Serum follistatin-like-3 levels in the diagnosis of tubal ectopic pregnancy

INTRODUCTION: Activin is necessary for maintaining normal pregnancy; follistatin and follistatin-like-3 (FSTL3) are known antagonists of activin. FSTL3 also has a role in the migration and invasion of trophoblasts. We aim to measure the value of serum FSTL3 levels in the diagnosis of tubal ectopic pregnancy.
METHODS: Seventy-six pregnant women including 39 women with surgically confirmed tubal ectopic pregnancy and 37 healthy, singleton controls whose gestational ages were between 5 and 8 weeks. Serum FSTL3 levels were measured in both groups through ELISA. Receiver operator characteristic (ROC) curve analysis was performed for the prediction of tubal ectopic pregnancy using serum FSTL3.
RESULTS: Serum FSTL3 levels were significantly lower in the ectopic pregnancy group than in controls (p<0.001). ROC analysis showed that the area under the curve in the curve (AUC) was 0.811 (0.713–0.909; 95% confidence interval). The highest value of the sum of sensitivity and specificity in the ROC curve is the point where the FSTL3 level was 2160.7535 (cutoff value) with a sensitivity and specificity of 75.7% and 79.5%, respectively. Furthermore, the subset analysis of patients with prior ectopic pregnancy showed that serum FSTL3 was the highest in patients without any previous ectopic pregnancy (p<0.001).
DISCUSSION AND CONCLUSION: Low levels of serum FSTL3 may be a potential biomarker in the early diagnosis of tubal ectopic pregnancy.