Sacral Meningoceles, ductal ectasia and pseudomeningoceles are all rare spinal defects that occur due to errors in collagen biosynthesis in the setting of Marfan’s Syndrome. Meningoceles, which are extradural collections of cerebrospinal fluid, can form large pelvic collections which can compress local structures. In rare cases, this can lead to extrinsic ureteric obstruction, which can result in acute renal failure and urosepsis. We present a case of a 35-year old female with Marfan’s syndrome, with one of the largest sacral meningoceles reported in the literature, causing acute ureteric obstruction, requiring urgent surgical intervention