Uterine Rupture: What Family Physicians Need to Know KEVIN S. TOPPENBERG, M.D., Laughlin Memorial Hospital, Greeneville, Tennessee WILLIAM A. BLOCK, JR., M.D., Johnson City Medical Center, Johnson City, Tennessee Vaginal birth after cesarean section is common in this country. Physicians providing obstetric care should be aware of the potential complications. Uterine rupture occurs in approximately one of every 67 to 500 women (with one prior low-transverse inci- sion) undergoing a trial of labor for vaginal birth after cesarean section. Rupture poses serious risks to mother and infant. There are no reliable predictors or unequivocal clin- ical manifestations of rupture, so physicians must maintain a high index of suspicion for possible rupture, especially in the presence of fetal bradycardia or other evidence of fetal distress. Management is surgery for prompt delivery of the infant and control of maternal hemorrhage. Newborns often require admission to an intensive care nurs- ery. Prevention of poor outcomes depends on thorough anticipation and preparation. The physicians and the delivery institution should be prepared to provide emergency surgical and neonatal care in the event of uterine rupture. (Am Fam Physician 2002; 66:823-8. Copyright© 2002 American Academy of Family Physicians.) aginal birth after cesarean sec- maintain vigilance as VBAC is more widely tion (VBAC) has become an implemented.1 integral part of modern obstet- rics. With more than 100,000 Historical Perspective VBACs achieved each year In 1916, Cragin6 published a widely quoted Vnationwide, this procedure may be viewed as a recommendation, “Once a cesarean, always a simple and routine method of delivery.1 How- cesarean.” His advice was probably influenced ever, experience has shown that VBAC is not by the high rate of ruptures known to occur risk free, and uterine rupture has been with the classic vertical incisions in use at that increasingly recognized as one of the compli- time.2,7-9 Cesarean sections using a safer, low- cations that physicians should be ready to transverse uterine incision later became quite manage.1,2 common. Uterine rupture is a catastrophic tearing In 1970, only 5 percent of all deliveries were open of the uterus into the abdominal cavity. cesarean, but this rate rose to 24.7 percent by Its onset is often marked only by sudden fetal 1988.2 Currently, approximately 1 million bradycardia, and treatment requires rapid sur- cesarean deliveries are performed each year.2,10 gical attention for good neonatal and mater- Promoting VBAC has been central to efforts nal outcomes. to minimize surgical deliveries, contributing Avoiding the morbidity of repeat cesarean to a reduction in the rate of cesareans to section through VBAC is a safe, attractive, and 20.8 percent by 1995.2 successful option in a majority of women.2-4 Initial enthusiasm for VBAC has now been The purpose of this article is not to discourage tempered by reports of poor maternal and or encourage VBAC, which would require a fetal outcomes that can occur with failed comparison of the relative risks of VBAC ver- attempts. It appears that the pendulum of sus elective repeat cesarean. That analysis is consensus has swung from a restrictive outside the scope of this article, but it has been approach to VBAC to active promotion and addressed elsewhere.5 Instead, this article now back again to a position of caution.1 focuses on an important complication of Accordingly, the American College of Obste- VBAC and encourages family physicians to tricians and Gynecologists (ACOG) has SEPTEMBER 1, 2002 / VOLUME 66, NUMBER 5 www.aafp.org/afp AMERICAN FAMILY PHYSICIAN 823 revised its guidelines for VBAC and now rec- ommends a more careful approach.2 Etiology Many clinical conditions have been associ- Incidence ated with uterine rupture.25,26 Table 1 2-4,7,11,15, True uterine rupture is typically distin- 21,24-29 outlines many of these factors. Labor is guished from asymptomatic scar separation usually, but not always, required for uterine (dehiscence) by the need for emergency rupture. One third of ruptures in patients surgery, although some reports combine these with a previous classic uterine incision occur separate processes and confuse the statis- before the onset of labor.7,9 Despite initial tics.3,9,11-13 The rate of true uterine rupture fears that epidural anesthesia would mask the with one prior low-transverse scar has been pain of uterine rupture, recent evidence shows reported by ACOG to be between 0.2 and that use of this anesthesia during VBAC is 1.5 percent (one of 67 to 500 women).2 Other safe.2,7,21 Amnioinfusion also appears to be studies involving more than 130,000 women safe and is not associated with an increase in undergoing a trial of labor for VBAC report rupture rates.18 rates that average 0.6 percent (approximately Excessive uterine stimulation can cause rup- one of every 170 women).10,12-19 ture, and this has occurred with alkaloidal In women with two or more prior cesare- ans, the rate of rupture rises as