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For Monitoring Labor, Is Inside the Uterus Better Than Outside?

Rates of operative delivery did not differ significantly for internal versus external measurement of uterine contractions.

Internal measurement of uterine contractions during induction or augmentation of labor has been advocated by organizations such as the American College of Obstetricians and Gynecologists and the Dutch Society of Obstetrics and Gynaecology, but whether this approach leads to better outcomes is uncertain. Dutch investigators conducted a randomized controlled nonblinded trial to compare outcomes of deliveries that involved internal (734) or external (722) monitoring. The primary outcome was rate of instrumental or cesarean deliveries. Participants had singleton, vertex pregnancies of >36 weeks' gestation and underwent induction or augmentation of labor with oxytocin.

Operative deliveries were performed in 31% of the internal group and 30% of the external group. Rates of adverse neonatal outcomes also were similar for both groups (14% of internal group, 15% of external group), and there were no reported complications associated with internal monitoring. Maternal parity did not affect outcomes.

Comment: The authors acknowledge that rates of epidural anesthesia in their study (39% of the internal group; 38% of the external group) were lower than those in the U.S. (80% to 90%); however, these rates were consistent with nationwide rates in the Netherlands. The authors believe that the lack of blinding in their study did not bias the delivery choices of the participating obstetricians. These results do not support routine use of internal monitoring in women who undergo induction or augmentation of labor with oxytocin; however, use of internal monitoring in selected situations (e.g., amnioinfusion, evaluation of Montevideo units to assess intensity of uterine contractions) still might be warranted.

— Diane J. Angelini, EdD, CNM, FACNM, FAAN, NEA-BC

Published in Journal Watch Women's Health January 27, 2010

Citation(s):

Bakker JJH et al. Outcomes after internal versus external tocodynamometry for monitoring labor. N Engl J Med 2010 Jan 28; 362:306.

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Review and add to remarks on this article

• Both internal and external are more harm than benefit
  Susan M. Jenkins, 28 Jan 2010 12:43 PM EST
  If we are looking for a benefit, the answer has to be "none of the above." It seems that BOTH... [more]

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