Holmgren, Calla MD; Scott, James R. MD; Porter, T. Flint MD, MPH; Esplin, M. Sean MD; Bardsley, Tyler MS
The increasing rate of primary and repeat cesarean delivery in the United States is of concern to physicians and patients, and vaginal birth after cesarean delivery is considered to be one way to lower the overall cesarean delivery rate. Trial of labor after cesarean delivery (TOLAC), which peaked at 31% in 1998,1 has decreased progressively since (8.5% by 2006), primarily because of issues surrounding uterine rupture. Although rupture of the uterus during TOLAC is rare, it can be devastating for both the mother and neonate when it occurs, and it is a major liability risk for physicians. The American College of Obstetricians and Gynecologists' guidelines advise physicians that TOLAC is most safely undertaken in hospitals where staff can immediately carry out an emergency cesarean delivery.2 This view is based on the premise that the ability to rapidly intervene will minimize adverse neonatal outcomes. However, immediate availability is loosely defined, and it is not clear how rapidly the fetus must be delivered after uterine rupture to prevent neonatal death or neurologic sequelae. The purpose of this study was to examine whether an association exists between neonatal outcomes and the time from diagnosis of uterine rupture to delivery of the neonate.
MATERIALS AND METHODS
Institutional review board approval was obtained at the University of Utah and Intermountain hospitals. Using International Classification of Diseases, 9th Revision codes (665.0, 665.1), we identified all cases of suspected uterine rupture in nine Intermountain Healthcare Hospitals and at the University of Utah from January 2000 through December 2009. Separate computerized databases within the Intermountain Healthcare system and the University of Utah were used, and the accuracy of the databases was verified by personally reviewing a randomly selected 1-month sample of records each year from all patients delivered. In total, 10 hospitals were represented. Four of these hospitals are tertiary referral centers with 24-hour in-house anesthesia and immediately available obstetric personnel, including faculty, fellows, residents, or all of these. Six hospitals do not have immediately available anesthesia or obstetric services. The total number of women attempting TOLAC for all 10 hospitals also was obtained from the available databases.
Clinically overt uterine rupture was defined as complete uterine scar disruption through all layers of the uterus with protrusion of the placenta or fetal parts partially or completely through the rupture into the maternal peritoneal cavity. Mother–neonate pairs were included only if uterine rupture occurred while attempting a vaginal birth after a cesarean delivery. Patients were excluded if the rupture was in a nonscarred uterus and those with previous cesarean deliveries with rupture before labor.
The signs and symptoms and time from clinical diagnosis (as documented in nursing notes and the clinical record) of suspected uterine rupture to delivery were determined. The primary adverse outcome was defined as an abnormal umbilical pH level less than 7.0 or a 5-minute Apgar score of 7 or less. Secondary adverse outcomes included fetal or early neonatal death and neonatal neurologic injury attributed to uterine rupture. Neonatal neurologic injury was defined as otherwise unexplained seizures, clinically obvious cerebral palsy, or developmental delay attributable to hypoxia resulting from the uterine rupture.
Medical records obtained for each mother–neonate pair were abstracted for 21 variables by two investigators. These included past and current pregnancy history, intrapartum events, and specific neonatal data with emphasis on resuscitation information and neonatal injury. Particular attention was paid to establishing the time of diagnosis of uterine rupture as defined by this study. We retrospectively assigned the point at which uterine rupture occurred as either the time that the attending physician suspected uterine rupture and ordered immediate surgery or at the time a medical professional observed an abnormal fetal heart rate tracing feature (ie, variable decelerations, tachycardia, or acute bradycardia without return to baseline) associated with uterine rupture. Fetal heart rate tracings were evaluated for the presence and time of onset of mild and severe variable decelerations, fetal tachycardia, and persistent bradycardia. Severe variable decelerations were defined as less than 70 beats per minute lasting longer than 60 seconds. Mild variable decelerations were defined as a periodic deceleration of the fetal heart rate below 100 beats per minute.
In addition, neonatal and pediatric medical records were reviewed for each child for up to 8 years of age. The length of time for pediatric follow-up was dependent on the year of delivery relative to the timing of the study (if the neonate was delivered in 2009, only follow-up to 1–2 years of age was possible) with neonate records evaluated for the maximum time permitted. Neonates who did not require admission to the neonatal intensive care unit (NICU) were examined at least twice by a pediatrician during the maternal hospitalization and were discharged as healthy neonates. For those neonates admitted to the NICU, investigators evaluated the medical record for evidence of otherwise unexplained seizures, clinically obvious cerebral palsy, or developmental delay based on examination of magnetic resonance imaging reports, ultrasonographic documentation, or findings on clinical examination by the attending NICU physician. Diagnosis after birth by the attending physician was obtained from the medical record. If there was no available pediatric record for evaluation, attempts were made to contact the pediatrician or parents.
