Sonographic parameters for diagnosing fetal head engagement during labour

Area of Science:

• Obstetrics and Gynecology
• Medical Imaging
• Fetal Monitoring

Background:

• Accurate assessment of fetal head station is crucial for managing labor and delivery.
• Digital vaginal examination is the traditional method, but it can be subjective and less precise.
• Intrapartum ultrasound offers a potentially more objective and detailed evaluation of fetal head engagement.

Purpose of the Study:

• To evaluate the diagnostic performance of specific intrapartum ultrasound parameters in determining fetal head engagement.
• To compare ultrasound measurements with digital vaginal examination findings for fetal head station.
• To establish reliable ultrasound cut-off values for identifying an engaged fetal head.

Main Methods:

• Two hundred and one women in labor were assessed using both transperineal ultrasound and digital vaginal examination.
• Ultrasound measured head-perineum distance, angle of progression, and head-symphysis distance.
• Receiver operating characteristic (ROC) analysis was employed to determine diagnostic performance and optimal cut-off values.

Main Results:

• Head-perineum distance ≤3.6 cm showed 78.7% sensitivity and 72.3% specificity for fetal head engagement.
• Head-symphysis distance ≤2.8 cm demonstrated 74.5% sensitivity and 70.8% specificity.
• Angle of progression ≥101° had 68.1% sensitivity and 68.2% specificity in detecting engagement.

Conclusions:

• Intrapartum transperineal ultrasound is a highly effective tool for assessing fetal head engagement.
• Specific ultrasound measurements (head-perineum distance, head-symphysis distance, angle of progression) provide reliable indicators of engagement.
• Ultrasound offers a valuable, non-invasive alternative or adjunct to digital vaginal examination for labor management.