Ectopic pregnancy subsequent to sterilization: histologic evaluation and clinical implications.

Ten ectopic pregnancies subsequent to tubal sterilization were histologically evaluated. In seven of the ten cases, the sites for the ectopic implantation appeared to be related to the presence of a distal remaining tubal segment that had a tuboperitoneal fistula on the medial side. As against a currently held opinion that the ectopic implantation occurs secondary to a relative disparity in the size of the sperm, the fertilized ovum, and the proximal tuboperitoneal fistula, we believe that the implantations are influenced by probable fluid movements within the remaining tubal segments. The need to consider conservative surgical approaches and good intraoperative notations in patients with an ectopic pregnancy subsequent to sterilization is stressed.