An exact conditional logistic regression model was used to relate the probability of an adverse outcome to the time until delivery as the primary predictor variable. To account for a possible correlation between observations within the same hospital, hospital type (University of Utah, Intermountain Tertiary, and Intermountain nontertiary) was controlled for in the model. We also provide proportions of patients experiencing the primary adverse outcome with associated exact binomial 95% confidence intervals for each of three time-to-delivery categories (less than 10, 11–30, and more than 30 minutes).
Within the 10 hospitals studied, 40,772 women were identified with a prior cesarean delivery between January 1, 2000, through December 31, 2009. Of these, 11,195 women (27.5%) attempted TOLAC, with successful vaginal delivery for 9,419 (84.1%) patients (Fig. 1). Within the Intermountain system, 116 cases of uterine rupture were listed, but a review of the charts revealed that only 30 were ruptured uteri possibly associated with TOLAC as defined by this study. Forty-three were uterine “windows” noted at the time of repeat cesarean delivery, and 15 were identified in patients without a prior cesarean delivery. In 28 cases, no rupture was identified on review of the operative report or medical record. Of the 30 patients with possible uterine rupture during TOLAC, four actually occurred before labor, leaving 26 with proven acute uterine rupture during a vaginal birth after cesarean delivery attempt. At the University of Utah, 17 cases were listed in the database as uterine rupture, but review of the patients' charts showed that two cases ruptured before labor and five were uterine “windows,” leaving 10 cases of uterine rupture occurring during TOLAC. In total, there were 36 cases of documented uterine rupture (0.32%) during TOLAC.
Because there are multiple levels of hospitals within the Intermountain Healthcare system, the 26 cases from Intermountain hospitals were further evaluated for location of delivery. Within the Intermountain Healthcare system, eight cases of uterine rupture occurred with TOLAC at tertiary care centers (30.7%) and 18 cases occurred during TOLAC at community hospitals (69.2%) without immediate obstetric and anesthesia personnel available.
Demographic information for the hospitals and patients included in this study are presented in Table 1. Two neonates were less than 36 weeks of gestation at delivery. Thirty-two patients began labor spontaneously, 25 (69.4%) received oxytocin during labor, and one received a cervical ripening agent.
As shown on Table 2, fetal heart rate characteristics associated with uterine rupture included the presence of variable decelerations in 30.5% of the patients and prolonged fetal bradycardia in 19.4%. Seven cases had multiple factors associated with the suspicion for uterine rupture. There were eight cases in which the uterine rupture was suspected for other reasons (maternal bleeding, hypotension, or pain) but with no concerning fetal heart rate tracing changes noted. In one case, uterine rupture was not suspected before delivery with no maternal symptoms and a reassuring fetal heart rate tracing. In this case, the rupture was determined after vaginal delivery secondary to maternal hypotension. Seven neonates were lost to long-term follow-up. Five of these seven were not admitted to the NICU at delivery, all but one had Apgar scores 7 or above, and all were normal at discharge.
Of the 36 patients, 13 (36.1%) met our criteria for a primary adverse outcome of umbilical artery pH level less than 7.0 or 5-minute Apgar score less than 7. These patients were compared with the 23 patients without this outcome. Median (range) time to delivery for the primary adverse outcome group (n=13) was 19 (9–40) minutes compared with 14 (0–38) for the nonadverse outcome group. Results after stratifying the sample by hospital type yield a similar result, with those experiencing the primary outcome having, on average, a 5.5-minute (95% confidence interval [CI] 0.0–15.0) longer time to delivery than those who did not experience the outcome.
The exact conditional logistic regression model yielded time until delivery as a significant predictor of the adverse outcome with an odds ratio of 1.088 (P<.038) and 95% CI of 1.004–1.195. Thus, the model estimates that every additional minute of time until delivery is associated with an approximately 8.8% increase in the odds of an adverse outcome. Hospital type was controlled for in the analysis but did not appear to be a significant predictor of the adverse outcome with a P<.9 (Table 3).
Seventeen neonates (47.2%) were delivered less than 18 minutes after identification of uterine rupture. Of these, two neonates had an abnormal 5-minute Apgar score, but both of these neonates had an umbilical pH level greater than 7.0 and none had neurologic injury. Eighteen patients were delivered more than 18 minutes after suspicion of uterine rupture (50.0%). Of these, 11 met criteria for a primary adverse outcome and three met criteria for an adverse secondary outcome. One patient did not have suspected uterine rupture during labor.
Table 4 presents time to delivery as a categorical variable with three levels: less than or equal to 10 minutes, 11 to 30 minutes, and more than 30 minutes. Counts, proportions, and 95% CIs are presented on the number experiencing the primary adverse outcome in each time-to-delivery level.
