Stop: using instruments to assist with delivery of the head at cesarean: start: disengaging the head prior to surgery.
Anticipate an impacted fetal head
The true incidence of an impacted fetal head at the time of cesarean is not known, although a number of risk factors have been described (TABLE, page 32). Obstetric care providers should be aware of these risk factors and anticipate the likelihood of a difficult delivery of the fetal head at cesarean.
Options for managing an impacted fetal head at cesarean
Several techniques have been reported in the literature for managing the delivery of a deeply engaged head, including:
Using an assistant to push the fetus's head up using a hand in the vagina ("push" technique). This can cause trauma to the fetus, since the force required to push the fetus up from below is uncontrolled. (5,6)
The reverse breech extraction ("pull" technique) involves pulling the infant out feet first through the uterine incision. (7)
Use of an instrument. The most common instrument used is a vacuum extractor, (8) although a number of other devices have been developed, including the Murless fetal head extractor (an instrument with a hinged shaft and sliding collar lock), (9) the C-Snorkel impacted fetal head release device (the device's tip contains ventilation ports to facilitate airflow and release of the vacuum/ suction created by the impacted fetal head), (10) and the Fetal Pillow (a balloon device inserted in the vagina and inflated with sterile saline to disimpact an engaged fetal head before cesarean delivery). (11)
While all of these techniques can cause injury to the mother and the fetus, available data favor use of the reverse breech extraction (pull) technique, since it is associated with fewer maternal risks, including lower rates of uterine incision extension, infection, and postpartum hemorrhage and a shorter operative time. (12-18)
Stop use of vacuum to deliver the fetal head at cesarean
Placement of a vacuum can be effective in assisting with delivery of the fetal head at cesarean. For this reason, vacuum-assisted deliveries at cesarean are becoming more common. While the rate of complications caused by vacuum extraction of the fetal head at cesarean is not known, injuries have been reported. (19,20) As such, routine use of vacuum extraction at the time of cesarean delivery cannot be recommended.
Start disengaging the fetal head prior to cesarean
One useful technique in planning a cesarean in the second stage of labor or when an impacted fetal head is anticipated is to disengage the fetal head vaginally prior to skin incision. This can be done in the delivery room or in the operating room immediately prior to surgery with the help of an assistant.
While supporting the patient's legs, the assistant inserts a hand into the vagina and pushes upward on the fetal head with gentle, sustained effort. The assistant should use a cupped hand or the palm of the hand while attempting to both elevate and flex the fetal head. It is best to avoid using 1 or 2 fingers to elevate the head, as this may cause excessive pressure at a single point and lead to injury, such as a skull fracture (FIGURE). The assistant should disengage his or her hand only when the operating surgeon is able to reach down and secure the fetal head from above.
Elevating the fetal head prior to skin incision offers 3 major advantages:
1. It avoids the embarrassing situation of having the fetus deliver vaginally before it can be pulled out through the abdominal incision. Although rare, this has been known to happen, because the dense regional anesthesia further relaxes the pelvic floor musculature, leading to flexion and rotation of the fetal head, which then descends and delivers. Performing a final bimanual examination in the operating room after the establishment of surgical level anesthesia and immediately prior to skin incision will avoid this situation.
2. It elevates the fetal head, thereby creating additional space between the bony pelvis and fetal presenting part for the provider's hand to fit. This helps minimize injury to the fetus and to the maternal soft tissues at the time of cesarean.
3. Lastly, it provides additional information about the extent to which the fetal head is impacted in the pelvis and may influence decision making around the time of cesarean. For example, if the fetal head were deeply impacted in the pelvis and could not be disimpacted vaginally, the surgeon may choose to make a different uterine incision (such as a low vertical hysterotomy), administer a uterine relaxant (an inhaled anesthetic agent or nitric oxide), ask for additional instrumentation, and/or ask an assistant to be ready to elevate the fetal head vaginally should this be necessary. (21)
Routine use of vacuum extraction at the time of cesarean delivery cannot be recommended
Elevating the fetal head prior to skin incision offers several major advantages
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(19.) Clark SL, Vines VL, Belfort MA. Fetal injury associated with routine vacuum use during cesarean delivery. Am J Obstet Gynecol. 2008,198(4):e4.
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Errol R. Norwitz, MD, PhD, MBA
Dr. Norwitz is Louis E. Phaneuf Professor and Chairman, Department of Obstetrics and Gynecology, Tufts Medical Center and Tufts University School of Medicine, Boston, Massachusetts. He is a member of the OBG Management Board of Editors.
The author reports no financial relationships relevant to this article.
TABLE Risk factors for an impacted fetal head at cesarean delivery * Failed operative vaginal delivery * Excessive caput and molding of the fetal head * Secondary arrest of dilation * Prolonged second stage of labor * Occiput-posterior position