Validation of the 1988 ACOG forceps classification system

In February 1988, an ACOG Committee Opinion substantially revised the classification of forceps operations. The revision addressed two significant shortcomings of the old system: Outlet forceps had been defined too narrowly and midforceps too imprecisely. We now report the results of a prospective study of 357 forceps deliveries classified using each system. Allowing up to 45° of rotation in an outlet forceps delivery did not increase morbidity measured by any criterion. Dividing the old midforceps group by precisely identifying station and rotation permitted greater stratification of the risks of short-term neonatal and maternal morbidity. We conclude that our results validate the 1988 classification scheme.