Original Articles
Active-phase labor arrest: oxytocin augmentation for at least 4 hours

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Abstract

Objective: To assess a labor-management protocol that mandated at least 4 hours of oxytocin augmentation before cesarean delivery for active-phase labor arrest.

Methods: We prospectively evaluated term gravidas in spontaneous labor with active-phase labor arrest (cervix at least 4 cm dilated and 1 cm or less of cervical progress in 2 hours). Exclusion criteria included nonvertex presentation, previous cesarean, multiple gestation, and a nonreassuring fetal heart rate tracing or chorioamnionitis at the time of labor arrest. After the diagnosis of active-phase arrest, oxytocin was initiated with an intent to achieve a sustained uterine contraction pattern of greater than 200 Montevideo units. Cesarean delivery was not performed for labor arrest until at least 4 hours of a sustained uterine contraction pattern of greater than 200 Montevideo units, or a minimum of 6 hours of oxytocin augmentation if this contraction pattern could not be achieved.

Results: Five hundred forty-two women were managed by the protocol, and 92% delivered vaginally. The subsequent vaginal delivery rate for parous women who had not progressed (1 cm of cervical dilation or less) despite 2 hours of oxytocin augmentation was 91%, and it was 74% for nulliparas. With no labor progress after 4 hours of oxytocin augmentation, the subsequent vaginal delivery rates were 88% for parous women and 56% for nulliparas. There were no severe maternal complications. One neonate had persistent fetal circulation and one had a positive blood culture, but both did well.

Conclusion: Extending the minimum period of oxytocin augmentation for active-phase labor arrest from 2 to at least 4 hours was effective and safe.

Section snippets

Material and methods

The protocol was instituted on February 1, 1996 at the Maternal-Fetal Medicine service of the University of Alabama at Birmingham Hospital, which has approximately 3000 deliveries annually. Deliveries on this service are performed by resident physicians under the direct 24-hour supervision of one of 11 members (faculty and fellows) of the Maternal-Fetal Medicine Division.

All members of the Maternal-Fetal Medicine Division agreed to manage eligible women according to protocol. Before institution

Results

From February 1, 1996 through April 6, 1998, 554 protocol-eligible women experienced active-phase labor arrest. Twelve (2%) of these women did not receive oxytocin because of spontaneous progress of labor before initiation of the drug. These women all delivered vaginally, and because they did not receive oxytocin, they were not considered further in the analysis of this protocol. Thus, 542 women were eligible for the protocol and received oxytocin.

Of the women managed by the protocol, 288 (53%)

Discussion

We conducted the present investigation to evaluate a protocol that focused on three principal elements: 1) an intent to achieve a sustained uterine contraction pattern of greater than 200 Montevideo units; 2) a more liberal minimum of 4 hours (as opposed to the currently sanctioned 2 hours5) of oxytocin-augmented labor arrest with a sustained uterine contraction pattern of greater than 200 Montevideo units before proceeding to cesarean delivery for active-phase labor arrest; and 3) for patients

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