Impact of trophoblast penetration through the basal membrane on the efficacy of drug therapy in tubal pregnancies.

Concentrations of beta-human chorionic gonadotrophin (HCG) of 2500 IU/l are generally considered to be maximal for successful drug therapy of tubal pregnancies [instillation of prostaglandin-F2 alpha (PGF2 alpha) or hyperosmolar glucose]. The purpose of our study was to ascertain if there was an association between the significantly higher failure rates above this threshold value and the histologically determined anatomopathological substratum. We therefore evaluated the impact of trophoblast penetration through the basal membrane of the Fallopian tube on the efficacy of drug therapy. Pre-operative serum beta-HCG concentrations were compared with the histologically determined trophoblast penetration, distinguishing between ectopic pregnancies with intra-luminal growths up to the myosalpinx, and those with extra-luminal growths going beyond the basal membrane and penetrating the myosalpinx. Basic data were obtained from a group of patients who received primary surgical treatment but it had never been the intention for them to receive drug therapy (independently of their initial beta-HCG values; group I, n = 43). These reference data were compared with the findings in preparations from another group of patients obtained during secondary surgical intervention, performed to achieve final cure of tubal pregnancy after failure of primary PGF2 alpha instillation (group II, n = 30). Group I patients showed a significantly higher rate of intra-luminal trophoblast growths (P = 0.0001) at beta-HCG values < 2500 IU/l; above this threshold value, extra-lumina spread was found significantly more often (P = 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)