Once the vacuum cup has been applied, traction is made coincident with uterine contractions. Traction on the head should be discontinued between contractions. If after three to five pulls there is no descent of the head, cesarean section should be undertaken.

Complications occur because of cup misplacement, incorrectly applied traction or excessive traction, and too long an application of the cup. The vacuum extractor should not be used in a breech, brow, or face presentation, or if the head is not engaged in the pelvis, and it cannot be used if the membranes are intact.