A male tetraplegic patient attended accident and emergency with a blocked catheter; on removing the catheter, he passed bloody urine. After three unsuccessful attempts were made to insert a catheter by nursing staff, a junior doctor inserted a three-way Foley catheter with a 30-mL balloon but inflated the balloon with 10 mL of water to commence the bladder irrigation. The creatinine level was mostly 19 µmol/L (range: 0-135 µmol/L) but increased to 46 µmol/L on day 7. Computerized tomography urogram revealed that the bilateral hydronephrosis with hydroureter was extended down to urinary bladder, the bladder was distended, prostatic urethra was dilated and filled with urine, and although the balloon of Foley catheter was not seen in the bladder, the tip of the catheter was seen lying in the urethra. Following the re-catheterization, the creatinine level decreased to 21 µmol/L. A follow-up ultrasound scan revealed no evidence of hydronephrosis in both kidneys. Flexible cystoscopy revealed inflamed bladder mucosa, catheter reaction, and tiny stones. There was no bladder tumor. This case report concludes that the cause of bilateral hydronephrosis, hydroureter, and distended bladder was inadequate drainage of urinary bladder as the Foley balloon that was under-filled slipped into the urethra resulting in an obstruction to urine flow. Urethral catheterization in tetraplegic patients should be performed by senior, experienced staff in order to avoid trauma and incorrect positioning. Tetraplegic subjects with decreased muscle mass have low creatinine level. Increase in creatinine level (>1.5 times the basal level) indicates acute kidney injury, although peak creatinine level may still be within laboratory reference range. While scanning the urinary tract of spinal cord injury patients with indwelling urinary catheter, if Foley balloon is not seen within the bladder, urethra should be scanned to locate the Foley balloon.