Maternal and fetal morbidity associated with uterine rupture of the unscarred uterus.

Objective: We sought to report obstetric and neonatal characteristics and outcomes following primary uterine rupture in a large contemporary obstetric cohort and to compare outcomes between those with primary uterine rupture vs those with uterine rupture of a scarred uterus.
Study Design: This was a retrospective case-control study. Cases were defined as women with uterine rupture of an unscarred uterus. Controls were women with uterine rupture of a scarred uterus. Demographics, labor characteristics, and obstetric, maternal, and neonatal outcomes were compared. Primary rupture case outcomes were also compared by mode of delivery.
Results: There were 126 controls and 20 primary uterine rupture cases. Primary uterine rupture cases had more previous live births than controls (3.6 vs 1.9; P < .001). Cases were more likely to have received oxytocin augmentation (80% vs 37%; P < .001). Vaginal delivery was more common among cases (45% vs 9%; P < .001). Composite maternal morbidity was higher among primary uterine rupture mothers (65% vs 20%; P < .001). Cases had a higher mean estimated blood loss (2644 vs 981 mL; P < .001) and higher rate of blood transfusion (68% vs 17%; P < .001). Women with primary uterine rupture were more likely to undergo hysterectomy (35% vs 2.4%; P < .001). Rates of major composite adverse neonatal neurologic outcomes including intraventricular hemorrhage, periventricular leukomalacia, seizures, and death were higher in cases (40% vs 12%; P = .001). Primary uterine rupture cases delivering vaginally were more likely to ultimately undergo hysterectomy than those delivering by cesarean (63% vs 9%; P = .017).
Conclusion: Although rare, primary uterine rupture is particularly morbid. Clinicians must remain vigilant, particularly in the setting of heavy vaginal bleeding and severe pain.
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