Point-of-care ultrasound for assessing fetal head descent during labor

Ultrasound assessment of fetal head station is more accurate than digital examination, but its use is limited by the lack of equipment dedicated to the labor ward. Point-of-care ultrasound (POCUS) may overcome this barrier. We assessed the agreement between a handheld POCUS device and a conventional high-end system in measuring fetal head descent.

Seventy singleton pregnancies were examined in the second stage of labor. Two experienced operators, blinded to each other's results, performed translabial scans in randomized sequence, one with a handheld wireless device and one with a conventional system. Angle of progression (AoP) and head-perineum distance (HPD) were compared by intraclass correlation coefficients (ICC) and Bland-Altman analysis. Intraobserver repeatability was assessed in a subgroup by repeating both measurements de novo with each device. A blinded observer scored image quality (IQS) and measurement quality (MQS) from 0 to 3.

Mean AoP was 121.8 (12.0)° with the conventional system and 121.9 (12.3)° with POCUS (p=0.71); mean HPD was 31.5 (7.8) and 31.4 (8.1) mm (p=0.69). The ICC was 0.96 (95 % CI 0.94-0.98) for AoP and 0.97 (0.95-0.98) for HPD, with a bias of 0.16° (limits of agreement -6.6 to 6.9) and -0.10 mm (-4.2 to 4.0). IQS and MQS did not differ between devices. Intraobserver ICC ranged from 0.93 to 0.98, with a within-subject coefficient of variation of 2.4-4.2 %.

Handheld POCUS measurements of fetal head descent agree closely with those obtained with conventional equipment, with comparable repeatability and image quality, and may facilitate wider use of intrapartum ultrasound.