Pre-Induction Transperineal Ultrasound Assessment for the Prediction of Labor Outcome

Abstract

Objective: To examine (1) the concordance of manual and automated para-symphyseal angle of progression (psAOP) measurements, (2) the repeatability of psAOP, head-symphysis distance, head-perineum distance, and sonographic cervical dilatation, and (3) the value of transperineal ultrasound (TPU) in predicting induction of labor (IOL) outcome. Methods: We performed a prospective study in 308 women with singleton pregnancies undergoing IOL at term. Logistic regression analysis was used to determine which maternal factors, Bishop score, method of IOL, and TPU parameters were significant predictors of cesarean section (CS) and CS due to no progress (CS-NP). Results: There was vaginal delivery in 225 (83.0%) and CS in 46 (17.0%) cases. The intra-class correlation coefficient between manual and automated psAOP was 0.866, but automated psAOP was 4.6° wider than manual measurement. All TPU parameters had an inter-observer intra-class correlation coefficient > 0.800. Significant independent prediction of CS and CS-NP was provided by maternal factors, previous vaginal delivery, and psAOP. There was no improvement in area under the receiver-operating characteristic curve with the addition of psAOP to maternal factors. Conclusions: All TPU parameters are reproducible. Comparing the three TPU parameters for fetal head station, only psAOP is a significant independent predictor of CS; however, it is unlikely to be useful in predicting IOL outcome.

Feasibility, Reliability, and Agreement of Transperineal Ultrasound Measurement: Results from a Longitudinal Cohort Study

“…Our group has reported a series of studies demonstrating that the TPU assessment of fetal head station has high interobserver intraclass correlation, and it can be used for the prediction of modes of delivery [21,25,28]. The cur-rent report has extended the aforementioned observations supporting the use of TPU along with vaginal examination for the monitoring of labor progress.…”

“…Briefly, a covered convex transducer (4C-RS) was placed between the labia majora, below the symphysis pubis, and an image was acquired to include the symphysis pubis and the fetal head. Small lateral movements of the probe were made to align the ultrasound beam in a parasagittal orientation to include the whole length of the parasagittal pubic bone and fetal skull [21]. The ps-AOP was measured between the longitudinal axis of the pubic bone and the lowest convexity of the fetal skull ( Fig.…”

“…In the same plane, the HSD was measured with standard calipers, which is the distance between the lowest edge of the parasagittal pubic bone and the nearest point of the fetal skull along a line passing perpendicular to the long axis of the pubic bone ( Fig. 1b) [21]. The SCD was measured by identifying the anterior edge of the cervix in the sagittal plane and turning the transducer 90° to acquire a full view of the cervix.…”

“…In recent years, the use of transperineal ultrasound (TPU) examination has been introduced as part of the assessment of labor progress [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29]. This approach is considered less intrusive, reproducible, objective, and wellaccepted compared to vaginal examination [7,12,14,28].…”

“…Last, a simple method for ultrasonographic measurement of cervical dilatation at the transverse section of the cervix has been described [33, 34]. Our group and other investigators have demonstrated that these TPU parameters during the first and second stages of labor are independent predictors of mode of delivery [8, 11, 13, 15, 17, 21, 28].…”