Ultrasound in labor is not a proposed standard of care; however, several studies have reported it to be more accurate and reproducible than clinical examination. It is especially helpful in knowing the fetal position and station and prediction of the arrest of labor.
The International Society of Ultrasound in Obstetrics and Gynecology (ISUOG) recently issued practice guidelines for Intrapartum Ultrasound. These Guidelines address exclusively the use of ultrasound in labor to determine fetal head station, position and attitude.
Intrapartum ultrasound can predict mode of delivery (vaginal or operative) and outcome of instrumental vaginal delivery. It is used in the labor ward as an adjunct to clinical digital examination to assess the position of the fetal head, fetal head station, progression, and attitude.
Ultrasound in labor is performed using a transabdominal or transperineal approach depending upon the clinical situation. A wide-sector, low-frequency (< 4 MHz) exposure is best suited to ultrasound in labor.
Indication for Ultrasound in labor room
Slow progress or arrest of labor in the first or second stage
To determine the fetal head station and position before attempting instrumental vaginal delivery
Assessment of fetal head malpresentation.
While performing ultrasound in labor, data documentation includes fetal viability and FHR, fetal presentation, the position of the spine and occiput, the position of the placenta in relation to the cervix and presenting part.
While performing a transperineal ultrasound, the sonographer should also look for following parameters, especially before operative vaginal delivery (OVD):
Angle of progression (AoP)
Head–perineum distance (HPD)
Head direction with respect to the
Midline angle (MLA)
Here is an informative and detailed video by ISUOG about practice guidelines on intrapartum ultrasound
