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Low anterior resection, explained | CION Cancer Clinics
A low anterior resection removes the part of the rectum with the cancer and joins the bowel back together, so you keep the anus and pass stool the normal way. The fatty tissue around the rectum, holding the lymph glands, comes out with it. Many people have a temporary stoma to protect the join. This page explains what happens, what recovery looks like, and who the operation may not suit. CION Cancer Clinics’ surgical oncologists in Hyderabad can talk this through with you.
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Medically reviewed by Dr. Muralidhar MuddusettyConsultant Surgical Oncologist · MBBS (AIIMS), MS (Surgery, AIIMS), DNB (Surgical Oncology), MRCS (Edinburgh) · last reviewed September 2026, next review due September 2027
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On this page
- What is a low anterior resection?
- What actually happens during the operation?
- What the first weeks after an LAR look like
- Words you will see, in plain language
- Who an LAR may not suit, and what this page cannot tell you
- Four things families tell us, and what is actually true
- Common questions about low anterior resection
The short answer
What is a low anterior resection?
A low anterior resection, usually written LAR, is an operation that removes the part of the rectum containing a cancer and then joins the bowel back together. Because the anus and its muscle are kept, you go on passing stool the normal way once you have recovered.
What the name means
"Anterior" means the surgeon works from the front, through the tummy, rather than from below. "Low" means the join is made low in the pelvis, close to the anus. "Resection" simply means removal. When the join is made right at the anus itself, your report may call it an ultra-low anterior resection or a coloanal anastomosis.
What is taken out
The rectum with the cancer, a rim of healthy bowel above and below it, and the fatty tissue that wraps around the rectum. That fatty envelope, the mesorectum, holds the lymph glands the cancer is most likely to spread to first, so it is removed in one piece with the bowel. The colon above is then brought down and joined to what remains.
LAR is one of two main operations for rectal cancer. The other, an abdominoperineal resection, removes the anus as well and leaves a permanent stoma.In the operating theatre
What actually happens during the operation?
Getting inside
Under a general anaesthetic, the surgeon reaches the rectum either through several small cuts with a camera (keyhole or robotic) or through one longer cut down the middle of the tummy (open).
Freeing the bowel
The left side of the colon is loosened from its attachments so it can reach down into the pelvis later. The blood vessel feeding the rectum is divided close to its origin, taking the lymph glands along it.
Removing the rectum
The rectum and its fatty envelope are lifted out along the natural plane around them, without cutting into the envelope. The bowel is divided below the cancer with a stapler.
Making the join
The colon is joined to the rectal stump, usually with a circular stapler passed through the anus. The join is then tested for leaks before the operation ends.
Protecting the join
For a low join, a loop of small bowel is often brought out on the right of the tummy as a temporary ileostomy, so stool bypasses the join while it heals.
Not sure whether this applies to you?
Ask an oncologistRecovery
What the first weeks after an LAR look like
The operation is the short part. Most of what people ask about is the recovery.
In hospital
You will be helped to sit out and walk early, usually from the day after surgery. Drips, a bladder catheter and sometimes a drain come out over the first days. Eating restarts gently once the bowel wakes up.
Before you go home
- Passing wind or stool, or a working stoma
- Eating and drinking without being sick
- Pain controlled on tablets
Learning the stoma
If you have a temporary ileostomy, a stoma nurse teaches you or a family member to empty and change the bag before discharge. Most people are surprised how quickly it becomes routine.
Bowel habit after the join
Once stool is passing through the join again, expect urgency, going more often, and going several times in a row. This is expected after a low join and usually settles over months.
Bowel retraining, diet changes and medicines all help. Ask about them early.The pathology report
What was removed goes to the laboratory. The report says how deep the cancer went, whether the lymph glands were involved, and whether the edges were clear. It decides whether chemotherapy is advised afterwards.
On your report
Words you will see, in plain language
- Anastomosis
- The join between the colon and the rectal stump. A "colorectal" anastomosis is a join to the remaining rectum; a "coloanal" one is a join at the anus.
- Total mesorectal excision (TME)
- Removing the rectum with its fatty envelope intact. Almost every LAR for cancer is done this way.
- Anastomotic leak
- The join failing to seal, so bowel contents escape into the pelvis. It is the complication surgeons worry about most, and the reason a temporary ileostomy is often made.
- Defunctioning or diverting ileostomy
- A temporary stoma made from small bowel that rests the join. Closed in a second, smaller operation once the join has healed.
- Distal margin
- The rim of healthy bowel below the cancer. "Clear" means no cancer cells were found at the cut edge.
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Did you know
The rectum is not just a tube. It stretches to store stool and tells you when it is time to go. After an LAR the colon has to learn to do that job, which is why bowel habit changes at first and why it improves with time rather than overnight.
