What is labor dystocia and how is it diagnosed and managed?

Updated: Jan 24, 2019
  • Author: Sarah Hagood Milton, MD; Chief Editor: Christine Isaacs, MD  more...
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While the ACOG defines labor dystocia as abnormal labor that results form abnormalities of the power (uterine contractions or maternal expulsive forces), the passenger (position, size, or presentation of the fetus), or the passage (pelvis or soft tissues), labor dystocia can rarely be diagnosed with certainty. [1] Often, a "failure to progress" in the first stage is diagnosed if uterine contraction pattern exceeds 200 Montevideo units for 2 hours without cervical change during the active phase of labor is encountered. [1] Thus, the traditional criteria to diagnose active-phase arrest are cervical dilatation of at least 4 cm, cervical changes of < 1 cm in 2 hours, and a uterine contraction pattern of >200 Montevideo units. These findings are also a common indication for cesarean delivery.

Proceeding to cesarean delivery in this setting, or the "2-hour rule," was challenged in a clinical trial of 542 women with active phase arrest. [55] In this cohort of women diagnosed with active phase arrest, oxytocin was started, and cesarean delivery was not performed for labor arrest until adequate uterine contraction lasted at least 4 hours (>200 Montevideo units) or until oxytocin augmentation was given for 6 hours if this contraction pattern could not be achieved. This protocol achieved vaginal delivery rates of 56-61% in nulliparas and 88% in multiparas without severe adverse maternal or neonatal outcomes. Therefore, extending the criteria for active-phase labor arrest from 2 to at least 4 hours appears to be effective in achieving vaginal birth. [55, 1]

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