Caudal epidural block based on trans-anal digital palpation of sacro-coccygeal bones in patients with extreme obesity

Abstract

A 38-year-old male, 168cm tall, weighing 124kg, and a 51-year-old male weighing 75kg with severe atrophy of the lower extremities after poliomyelitis in infancy were scheduled for perianal fistulectomy. Extreme obesity obscured the usual landmarks of the lumbar vertebral bones and the iliac crest. Subarachnoidal punctures with an 89mm needle from an estimated median line, as well as a paramedian line, were unsuccessful. For caudal epidural anesthesia, no sacro-coccygeal bones were palpable. The landmarks were eventually obtained by trans-anal digital palpation. In contrast to the external morphology of obesity, the pre-sacro-coccygeal region was relatively free of excessive tissue. The contours of the sacro-coccygeal bones were felt easily with the finger tip through the rectal wall. A successful puncture via the sacro-coccygeal ligament was made for epidural anesthesia using these internal landmarks. Pain-clinicians and anesthesiologists can benefit from occasional trans-anal digital exams to refresh their approach to caudal anesthesia.