ObjectiveTo evaluate the applicability and safety of the Zavanelli maneuver (manual return to the vagina of the partially born but undeliverable fetus with subsequent extraction by cesarean).Data SourcesMEDLINE computer database, Science Citation Index, and Index Medicus, 1985 through 1997 using the search terms Zavanelli maneuver, cephalic replacement, abdominal rescue, head entrapment, and shoulder dystocia.Method of Study SelectionEfforts to return 103 partially born but undeliverable fetuses to the uterus have been reported in 30 publications since the first case was reported in 1985. All cases were accepted for review, successful or not.Tabulation, Integration, and ResultsClinically relevant features were extracted from each case report. In 92 cases, fetuses presented by the vertex. Cephalic replacement was successful in 84 of those. In 11 cases, the fetus presented by the breech. Podalic replacement was successful in all of those. Seven women suffered tissue-disruptive trauma. There were no maternal deaths or fetal injuries ascribed to the maneuver.ConclusionThe 92% overall success rate is remarkable for a new procedure; even more noteworthy, in most cases it was applied by operators with no experience with it, and for cephalic replacement, it was used only after conventional maneuvers had failed. Using it early in the treatment of obstructed partial vaginal delivery is recommended.