Low Anterior Resection Syndrome

Low anterior resection syndrome is a collection of bowel-related symptoms that can significantly affect daily life after rectal cancer surgery. Studies suggest that as many as 60 to 90 percent of people who undergo sphincter-preserving rectal surgery experience these symptoms, which can persist long after recovery from cancer treatment.

Table of contents

• What is low anterior resection syndrome?
• Understanding low anterior resection surgery
• Symptoms of low anterior resection syndrome
• Why does low anterior resection syndrome occur?
• How is low anterior resection syndrome diagnosed?
• Managing low anterior resection syndrome
• Impact on quality of life

What is low anterior resection syndrome?

Low anterior resection syndrome, commonly known as LARS, is a group of symptoms related to changes in bowel function that occur after surgery to treat rectal cancer. The syndrome develops as a result of low anterior resection, a surgical procedure that removes part or all of the rectum while preserving the anus^[1].

While this type of surgery allows patients to avoid a permanent colostomy (an opening in the abdomen through which waste exits the body), it often results in significant changes to how the bowel works. These changes can be temporary for some people, but for many others, they become long-term challenges that affect everyday activities^[2].

Low anterior resection syndrome is difficult to define because patients experience different combinations of symptoms. The condition has only gained recognition in recent years, even though the problems it causes have existed since sphincter-preserving surgeries became common practice^[2].

Understanding low anterior resection surgery

A low anterior resection is a type of surgery performed primarily to treat rectal cancer. During this procedure, the surgeon removes the diseased portion of the rectum along with some healthy tissue around it. Sometimes this also involves removing part of the colon, which is the large intestine segment above the rectum^[1].

The rectum is approximately six inches long and serves as a storage area for stool before it leaves the body. After removing the cancerous section, the surgeon reconnects the remaining parts of the intestine through a process called anastomosis. This means the two ends are sewn or stapled back together, allowing the bowel to function as one continuous tube^[4].

This surgery is also called restorative proctectomy or sphincter-sparing surgery because it keeps the anal sphincter muscles intact, allowing patients to maintain control over bowel movements. However, the shorter colon that results from this procedure is what leads to the symptoms of low anterior resection syndrome^[1].

The surgery can be performed as open surgery or as minimally invasive laparoscopic surgery. In some cases, surgeons may create a temporary ostomy to divert stool away from the reconnected intestine while it heals. This temporary opening can be reversed later^[1].

Symptoms of low anterior resection syndrome

Low anterior resection syndrome includes a wide range of bowel-related symptoms. The specific symptoms and their severity vary greatly from person to person. Researchers have identified that patients typically fall into two main categories, though some people experience symptoms from both groups^[3].

The first group of patients experiences increased frequency and urgency. The most common symptoms in this category include^[3]:

• Extremely increased frequency of bowel movements
• Urgent need to have bowel movements, often with little warning
• Clustering of stools, where a person has multiple bowel movements within a short time period, sometimes needing to return to the bathroom several times within hours
• Fecal incontinence, which means reduced control over bowel movements or leakage
• Increased gas production that may be difficult to control
• Soiling, where small amounts of stool leak without the person being aware

The second group of patients faces different challenges related to emptying the bowel. These symptoms include^[3]:

• Feelings of incomplete emptying after a bowel movement
• Constipation lasting several days
• Difficulty emptying the bowels
• Pain during bowel movements
• A sensation of needing to go to the bathroom, but finding nothing there when attempting

Some patients alternate between these two patterns, experiencing constipation for several days followed by clustering of multiple bowel movements. Others have symptoms from both categories occurring at the same time^[3].

Additional symptoms that patients report include extreme sensitivity to foods high in certain types of fiber, altered stool consistency, unpredictable bowel function, and swelling of rectal tissue. According to recent research, diarrhea is the symptom most strongly associated with decreased quality of life^[2].

Why does low anterior resection syndrome occur?

Low anterior resection syndrome results from multiple factors related to the surgery and surrounding cancer treatments. The condition is believed to have several underlying causes that work together to create the symptoms patients experience^[5].

One major cause is the direct structural damage that occurs during surgery. Removing part of the rectum means there is less storage space for stool before it needs to be eliminated. The rectum normally allows stool to collect and signals when it’s time to have a bowel movement. With a shortened or absent rectum, this storage and signaling system doesn’t work as effectively^[5].

The surgery can also damage the nerves that control bowel function. The rectum and surrounding pelvic area contain complex nerve networks that coordinate the storage and release of stool. When these nerves are damaged during surgery, they may not send proper signals about when the bowel is full or coordinate the muscles needed for controlled bowel movements^[5].

Another factor is the loss of the rectoanal inhibitory reflex, a normal response where the anal sphincter automatically relaxes when the rectum fills with stool. This reflex helps with sensing what type of material is in the rectum (gas versus liquid versus solid stool). When this reflex is disrupted, people may have difficulty distinguishing between these sensations^[5].

Decreased rectal volume and compliance (the ability of the rectum to stretch and hold stool) also contribute to symptoms. The reconstructed bowel may not expand as easily as a normal rectum, leading to more frequent urges to have bowel movements^[5].

