Low Anterior Resection Syndrome (LARS)

Low anterior resection syndrome (LARS) is a collection of symptoms that can occur after surgery to remove part or all of your rectum (low anterior resection or LAR). Symptoms can vary, but they mainly involve trouble with bowel movements and bowel control. Other symptoms can include trouble with urination and sexual function, as well as anxiety and depression. Because of these symptoms, LARS can have a long-term impact on your quality of life.

Most people who have a low anterior resection will have some degree of LARS symptoms after the surgery. These symptoms typically improve with time, with the most noticeable improvements over the first six months. These improvements may continue for the first two years. But your bowel function may never go back to the old “normal.”

While there’s no cure, your healthcare provider can offer therapies and strategies to help manage your symptoms. This can help improve your quality of life.

Symptoms of LARS

LARS symptoms can include:

• Feeling like you aren’t fully emptying your bowels (incomplete evacuation)
• Needing to poop more often and urgently (fecal urgency)
• Feeling like you need to poop but can’t (tenesmus)
• Having small bowel movements multiple times per hour (fecal clustering)
• Leaking poop (bowel incontinence)
• Leaking gas (gas incontinence)
• Loose stools (diarrhea)
• Discomfort or trouble pooping (dyschezia)
• Not pooping enough (constipation)

Some people also have other issues associated with LARS, like:

• Urinary problems
• Sexual function problems
• Psychological and social effects

LARS causes

LARS is a common and expected side effect of removing part or all of your rectum. It happens even when everything goes well, and there are no other complications. Researchers believe it’s likely a combination of things that cause it. Some of these factors may include:

• Weak anal sphincter muscles: Surgery may damage the muscles in your anus (butthole) that control your bowel movements. Other cancer treatments, like radiation therapy, can also stiffen and irritate these muscles, which can weaken them. Many people have both radiation and LAR because they’re both common treatments for rectal cancer.
• Nerve damage: Nerve damage from surgery or radiation may affect your anal reflexes. These are signals that tell you when to poop (and when not to). This can make your anal muscles less responsive. It can also make it harder to tell when you have to poop, or if poop is coming out.
• Loss of poop storage: LAR removes a part of your rectum, and sometimes all of it. This leaves the end of your colon to replace your rectum. But your colon isn’t designed to hold poop like your rectum is. It’s designed to move poop forward, not store it. This can lead to many bowel movements in a short period of time, and the feeling that you have to go quickly.
• Faster colonic transit time: Your colonic transit time is how fast poop moves through your colon. After LAR, poop may move through faster, meaning your colon has less time to absorb fluids. This makes your poop more liquidy, more abundant or more frequent.

Risk factors

Risk factors for LARS include:

• Extent of rectal removal: The more rectum that must be removed, the more likely you are to experience LARS.
• Radiation therapy: Many people who have LAR for rectal cancer will also have radiation. Radiation works to shrink the tumor. But it can also cause damage to nearby bowels and leftover tissue.
• Anastomotic leak: If the new surgical connection (anastomosis) in your bowel doesn’t heal well, it may leak into your abdomen. Leaking stool may irritate your tissues, cause infection and contribute to LARS.
• Temporary ileostomy: The longer you have a temporary ileostomy (ostomy bag) to protect the new anastomosis, the higher your risk of LARS.
• Younger age: LARS seems to affect younger people more often, though the cause isn’t clear.
• Previous bowel dysfunction: If you had bowel issues before surgery, they’re more likely to be worse afterward.

How doctors diagnose LARS

Healthcare providers diagnose this condition based on your symptoms. Instead of ordering tests, they’ll ask you detailed questions. They might use one of several formal questionnaires to evaluate your symptoms. A common one is called the LARS score. It uses a formula to rate your symptoms from mild to severe.

Sometimes, healthcare providers rule out small intestinal bacterial overgrowth (SIBO) to make sure it’s not making symptoms worse. LARS can have similar symptoms to other conditions. So, your provider may think about the following when diagnosing LARS:

• Irritable bowel syndrome (IBS)
• Chronic radiation proctitis
• Small intestinal and bile acid malabsorption

But LARS may not come up in discussion with your healthcare team unless you mention it. It’s important to share your symptoms with your provider so they can address them.

