Operative vaginal delivery is a dying art. National databases in the United States and elsewhere have shown this trend for decades.1 Women no longer can be reliably predicted to prefer operative vaginal delivery over cesarean section, and providers caring for delivering mothers (and their families) should not assume that they do. Nor does the 20th century paradigm of operative vaginal delivery as the accepted “next step” between spontaneous vaginal delivery and cesarean section hold up, given the decreased maternal and neonatal morbidity and mortality associated with modern techniques of cesarean section. Nevertheless, operative vaginal delivery remains a viable option in some cases.
This article—based on personal opinion and experience, as well as published data whenever possible—describes 10 selected aspects of operative vaginal delivery, offering recommendations for each.
1. Consider obstetric history
How a woman fared in previous deliveries has a bearing on the current delivery. For example, if she has a history of persistent occiput posterior position, as in the case described on page 56, she may have an anthropoid pelvis, placing her at increased risk for another malposition.1 In such cases, the patient should be counseled about the potential for operative vaginal delivery, and the risks and benefits should be discussed prenatally.
A history of obesity, excessive weight gain, and glucose intolerance should be considered warning signs of a large-for-gestational-age infant.
2. Ensure adequate informed consent
Patients should be informed of the risks of any procedure they are offered, and operative vaginal delivery—like any operative procedure—has definite risks.
It is unbalanced to mention only the perceived benefits of a procedure and to avoid the discomfort of discussing the potential significant fetal and maternal injury that may result from a procedure. It is far better for the patient and her family to learn—before an adverse outcome occurs—that forceps delivery sometimes leads to maternal and fetal lacerations, and that operative vaginal delivery can be associated with an increased risk for shoulder dystocia in some circumstances.
The best way to educate patients about operative vaginal delivery is during prenatal care. I recommend a written informed consent document similar to the one used for cesarean section. If such a form is not signed during the course of office prenatal care, it should be offered upon admission for delivery.
In some cases, operative vaginal delivery may be safer than cesarean
Operative vaginal delivery clearly increases the risk of neonatal intracranial bleeds when compared with normal spontaneous vaginal delivery or elective cesarean section.2 However, a patient should understand that cesarean section carries a risk of neonatal intracranial hemorrhage similar to that of operative vaginal delivery once a woman has labored to complete dilation and pushed for some time.2 In fact, a baby with a well-engaged head can experience significant increases in intracranial pressure during cesarean delivery when concerted efforts have to be used to deliver a deeply engaged fetal head out of a hysterotomy incision. Such maneuvering can also injure the fetal neck and brachial plexus.
3. The abdominal examination is critical
Examination of the maternal abdomen helps to confirm the fetal lie and presentation and may give an idea of the position of the fetal back in relation to the uterine midline. If the fetal back cannot be felt or is palpated far laterally, the fetus may be in an occiput posterior or transverse position. Often this knowledge helps the examiner make sense of an otherwise difficult vaginal examination.
Estimate fetal weight
Fetal weight estimations from a careful abdominal examination can be as accurate as ultrasonographic evaluation.3 It is strongly recommended that fetal weight be estimated and considered in context with maternal diabetes, obesity, excessive weight gain, and previous ultrasound examinations before operative vaginal delivery is undertaken.
Is the fetal head engaged?
The average term (3,200 g) fetus has a basovertical head diameter of approximately 9 to 10 cm,4,5 and the average adult finger has a diameter of 2 cm (one fifth of the head). Using this information, an estimate of how many “fifths” of the fetal head are above the pelvic brim can be made by evaluating how many fingerbreadths of fetal head can be palpated above the symphysis pubis on abdominal examination.