Transperineal ultrasonography for labor management: accuracy and reliability

To compare ultrasound measurements and clinical assessments of cervical dilatation, fetal head station and fetal head position.

Prospective, observational study.

Tertiary care center (Ankara University Hospital), labor ward.

Forty-three women in labor.

Women were prospectively evaluated through simultaneous examinations (79 in total). Dilatation, head station, and position were recorded via digital examination whenever possible and were compared with ultrasonographic measurements of dilatation, angle of progression, head-perineum distance, and head position by two independent operators. Operators were blinded to each other's findings.

Agreement between sonographic measurements and digital examinations.

Ultrasonographic assessment of dilatation correlated significantly with digital examination. The interclass correlation coefficient of the two methods was 0.82 (95% confidence interval 0.73-0.88). Ultrasonography showed a mean lower cervical dilatation of 10 mm (95% limits of agreement: -36 to 16 mm) compared with digital examination. The angle of progression and head-perineum distances correlated moderately with the palpated head station (Pearson's correlation coefficients: 0.55 and -0.42, respectively; p < 0.001). Position could only be assessed in 40 of 79 examinations by digital examinations and the results showed low agreement with ultrasound findings.

We observed good agreement between clinical and ultrasound assessment of dilatation, moderate agreement in assessing fetal station and low agreement assessing head position.