How is LARS treated?

Treatment for LARS focuses on addressing your specific symptoms. Your healthcare provider will suggest medications, therapies and lifestyle changes to help make these symptoms more manageable. There isn’t a one-size-fits-all solution. It may take some trial and error before you and your provider find what works for you and your lifestyle.

Some treatment options include:

Medications

Common medications for diarrhea and constipation include:

• Antidiarrheals
• Antispasmodics
• Bulking agents (like psyllium)
• Laxatives

Dietary changes

You might notice your symptoms get better or worse with certain foods or drinks. One way to manage them is to identify which foods make your symptoms flare up. You should avoid them when you can. Use a food diary to keep track of what you eat and how it affects you.

Also, it’s important to note there’s a difference between soluble and insoluble fiber. Soluble fiber is typically useful for LARS symptoms. Insoluble fibers can worsen symptoms. Discuss this with your provider. Common trigger foods include:

• Artificial sweeteners (these are indigestible sugars)
• Caffeine (coffee, tea or even chocolate may stimulate your bowels)
• Cruciferous vegetables (like broccoli, leafy greens and onions)
• Fruits (fresh and dried)
• Gluten (if you’re sensitive to it)
• Insoluble fiber (found in nuts, seeds, corn and whole grains)
• Lactose (found in dairy products)
• Spicy foods (curries and chillis can activate your bowels)

Physical therapy

Physical therapy may help you develop better control over your bowels. This might include:

• Pelvic floor exercises
• Biofeedback therapy

Bowel irrigation

If you continue to have trouble with unpredictable, uncontrollable or incomplete bowel movements, one option is to clear out your bowels manually with water. Transanal irrigation (TAI) is an important method that you can use to clear out your bowels at home. You can use it regularly, completely and on a predictable schedule. You and your healthcare provider may also discuss using it on an as-needed basis.

TAI is similar to an enema. But it uses more water and a balloon to hold the larger amount of water within your colon. This method allows you to control when you go to the bathroom. The need to go to the bathroom won’t control your lifestyle. Most people irrigate daily and then don’t have a bowel movement for the rest of the day.

Sacral neurostimulation

If first-line therapies and lifestyle changes don’t improve your symptoms and quality of life, you may consider sacral nerve stimulation (SNS). This is an outpatient surgery. Your provider places an electrode near the third sacral nerve root, with a pacemaker under the skin of your buttocks, to stimulate the nerve. The procedure can help with urgency, frequency and incontinence of stool.

Reoperation

If none of these treatments do enough to improve your symptoms, you might choose to have surgery again. This is rare, but it’s an option. You can bypass LARS issues by having your surgeon create a permanent colostomy (ostomy bag). This way, your poop will come out automatically into an ostomy bag.

When should I seek care for LARS?

If you have any symptoms of LARS after rectum removal surgery, don’t hesitate to mention them to your healthcare provider. These symptoms are common. They may improve with time, and you don’t have to endure them without support. Your provider can offer self-management strategies or treatments or refer you to a LARS specialist.

How long does LARS last?

For most people, symptoms are the worst immediately after surgery. Then, they gradually improve over the next two years. At the end of those two years, you’ll have a better sense of what your new “normal” is.

Is there any way to prevent LARS?

There’s no known way to prevent LARS. But a few things can minimize some of the symptoms. These include:

• The construction of a rectal reservoir
• Avoiding radiation whenever possible
• Removing less rectum

That’s why it’s important to know about LARS before you have treatment. Make sure to discuss all the options and potential outcomes with your healthcare provider. This includes the potential for LARS.

Healthcare providers often assume that a person who needs rectal surgery will prefer LAR to avoid having a permanent stoma. Many people do feel this way. But some who experience severe LARS feel that if they had understood what it would really be like, they might have chosen the stoma instead.