Category: Oncology · Colorectal surgery · Ostomy care
Stage 4 Colon Cancer and a Recommended Stoma Bag: Why Surgery Is Needed, Temporary or Permanent, How to Prepare, and Life With a Pouch
AI Overview / Quick Answer (BLUF)
A tumour that narrows or nearly blocks the bowel, bleeds, or causes severe symptoms stops stool passing safely. A stoma diverts stool out through the abdomen before the tumour, so the person can eat, recover, and restart systemic therapy. It is enabling surgery, not the end of treatment.
the time after a surgeon recommends a stoma in stage 4 colorectal cancer and before the operation —
why it is needed, the alternatives, stoma types, preparing for surgery, and life with an ostomy pouch.
If surgery is already done and you want details on changing or reversing the pouch, read
Rectal cancer surgery and a stoma: pouch changes, ileostomy dehydration, and reversal.
For stage 4 drug treatment, read
Unresectable stage 4 colon cancer: chemotherapy, targeted therapy, and conversion therapy ·
Red flags ·
Preparing for surgery ·
Comparison table ·
FAQ
A family’s voice: the doctor wants to operate and put in a stoma bag, and the patient is so stressed
Direct answer: in stage 4 colon cancer, stoma surgery is usually done to relieve problems from the tumour and to make further treatment possible — it is not giving up.
Stress before surgery is normal. What helps most is understanding the reason, knowing what to ask, and preparing before the day of surgery.
A relative shared that the doctor had recommended stoma surgery for a family member with stage 4 colon cancer. The patient was lying in bed, very stressed,
and the family was telling each other they would get through it together. This article is written for that moment — before the operation.
(5) how to live with a pouch (6) common problems (7) when treatment restarts and which drugs suit whom
Red flags after stoma surgery — go to hospital now
Direct answer: after surgery, if the stoma changes colour, stops working with abdominal pain and vomiting, puts out so much that the person becomes dehydrated, bleeds heavily, or there is fever, wound infection, or fever during chemotherapy, contact the surgical team or go to the emergency department right away. Do not wait for the next appointment.
Symptoms that should not wait
- The stoma turns dark red-purple, black, or very pale (a healthy stoma is moist and red-pink, like the inside of the cheek) — this may mean poor blood supply
- Once the stoma has started working, no stool or gas comes out for about 6–12 hours, with cramps, swelling, nausea, or vomiting — possible blockage
- An ileostomy puts out more than about 1.5–2 litres a day, or there is dizziness, little or very dark urine, or extreme thirst — dehydration
- Heavy bleeding from inside the stoma, or bleeding that does not stop with gentle pressure (a little spotting from the stoma surface when wiping can be normal)
- The stoma sinks below the skin, pushes out a lot, or the skin around it separates
- Fever, a red, swollen, or pus-draining wound, or abdominal pain that keeps getting worse
- During chemotherapy, a fever of 38.0°C or higher — go to the emergency department now. Read Fever after chemotherapy (febrile neutropenia)
1. Why stage 4 colon cancer may need stoma surgery
Direct answer: in stage 4, a stoma is surgery to relieve symptoms and make further treatment possible, not a sign that treatment has stopped.
The goal is for stool to leave safely, so the person can eat, recover, and start or return to chemotherapy or targeted therapy.
Common medical reasons
- The tumour has blocked or nearly blocked the bowel — bloating, cramps, no stool, no gas, vomiting. Read more in Persistent bloating: bowel obstruction or ascites
- Risk of perforation when the bowel above the tumour becomes very distended
- Bleeding from the tumour causing anaemia or repeated transfusions
- A fistula from the bowel into the bladder, vagina, or skin
- A low rectal tumour causing severe pain, constant urges without emptying (tenesmus), or incontinence
- Getting the body ready for treatment — eating, stopping weight loss, and avoiding interruptions to treatment from a blockage
How often does bowel obstruction happen?
of people with colorectal cancer present with large-bowel obstruction — a minority, not everyone (WSES 2018)
of obstructing tumours lie in the left colon (beyond the splenic flexure), most often the sigmoid colon (WSES 2018)
ESGE recommends stenting first to relieve obstruction in the palliative setting — but it does not suit everyone (see section 2)
The World Society of Emergency Surgery (WSES) guideline reports that large-bowel obstruction occurs in about 15–30% of people with colorectal cancer
(Pisano 2018).
