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The benefits of Sonography-Based Volume Computer Aided Displaylabor (SonoVCADlabor) during second stage labor
INTRODUCTION
Infrapubic translabial ultrasound in the second stage of labor has been recently suggested to improve a physician's ability to assess fetal head station and position.
Dietz et al were the first to propose the use of a translabial approach and suggested calculation of the distance between the pubis and the lowest edge of the fetal head to evaluate engagement.1
Henrich et al observed that descent of the fetal head during second stage of labor followed a curvilinear path. In a sagittal plane, the head was progressively directed downward, horizontally and eventually upward. Using a 3D CT reconstruction of maternal pelvis they also demonstrated that the ischial spine level is usually 3 cm below the pubic bone which allows for a more precise evaluation of the fetal station. Finally they reported that the upward direction of the fetal head was highly predictive of imminent vaginal delivery or easy vacuum extraction, particularly if upward movement was sonographically observed during patient pushing.2
In a later publication, the same authors used volume reconstruction and demonstrated internal rotation of the fetal head by surface rendering of the fetal skull.3
Authors:
T. Ghi,* N. Salomon,** W. Henrich,** G. Pilu*
* Department of Obstetrics and Gynaecology, University of Bologna, Italy
** Department of Obstetrics, Charité-Universitätsmedizin Berlin, Germany