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Assisted or operative vaginal birth refers to the use of a vacuum or forceps to achieve a vaginal delivery in the second stage of labor. When the decision is being made as to whether or not a birth requires assistance, including the timing and choice of instrument, considerations must include indications and contraindications to the procedure, the maternal or fetal risks of using either instrument, the urgency of the need to expedite delivery, the experience and skills of the birth attendant, and the risks associated with the alternative choice of cesarean section. Assisted vaginal delivery should only be attempted if there is a reasonable chance of success, and a backup plan should be in place in case the attempt is not successful.
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Indications for an operative vaginal birth include nonreassuring fetal status, maternal conditions that preclude Valsalva maneuvers such as congestive heart failure or cerebral vascular malformations, and inadequate progress in the second stage of labor (provided that there is adequate uterine activity and there is no evidence of cephalopelvic disproportion [CPD]).
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INCIDENCE OF OPERATIVE VAGINAL DELIVERY
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Between 9 and 10 percent of all deliveries in North America are assisted vaginal deliveries. The vacuum is used in 7 percent of all births, while forceps are used in only 3 percent of all births. The rate of forceps delivery is decreasing. This may be because of increased litigation, unfavorable publicity regarding forceps, decreasing family size, and improved safety of cesarean section. The decrease in forceps use and the increase in cesarean section rates may also be secondary to a decrease in the skills required to perform a forceps delivery because obstetric trainees now receive less exposure to forceps training.
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The obstetric forceps are instruments designed for extraction of the fetal head. Forceps cradle the parietal and malar bones of the fetal skull and apply traction to these areas as well as laterally displacing maternal tissue. There are many varieties of forceps, but the basic design and purpose are the same. They may be used to provide traction, rotation, flexion, and extension.
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All forceps consist of two crossing branches. Each branch consists of four parts: the blade, shank, lock, and handle. Each blade has two curves: the cephalic curve that conforms to the shape of the fetal head and the pelvic curve that conforms to the shape of the birth canal. Some blades are fenestrated, and some are solid (Fig. 17-1A).
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Handles: These are used to grip the forceps
Lock: This holds the forceps together. It is constructed so that the right one fits on over the ...