Medical Oncologist
CION Cancer Clinics
How close to the anus can the sphincter be saved? | CION Cancer Clinics
The sphincter, the ring of muscle that holds stool in, can usually be saved as long as the cancer has not grown into it and a small rim of healthy bowel can be left below the cancer for a safe join. There is no single distance that decides it. This page explains what the team weighs and why a join is not always the kinder choice. 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
- How close to the anus can the sphincter still be saved?
- The five things that decide whether a join is possible
- How the decision is reached, step by step
- Words you will see, in plain language
- Four things families tell us, and what is actually true
- Who a very low join may not suit, and what this page cannot tell you
- Common questions about saving the sphincter
The short answer
How close to the anus can the sphincter still be saved?
The sphincter, the ring of muscle that holds stool in, can usually be saved as long as the cancer has not grown into it and a small rim of healthy bowel can be left below the cancer for a safe join. There is no single distance that decides it.
Why distance alone does not settle it
The rectum ends at the top of the anal canal, and the anal canal is wrapped in two layers of muscle. What matters is whether the cancer has reached that muscle, and whether what is left after removing it would still work. Two people with cancers at the same height can get different answers.
What "saving the sphincter" actually means
It means the anus stays, the bowel is joined to it or just above it, and you pass stool the normal way once the join has healed. It does not mean bowel habit goes back to how it was. Saving the muscle and keeping good control are two different questions.
This page explains what the team weighs. It cannot tell you whether your own sphincter can be saved. That comes from your MRI and your surgeon's examination.What the team weighs
The five things that decide whether a join is possible
Your surgeon looks at all of these together. None of them settles it on its own.
Height of the cancer
Measured from the anal verge on the MRI and by examination. Lower cancers make a join harder, but height alone is a rough guide, not a rule.
Whether the muscle is involved
The MRI shows whether the cancer has grown into the inner or outer sphincter, or the muscle of the pelvic floor. If it has, the muscle cannot be kept without leaving cancer behind.
Report words for this
- Internal sphincter
- External sphincter
- Levator or puborectalis
How well the muscle works today
A finger examination, and sometimes a pressure test, show how strongly the muscle squeezes. A weak sphincter joined very low may leave someone with less control than a well-managed stoma.
Response to radiation
Radiation with chemotherapy given first can shrink a low cancer away from the muscle. The repeat MRI afterwards sometimes turns a planned permanent stoma into a possible join.
Your body and your fitness
A narrow pelvis, a heavy build or previous pelvic surgery make a very low join technically harder. Heart or lung disease makes a second operation to close a temporary stoma riskier.
Not sure whether this applies to you?
Ask an oncologistThe pathway
How the decision is reached, step by step
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The first MRI
The radiologist measures the height of the cancer, how deep it has gone, and its relation to the sphincter and pelvic floor. This is the map the whole decision is drawn on.
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The examination under the surgeon's finger
Often done at the first visit, and sometimes again under anaesthetic. The surgeon feels where the cancer starts, whether it is fixed or mobile, and how the muscle squeezes.
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Radiation and chemotherapy first, for most low cancers
Given to shrink the cancer and pull it back from the muscle. The decision on the operation is deliberately left until this is finished.
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The repeat MRI and re-examination
Some weeks after radiation, the MRI is repeated and the surgeon examines again. Only now is the operation chosen: a join, or removal of the anus.
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The conversation about both options
You are told what a very low join would mean for bowel habit, and what a permanent colostomy would mean day to day. Both are explained before you agree to either.
On your report
Words you will see, in plain language
- Anal verge
- The outer edge of the anus. Heights on the MRI and at examination are usually measured from here.
- Anorectal junction
- Where the rectum ends and the anal canal begins. A cancer at or below this line is a "low" cancer.
- Intersphincteric resection
- An operation that removes the inner layer of the sphincter along with the rectum, keeping the outer layer, so a join can still be made for some very low cancers.
- Coloanal anastomosis
- A join made directly between the colon and the anus, with no rectum left in between.
- Distal margin
- The rim of healthy bowel below the cancer that the surgeon needs to leave to be confident the cut edge is clear.
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Commonly believed
Four things families tell us, and what is actually true
"A good surgeon can always save the sphincter."
If the cancer has grown into the muscle, keeping the muscle means leaving cancer behind. No amount of skill changes that. A surgeon who says the anus must go is protecting you from a worse outcome.
"Saving the sphincter is always the better result."
A very low join in someone with a weak muscle can mean leaking, urgency and never being far from a toilet. For some people a well-managed colostomy gives a freer life. Which is better is a personal question, and you are allowed to weigh it yourself.
"The MRI decides it. The examination is just a formality."
The MRI shows where the cancer is. Only the surgeon's finger shows how the muscle works and whether the cancer is fixed to it. Both are needed, and the decision is often changed by the examination.
"If radiation shrinks it, we will not need the operation at all."
Radiation is given to make the operation safer and sometimes to make a join possible, not to replace it. A small number of people whose cancer disappears completely are offered close watching instead, but that is the exception and needs very strict follow-up.