Most people therefore do not present with obstruction. When a surgeon recommends a stoma, there is usually a specific reason — ask clearly what the main reason is.
Read more: Stage 4 colon cancer: chemotherapy and disease control
2. Options the surgeon weighs: stent, stoma, or tumour removal
Direct answer: surgeons choose based on tumour location, the person’s fitness, and the drug plan that follows.
The three main options are a colonic stent, a stoma alone, or removing the tumour with or without rejoining the bowel.
Colonic stent
The 2020 European Society of Gastrointestinal Endoscopy (ESGE) guideline recommends colonic stenting as the preferred treatment for palliation of malignant colonic obstruction,
used only when symptoms and imaging confirm obstruction — not as a preventive step
(van Hooft 2020).
But stents carry a risk of perforation. The 2014 ESGE guideline therefore made an exception for people treated or considered for treatment with anti-angiogenic drugs such as bevacizumab
(van Hooft 2014),
and WSES advises considering alternatives to a stent when bevacizumab-based therapy is planned, with the oncologist involved — a meta-analysis cited by WSES found perforation in 12.5% of people on bevacizumab vs 9.0% without concomitant chemotherapy.
Stents are also unsuitable for low rectal tumours near the sphincter and can block again.
Stoma alone (diverting stoma)
The surgeon brings a loop of bowel above the tumour out to the abdominal wall. It is usually a shorter operation, the tumour is not removed, recovery is quicker than after major surgery, and treatment can start sooner.
It suits people for whom a stent is unsuitable or unavailable, those with a low tumour, or those planned for anti-angiogenic therapy.
Removing the tumour: rejoining the bowel, or not rejoining and making a stoma
Some people have the primary tumour removed, for example when it bleeds or perforates, with the bowel rejoined (anastomosis) or not rejoined and an end stoma made,
depending on the bowel condition, fitness, and the risk of a leak. Major surgery takes longer to recover from, which may delay the start of treatment.
Questions the family should ask the surgeon
- In our case, why a stoma rather than a stent or removing the tumour?
- Will it be a colostomy or an ileostomy, loop or end, and on which side of the abdomen?
- Is it intended to be temporary or permanent, and what would make reversal possible?
- Will a stoma nurse mark the site and teach pouch care before surgery?
- When is treatment expected to restart, and will the plan include bevacizumab?
- Have tumour tests for RAS, BRAF, MSI/MMR, and HER2 been done?
3. Stoma types: colostomy vs ileostomy, temporary or permanent
Direct answer: a colostomy is made from the large bowel, gives thicker stool, and usually sits on the left; an ileostomy is made from the small bowel, gives liquid output with a dehydration risk, and usually sits on the right.
A stoma is permanent if the rectum and sphincter are removed or reversal is unsafe; in stage 4 many people keep a stoma long term.
Table: stoma types, output, reversal chance, and long-term care
Use it to talk with the surgeon and stoma nurse — the actual type depends on each person’s operation
| Type | Who / when | Output | Reversal chance | Long-term care |
|---|---|---|---|---|
| Colostomy (large bowel) | Tumour in the lower colon or rectum; usually on the left | Thick to formed, comes in episodes | Depends on loop vs end and on disease control | Skin care, avoid constipation, watch for a parastomal hernia |
| Ileostomy (small bowel) | Bypassing the whole colon, or protecting a join; usually on the right | Liquid to porridge-like, frequent, with digestive enzymes that irritate skin | Often intended as temporary, but depends on disease control | Extra fluids, oral rehydration when output is high, chew well, watch for food blockage |
| Loop stoma | Stoma alone without removing the tumour, or protecting a join | Two openings in one stoma; stool comes from the upstream opening | Often intended as temporary — reversed for some when disease is controlled | Usually larger; can prolapse |
| End stoma | After removing bowel without rejoining, or after removing the rectum and sphincter (APR) | Single opening | Permanent after sphincter removal; after a Hartmann procedure, rejoining is possible for some | Smaller, easier baseplate fit |
| Intended-temporary stoma | When rejoining the bowel is expected to be possible later | Depends on the bowel used | In stage 4, reversed for some, depending on disease control, fitness, and anatomy — never promised | Care as for a permanent stoma until reversal; reversal needs another operation |
| Permanent stoma | Rectum and sphincter removed, or reversal unsafe | Depends on the bowel used | Not reversed | Normal life is possible: work, bathing, travel. See Loop colostomy prolapse and pouch fitting |
Can it be reversed? An honest answer
Reversal depends on (1) how well the cancer is controlled (2) whether the person is fit for another operation (3) the remaining bowel and sphincter.
