Neural tube defects are caused by complex genetic and environmental factors. The congenital anomaly most specific to pregnant women with diabetes mellitus is caudal regression syndrome.A 4-year-old boy with a history of mild delay in motor development presented with primary enuresis and encopresis. On physical examination, he had no sensory and motor deficits, but a short anal cleft. On questioning, the mother reported insulin-dependent diabetes mellitus during pregnancy. MRI of the spinal cord demonstrated a thoracic syringomyelia, a dysplastic conus medullaris, and an absence of coccyx and distal sacrum, called caudal regression syndrome or caudal agenesis.The caudal regression syndrome refers to sacral agenesis associated with spinal cord anomalies, e.g. syringomyelia. Sacral agenesis is marked by total absence of the coccyx and total or distal absence of the sacrum. An abnormal backside combined with a history of maternal diabetes mellitus in pregnancy is highly suggestive for the presence of caudal regression syndrome.