When the contraction subsides, the suction pressure is reduced to 100 mm Hg. The sequence is repeated with each contraction. More than three good attempts are not recommended unless progress is being made. As the head crowns, an episiotomy may be cut. Traction is then changed to a 45-degree angle upward as the vertex clears the symphysis.
Suction is released and the cup removed after delivery of the fetal head.
The procedure should be discontinued if one fails to achieve extraction after 10 minutes at maximal pressure, extraction is not achieved within 30 minutes of initiation, the cup disengages three times, fetal scalp trauma is sustained, or no progress is made after three pulls. All rights reserved.