The Effect of Fundal Pressure Manoeuvre on Intrauterine Pressure in the Second Stage of Labour

Abstract

Fundal pressure is the application of external force to the uppermost part of the uterus in the caudal direction in an attempt to shorten the duration of the second stage of labor. Although a large majority of US centersuse fundal pressure, many fail to document the practice in medical records. Studies of how fundal pressure might speed delivery are lacking. The authors report a prospective study in 40 healthy, full-term women in spontaneous labor who had intrauterine pressure recorded during the second stage. The authors' hypothesis was that fundal pressure might act in part through increasing intrauterine pressure. All participants were in active labor at term (defined as a gestational age >37 weeks) and had a singleton fetus in vertex presentation. Epidural or combined spinal-epidural analgesia was used in all cases; the women remained alert and responsive throughout. The median oxytocin dose was 6 mU/min. Intrauterine pressure was monitored using a sensor-tip catheter introduced into the uterine cavity. Fundal pressure was applied at a 30- to 40-degree angle to the spine in the direction of the pelvis, using a semi-inflated pressure cuff interposed between the clinician's hand and the abdominal wall. Applied pressure was maintained at 80 to 90 mm Hg. All but 4 of the 40 women delivered vaginally without intervention. A Valsalva maneuver during contraction increased the expulsive force by 55% of the spontaneous contraction. Adding fundal pressure to the Valsalva led to an 86% increase over baseline intrauterine pressure (which represents expulsive force). Fundal pressure alone increased the active contraction area 28% over baseline. When measured between contractions, both fundal pressure and the Valsalva increased uterine pressure, but significantly less than during baseline uterine contractions. Analyzing the peak expulsive force achieved showed that 53% of overall performance reflected uterine contraction. The Valsalva added another 30%, and fundal pressure, an additional 17%. In certain patients, fundal pressure contributed significantly to overall expulsive force, but in others it added nothing. On multivariate linear regression analysis, fundal pressure and the Valsalva were most effective when the myometrium was relatively thin and gestational age was greater. Parity was not a factor in how efficiently either fundal pressure or the Valsalva increased expulsive uterine force. Fundal pressure can substantially augment intrauterine pressure in some parturients, and they can be identified in the labor room. Excessive force may be avoided by monitoring intrauterine pressure as fundal pressure is applied.