Log-linear human chorionic gonadotropin elimination in cases of retained placenta percreta.

PURPOSE: To describe the human chorionic gonadotropin (hCG) elimination rate in patients with intentionally retained placenta percreta. METHODS: Medical records for cases of placenta percreta with intentional retention of the placenta were reviewed. The natural log of the hCG levels were plotted versus time and then the elimination rate equations were derived. RESULTS: The hCG elimination rate equations were log-linear in three cases individually (R (2) = 0.96-0.99) and in aggregate R (2) = 0.92). The mean half-life of hCG elimination was 146.3 h (6.1 days). CONCLUSION: The elimination of hCG in patients with intentionally retained placenta percreta is consistent with a two-compartment elimination model. The hCG elimination in retained placenta percreta is predictable in a log-linear manner that is similar to other reports of retained abnormally adherent placentae treated with or without methotrexate.