Postoperative Serological Monitoring after Conservative Surgery for Hepatic Cystic Echinococcosis: A Prospective Cohort Study

Abstract Background Postoperative serologic follow-up after surgery for hepatic cystic echinococcosis (HCE) is widely used, but the kinetics of antibody decline and the factors influencing time to seronegativation remain poorly characterized. This study aimed to describe the postoperative evolution of hydatid serology, characterize its kinetics during long-term follow-up, and evaluate its practical contribution to post-therapeutic surveillance. Methods We conducted a prospective, single-center cohort study of 60 patients (99 hepatic hydatid cysts) who underwent standardized conservative surgery for HCE between June 2017 and December 2023, with a median follow-up of 61 months. Enzyme-linked immunosorbent assay (ELISA) and indirect hemagglutination assay (IHA) were performed preoperatively and at scheduled postoperative intervals. Time to seronegativation was analyzed using Kaplan-Meier estimates and Cox regression; longitudinal titer kinetics were analyzed using segmented regression for repeated measures. Results Among initially seropositive patients, seronegativation occurred late, with a median of 65 months for ELISA and 71 months for IHA, and more than 60% of patients remained seropositive at 5 years. Serologic titers followed a biphasic pattern, with an early transient rebound (3.04 months for IHA, 6.67 months for ELISA) followed by a significant linear decline (− 2.4 dilutions/month for IHA and − 0.01012/month for ELISA; P < .001 for both). On multivariate Cox regression, preoperative C-reactive protein and initial dual ELISA/IHA positivity were the only factors independently associated with time to seronegativation. Conclusions Postoperative serologic decline after HCE surgery is slow, and isolated persistent seropositivity should not, by itself, be interpreted as recurrence. A persistent secondary re-elevation of titers after the postoperative rebound should raise suspicion of recurrence and prompt radiological re-evaluation.