A randomized comparison of vacuum extraction delivery with a rigid and a pliable cup.

Objective: To compare the effectiveness and complications of obstetric vacuum extraction with a rigid and a pliable cup, with a focus on neonatal retinal hemorrhage.

Methods: One hundred women requiring assisted delivery who met predefined criteria for vacuum extraction were randomly assigned to be delivered by the classic rigid Malmström cup or the pliable Silastic cup.

Results: Because of the faster induction of vacuum, delivery occurred more rapidly with the pliable cup, but the pliable cup detached significantly more often than the rigid cup. The overall failure rate was not significantly different between the cups. There were no significant differences between the groups with regard to Apgar scores, umbilical artery pH, birth canal trauma, or maternal blood loss, but scalp injury occurred less frequently with the soft than with the rigid cup. Retinal hemorrhage in the newborns showed a similar incidence of about 50%, and neonatal neurologic examination showed no significant differences between the groups.

Conclusion: In comparison with the rigid cup, the advantage of the pliable cup is limited to a smaller incidence of neonatal scalp injury.