Serum inhibin levels are lower in ectopic than intrauterine spontaneously conceived pregnancies.
Seifer DB, Lambert-Messerlian GM, Canick JA, Frishman GN, Schneyer AL. Serum inhibin levels are lower in ectopic than intrauterine spontaneously conceived pregnancies. Fertil Steril. 1996 Mar; 65(3):667-9.