Sacral agenesis

Key points

Caudal regression syndrome

Also known as sacral agenesis/dysgenesis, caudal dysplasia

Main risk factor: Maternal diabetes

Shortened trunk due to absence of vertebrae

Lumbosacral agenesis + cord abnormalities - spectrum of severity

Flexion contracture of hips, knees - can be sirenomielia (mermaid syndrome)

Club feet

Flattened buttocks with a low short gluteal cleft

Neuropathic bladder common

MRI - consistent finding of a sharp cut-off of the conus medullaris opposite T12 vertebra

Also associated with:

Anorectal malformations

Renal abnormalities

References

Kylat RI, Bader M. Caudal Regression Syndrome. Children (Basel). 2020 Nov 4;7(11):211. doi: 10.3390/children7110211. PMID: 33158301; PMCID: PMC7694368./d