Ultrasound determination of the dural sac to sacrococcygeal membrane distance in premature neonates.

Ultrasound can be used to measure the sacrococcygeal membrane to dura distance in preterm neonates prior to needle insertion when performing caudal block and demonstrates large variability. Ultrasound imaging may identify patients at risk for dural puncture. When ultrasound is not available, needle insertion less than 3 mm/kg beyond the puncture of the sacrococcygeal membrane should prevent dural contact in 99.9% of neonates.