If the rectum and sphincter are removed (APR), the stoma is permanent. Read more on reversal in rectal cancer:
Locally advanced rectal cancer: TNT and sphincter preservation
How urgent are symptoms while waiting for surgery or during treatment?
Analyse the severity level and get personalised guidance from our Advisory team.
The score helps grade the urgency of symptoms during cancer treatment — it does not diagnose disease. If any symptom in the red-flag section applies, go to hospital now.
4. Before surgery: what the family can do starting today
Direct answer: ask a wound, ostomy and continence (WOC/ET) nurse to mark the stoma site before surgery.
Choose a spot the patient can see, on flat skin, away from folds, scars, the navel, and the belt line — this reduces leaks and skin problems.
Why stoma site marking matters
The American Society of Colon and Rectal Surgeons (ASCRS) ostomy surgery guidelines
(Davis 2022)
and the joint WOCN and ASCRS position statement
(Salvadalena 2015)
recommend preoperative stoma site marking and education. The nurse checks the patient sitting, standing, and lying down to find a spot that does not crease when sitting and that the patient can see to change the pouch.
In a study of 105 patients, those marked before surgery had better quality of life on 18 of 20 items, greater independence, and fewer complications
(Person 2012).
Emergency surgery may leave no time, but if surgery is scheduled, ask for it.
Checklist before the day of surgery
- Meet the stoma nurse for site marking and to see a sample pouch, baseplate, and how to empty it
- Write down questions for the surgeon (see section 2) and ask which stoma type is planned
- Eat enough — if eating is possible, focus on protein and energy; if there is partial obstruction, follow the team’s instructions (a liquid diet or fasting may be needed)
- Walk or move as able — it helps recovery after surgery
- Bring a full list of medicines, especially blood thinners, diabetes medicines, and oral chemotherapy
- Talk about feelings — fears about body image, odour, and relationships are normal; tell the team
The overall path: from before surgery to restarting treatment
5. Living with a stoma: emptying, changing, skin care, odour, and daily life
Direct answer: empty the pouch when it is about 1/3–1/2 full, change the baseplate typically every 3–5 days, and cut the opening only 1–2 mm larger than the stoma.
Re-measure often, because the stoma shrinks over the first 6–8 weeks. Most people can shower, work, dress, and travel normally.
Pouch care routine
- Empty the pouch when it is about 1/3–1/2 full — a heavy pouch pulls the baseplate off and leaks
- Change the baseplate typically every 3–5 days, or as the product and nurse advise. An ileostomy may need more frequent changes, and change it at once if it starts to leak or the skin under it itches or burns — do not wait for a leak
- The stoma shrinks over the first 6–8 weeks as post-operative swelling settles; measure with a guide at every change during this time and re-cut the opening
- Keep the opening only 1–2 mm larger than the stoma. Clean the skin with warm water, pat dry, and use skin-protection products as the nurse advises
Odour and leaks
Modern pouches use odour-proof film and many have a charcoal filter to vent gas. They control odour well when fitted correctly and sealed, so odour is usually noticed only when emptying or changing.
That does not mean there will never be any odour in every situation. A constant smell suggests a leak. Leaks can happen and are fixable by re-measuring, using a convex baseplate or seal ring, or changing the appliance with a stoma nurse.
Most people wear a pouch under normal clothing without anyone noticing.
