A 23-month-old female with giant sacral (S1-S5) and intrasacral (L4-S5) haemangioma, lipomyeloschisis and a tethered cord presented for correction of a sinus venosus atrial septal defect. Angiography revealed a large perisacral hypervascular mass with large veins and an intraspinal extension. The patient had a neurogenic bladder and left extremity weakness due to spinal cord compression. The potential for additional neurological injury secondary to bleeding, venous congestion, ischaemia and steal phenomenon during cardiopulmonary bypass is discussed.