EVALUATION OF SERUM INHIBIN-A AS A SURVEILLANCE MARKER AFTER CONSERVATIVE MANAGEMENT OF TUBAL PREGNANCY

Tubal pregnancy is now commonly managed by laparoscopic salpingostomy or systemic methotrexate. A disadvantage of such conservative manageme nt is the need for appropriate follow-up, with serial measurement of s erum concentrations of human chorionic gonadotrophin (HCG), to exclude persistent ectopic pregnancy (PEP), Concentrations of inhibin A, also a placental product, are significantly increased during pregnancy and the half-life of inhibin A is significantly shorter than that of HCG, To assess the suitability of inhibin A as a marker of PEP, we studied 16 women who had undergone surgery for a tubal pregnancy, measuring H CG and inhibin during follow-up. The mean +/- SEM time taken to achiev e non-pregnant concentrations of inhibin A was significantly shorter t han for HCG (4.2 +/- 0.8 days versus 21.6 +/- 4.4 days respectively; P < 0.001 Wilcoxon signed rank test). However, in all women the inhibin A concentration increased rapidly after reaching a nadir, reflecting the return of ovarian function, complicating the interpretation of res ults. In four women inhibin A was almost undetectable preoperatively, while the corresponding HCG concentration was high. These data suggest that inhibin A will not be a useful marker for PEP but that it may pr ovide a more accurate preoperative assessment of trophoblast viability than HCG, thereby improving management.