For many patients, radiation therapy used to treat the cancer before or after surgery increases the risk and severity of low anterior resection syndrome. Radiation can cause inflammation, scarring, and changes in tissue that affect how well the intestines work^[2].

How is low anterior resection syndrome diagnosed?

Low anterior resection syndrome is diagnosed based on the symptoms patients report after having rectal cancer surgery. There is no single test that confirms the condition. Instead, healthcare providers evaluate the combination and severity of bowel-related symptoms^[2].

The most frequently used tool to evaluate low anterior resection syndrome is called the LARS score. This is a questionnaire that asks patients about specific symptoms including frequency of bowel movements, clustering, urgency, incontinence for liquid stool, and incontinence for gas. Based on the answers, patients receive a score that categorizes their symptoms as no LARS, minor LARS, or major LARS^[5].

Healthcare providers may also use other evaluation methods to understand how the bowel is functioning. An anorectal manometer is a device that measures the pressures and reflexes in the anal canal and rectum. This objective test can show how well the sphincter muscles are working and whether certain reflexes are present^[5].

Medical experts recommend that all patients who have sphincter-preserving rectal surgery should be routinely screened for low anterior resection syndrome during their follow-up appointments. Early identification of symptoms allows treatment to begin sooner, which may help improve outcomes^[5].

Because low anterior resection syndrome has such a significant impact on quality of life, systematic recording of bowel function has become an important part of monitoring patients after rectal cancer surgery. This helps healthcare teams track whether symptoms are improving, staying the same, or getting worse over time^[2].

Managing low anterior resection syndrome

Treatment for low anterior resection syndrome aims to reduce symptoms and improve quality of life. Because the condition results from multiple factors and affects each person differently, management approaches are individualized. Most treatment plans begin with simpler interventions and progress to more complex options if needed^[6].

Dietary modifications are often the first step in managing symptoms. Many patients benefit from following a low-residue diet, which limits foods high in insoluble fiber. This type of diet can help reduce the frequency and urgency of bowel movements. Patients are encouraged to identify specific foods that trigger their symptoms and avoid them. Keeping a food diary can help track which foods cause problems^[12].

Medications can help control specific symptoms. For patients with diarrhea and frequent bowel movements, medications that slow down bowel activity may provide relief. For those experiencing constipation, fiber supplements or other treatments to promote bowel movements may be recommended. The choice of medication depends on which symptoms are most troublesome^[6].

Pelvic floor muscle training and biofeedback are rehabilitation techniques that help patients improve control over their bowel movements. Biofeedback training uses sensors to help patients learn how to better coordinate and strengthen the muscles involved in bowel control. Studies have shown improvement in low anterior resection syndrome scores and reduced incontinence with these techniques, though more research is needed^[6].

For patients whose symptoms don’t improve with these initial treatments, transanal irrigation or rectal irrigation can be added. This involves regularly flushing the lower bowel with water to help empty it completely. This approach has gained attention recently as an effective treatment option for low anterior resection syndrome, with several studies showing promising results in controlling symptoms and improving quality of life^[6].

If symptoms remain severe and significantly impair quality of life even after one to two years despite trying various treatments, more advanced options may be considered. These include antegrade irrigation (flushing the bowel from above), sacral nerve stimulation (using an implanted device to stimulate nerves that control bowel function), or, in rare cases, creation of a permanent stoma^[5].

Many experts emphasize that early evaluation and timely initiation of appropriate treatment are crucial. Starting treatment soon after surgery may lead to better outcomes than waiting until symptoms become severe^[5].

It’s important to note that high-quality research on treatments for low anterior resection syndrome is still limited. Most available evidence comes from smaller studies, and there is a need for larger randomized controlled trials to develop clear, evidence-based treatment guidelines^[16].

Impact on quality of life

Low anterior resection syndrome can have a profound effect on quality of life. Studies show that up to 90 percent of patients experience long-term changes in their quality of life due to symptoms following low anterior resection surgery^[2].

The unpredictable nature of bowel symptoms often forces patients to plan their daily activities around access to bathrooms. This can limit their ability to work, socialize, travel, and participate in activities they previously enjoyed. The constant worry about having an accident or needing urgent bathroom access creates significant anxiety and stress^[2].

Research has documented a direct correlation between higher low anterior resection syndrome scores and decreased quality of life measures. Patients with severe symptoms report substantial impacts on their emotional well-being, social relationships, and ability to maintain their previous lifestyle^[2].

For some patients, the symptoms become so challenging that they consider or request a permanent colostomy, even though they initially had surgery to avoid one. This decision reflects the significant burden that low anterior resection syndrome can place on a person’s daily life^[2].

Many patients report that they were not fully informed about the possibility of developing these symptoms before their surgery. Surgeons and patients often focus primarily on cancer treatment and survival, with the assumption that preserving the sphincter will maintain normal bowel function. However, the reality for many patients involves adapting to what healthcare providers now call a “new normal” in terms of bowel function^[7].

Increased awareness of low anterior resection syndrome among healthcare providers and better patient education before surgery may help set more realistic expectations. When patients understand what symptoms they might experience and know that effective management strategies exist, they may be better prepared to cope with the challenges^[5].