Rates of uterine rupture and associated complications clearly are increased with TO LAC. Uterine rupture typically is classified as either (1) complete, when all layers of the uterine wall are separated, or (2) incomplete, when the uterine muscle is separated but the visceral peritoneum is intact. Incomplete rupture is also commonly referred to as uterine dehiscence. It is these risks that underpin most of the angst in attempting TOLAC. Despite this, some have argued that these factors should weigh only minimally in the decision because their absolute risk is low. One systematic review by Guise and colleagues (2010) concluded that the risk of uterine rupture was significantly elevated in women undergoing TOLAC-absolute risk of 0.47 percent and relative risk of 20.7-compared with those choosing ERCD.
he Maternal-Fetal Medicine Units Network conducted a prospective study at 19 academic centers (Landon, 2004). The outcomes of nearly 18,000 women attempting TOLAC were compared with more than 15,000 gravidas undergoing ERCD. The absolute risk of uterine rupture was 0.7 percent compared with no reported uterine ruptures in the ERCD cohort (Table 31-2). .10st studies suggest that the maternal mortaliy rate does not difer significantly between these two groups (Landon, 2004; Mozurkewich, 2000). But, the aforementioned systematic review by Guise (2010) found the
Single mother Classical or T incision Increased maternal age Prior rupture Macrosomic fetus Patient refusal Obesity Transfundal surgery Breech Obstetrical contraindication,
Multifetal pregnancy e.g., previa Preeclampsia Inadequate facilities risk of maternal death to be signiicantly reduced for women undergoing TOLAC compared with ERCD. In a retrospective Canadian cohort study, the maternal death rate for women undergoing ERCD was 5.6 per 100,000 cases compared with 1.6 per 100,000 for those attempting TOLAC (Wen, 2005).
Estimates of maternal morbidiy are also conflicting. he review by Guise (2010) observed no significant diferences in the risk of hysterectomy or transfusion. But, another metaanalysis reported that women undergoing TOLAC were approximately half as likely to require a blood transfusion or hysterectomy compared with those undergoing ERCD (Mozurkewich, 2000). Conversely, in the Network study, investigators observed that the risks of transfusion and infection were significantly greater for women attempting TOLAC (Landon, 2004). This disparity is also found among other studies. Notably, compared with a successful TOLAC, the risk of these major complications was ivefold greater with an attempted vaginal delivery that failed (Babbar, 2013; Rossi, 2008).
TOLAC is associated with significantly higher perinatal mortaliy rates compared with ERCD. he perinatal rate with TOLAC is 0.13 compared with 0.05 percent for ERCD, and the neonatal mortality rates are 0.i11 versus 0.06 percent, respectively (Guise, 2010). In another study of nearly 25,000 women with a prior cesarean delivery, the vaginal-delivery-related perinatal death risk was 1.3 per 1000 among 15,515 women electing TOLAC. Although this absolute risk is small, it is 11 times greater than the risk found in 9014 women with ERCD (Smith, 2002).
TOLAC also appears to be associated with a higher risk of hypoxic ischemic encephalopathy (HIE) than ERCD. The Network study reported the incidence of HIE at term to be 46 per 100,000 TOLACs compared with zero cases in women undergoing ERCD (Landon, 2004).