Showering, work, clothing, travel, and lifting
- You can shower or bathe with the pouch on or off; water does not flow into the stoma
- Return to work and normal clothing once recovered; always carry spare supplies, especially when travelling
- Avoid heavy lifting for the first several weeks after surgery to lower the risk of a parastomal hernia; ask the surgeon how long
With an ileostomy: fluids, salts, and food
- Drink extra fluids every day. If output is high, the team may advise an oral rehydration solution and limiting large amounts of plain water — do not adjust this on your own
- Dehydration is the leading cause of readmission after a diverting loop ileostomy: 43.1% of readmissions within 60 days (Messaris 2012), and early high output occurred in 16% of ileostomies (Baker 2011)
- Chew food well and introduce high-fibre foods slowly at first, such as corn, nuts, fruit skins, and mushrooms, to reduce food blockage
Emotions and relationships
A review of 14 studies found that living with a colostomy affects quality of life, including sexual problems, low mood, gas, body image, clothing, and travel
(Vonk-Klaassen 2016).
Struggling at first is normal, not weakness. Stoma nurses, ostomy support groups, and the palliative care team can help.
Families can help by listening without judgement and letting the patient try pouch care when ready.
6. Common stoma problems: causes, first steps, and when to call the team
Direct answer: most problems, such as leaks, sore red skin, and odour, are fixable by re-measuring and choosing the right appliance.
Dehydration, blockage, and a change in stoma colour need the team right away.
Table: common stoma problems
First-step information to discuss with the stoma nurse — symptoms in the red-flag section need hospital care now
| Problem | Common cause | Prevention / first steps | When to call the nurse or team |
|---|---|---|---|
| Leaks, baseplate lifting | Opening does not fit, stoma shrank without re-measuring, skin folds, overfull pouch | Re-measure and re-cut, empty at 1/3–1/2 full, change the baseplate as soon as it leaks | Leaks more than once a day or for several days — a convex baseplate or seal ring may be needed |
| Red, sore, or broken skin around the stoma | Output touching skin (especially ileostomy), adhesive sensitivity, rough removal | Opening only 1–2 mm larger than the stoma, gentle removal, skin-protection powder or spray as advised | Open wounds, pustules, spreading rash, or no improvement in 2–3 days |
| Odour or a lot of gas | Leaking baseplate, wet or blocked filter, gas-forming foods | Check for leaks, change the pouch or filter, reduce gas-forming foods one at a time | Constant smell even after changing — have the nurse check the fit |
| Food blockage (ileostomy) | High-fibre foods not chewed well, such as corn, nuts, fruit skins | Chew well, add fibre slowly, warm drinks, gentle walking | No output for about 6–12 hours with cramps, swelling, or vomiting — go to hospital |
| High output / dehydration | Early ileostomy, infection, some medicines, large amounts of plain water | Oral rehydration solution, record the daily volume emptied | More than about 1.5–2 litres a day, or dizziness and little urine — contact the team now |
| Parastomal hernia (bulge around the stoma) | Weak abdominal wall around the stoma, heavy lifting, chronic cough, weight gain | Avoid heavy lifting early, use a support belt as advised | A hard, very painful bulge that will not go back, with vomiting — go to hospital now |
| Prolapse (pushes out) or retraction (sinks in) | More common with loop stomas; raised abdominal pressure | Use a large enough pouch, adjust the baseplate with the nurse. See Loop colostomy prolapse | Stoma turns dark purple or black, or sinks below the skin — go to hospital now |
7. After surgery: when treatment restarts and which drugs suit whom
Direct answer: treatment usually restarts about 2–4 weeks after surgery, once the person has recovered, is eating, and the wound is healing — the treating team decides.
Bevacizumab should not start until at least 28 days after major surgery and the wound has healed. Drug choice depends on tumour tests: RAS, BRAF, MSI/MMR, and HER2.
Timing of treatment after surgery
The bevacizumab prescribing information says not to start it until at least 28 days after major surgery and until the wound is fully healed, because anti-VEGF drugs slow the blood-vessel growth wounds need to heal.
In metastatic colorectal cancer, starting bevacizumab 28–60 days after surgery gave wound problems in 1.3% vs 0.5% without it, not clearly different,
but major surgery during bevacizumab treatment gave wound problems in 13% vs 3.4%
(Scappaticci 2005).
