Advanced midwifery practice: intrapartum ultrasonography to assess fetal head station and comparison with vaginal digital examination.

Background: Vaginal digital examination is considered the gold standard to evaluate patients during labor and delivery. However, transperineal ultrasound has been suggested as an effective tool in determining fetal head station during labor. Angle of progression (AOP), head-perineal distance (HPD) and head-symphysis distance (HSD) are reliable parameters to assess fetal head station during labor. The study aims were to evaluate how midwives can use AOP, HSD, HPD to assess the accuracy of digital vaginal exploration limited to the fetal head station.

Methods: Trained midwives for ultrasound analyses performed transperineal ultrasounds during the first stage of labor with 2D-convex probe in 62 pregnant women at term with a single fetus in cephalic presentation. Immediately before the intrapartum ultrasound, the birth attendant performed a digital examination to assess cervical dilatation and head station. The ultrasound scans were compared to the digital vaginal examination through the Tutschek's formula.

Results: AOP was wider in women who delivered vaginally without any complication if compared to "complicated delivery" group. HPD and HSD were greater in women who underwent an operative vaginal delivery or caesarean section. The vaginal exploration accuracy was 34%, but when ±1 cm was considered as tolerated, the overall accuracy was 74.19%.

Conclusions: Midwives may include ultrasounds in their clinical practice after adequate training or under the supervision of an ultrasound professional as an adjunct tool during labor to evaluate its progress and prevent any deviation from physiology.