Basis and effects of local drug therapy in tubal pregnancies

Objective: An empirically established serum beta human chorionic gonadotropin (beta-HCG) threshold level of 2,500 IU/l is considered as the limit for successful drug therapy. The purpose of our study was to ascertain if this threshold level correlates with the histopathology. Further, we evaluated the effects of local drug therapy on the tubal wall. Methods: Between 1988 and 1993 129 cases of tubal pregnancies were treated by local prostaglandin F-2 alpha instillation. For final cure 30 patients had to undergo further surgical measures. Our study was based upon the histological samples which were excised during secondary operation. Results: Below 2, 500 IU/l beta-HCG, intraluminal growth of the trophoblast is more frequent, whereas at higher values extraluminal spread predominates (p = 0.0045). Cells of ectopic trophoblast proliferate significantly slower than those of intrauterine pregnancies. Prostaglandin F-2 alpha application selectively destroys ectopic gestational tissue and preserves the tubal wall. Conclusion: The integrity of the tubal wall with its contractile potential is essential for successful therapy by local instillation of prostaglandin F-2 alpha.