Tubal pregnancy with normal hysterosalpingogram and negative serum pregnancy test

A patient undergoing evaluation for primary infertility with regular menses had a normal hysterosalpingogram in the follicular phase and underwent diagnostic laparoscopy the next day, with the finding of a tubal pregnancy. The patient had a negative serum pregnancy test. Although a normal hysterosalpingogram and negative serum pregnancy test are each rare with a tubal pregnancy, the combination of the two occurring in a tubal pregnancy is previously unreported and did not exclude the diagnosis in this case.