Sonography only, few internal examinations (SOFIE): Birth progress in normal deliveries followed with intrapartum...

Intrapartum transperineal ultrasound (ITU) is objective and more reproducible than clinical palpation. We developed and tested a protocol to follow normal, low-risk laboring women. The aim was to provide safe and minimally or non-invasive intrapartum care based primarily on ITU and fetal heart rate tracing, with as little vaginal digital palpation as possible. In a pilot study, we evaluated the feasibility of "Sonography Only, Few Internal Exams" (SOFIE) in a university maternity unit.

Women aged at least 18 years with normal pregnancies and singleton fetuses in cephalic presentation and gestational age >= 37 + 0 weeks with no known abnormalities or relevant maternal conditions were recruited on admission to the labor ward. The first ultrasound examination (biometry for estimated fetal weight, amniotic fluid volume, placental position, spinal and occipital position) and the only planned digital vaginal examination (for the head station, expressed in cm +/- and related to the interspinal plane, and cervical dilatation expressed as 0-10 cm) were performed. No further routine vaginal examinations were performed thereafter. Two sets of ITU measurements were then also taken at rest and at the height of a contraction: first, in a transperineal median insonation to measure (i) the angle of progression (AOP) as a marker of head station and (ii) head direction; then a transperineal transverse insonation to measure the midline angle for head rotation and position. ITU measurements were repeated 1-2 hourly. Additional vaginal examinations were only allowed (i) if there was no progress on the ITU for more than three hours, (ii) if there was an abnormal fetal heart rate tracing as defined by FIGO criteria, or (iii) in an emergency. The birth charts of a further 40 women, who matched the inclusion criteria as a control group, were analyzed retrospectively.

The protocol was first discussed and agreed upon with the labor ward staff, including the midwives, and then implemented in a pilot study. This study included 21 women in labor. In 13/21 women, the labor was completed as planned (no vaginal examination except for the initial examination and labor, then birth progress followed by ultrasound only). 8/21 women had additional examinations according to the protocol, six patients for arrest of labor and 2 for pathological fetal heart rate tracing. We found a significant difference in the number of vaginal examinations between the ultrasound alone group and the control group (mean 2.33 (range 1-6) vs mean 4.83 (range 2-11), p < 0.001). We also found a significant difference in maternal infectious morbidity, which was absent in the study group but present in the control group (p = 0.02). There was also less time in labor in the study group (5.6 h vs 9 h, p = 0.01). Other clinical outcomes were not different between the SOFIE and control groups.

ITU has beneficial effects on normal childbirth. It could improve the accurate assessment of labor progress. It is non-invasive and is likely to prevent infectious morbidity. This novel approach is currently being studied under the protocol outlined above, including assessment of pain perception and intimacy of examination.