Comparison between the conventional Malmström extractor and a new extractor with Silastic cup.

One hundred women for whom instrumental delivery had to be performed due to fetal asphyxia or uterine inertia were randomized to a vacuum extraction with the conventional Malmström instrument or the Silastic cup of Kobayashi. With the Silastic cup, extraction time was shorter and injuries to the scalp were less common. On the other hand, extraction with the Silastic cup failed more often, especially in occiput posterior position. There were no differences in Apgar scores between the two groups.