Uterine Rupture in the Unscarred Uterus

A ruptured uterus is a potentially catastrophic event in which the integrity of the myometrial wall is breached. We all have memorized the usual red flags and contraindications to labor as prior classical cesarean, multiple (more than 2) low transverse cesarean, prior transmural gyn surgery, or grand multiparity. In the absence of previous surgery or multiparity, uterine rupture may go unnoticed, resulting in late diagnosis and considerable mortality and morbidity. Uterine rupture intrapartum has also been reported in primiparous patients, without a history of uterine surgery. Although more likely to go unrecognized and/or underreported, the proposed incidence of rupture in the unscarred uterus has been recently published at less than 0.01% deliveries! Rare right? Well, it’s rare until it happens to you. In contrast, uterine rupture has been reported to occur in 0.2–1% in those with one previous low-transverse scar.
Diagnosing this condition in the absence of uterine scar requires a high degree of suspicion and fetal heart tracing abnormalities remain the most common symptom. In this episode, we will look at published data- including a recent review from the Green Journal from April 2023- regarding this terrifying event and review risk factors that may raise the risk of uterine rupture in a patient without the classic historical red flags. And, we will review how 2 GYN diagnoses influence the risk of uterine rupture in labor. Plus, we will review what the published data says regarding characteristic uterine and fetal heart rate patterns in those found to have uterine rupture.