Dystocia in Nulliparous Women
SARA G. SHIELDS, MD, MS, University of Massachusetts, Worcester, Massachusetts
STEPHEN D. RATCLIFFE, MD, MSPH, Lancaster General Hospital Family Medicine
Residency Program, Lancaster, Pennsylvania
PATRICIA FONTAINE, MD, MS, University of Minnesota, Minneapolis, Minnesota
LARRY LEEMAN, MD, MPH, University of New Mexico, Albuquerque, New Mexico
mon in nulliparous women, as indicated by
the number requiring augmentation, opera-
tive vaginal delivery, or cesarean section. In
2003, 17 percent of women in the United
States received oxytocin augmentation,1 and
in 2004, the primary cesarean delivery rate
(i.e., cesarean delivery in women without
previous cesarean) rose to 20.6 percent.2
Dystocia is responsible for more than 50 per-
cent of primary cesarean deliveries.3 With the
overall cesarean delivery rate at an all-time
high of 30.2 percent4 (Figure 12,4), optimal
management of dystocia can significantly
impact labor outcomes.
aring for women with dystocia is a
major challenge in maternity care.
Dystocia refers to prolonged or
slowly progressing labor. It is com-
Normal progress in labor was initially defined
by Friedman in the 1950s based on data from
labors of several hundred women.5 Labor
abnormalities are characterized as protrac-
tion or arrest disorders (Table 15,6). To aid in
diagnosis, labor progression may be followed
using a graph called a partogram, which plots
cervical dilation and station across time.7,8
The range of normal labor now appears
to be broader than Friedman’s definitions.
A more recent study of labor progress
among 1,329 nulliparous women deliver-
ing vaginally found it took an average of
5.5 hours to dilate from 4 to 10 cm (a mean
rate of approximately 1.1 cm per hour).9
These findings contrast with Friedman’s
data, which had 1.2-cm dilation per hour
defined as the 95th percentile (i.e., the outer
limit of normal progress).5 The more recent
analysis found that women who had not yet
reached 7 cm dilation often had no cervi-
cal change for more than two hours. Fetal
descent in the second stage of labor also
appeared to take longer.9 Thus, the need for
routine intervention for labor that is pro-
gressive yet protracted is questionable.10
Physicians need to consider four issues when
caring for women with dystocia: (1) if the
contractions are adequate; (2) if there is fetal
malposition; (3) if there is cephalopelvic
Dystocia is common in nulliparous women and is responsible for more than 50 percent of pri-
mary cesarean deliveries. Because cesarean delivery rates continue to rise, physicians providing
maternity care should be skilled in the diagnosis, management, and prevention of dystocia. If
labor is not progressing, inadequate uterine contractions, fetal malposition, or cephalopelvic
disproportion may be the cause. Before resorting to operative delivery for arrested labor, phy-
sicians should ensure that the patient has had adequate uterine contractions for four hours,
using oxytocin infusion for augmentation as needed. For nulliparous women, high-dose
oxytocin-infusion protocols for labor augmentation decrease the time to delivery compared
with low-dose protocols without causing adverse outcomes. The second stage of labor can be
permitted to continue for longer than traditional time limits if fetal monitoring is reassuring
and there is progress in descent. Prevention of dystocia includes encouraging the use of trained
labor support companions, deferring hospital admission until the active phase of labor when
possible, avoiding elective labor induction before 41 weeks’ gestation, and using epidural anal-
gesia judiciously. (Am Fam Physician 2007;75:1671-8. Copyright © 2007 American Academy
of Family Physicians.)
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1678 American Family Physician
Volume 75, Number 11 ◆ June 1, 2007?
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