Being straight with you
Who an LAR may not suit, and what this page cannot tell you
An LAR is not the right operation for everyone with rectal cancer. If the cancer has grown into the sphincter muscle, or sits so low that no healthy bowel can be left beneath it, a join is not safe and the anus has to be removed instead.
When a join is possible but unwise
Someone whose bowel control was already poor before the cancer may end up worse off with a very low join than with a colostomy. So may someone whose heart or lungs make two operations, the LAR and the later stoma closure, a real risk. In those cases the surgeon may suggest a permanent stoma even though a join could technically be made. That is a conversation to have, not a verdict.
What the page cannot tell you
It cannot tell you whether your cancer can be joined, whether you will need a temporary stoma, or what your bowel habit will be like in a year. Those answers come from your MRI, your examination and your surgeon. Nor can it tell you how well the operation will work against the cancer. That depends on the pathology report and on treatment before and after.
If you have been offered an LAR and want a second opinion, call the helpline. Bring your MRI and biopsy reports.Commonly believed
Four things families tell us, and what is actually true
"The temporary bag means the operation went wrong."
It usually means the opposite. A temporary ileostomy is planned before the operation for most low joins, to protect the join while it heals. It is a sign of a careful plan, not a problem found on the table.
"After an LAR everything goes back to normal."
Bowel habit changes for most people after a low join. Urgency and frequency are common early on and improve over months with retraining and diet. Many people reach a habit they can live with, but exactly how things were before is not something anyone can promise.
"Keyhole surgery is a smaller operation."
The cuts on the outside are smaller. What is removed inside is the same, and so is the join. Keyhole often means less pain and a shorter stay, but it is the same major operation. Ask your centre which approach it uses and why.
"We can skip the radiation and go straight to surgery."
For some early cancers, surgery alone is right. For many others, radiation first shrinks the cancer and lowers the chance of it returning in the pelvis. The order is decided by the tumour board on your MRI, and skipping a step is not a shortcut.
Questions we are asked
Common questions about low anterior resection
How long does the operation take?
Several hours. A low join, a large cancer, a narrow pelvis or previous surgery all add time. The family is usually told an expected finish and then updated if it runs over. Running over does not on its own mean something has gone wrong.
Will I have a temporary stoma?
Many people do, especially when the join is low or radiation was given first. It is a loop of small bowel brought out on the right side, closed later in a smaller operation once scans show the join has healed. Your surgeon should tell you before the operation whether one is planned.
How long until the stoma is closed?
Usually some months, once the join has been checked and any chemotherapy after surgery is finished. The timing is set by your surgeon and oncologist together. It is common for the closure to wait until chemotherapy is complete rather than interrupt it.
What is a leak at the join, and how would I know?
A leak means the join has not sealed and bowel contents are escaping. Signs are a new fever, worsening tummy pain, a fast heart rate or feeling suddenly unwell in the first week or two. Tell the ward or call the helpline the same day. Do not wait to see if it settles.
How many times a day will I go to the toilet?
More often than before, at least at first, and sometimes several times in a row. This is called clustering. It happens because the colon is doing a job the rectum used to do. The number usually falls over months with bowel retraining and, if needed, medicines.
Can I eat normally after an LAR?
Yes, in time. Early on you may be asked to keep meals small and low in fibre, and to avoid foods that cause wind or loose motions. With an ileostomy, chewing well and keeping salt and fluids up matters. A dietitian can help you work out what suits you.
Will I need chemotherapy afterwards?
It depends on what the pathology report shows, particularly whether the lymph glands were involved and how deep the cancer went. Your case goes back to the tumour board once the report is ready, usually a week or two after surgery, and the recommendation is explained to you.
Is LAR covered by Aarogyasri or my insurance?
Often yes, when it is part of an approved cancer treatment plan. Aarogyasri, CGHS, ECHS and EHS are accepted, and most cashless insurers are empanelled. The stoma closure later is a separate admission. Call the helpline with your card details and we will check your cover.
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Sources
- Cancer Research UK — Surgery for bowel cancer
- American Cancer Society — Surgery for Rectal Cancer
- National Cancer Institute — Rectal Cancer Treatment (PDQ) - Patient Version
- NHS — Ileostomy
This page is general information, not a prescription. Do not change or stop any treatment based on what you read here. If anything is worrying you, contact your own treating team — or call our helpline and we will help you reach the right specialist.
Keep reading
Related pages
Rectal Cancer Surgery: What Your Options AreLAR alongside the other operationsTotal Mesorectal Excision: Why It MattersThe technique inside every LARThe Temporary Ileostomy After Rectal SurgeryThe stoma that protects the joinLow Anterior Resection SyndromeThe bowel habit changes after a low joinICU and the First Days After SurgeryWhat the first days in hospital look like
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Been offered a low anterior resection?
Send us your MRI and biopsy reports or call the helpline. A surgical oncologist will explain what the operation would involve in your case. One helpline serves every CION centre.