The caudal space in fetuses: an anatomical study

Area of Science:

• Anatomy
• Pediatric Anesthesiology
• Fetal Development

Background:

• Caudal epidural blocks are frequently used for pediatric analgesia.
• Blind needle placement during caudal epidurals carries risks of intravascular and intrathecal spread.
• Understanding anatomical landmarks is crucial for safe caudal epidural procedures in neonates.

Purpose of the Study:

• To investigate the anatomical parameters of the sacrum in fetuses to improve the safety of caudal epidural blocks in premature infants.
• To determine safe distances and angles for accessing the caudal epidural space.

Main Methods:

• Dissection of the sacrum in 39 fetuses (33-50 cm crown-heel length).
• Measurements of dorsal surface and midsagittal sections.
• Goniometric measurement of needle depression angle using a two-step insertion method.

Main Results:

• Sacral cornua were palpable in 58.97% of fetuses.
• Dural sac terminated at S2 in 53.84% and sacral hiatus apex at S3 in 58.97%.
• Significant correlation between sacral parameters and crown-heel length, except for specific measurements like inter-cornual distance.

Conclusions:

• Fetal sacral anatomy, including the sacral hiatus apex and dural sac termination, exhibits wide variation.
• These anatomical variations limit the predictability of safe distances and angles for caudal epidural blocks in premature and low birth weight infants.
• Further research may be needed to refine techniques for safer caudal epidural access in vulnerable infant populations.