Chapter 226 Uterine Rupture
INTRODUCTION
Description: Uterine rupture is characterized by breach of the uterine wall (new or after previous uterine surgery such as cesarean delivery) that may result in significant maternal or fetal morbidity or mortality. This should be distinguished from uterine scar dehiscence, in which there is separation of an old scar that does not penetrate the uterine serosa or result in complications. Rupture of an intact uterus (without scars) does occur on rare occasions (1 in 15,000 deliveries) and is generally associated with significant uterine distention (polyhydramnios, multiple gestation).
Prevalence: Found in 0.5% to 3.7% of patients with a previous cesarean delivery and 5% of patients for whom vaginal birth after cesarean delivery (VBAC) fails. Uterine rupture rates in women with previous classical incisions and T-shaped incisions range between 4% and 9%. Roughly 7% of emergency cesarean hysterectomies are for rupture.
ETIOLOGY AND PATHOGENESIS
Causes: Abnormal healing of a previous uterine scar, mechanical disruption of the uterine wall weakened by previous surgery, congenital anomalies, or abnormalities of placentation. (The uterine wall may also be breached by injudicious manual removal of the placenta or manual exploration of the uterus after delivery of the placenta.) Traumatic rupture of the uterus may occur with blunt trauma to the abdomen such as occurs to an unrestrained passenger during an automobile accident. (The proper use of automobile lap and shoulder belts significantly reduces the risk of injury to both mother and fetus.)
Risk Factors: Previous uterine surgery (cesarean delivery; greatest for vertical incisions, myomectomy, septoplasty), multiple gestation, grand multiparity (20-fold increase), short interval between pregnancies, fetal malpresentation, polyhydramnios, oxytocin stimulation (unproved), congenital anomalies, and disuse or misuse of vehicle passenger restraints. There is considerable evidence that cervical ripening with prostaglandin preparations increases the likelihood of uterine rupture (15-fold increase).
