomitant intrauterine and tubal pregnancy, bilateral tubal pregnancy, and tubal pregnancy years after bilateral tubal ligation. The algorithm, which remains to be validated, is recommended as an additional tool when the clinical situation is equivocal.