high as 3.9 per- 20 cent (one of 26 women). Such rates are TABLE 1 threefold to fivefold higher than rates in Conditions Associated with Uterine women having only one prior cesarean deliv- Rupture ery.10,21,22 A history of a successful prior vagi- nal delivery was found to reduce the risk of Uterine scars rupture from 1.1 to 0.2 percent (one of 511 Prior cesarean section women).20 Among less common incisions, Prior rupture classic and T-shaped uterine incisions are Trauma reported to rupture in 4 to 9 percent of cases, Injury from instrumentation during an abortion while low-vertical incisions carry a rupture Significant myomectomy risk of 1 to 7 percent.2 In comparison, rupture Any cause of uterine perforation of an unscarred uterus occurs in one of 8,000 Uterine anomalies (i.e., undeveloped uterine horn) to 17,000 deliveries.3,23,24 Prior invasive molar pregnancy History of placenta percreta or increta Difficult forceps delivery The Authors Malpresentation KEVIN S. TOPPENBERG, M.D., provides obstetric care within a family practice group in Fetal anomaly Greeneville, Tenn. Dr. Toppenberg graduated from Loma Linda University School of Med- Obstructed labor icine, Loma Linda, Calif., and obtained postgraduate training in family medicine at Florida Induction of labor (suspected association) Hospital’s Family Practice Residency Program. He completed additional training in family practice obstetrics at Florida Hospital’s family practice/obstetrics fellowship program. Excessive uterine stimulation WILLIAM A. BLOCK, JR., M.D., is assistant professor of maternal-fetal medicine at East Prostaglandin E1 (misoprostol [Cytotec]) Tennessee State University (ETSU) and co-director of the Northeast Tennessee Regional Prostaglandin E2 (dinoprostone [Cervidil]) Perinatal Center in Johnson City, Tenn. A graduate of ETSU James H. Quillen College Oxytocin (Pitocin), especially high infusion rates of Medicine, with residency training at the University of South Carolina, Columbia, he Alkaloidal/crack-cocaine abuse completed a fellowship in maternal-fetal medicine at Wake Forest University School of Medicine, Winston-Salem, N.C. Information from references 2 through 4, 7, 11, 15, Address correspondence to Kevin S. Toppenberg, M.D., Greeneville Family Practice 21, and 24 through 29. Associates, 314 Tusculum Blvd., Greeneville, TN 37745 (e-mail: [email protected]). Reprints are not available from the authors. 824 AMERICAN FAMILY PHYSICIAN www.aafp.org/afp VOLUME 66, NUMBER 5 / SEPTEMBER 1, 2002 Uterine Rupture cocaine abuse.27 Oxytocin (Pitocin) is widely used, so it is not surprising that this uterine Prolonged, late, or variable decelerations and bradycardia stimulant has been administered in a majority seen on fetal heart rate monitoring are the most common— of ruptures.7,24 One center found that oxytocin and often the only—manifestation of uterine rupture. had been given in 77 percent of their ruptures and was typically used to stimulate labor in women with a prolonged latent phase.21 Misuse of oxytocin carries significant risks variable decelerations and bradycardia seen in any mother, and this risk may be increased on fetal heart rate monitoring are the most during VBAC, especially at high infusion common—and often the only—manifesta- rates.2,11 ACOG guidelines and other authors tions of uterine rupture.13,15,17 Furthermore, indicate that oxytocin use during VBAC is uterine contraction patterns are unreliable for acceptable.2,15,21 Induction of labor, regardless detecting rupture and often appear normal. of the method used, is increasingly recognized Even ruptures monitored with an intrauterine as a risk factor for uterine rupture. Recent pressure catheter (IUPC) often fail to show a VBAC studies have shown three to five times loss of uterine tone or contractile pattern after more ruptures among induced mothers com- uterine rupture.31-33 pared with those having spontaneous onset of Shoulder dystocia related to fetal parts lodg- labor.4,19 Experience with more potent uterine ing outside the uterus can also be a presenting 34 3,13,15,31-33 stimulants, such as prostaglandin E1 (miso- sign. Table 2 summarizes manifes- prostol [Cytotec]) and prostaglandin E2 tations seen in several studies of reported rup- (dinoprostone [Cervidil]) continues to accu- ture. Figure 133 shows a tracing from a pub- mulate. While they were initially considered lished case of uterine rupture. It should be safe for use during VBAC, current reports noted that it differs little from tracings that describe ruptures in approximately 2.5 per- might be seen in other cases of fetal distress— cent of women after their use (one out of uterine contractions continue (as measured 2,4,11,19,28,29 40 cases). Prostaglandin E2 appears by an IUPC), while fetal bradycardia develops. to be weaker than prostaglandin E1 and yet has One author has concluded that “if a pro- been found to cause 6.4 times more ruptures than a spontaneous trial of labor.4,19 Thus, these agents should be used with great caution TABLE 2 during a trial of labor.