Uterine Rupture During VBAC Trial Of Labor: Risk Factors and Fetal Response

Nancy O'Brien-Abel, RNC, MN


J Midwifery Womens Health. 2003;48(4) 

In This Article

Fetal Heart Rate and Uterine Rupture

Studies examining the fetal heart rate (FHR) prior to uterine rupture consistently report that non-reassuring fetal heart rate patterns are the predominant sign suggesting impending or actual uterine rupture. Menihan[57] examined the FHR tracings of 11 women attempting VBAC-TOL and reported fetal bradycardia in 82% (n = 9/11) prior to uterine rupture. Prior to the bradycardia, 73% (n = 8/11) had variable decelerations, 36% (n = 4/11) had late decelerations, 27% (n = 3/11) had early decelerations, and none had tachycardia. In a review of eight fetal monitor tracings for 2 hours preceding uterine rupture, Ayres et al.[58] identified recurrent late decelerations in 88% (n = 7/8) and terminal bradycardia in 50% (n = 4/8) of the tracings.

In a larger study, Leung et al.[14] analyzed the FHR and uterine contraction pattern immediately prior to 78 cases of uterine rupture. Prolonged deceleration was defined as a FHR less than 90 beats per minute that exceeded 1 minute without return to baseline. Prolonged deceleration (alone or proceeded by either severe late or variable decelerations) occurred in 71% (n = 55/78) of the cases of uterine rupture. In addition, prolonged deceleration occurred in 100% (n = 36/36) of the FHR tracings in which total fetal extrusion occurred. If more than one type of periodic deceleration, in addition to a prolonged deceleration was present, only the most ominous pattern was recorded. Late decelerations were considered most ominous, followed by variable and early deceleration. Although late decelerations were more common preceding the prolonged deceleration that heralded uterine rupture, this finding may be an artifact of the study methodology.


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