Descent of fetal head during active pushing: secondary analysis of prospective cohort study investigating ultrasound examination before operative vaginal delivery

Abstract

Objectives To investigate if descent of the fetal head during active pushing is associated with duration of operative vaginal delivery, mode of delivery and neonatal outcome in nulliparous women with prolonged second stage of labor. Methods This was a prospective cohort study of nulliparous women with prolonged second stage of labor, conducted between November 2013 and July 2016 in five European countries. Fetal head descent was measured using transperineal ultrasound. Head–perineum distance (HPD) was measured between contractions and on maximum contraction during active pushing, and the difference between these values (ΔHPD) was calculated. The main outcome was duration of operative vaginal delivery, estimated using survival analysis to calculate hazard ratios (HRs) for vaginal delivery, with values > 1 indicating a shorter duration. HR was adjusted for prepregnancy body mass index, maternal age, induction of labor, augmentation with oxytocin and use of epidural analgesia. Pregnancies were grouped according to ΔHPD quartile, and delivery mode and neonatal outcome were compared between groups. Results The study population comprised 204 women. Duration of vacuum extraction was shorter with increasing ΔHPD. Estimated mean duration was 10.0, 9.0, 8.8 and 7.5 min in pregnancies with ΔHPD in the first to fourth quartiles, respectively, and the adjusted HR for vaginal delivery, using increasing ΔHPD as a continuous variable, was 1.04 (95% CI, 1.01–1.08). Mean ΔHPD was 7 mm (range, −10 to 37 mm). ΔHPD was either negative or ≤ 2 mm in the lowest quartile. In this group, 7/50 (14%) pregnancies were delivered by Cesarean section, compared with 8/154 (5%) of those with ΔHPD > 2 mm (P < 0.05). There was no significant association between umbilical artery pH < 7.10 or 5‐min Apgar score < 7 and ΔHPD quartile. Conclusion Minimal or no fetal head descent during active pushing was associated with longer duration of operative vaginal delivery and higher frequency of Cesarean section in nulliparous women with prolonged second stage of labor. © 2019 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of the International Society of Ultrasound in Obstetrics and Gynecology.

New technique for automatic sonographic measurement of change in head–perineum distance and angle of progression during active phase of second stage of labor

“…reported that a change in the AoP > 15° predicted 73% of successful vaginal extractions in their cohort 18 . In a recent multicenter prospective study of women with prolonged second stage of labor, delta‐HPD was found to be inversely related to the duration of operative vaginal delivery, the risk of failure and the need of a subsequent Cesarean delivery 19 .…”

“…Among the different ultrasound parameters that have been proposed for the evaluation of fetal head progression and prediction of delivery outcome, the AoP and HPD have gained popularity and are increasingly used in the management of abnormal labor progression [4][5][6][7][8][17][18][19][20][31][32][33][34][35][36] . On this basis, the recent ISUOG guideline has recommended their routine measurement in pregnancies with prolonged second stage of labor or before considering operative delivery 16 .…”

“…Rather than the absolute value obtained at rest, the dynamic change in these parameters during maternal pushing has been shown to be helpful in assessing the progression of the head during the second stage of labor and in anticipating the outcome of instrumental vaginal delivery [17][18][19][20] . Furthermore, evaluation of the dynamic change in AoP has been proven to be useful in sonographically coached pushing during the active second stage of labor, as a quantitative measure of the effectiveness of maternal pushing efforts 21,22 .…”

Transperineal ultrasound assessment of maternal pelvic floor at term and fetal head engagement

“…Kahrs et al 42,43 performed a multicenter study on the use of ultrasound before vacuum delivery. Recently, they performed a secondary analysis of their data assessing fetal head descent during active pushing and found that a lack of fetal descent during active pushing was associated with longer duration of operative vaginal delivery 44 . Interestingly, in some women, the fetal head was higher in the birth canal during maternal pushing than at rest.…”

The dynamic change of the anteroposterior diameter of the levator hiatus under Valsalva maneuver at term and labor outcome

“…LAM coactivation was recently found to be associated with longer second, active second stage of labor and with less engaged fetal head at term 15,17,22 . In a recent study conducted on women undergoing vacuum delivery, LAM coactivation was assumed to be the cause of lack of fetal head descent with maternal pushing 23 …”