Cesarean delivery defines the birth of a fetus via laparotomy and then hysterotomy. The origin of caesarean is uncertain and was reviewed in the 23rd edition of Williams Obstetrics (Cunningham, 2010). There are two general types of cesarean delivery—primary refers to a first-time hysterotomy and secondary denotes a uterus with one or more prior hysterotomy incisions. Neither definition includes removal of the fetus from the abdominal cavity in the case of uterine rupture or with abdominal pregnancy. Rarely, hysterotomy is performed in a woman who has just died or in whom death is expected soon—postmortem or perimortem cesarean delivery (Chap. 47, Cardiopulmonary Resuscitation).
In some instances, and most often because of emergent complications such as intractable hemorrhage, abdominal hysterectomy is indicated following delivery. When performed at the time of cesarean delivery, the operation is termed cesarean hysterectomy. If done within a short time after delivery, it is termed postpartum hysterectomy. Peripartum hysterectomy is a broader term that combines these two. In most cases, hysterectomy is total, but supracervical hysterectomy is also an option. The adnexa are not typically removed.
Cesarean Delivery in the United States
From 1970 to 2010, the cesarean delivery rate in the United States rose from 4.5 percent of all deliveries to 32.8 percent. In 2010, this rate actually declined from a peak of 32.9 percent in 2009 (Martin, 2012). The other, albeit brief, decline was between 1989 and 1996 (Fig. 31-1, Factors that Influence a Trial of Labor). This more profound decrease was largely due to a significantly increased rate of vaginal birth after cesarean (VBAC) and to a closely mirrored decrease in the primary rate. These trends were short lived, and in 2007, the primary cesarean delivery rate was above 30 percent, whereas VBAC rates had dropped to 8 percent (MacDorman, 2011).
The reasons for the continued increase in the cesarean rates are not completely understood, but some explanations include the following:
Women are having fewer children, thus, a greater percentage of births are among nulliparas, who are at increased risk for cesarean delivery.
The average maternal age is rising, and older women, especially nulliparas, are at increased risk of cesarean delivery.
The use of electronic fetal monitoring is widespread. This technique is associated with an increased cesarean delivery rate compared with intermittent fetal heart rate auscultation (Chap. 24, Human Evidence). Cesarean delivery performed primarily for “fetal distress” comprises only a minority of all such procedures. In many more cases, concern for an abnormal or “nonreassuring” fetal heart rate tracing lowers the threshold for cesarean delivery.
Most fetuses presenting as breech are now delivered by cesarean. As discussed in Chapter 28 (Delivery Complications), concern for fetal injury, as well as the infrequency with which a breech presentation meets criteria for a ...