Stranding around the rectum on CT means that the normally dark fat becomes hazy and lighter. Stranding around the rectum on CT can be seen with multiple conditions to include inflammation, infection, treatment of cancer, cancer itself, and fecal impaction. Clinical history and additional findings on the CT are often helpful with this finding.
Proctitis or inflamed rectum is one of the more common causes. This can be seen with infections like gonorrhea and syphilis from sexually transmitted diseases. Inflammatory conditions can be seen like inflammatory bowel disease. In these cases we will see a thickened rectal wall and haziness or stranding of the surrounding fat. Often times, the blood vessels around the rectum will be enlarged.
Stranding around the rectum can also be seen with cancer. Sometimes a mass will be seen in the rectal wall. The fat next to the mass may be hazy potentially representing tumor spread. Hazy fat next to the rectum can also be seen following radiation treatment for cancer. In these cases, the haziness will be more generalized and around the organ treated with radiation. The history will be important in these cases.
Fecal impaction is another cause of haziness around the rectum. Patients who are bed bound, debilitated or demented may have development of a fecaloma. This is dehydrated stool which becomes impacted in the rectum. The stool produces pressure on the rectal wall. This may reduce blood flow and death of the wall. Perforation of the wall can occur and results in death. This is called stercoral proctitis.
Stranding around the rectum on CT is often a secondary finding of something abnormal in the rectum. This can be from infection, inflammation, treatment change, cancer or severe fecal retention. Often additional findings on CT and the clinical history are very helpful with identifying the cause of the stranding around the rectum. At times, additional testing may be needed. Rectal MR is another imaging test which can be done to get a closer look at the rectum. Colonoscopy will allow a direct look and potential biopsies.