Delayed implantation. A case report.

In cycles in which conception takes place, serum human chorionic gonadotropin (hCG) becomes detectable between 8 and 12 days after ovulation. A delayed appearance of hCG has been reported in a limited number of cases, most of them ending in spontaneous abortion. We encountered a case of ectopic pregnancy characterized by a delayed appearance of hCG and accompanied by a complete, albeit temporary, halt in the steroidogenic activity of the corpus luteum. Although the patient was at risk of developing an ectopic pregnancy, the findings made an early diagnosis extremely difficult.