Tumour tests that guide drugs
- Chemotherapy backbone — a fluoropyrimidine (5-FU or capecitabine) with oxaliplatin or irinotecan is the core for most people
- Anti-VEGF (bevacizumab) — used broadly with chemotherapy, regardless of RAS status
- Anti-EGFR (cetuximab, panitumumab) — only for RAS wild-type tumours, with more benefit in left-sided tumours
- Immunotherapy (such as pembrolizumab) — works strikingly only in MSI-H/dMMR tumours, about 5% of metastatic colorectal cancer
- BRAF V600E and HER2 — if present, specific targeted options exist in some treatment lines. ESMO recommends testing RAS, BRAF, and MSI/MMR at the start of planning, and recommends HER2 testing (Cervantes 2023)
Immunotherapy: very effective, but for a small group
(Venderbosch 2014).
For this group, KEYNOTE-177 found that first-line pembrolizumab gave longer progression-free survival than chemotherapy (median 16.5 vs 8.2 months) with fewer severe side effects (22% vs 66%)
(André 2020).
But most tumours are MSS/pMMR, where immunotherapy alone is not standard — ask whether MSI/MMR testing has been done.
Stage 4 as a chronic disease, and early palliative care
Many people with stage 4 colorectal cancer are managed like a chronic disease, with ongoing treatment adjusted when needed; some with spread limited to the liver or lungs may become operable when tumours shrink (conversion).
Read Colorectal cancer with liver and peritoneal spread: conversion therapy in reality.
Early palliative care helps with pain, nausea, eating, and stress alongside treatment — it does not mean stopping treatment.
8. Comparison table: options for an obstructing stage 4 tumour, and drugs by tumour tests
Direct answer: a stent, a stoma, and tumour removal differ in speed of recovery, risk, and effect on the drug plan.
Drugs after surgery are chosen by tumour tests — no single regimen is best for everyone.
Table: comparing surgical options, drugs, and palliative care
Summarised from ESGE, WSES, ASCRS, and ESMO guidance — the real choice is made by the multidisciplinary team
| Option | Who it suits | Main benefit | Limits / risks | Numbers to know |
|---|---|---|---|---|
| Colonic stent | Obstruction from a colonic tumour, confirmed on CT, no perforation | No operation, may avoid a stoma, shorter hospital stay | Perforation, migration, or re-blockage; unsuitable with current or planned bevacizumab and for low rectal tumours | Perforation 12.5% with bevacizumab vs 9.0% (data cited by WSES) |
| Stoma alone (diverting stoma) | Stent unsuitable, low tumour, symptoms from a low rectal tumour, anti-angiogenic therapy planned | Smaller operation, quick recovery, treatment starts sooner | Pouch care; the tumour remains and may still pass blood or mucus from the anus | Chemotherapy often restarts about 2–4 weeks after surgery |
| Tumour removal with rejoined bowel | Fit person, healthy bowel, tumour bleeding or causing marked symptoms | Removes the primary tumour, may avoid a stoma | Major surgery, leak risk, longer recovery, may delay treatment | Bevacizumab at least 28 days after major surgery and a healed wound |
| Tumour removal without rejoining + end stoma | Emergency surgery, very swollen or infected bowel, high leak risk | No join at risk of leaking | A stoma; rejoining needs another major operation, and many are never rejoined | Rejoining depends on disease control, fitness, and anatomy |
| Chemotherapy backbone | Most people fit for treatment | Fluoropyrimidine + oxaliplatin or irinotecan forms the core of the plan | Low white cells, diarrhoea, numb hands and feet | Fever of 38.0°C or higher during chemotherapy: emergency department |
| Anti-VEGF (bevacizumab) | Used broadly with chemotherapy, regardless of RAS | Adds disease control with chemotherapy | Slow wound healing, bleeding, high blood pressure, perforation risk | Surgery during treatment: wound problems 13% vs 3.4% |
| Anti-EGFR (cetuximab, panitumumab) | RAS wild-type, mainly left-sided tumours | Improves tumour response in suitable patients | No benefit with RAS mutation; acne-like rash, low magnesium | RAS (KRAS/NRAS) testing required first |
| Immunotherapy (pembrolizumab) | Only MSI-H/dMMR tumours | Longer progression-free survival than chemotherapy as first-line treatment | Not standard in MSS/pMMR tumours; immune-related side effects | dMMR 5.0% of metastatic colorectal cancer; PFS 16.5 vs 8.2 months |
| Palliative care | Anyone with symptoms or distress, early and alongside treatment | Controls pain, nausea, eating, sleep; helps the family plan | Often misunderstood as stopping treatment | Can be combined with drugs; no need to wait for the end of life |
9. How the family can help a patient who is stressed before surgery
Direct answer: listen to fears without rushing to say it is fine, help write down questions, meet the stoma nurse together, and share household tasks.