Being straight with you
Who a very low join may not suit, and what this page cannot tell you
A join at the anus is technically possible for more people than it is wise for. If your control was already poor before the cancer, or if you are older and frail, a very low join can leave you worse off than a stoma. Surgeons say this openly because they have seen both.
What to ask before you decide
Ask how far the cancer is from the anal verge and whether the MRI shows the muscle involved. Ask whether the decision will wait until after radiation. Ask what bowel habit is expected a year after a very low join, and to speak to the stoma nurse about what a colostomy involves.
What the page cannot tell you
It cannot tell you whether your sphincter can be saved, or whether it should be. That answer changes with your MRI, your examination, your response to radiation and what you want from life afterwards. Only your treating team, with your scans in front of them, can do that.
If you have been told the anus must be removed and want that reviewed, call the helpline. Bring the MRI films, not only the report.
Did you know
The height of a rectal cancer measured by a flexible scope is often different from the height on the MRI or under the surgeon's finger, because the scope stretches the bowel. This is why the surgeon repeats the measurement rather than relying on the colonoscopy report.
Questions we are asked
Common questions about saving the sphincter
Is there a cut-off distance below which a join is impossible?
Not a fixed one. Surgeons need a small rim of healthy bowel below the cancer and a muscle that is not involved and still works. Some cancers right at the top of the anal canal can be joined; some higher ones cannot because of how the muscle looks. Ask your surgeon about your own case.
What is an intersphincteric resection?
An operation for some very low cancers that removes the inner layer of the sphincter along with the rectum and keeps the outer layer, so a join to the anus is still possible. It is offered only when the outer muscle is strong and the cancer has not reached it.
Will radiation make a join more likely?
Sometimes. Radiation with chemotherapy can shrink a low cancer away from the muscle, and the repeat MRI may then show a join is possible. It is not certain, and the decision is made after the repeat scan, not before.
If the sphincter is saved, will I be continent?
Most people keep control of solid stool but find urgency, frequency and sometimes leaking of wind or liquid early on. This usually improves over months with retraining. How well it settles depends on how low the join is, whether radiation was given, and how strong the muscle was before.
Can I ask for a colostomy even if a join is possible?
Yes, and it is a reasonable request in the right situation. Some people prefer the predictability of a stoma to the uncertainty of a very low join. Ask to meet the stoma nurse and talk it through with your surgeon before the operation is booked.
Why does my surgeon want to examine me under anaesthetic?
Because a relaxed, pain-free examination gives a clearer feel of where the cancer starts and whether it is fixed to the muscle. It is short, usually a day case, and is often done just before the operation is planned.
Will I have a temporary stoma if the join is very low?
Almost always. A join at the anus is the one most at risk of leaking, so a loop of small bowel is brought out on the right side to rest it while it heals. It is closed later in a smaller operation once scans confirm the join is sound.
Is this surgery 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. A later stoma closure is a separate admission. Call the helpline with your card details and we will check your cover.
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Medical Oncologist
Dr. C. Raghavendra Reddy
MBBS(Gold Medal), DNB(General Medicine), DM(Medical Oncology)(Gold Medal)
Medical Oncologist
Dr. Bharati Devi Gorantla
MBBS, MD(General Medicine), DM(Medical Oncology)(Adyar,Chennai), ECMO, MRCP SCE(UK)
Medical Oncologist
Dr. Owais Mohammed
MBBS, MD (General Medicine), DrNB (Medical Oncology), ECMO, MRCP SCE (Medical Oncology) (UK)
Medical Oncologist
Medical Oncologist
Surgical Oncologist
Dr. Muralidhar Muddusetty
MBBS (AIIMS), MS (Surgery) (AIIMS), DNB (Surgical Oncology), MRCS (Edinburgh)
Surgical Oncologist
Surgical Oncologist
Surgical Oncologist
Dr. Vinay Mamidala
MBBS, MS(General Surgery), M.Ch(Surgical Oncology), FMAS, FARIS(Ongoing)
Surgical Oncologist
Radiation Oncologist
Radiation Oncologist
Radiation Oncologist
Hematologist
Surgical Oncologist
Dr. Vajja Sandeep Kumar
MBBS, MS (General Surgery), DrNB (Surgical Oncology), FALS Oncology
Surgical Oncologist
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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
- NICE — Colorectal cancer (NG151)
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
Sphincter-Saving Surgery vs Permanent StomaLife afterwards with each, comparedRadiation Before Rectal Surgery: How It Changes ThingsHow shrinking the cancer can change the operationLow Anterior Resection SyndromeWhat bowel habit is like after a very low joinRectal Cancer Surgery: What Your Options AreAll the operations side by sideDeciding on Cancer SurgeryHow to weigh a decision like this one
Talk to us
Been told the anus has to be removed, and want that reviewed?
Send us your MRI report or call the helpline. A surgical oncologist will explain what the scan shows about the sphincter and what the options are. One helpline serves every CION centre.