A 29-year-old gentleman underwent a transverse colostomy for intestinal obstruction caused by advanced rectal carcinoma. On the 5(th) postoperative day, the patient developed a painful swelling on the right side of the abdomen. The contrast enhanced computed tomography of the abdomen revealed a right sided hydronephrosis, a large rent in the renal pelvis, and a large retroperitoneal fluid collection on the right side. Percutaneous nephrostomy and pigtail catheter drainage of the urinoma led to resolution of abdominal swelling. Development of a urinoma as a consequence of rectal carcinoma is highly unusual. Prompt imaging for confirmation of diagnosis, decompression of the renal pelvicalyceal system, and drainage of the urinoma limits morbidity.