Patients develop a variety of bowel dysfunction following low or very low anterior resection for rectal cancer. These symptoms are known collectively as low anterior resection syndrome (LARS), and the extent to which it affects the quality of life of these patients can be assessed by the LARS score. Knowledge about anorectal functional anatomy is a prerequisite to understanding the aetio-pathology and clinical manifestation of LARS. Structural and functional impairment of the internal and external anal sphincter and the anal transition zone, loss of reservoir function of the rectum, increased colonic motility, proximal diversion, enteric nervous system remodelling and neuropathy of autonomic nerves in the pelvis are known to cause LARS.
Assessment of patients with LARS with MRI scan, endoanal ultrasound and anorectal manometry will help to identify the cause for LARS. Treatment of LARS will have to be tailored to the individual patient. The treatment protocol can start with conservative measures like pelvic floor rehabilitation, colonic irrigation and biofeedback therapy. Medication with Imodium and serotonin receptor antagonists may help some patients with LARS. Sacral nerve stimulation is a minimally invasive technique that has been used to treat patients with LARS for more than one year. Stoma creation will be considered in those with major LARS persisting for more than two years. Meticulous dissection with preservation of nerves and anal sphincters and anastomotic reconstruction techniques such as an end to side anal anastomosis or a colonic–J pouch anal anastomosis can minimize the occurrence of LARS.