RESUMEN
We evaluated the diagnostic accuracy of activin B in discriminating tubal ectopic pregnancy (tEP) from intrauterine miscarriages (IUM), and normal viable intrauterine pregnancy (IUP). We included 28 women with tEP, 31 women with IUM, and 29 normal IUP, confirmed both by clinical examination and ultrasonography. Serum activin B concentration was measured at the time of admission using the ELISA kit. The median serum activin B concentration was found to be significantly decreased in both tEP (p=0.004) and IUM (p=0.022) compared to normal IUP. When compared between tEP and IUM, activin B concentrations did not differ significantly. ROC analysis of activin B and free ß-hCG demonstrated AUC of 0.722 and 0.805, respectively to discriminate tEP from viable IUP. The model including both activin B and free ß-hCG improved the discriminating potential with greater AUC (0.824), and specificity (93%) than individual one. To discriminate tEP from IUM, activin B, free ß-hCG and combination of both performed poorly. We conclude that serum activin B concentration is lower in tubal ectopic pregnancy, and can discriminate it from normal pregnancy with moderate accuracy. It also shows improved diagnostic potential along with free ß-hCG, but cannot distinguish tEP from IUM reliably.