Many patients fear changes in body image, odour, and being a burden — these feelings are understandable.
- Ask “what worries you most?” and help find answers from the team, instead of telling them to stop worrying
- Have at least one relative learn pouch changes too, but let the patient try when ready, to keep a sense of control
- Caregivers get tired too — rest, ask others for help, and tell the team if you feel exhausted. See Advanced cancer caregiver guide
Frequently asked questions (FAQ)
Why would a surgeon recommend a stoma bag in stage 4 colon cancer, and does it mean treatment has stopped?
No. In stage 4, a stoma is surgery to relieve problems from the tumour and to make further treatment possible. Common reasons are a tumour that has blocked or nearly blocked the bowel, a risk of perforation, bleeding, a fistula into another organ, or a low rectal tumour causing pain, constant urges to pass stool, or incontinence. Bowel obstruction affects a minority, about 15 to 30 percent of people with colorectal cancer. Once stool can leave through the abdomen, the person can eat, recover, and return to chemotherapy or targeted therapy more safely.
Is this stoma temporary or permanent, and can it be reversed?
It depends on the operation and on disease control. If the rectum and anal sphincter are removed, or reversal would be unsafe, the stoma is permanent. A loop stoma is often intended to be temporary, but in stage 4 many people keep their stoma long term. Reversal is possible for some people, depending on how well the cancer is controlled, whether the person is fit for another operation, and the remaining bowel anatomy, so nobody can promise it in advance. Ask the surgeon directly which type is intended and what conditions would allow reversal.
Why not use a colonic stent or remove the tumour instead of a stoma?
Surgeons weigh several options based on tumour location, fitness, and the treatment plan. ESGE guidelines recommend a colonic stent as the preferred way to relieve malignant colonic obstruction in the palliative setting, but stents carry a risk of perforation. The 2014 ESGE guideline therefore made an exception for people treated or considered for anti-angiogenic drugs such as bevacizumab, and WSES guidance advises considering alternatives to a stent in that situation. Stents are also unsuitable for very low rectal tumours. Removing the tumour may be done with or without rejoining the bowel. A good question is: in our case, why a stoma rather than a stent or tumour removal?
What should the family prepare and ask before stoma surgery?
Most important is to ask a wound, ostomy and continence nurse to mark the stoma site before surgery, choosing a spot the patient can see, on flat skin, away from folds, scars, the navel, and the belt line. ASCRS guidelines and a joint WOCN and ASCRS position statement recommend this. In a study of 105 people, those who were marked had better quality of life and fewer complications. Also ask for pouch teaching before surgery, whether it will be a colostomy or ileostomy, temporary or permanent, when treatment can restart, and whether RAS, BRAF, and MSI tests have been done. Eat enough and walk as able.
With a stoma bag, will other people smell it?
Usually not, when the pouch fits correctly and is sealed. Modern pouches use odour-proof film and many have a charcoal filter to vent gas, so odour is usually noticed only when emptying or changing the pouch. That does not mean there will never be any odour in every situation. A constant smell suggests a leaking baseplate or a poorly fitted opening, which can be fixed by re-measuring or changing the appliance with a stoma nurse. Most people wear a pouch under normal clothing without anyone noticing.
With a stoma, can I shower, work, or travel?
Yes. You can shower or bathe with the pouch on or off, because water does not flow into the stoma. You can return to work, dress normally, and travel once recovered. Always carry spare supplies. Avoid heavy lifting for the first several weeks after surgery to lower the risk of a hernia beside the stoma, and ask the surgeon how long. With an ileostomy, drink extra fluids and chew food well.
After stoma surgery, when can chemotherapy or targeted therapy restart?
Treatment usually restarts once the person has recovered, is eating, and the wound is healing, often around 2 to 4 weeks after surgery, but the treating team decides. For bevacizumab, the prescribing information says not to start it until at least 28 days after major surgery and until the wound is fully healed. A study found that starting it 28 to 60 days after surgery did not clearly increase wound problems. The choice of drugs depends on tumour tests: RAS, BRAF, MSI, and HER2.
