Uterine Rupture During Labor Among Women with Prior Cesarean Delivery Michael Mendoza, MD, MPH Evidence Based Medicine Clerkship August 2001 Overview Vaginal Birth After Cesarean (VBAC) History Advantages and Disadvantages Current Practice as of 1999 ACOG Guidelines Lydon-Rochelle, M, Holt VL et al. Risk of Uterine Rupture During Labor Among Women with Prior Cesarean Delivery. New England Journal of Medicine. 2001;345:3-8. History of VBAC 1900: “Once a cesarean, always a cesarean.”3 1981: NICHD Conference on Child Birth concluded that vaginal delivery after cesarean birth is an appropriate option.3 1987: Still more than 90 percent of women with a prior cesarean delivery had a repeat procedure.3 Recent History of VBAC Limited studies Nova Scotia, Canada (1996): Too few women in sample to detect rare event.5 Switzerland (1999) and California (1999): Demonstrated higher risk of uterine rupture in VBAC but did not account for obvious biases. 4,6 Still no randomized trials comparing neonatal and maternal outcomes in VBAC vs. repeat C/S… Advantages of VBAC7 Lower risk of infection Shorter hospital stays Lower overall delivery costs Opportunity to experience family-centered birthing More rapid recovery Lower morbidity for mother and baby Fewer blood transfusions Lower overall mortality rate Ratcliffe SD, Baxley EG, Byrd JE, Sakornbut EL, eds. Family Practice Obstetrics. Philadelphia: Hanley & Belfus. 2001. Disadvantages of VBAC7 Increased risk of uterine rupture (therefore increased risk of hysterectomy) Maternal fever Cesarean delivery may still be required Possibility of serious perineal lacerations Maternal frustration and anger VBAC cannot be scheduled in advance Ratcliffe SD, Baxley EG, Byrd JE, Sakornbut EL, eds. Family Practice Obstetrics. Philadelphia: Hanley & Belfus. 2001. Current Practice Recommendations based on good and consistent evidence Most women with one previous cesarean delivery with a low-transverse incision are candidates for VBAC, should be counseled about VBAC, and should be offered a TOL. A previous uterine incision extending into the fundus is a contraindication for VBAC. ACOG Practice Bulletin: Vaginal Birth After Previous Cesarean Section. No. 5, July 1999. Current Practice (cont.) Recommendations based on limited or inconsistent evidence Women with two previous low-transverse cesarean deliveries and no contraindications who wish to attempt VBAC may be allowed a TOL. Use of oxytocin or prostaglandin gel for VBAC requires close patient monitoring Women with a vertical incision within the lower uterine segment that does not extend into the fundus are candidates for VBAC. ACOG Practice Bulletin: Vaginal Birth After Previous Cesarean Section. No. 5, July 1999. Current Practice (cont.) Recommendations based primarily on consensus and opinion VBAC should be attempted in institutions equipped to respond to emergencies with physicians immediately available to provide emergency care ACOG Practice Bulletin: Vaginal Birth After Previous Cesarean Section. No. 5, July 1999. The Research Question… Is the risk of uterine rupture among post- cesarean women who under go a spontaneous or induced trial of labor significantly higher than those who deliver by repeat cesarean without trial of labor? Methods: Study Design Population-based retrospective cohort study Advantages: can detect rare outcomes (e.g., uterine rupture) in a study over longer duration, cheaper than prospective cohort studies, less subject to bias Disadvantages: limited to available dataset (may not have data on desired characteristics), dataset may be incomplete, possibility for improper coding into dataset Methods: Sample Characteristics All primiparous women who gave birth to singleton infants by cesarean section in civilian hospitals in Washington State from 1/1/87 to 12/31/96 AND who delivered a singleton infant during the same period. Initial cohort: 20,525 (430 excluded who had a second delivery before 1989 when “repeat cesarean no labor” was added to birth certificates). Table 1. Demographics At the time of second delivery, women with spontaneous onset of labor and repeat cesarean were similar with respect to demographic and perinatal characteristics. Women who underwent induction without PG were more likely than women without TOL to deliver EGA >42wks. Women who got PG were less likely to deliver within two years of their first deliver AND more likely to deliver at a level II hospital than women without TOL. Table 2. Perinatal Characteristics The frequency of medical conditions and complications of pregnancy differed: Women who had spontaneous labor were significantly less likely than women with no trial of labor to have DM, HTN, preeclampsia, breech, HSV, placenta previa. Women with induction without PG were less likely than women who did not undergo TOL to have breech, HSV, or placenta previa. Women with PG induction were significantly less likely to have breech or HSV than women who did not TOL. Results: Rate of Uterine Rupture Repeated C/S without labor: 1.6 / 1000 Spontaneous onset of labor: 5.2 / 1000 Induction of labor without PG: 7.7 / 1000 Induction of labor with PG: 24.5 / 1000 Table 3. Relative Risk: C/S vs. TOL A greater relative risk (RR) was observed among women induced without PG, and an even greater RR was observed among those induced with PG. Assessing the Risk of TOL vs. C/S Absolute Number Relative Incidence Risk Relative Risk Needed Risk (per 1000) Increase (95% CI) to Harm Increase (per 1000) (1/ARI) Repeat C/S (no TOL) 1.6 -- 1.0 -- -- Spontaneous onset of labor 5.2 3.6 3.3 (1.8-6.0) 2.3 277 Induction without PG 7.7 6.1 4.9 (2.4-9.7) 3.9 165 Induction with PG 24.5 22.9 15.6 (8.1-30.0) 14.6 43 Table 4. Complications of Rupture Women with uterine rupture were more likely than women without rupture to experience: Anemia Hysterectomy Infection Maternal hospital Bladder injury stay > 5 d Paralytic ileus Death of infant Conclusions Trial of labor (of any kind) in women with prior cesarean was associated with at least a three-fold increase in risk of uterine rupture, but risk of rupture remains low. Even when controlling for preexisting medical conditions or complications of pregnancy, results were similar. Even though induction with PG is associated with greater risk of uterine rupture, the nature of this association is unclear (i.e. it may be dose- dependent). Assessing the Validity of this Study Internal Validity Bias? External Validity Will this change my practice? CHN patients unlikely to match demographic characteristics of Washington State References Cited 1. ACOG Practice Bulletin: Vaginal Birth After Previous Cesarean Section. No. 5, July 1999. 2. Cesarean Childbirth: Report of a Consensus Development Conference Sponsored by the National Institute of Child Health and Human Development. DHHS Pub. No. 82-2067. Government Printing Office, Washington, DC, October 1981. 3. Gabbe S. Obstetrics - Normal and Problem Pregnancies, 3rd ed., Churchill Livingstone, Inc. 1996. 4. Gregory KD, Korst LM, Cane P, Platt LD, Kahn K. Vaginal birth after cesarean and uterine rupture rates in California. Obstet Gynecol 1999;94:985-9. 5. McMahon MJ, Luther ER, Bowes WA Jr, Olshan AF. Comparison of atrial of labor with an elective second cesarean section. N Engl J Med 1996;335:689- 95. 6. Rageth JC, Juzi C, Grossenbacher H. Delivery after previous cesarean: a risk evaluation. Obstet Gynecol 1999;93:332-7. 7. Ratcliffe SD, Baxley EG, Byrd JE, Sakornbut EL, eds. Family Practice Obstetrics. Philadelphia: Hanley & Belfus. 2001.