Serum activin A levels are lower in tubal than intrauterine spontaneously conceived pregnancies.

Objective: To measure serum activin A levels together with progesterone and hCG, in women with overt clinical signs and symptoms of ectopic pregnancy (EP) and, in gestational age-matched intrauterine pregnancy (IUP).

Design: Retrospective case-control study.

Setting: Department of Pediatrics, Obstetrics and Reproductive Medicine, Section of Obstetrics and Gynecology, University of Siena, Siena, Italy.

Population: The study group was composed by 30 women with an EP; the control group was composed by 30 women with a sonographic evidence of a single spontaneous IUP.

Methods: Clinical examination; transvaginal ultrasound scan; hCG, progesterone and activin-A measurements; laparoscopy; uterine curettage; histological examination.

Main Outcome Measure: Pregnancy outcome; sensitivity and specificity of hCG, progesterone, and activin A for EP.

Results: Serum hCG levels did not differ significantly between tubal EP and IUP, while P concentrations were significantly (P < 0.001) lower in tubal EP than IUP. Serum levels of activin A were significantly (P < 0.0001) lower in tubal EP than in IUP and, at the cutoff 0.43 ng/mL achieved a sensitivity of 96.7% and a specificity of 100% for EP.

Conclusion: Activin A secretion in EP is reduced and measurement of its serum levels may have the potential clinical advantage to signal the presence of EP.