Colorectal - Low Anterior Resection Syndrome (LARS)

You will be having an operation called an anterior resection or a total mesenteric excision (TME). This operation removes the mid to lower bowel, depending on where the cancer is situated. The two remaining ends of the bowel are then reconnected, this is called an anastomosis. Some people will have a stoma (ileostomy), this is where a section of the small bowel is brought through the surface of the abdominal wall. Stools are then passed through the ileostomy and collected into a bag attached to the abdomen. Having an ileostomy prevents stools passing through the anastomosis, allowing it time to heal. Your surgeon will discuss with you when the time is right to reverse the ileostomy.

LARS is a collection of symptoms that many patients experience following rectal cancer surgery. Up to half of patients will have some problems with their bowel function and it can take between 6 to 9 months for this to settle to the level it will be long term.

The way your rectum worked before surgery will be different to how it works afterwards, it is important to discuss these changes with your colorectal team before your rectal operation or reversal of ileostomy, so you know what to expect.

Going to the toilet before rectal cancer treatment

The function of the large bowel is to absorb water from the waste inside your colon and form it into stools (poo). Stool is passed through the colon into the rectum which is the last 16cm of the large bowel. The rectum is like a storage chamber designed to stretch and store stools until it is full, then messages are sent to the brain to let you know you need to go to the toilet. The anus is the opening at the end of the large bowel, it has a complex neve supply which lets you know if you need to pass wind or stool. The anal sphincters are muscles that form a ring around the back passage that snap shut to prevent wind and stool leaking out.

The pelvic floor is made up of layers of muscle that stretch like a hammock from the tail bone to the pubic bone and prevent incontinence of urine and stool.

How surgery can change the way your bowels work

Removing part of the rectum will alter the structure and function of the bowel, as the storage chamber will be smaller and less stretchy, therefore it cannot hold as much stool as before. This can lead to going to the toilet more often.

Surgery can damage the anal nerves and sphincters which are important for bowel control. You may find that you have to rush to the toilet urgently. Sometimes the nerves in the anal canal can be damaged, so you may not be able to tell if you need to pass wind or stool.

Occasionally surgery can cause a narrowing (stricture) inside the bowel wall which restricts the stool from passing out.

Common symptoms you may experience following rectal surgery

• Frequency - having your bowels open more often
• Clustering - numerous bowel movements close together
• Urgency - little warning of when you need to go to the toilet
• Tenesmus - a sensation of wanting to pass a stool despite the bowel being empty
• Altered bowels - constipation followed by frequent bowel motions
• Increased wind or trouble telling the difference between passing wind and stools
• Incontinence - leakage of stool or wind without knowing

For most patients, symptoms can be managed with simple interventions

• Dietary changes - a low fibre diet is recommended for the first few weeks after surgery, gradually increasing the amount once your bowels can cope
• Good drinking habits - caffeine can cause increased bowel activity and loose stools. If you are having these symptoms reduce caffeine for the first few weeks until the bowels improve. Caffeine is found in tea, coffee, fizzy drinks, beer lager and cider
• Good toileting habits - check you are sitting in the correct position to encourage your bowel to empty completely. If you are not sure whether you need to pass wind or stool, you may need to sit on the toilet just in case. Over time this should resolve itself
• Medications - Loperamide is useful if you have loose stools or/and frequency, it works by absorbing more water from the stool, slowing down the passage and firming it up
• Fybogel and Normacol - are bulking agents to help bulk up loose stools if you are passing frequent small stools
• Strengthening pelvic floor exercises can help control the bowels. Having strong pelvic floor muscles will allow you to consciously tighten the anal sphincter to prevent leakage of wind liquid and formed stools

If you would like more information about diet, medication, or pelvic floor exercises, please contact your colorectal nurse who can provide additional advice and information.

It can take several weeks before you notice any improvements, but most patients are able to adjust to a new ‘normal’ bowel function and settle into a manageable habit.

If you are still having problems a few months after your rectal surgery or ileostomy reversal which are embarrassing or affecting your lifestyle on a regular basis, you need to discuss this with your colorectal nurse specialist. The right intervention can make a big difference to help improve your symptoms. You may need to be referred to a gastroenterologist or another health professional to discuss other treatment options.

Biofeedback - a treatment used to retrain the bowel and strengthen the muscles and sphincters controlling bowel function.

Transanal irrigation - this uses a catheter to insert water through the back passage to help reduce clustering and frequency of bowel movements.
 
You will be contacted by a colorectal nurse specialist a few weeks following your ileostomy reversal or after your rectal surgery and asked to complete a LARS assessment. This simple questionnaire is to check the type, severity, and duration of your symptoms. The results will help the colorectal nurse understand how you are feeling and whether any interventions are required.

LARS Score

1.    Do you ever have occasions when you cannot control your wind?

• No, never - 0
• Yes, less than once a week - 4
• Yes, at least once a week - 7

2.    Do you ever have accidental leakage of liquid stool?

• No, never - 0
• Yes, less than once a week - 3
• Yes, at least once a week - 3

3.    How often do you open your bowels?

• More than 7 times in 24 hours - 4
• 4 to 7 times in 24 hours - 2
• 1 to 3 times in 24 hours - 0

 
4.    Do you ever have to open your bowels again within one hour of the last time?

• No, never - 0
• Yes, less than once a week - 9
• Yes at least once a week - 11

5.    Do you ever have such a strong urge to open your bowels that you have to rush to the toilet?

• No, never - 0
• Yes, less than once a week - 11
• Yes at least once a week - 16

Please add up the scores from each question

• 0 - 20 - No symptoms
• 21 - 29 - Minor symptoms
• 30 - 42 - Major symptoms