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Low anterior resection syndrome (LARS)

Jacopo Martellucci, MD, PhD
Section Editor
Martin Weiser, MD
Deputy Editor
Wenliang Chen, MD, PhD


Surgery is the only curative therapy for rectal cancer. Transabdominal surgery can be performed with either sphincter-sparing techniques (ie, anterior resection) or an abdominal perineal resection. Historically, abdominal perineal resection was the gold standard for treating low-lying rectal cancers. With the advent of better surgical techniques and equipment (eg, staplers) as well as neoadjuvant therapy, abdominal perineal resection has been gradually replaced by sphincter-sparing procedures. For patients in whom a negative distal margin can be achieved, sphincter-sparing procedures are preferred because they maintain bowel continence and avoid a permanent colostomy. In contemporary practices, sphincter-sparing procedures are feasible in up to 80 percent of patients requiring surgery for rectal cancer.

However, functional disturbances constitute a major problem for many surviving rectal cancer patients following a sphincter-sparing procedure, with symptoms ranging from daily episodes of incontinence to obstructed defecation and constipation. Although such symptoms have an immense impact on the patients' quality of life, there is presently no specific treatment. Instead, management is empirical and symptom based, using existing therapies for fecal incontinence, fecal urgency, and rectal evacuatory disorders.

In this topic, we discuss the clinical manifestations, diagnosis, and treatment of bowel symptoms that develop following sphincter-sparing resections of the rectum. Such symptoms have been collectively referred to as low anterior resection syndrome (LARS). The techniques of sphincter-sparing resection and the treatment of fecal incontinence, urgency, or other rectal evacuatory disorders of the gastrointestinal tract not necessarily related to surgery are discussed separately. (See "Rectal cancer: Surgical techniques" and "Fecal incontinence in adults: Management" and "Management of chronic constipation in adults".)


Low anterior resection syndrome is a constellation of symptoms, such as fecal incontinence or urgency, frequent or fragmented bowel movements, emptying difficulties, and increased intestinal gas, that occur after a sphincter-sparing resection (ie, anterior resection) of the rectum.


It is estimated that between 25 and 80 percent of patients develop one or more symptoms of LARS following a sphincter-sparing rectal surgery. For individual patients, symptoms vary in type, severity, and duration as a reflection of different underlying etiologies.

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Literature review current through: Dec 2017. | This topic last updated: Dec 05, 2017.
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