Management of the nonvertex second twin: primary cesarean section, external version, or primary breech extraction.

Six hundred eighty-two consecutive twin deliveries were reviewed. Included in the study were 136 sets of vertex-nonvertex twins with birth weights greater than 1500 gm. A primary attempt at delivery of the second twin by external version was performed on 41 twins, 55 twins underwent attempted breech extraction, and 40 patients had a primary cesarean section solely because of physician preference. There were no differences in the incidence of neonatal morbidity or mortality among the modes of delivery. External version was associated with a higher failure rate than primary breech extraction (p less than 0.01). External version was associated with complications (fetal distress, cord prolapse, and compound presentation) that were not seen in the other two groups. Primary breech extraction of the second nonvertex twin weighing greater than 1500 gm appears to be a reasonable alternative to either cesarean section or external version.