Analysis of Hysterotomy Extension at Unscheduled Cesarean Delivery

This study aimed to determine if the rate of hysterotomy extensions increases with increasing cervical dilation in unscheduled cesarean deliveries, and to develop a measure of the severity of hysterotomy extension for quantifying morbidity.This is a retrospective study of unscheduled cesarean deliveries relating to labor dystocia and/or nonreassuring tracings from January 1, 2021, to December 31, 2021. Severe extension was defined as bilateral or adjacent to a structure such as the uterine artery, broad ligament, or cervix, and was compared with uterine artery extensions alone.There were 990 unscheduled cesarean deliveries included. Extensions (<i>n</i> = 233) significantly increased with increasing cervical dilation (<i>p</i> < 0.0001), complicating more than 30 and 50% at 6 and 10 cm of cervical dilation, respectively. Apart from this trend, a logistic regression analysis indicated cervical dilation was an independent risk factor for extension. Transfusions of at least 2 units of blood were five times (26 vs. 5%) more likely for patients with severe extensions than no extension (<i>p</i> < 0.0001).Hysterotomy extensions significantly increase with increasing cervical dilation, and cervical dilation is an independent risk factor for extension. A composite measure of severity accounts for different types of extension when quantifying morbidity, but uterine artery extension is the primary driver of maternal morbidity in cases without hysterectomy. · We report higher than previously published rates of extension, in our study of unscheduled cesareans.. · Extension rates rise with cervical dilation-33% at 6 cm, over 50% at 10 cm.. · Cervical dilation is an independent risk factor for extension.. · Severe extensions were fivefold more likely to be transfused two units than no extension.. · The composite measure for severity was driven by uterine artery extensions..