Introduction
One of the areas of obstetrics that has dramatically changed in the past several years is operative vaginal delivery. In 1970 the operative vaginal delivery rate in the United States was approximately 30%. By 1997 this rate had decreased to less than 10%. The most current statistics show the operative vaginal delivery rate to be approximately 6%. At the same time the number of forceps-assisted vaginal deliveries has decreased, while vaginal deliveries using the vacuum extractor have increased as a proportion of operative deliveries. The reasons that are often cited as contributing to the decline in the use of forceps are: fear of litigation, reliance on cesarean section as a remedy for abnormal labor and suspected fetal jeopardy, perception that the vacuum is easier to use and less risky to the fetus and mother, and decreased number of programs that are actively training residents in the use of forceps. These factors have resulted in a cycle, in which less teaching has led to a decline in technical skills. This decline in technical skills may increase adverse outcomes and fear of litigation, resulting in a further decrease in the use of forceps.
Indications and prerequisites for operative vaginal delivery
The indications for operative vaginal delivery are the following: nonreassuring fetal heart rate pattern, impairment of maternal health due to pushing during the second stage, and poor maternal expulsive efforts in the second stage of labor. This latter indication most commonly applies when the second stage of labor is prolonged. According to the American College of Obstetricians and Gynecologists (ACOG), the second stage of labor is considered prolonged in a nulliparous patient if it lasts greater than 3 hours for a woman with a regional anesthetic or more than 2 hours for a woman without a regional anesthetic. In a multiparous patient, greater than 2 hours with a regional anesthetic or more than 1 hour without a regional anesthetic constitute a prolonged second stage of labor.
In order for a patient to be considered a candidate for an operative vaginal delivery, the following prerequisites must be met:
- complete cervical dilation
- ruptured membranes
- vertex presentation (unless forceps application during vaginal breech delivery)
- fetal head engaged with fetal head position known
- empty bladder
- absence of evidence of cephalopelvic disproportion
- adequate analgesia
- cesarean section capability
- experienced operator
In 1988 the classification of forceps deliveries was redefined by the ACOG (see Box 11.1). The same classification should be applied to vacuum delivery. Only very rarely should an attempt be made at operative vaginal delivery above station +2. Because of safety concerns, the prior classification of high forceps application was eliminated. Under no circumstances should forceps or vacuum be applied to an unengaged head.
Box 11.1 ACOG forceps classification
Outlet forceps
Fetal scalp visible at introitus without separating the labia
Fetal skull has reached the pelvic floor
Sagittal suture is in the anterior-posterior diameter or in the right or left occiput anterior or posterior position
Fetal head at or on the perineum
Rotation ≤45°
Low forceps
Leading point of fetal skull at ≥ station 2:
- with rotation ≤45°
- or rotation ≥45°
Midforceps
Above +2 station with head engaged
Types of forceps
While it is beyond the scope of this chapter to discuss all the different varieties of forceps and their indications, it is appropriate to briefly comment on the more common types. Simpson or Elliot forceps are most often used for outlet vaginal deliveries. Kielland or Tucker–McLane forceps are used for rotational deliveries. Lastly, Piper forceps are used to assist in delivery of the aftercoming head for breech deliveries. The pelvic and cephalic curves, shanks, blades, and locks are different for each type of forceps. These features determine the types of forceps that are best suited for the given indication. The Piper forceps, for example, have a reverse pelvic curve suitable for delivery of the aftercoming head. The Simpson forceps have blades that are best suited for application to the molded fetal head, while those of the Kielland forceps are more appropriate for application to the fetal head with little or no molding.
Forceps application
What follows is a brief description of how forceps should be applied. For a more thorough discussion on the application of forceps, the reader is referred to additional references cited at the end of the chapter.
The concept underlying the correct application of forceps is finesse rather than force. Before actually applying the forceps to the fetal head, a “phantom application” should be performed first. The forceps are inspected to make sure that there is a complete and matched set, and that the forceps articulate (lock) easily. Forceps should be applied in a delicate fashion in order to avoid potential injury to the vagina and perineum. The goal is for the blades to fit the fetal head as evenly and symmetrically as possible. The blades should lie evenly against the side of the head, covering the space between the orbits and ears. After the forceps have been applied, they should articulate easily. If this does not occur, the forceps should be removed and a second attempt should be made. The forceps should never be forced or “jammed” into the vagina!
After the forceps have been comfortably applied to the fetal head and have been locked into place, the following safety checks should be performed for delivery of an occiput anterior position before any traction is applied to the fetal head.
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