Serum calponin 2 is a novel biomarker of tubal ectopic pregnancy.

Objective To evaluate serum protein calponin 2 (CNN2) as a candidate biomarker for tubal ectopic pregnancy (EP). Design Retrospective study. Setting Single University affiliated tertiary hospital. Patient(s) Serum samples were obtained from 84 patients with EP, 39 with viable intrauterine pregnancy (vIUP), and 42 with miscarriage. Moreover, 10 fallopian tube and corresponding villous tissue samples from patients with EP, 6 villous tissue samples from patients with vIUP, and 10 villous tissue samples from patients with miscarriage were collected. Intervention(s) Serum CNN2 concentrations were measured using enzyme-linked immunosorbent assay; CNN2 expression in tissues was evaluated via immunohistochemistry and quantitative real-time polymerase chain reaction analysis. Main Outcome Measure(s) The diagnostic performance of serum CNN2 to discriminate an EP from vIUP and miscarriage. Result(s) CNN2 was highly expressed in villous stromal cells isolated from patients with EP, and CNN2 messenger ribonucleic acid expression was upregulated in villous tissues from women with EP compared with that in women with vIUPs and miscarriages. Serum CNN2 concentration was higher in women with EP than that in women with vIUP and miscarriage. The serum CNN2 predicted EP from vIUP and miscarriage with areas under the curve (AUCs) of 0.931 (95% confidence interval: 0.889–0.975). For discriminating EP from miscarriage only, the AUC was 0.906 (95% confidence interval: 0.835–0.977). In contrast, the AUCs for serum human chorionic gonadotropin were 0.809 and 0.637, respectively. Conclusion(s) Our data highlight the possibility of serum CNN2 as a single biomarker for the diagnosis of EP. Clinical Trial Registration Number ChiCTR 1900020483