Forceps operations in perspective. I. Midforceps rotation operations

Four hundred fifty-eight consecutive midforceps rotation operations were evaluated with a specially designed Perinatal Morbidity Index (PMI) and Maternal Morbidity Index (MMI). An unfavorable fetal outcome occurred in 30.8% of the midforceps rotation operations, and an unfavorable maternal outcome occurred in 13.5% of the cases. Twelve risk factors were found to be associated with suboptimal results. Among patients with no risk factors, an unfavorable fetal outcome occurred in 11% of the cases. Of the patients with three or more risk factors, in contrast, an unfavorable fetal outcome was found in 47% of the cases. A uniformly good fetal outcome was noted among patients selected as controls. Under ordinary circumstances, midforceps rotation operations should not be attempted in a patient already at significant risk. "Significant risk" is defined in the article.