There were no cases of maternal or neonatal death. The three neonates with neonatal neurologic injury attributed to uterine rupture are shown in Table 5 with peripartum information associated with their deliveries. Two of these cases with prolonged neurologic deficit occurred at hospitals without 24-hour inpatient coverage where limited availability of personnel was a factor. One case occurred at a tertiary care hospital and was related to physician failure to expedite delivery despite availability of personnel.
The decision for TOLAC or a repeat cesarean delivery is a complicated one because both methods have advantages and disadvantages. In actual practice, the primary concern with TOLAC is the fear of uterine rupture, the most serious complication, and its consequences.3–5 However, vaginal birth has a more rapid recovery,4 is preferred by many women,1,5 and it is associated with fewer hazards in future pregnancies.6,7 A number of studies have shown that 60–80% of women who attempt TOLAC are successful and that uterine rupture occurs in less than 1% of all attempts.7–10 Our results support these data, with a success rate of 84% and an overall uterine rupture rate during TOLAC of 0.32%.
The 2010 National Institute of Child Health and Human Development Consensus Development Conference on vaginal birth after cesarean delivery11 and the latest American College of Obstetricians and Gynecologists Practice Bulletin2 state that TOLAC is a safe and appropriate choice for most women who have had a previous cesarean delivery. The Practice Bulletin reaffirmed that TOLAC is most safely undertaken where staff can immediately provide an emergency cesarean delivery, but it also recognized that such resources are not universally available. The guidelines state that restrictive vaginal birth after cesarean delivery policies should not be used to force a woman to undergo a repeat cesarean delivery against her will. This poses a dilemma for physicians and patients in settings where there is not 24-hour in-house coverage.4
There is a need for precise information on the risks for neonates delivered after uterine rupture. An asymptomatic dehiscence of the prior cesarean scar rarely results in an adverse maternal or fetal event.8,12–14 In contrast, complete rupture of the uterus with partial or complete extrusion of placenta or the fetus can be catastrophic for the neonate, parents, and physician. It is likely that the time from uterine rupture to delivery necessary to prevent neonatal injury depends on the severity of the rupture, location of the placenta, pre-existing fetal status, and the degree of umbilical cord compression. In 23 cases of complete uterine rupture published in 2002, neonatal hypoxic–ischemic encephalopathy was diagnosed in three neonates and one neonate died. The three neonates with encephalopathy were delivered at 15, 16, and 23 minutes after the onset of prolonged fetal heart rate deceleration. All three were completely extruded from the uterus, had a metabolic acidosis at birth, and developed motor delay.15,16 It has also been shown that after maternal cardiac arrest, few neonates delivered more than 10 minutes after maternal collapse survive and are healthy.16
Our study focused on serious neurologic morbidity in cases of confirmed uterine rupture during TOLAC. In 36 cases of acute uterine rupture, there were no fetal or neonatal deaths. Delivery within less than 18 minutes was associated with adverse primary outcome in two cases, but this was based on a 5-minute Apgar score less than 7; both neonates had normal umbilical pH levels. Three neonates in our study sustained long-term neurologic damage. These neonates were delivered 31, 40, and 42 minutes after uterine rupture was suspected on clinical grounds. When uterine rupture was identified in a timely fashion and delivery occurred in less than 30 minutes, there was no long-term neonatal morbidity in our study. However, delivery within 30 minutes did not prevent every case of low umbilical cord pH level or low 5-minute Apgar score, so these results should be interpreted with caution. Our results are similar to those from a published series of complete uterine rupture managed between 1983 and 1992 that also reported no adverse outcomes when the neonate was delivered within 18 minutes of the onset of prolonged fetal heart rate decelerations.14
Strengths of this study include evaluation of uterine rupture during a vaginal birth after cesarean delivery attempt at multiple institutions with and without immediate availability of anesthesia and obstetric personnel. We identified cases using a large database, and a thorough chart review of all cases assured the accuracy and reliability of the diagnosis, time to delivery, and management. We also include long-term pediatric follow-up for the majority of our cases. The primary weakness is the limited number of cases because of the rarity of the condition. However, this is the largest contemporary series of uterine rupture with the neonatal outcome stratified by time to delivery.
Uterine rupture during TOLAC is a rare but serious complication that requires prompt recognition and delivery of the fetus. The response time necessary to prevent neonatal injury has been uncertain and controversial. In our study, all neonates delivered within 18 minutes from decision to delivery had normal umbilical cord pH levels. Delivery within 30 minutes was associated with good long-term outcomes. This information may be useful to hospitals and physicians for establishing guidelines, coverage arrangements, and simulation drills to provide a safe environment for women who want to be able to deliver by a vaginal birth after cesarean delivery.
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