After stoma surgery, which symptoms need hospital care right away?
Go to hospital right away if the stoma turns dark red-purple, black, or very pale; if no stool or gas comes from the stoma for about 6 to 12 hours with cramps, swelling, nausea, or vomiting; if an ileostomy puts out more than about 1.5 to 2 litres a day or there is dizziness, little urine, or extreme thirst; if there is heavy bleeding from inside the stoma; if the stoma sinks in, pushes out a lot, or the skin around it separates; or with fever, a red or pus-draining wound, or severe abdominal pain. During chemotherapy, a fever of 38.0 °C or higher means go to the emergency department.
Scientific mechanism
Mechanism summary by Asst. Prof. Dr. Norawit Raatpiboon:
when a tumour narrows the colon, the bowel above it distends with stool and gas, and rising wall pressure reduces its blood supply.
If the valve between the small and large bowel stays closed, the colon becomes a closed loop at risk of perforation, especially at the caecum.
A stoma lets stool leave before the narrowing, relieving pressure and allowing eating and treatment.
Output differs because the colon reabsorbs water: a colostomy comes after the colon, so stool is thicker, while an ileostomy bypasses the whole colon, so output is liquid and water and sodium are lost easily.
A new stoma is swollen from surgery and gradually shrinks over 6–8 weeks, so the baseplate opening must be re-measured.
Bevacizumab blocks VEGF, which new blood vessels in a healing wound depend on, so a gap after major surgery is needed.
Anti-EGFR drugs act on the receptor at the cell surface, but if RAS — further down the signalling chain — is mutated, the signal stays switched on and the drugs do not work.
MSI-H/dMMR tumours carry very many mutations, producing abnormal proteins (neoantigens) that the immune system can recognise once the PD-1 brake is released by pembrolizumab.
E-E-A-T and academic citations
Written by Asst. Prof. Dr. Norawit Raatpiboon (ผศ.ดร.นรวิชญ์ ราษฎร์พิบูลย์) — synthesised from ESGE, WSES, ASCRS, WOCN, and ESMO guidance and research on PubMed
- van Hooft JE, et al. Self-expandable metal stents for obstructing colonic and extracolonic cancer: ESGE Guideline – Update 2020. Endoscopy 2020 (PMID 32259849)
- van Hooft JE, et al. Self-expandable metal stents for obstructing colonic and extracolonic cancer: ESGE Clinical Guideline. Endoscopy 2014 (PMID 25325682)
- Pisano M, et al. 2017 WSES guidelines on colon and rectal cancer emergencies: obstruction and perforation. World J Emerg Surg 2018 (PMID 30123315)
- Davis BR, et al. The American Society of Colon and Rectal Surgeons Clinical Practice Guidelines for Ostomy Surgery. Dis Colon Rectum 2022 (PMID 35616386)
- Salvadalena G, et al. WOCN Society and ASCRS Position Statement on Preoperative Stoma Site Marking for Patients Undergoing Colostomy or Ileostomy Surgery. J Wound Ostomy Continence Nurs 2015 (PMID 25695929)
- Person B, et al. The impact of preoperative stoma site marking on the incidence of complications, quality of life, and patient’s independence. Dis Colon Rectum 2012 (PMID 22706131)
- André T, et al. Pembrolizumab in Microsatellite-Instability-High Advanced Colorectal Cancer (KEYNOTE-177). N Engl J Med 2020 (PMID 33264544)
- Cervantes A, et al. Metastatic colorectal cancer: ESMO Clinical Practice Guideline for diagnosis, treatment and follow-up. Ann Oncol 2023 (PMID 36307056)
- Venderbosch S, et al. Mismatch repair status and BRAF mutation status in metastatic colorectal cancer patients: a pooled analysis of the CAIRO, CAIRO2, COIN, and FOCUS studies. Clin Cancer Res 2014 (PMID 25139339)
- Scappaticci FA, et al. Surgical wound healing complications in metastatic colorectal cancer patients treated with bevacizumab. J Surg Oncol 2005 (PMID 16118771)
- Messaris E, et al. Dehydration is the most common indication for readmission after diverting ileostomy creation. Dis Colon Rectum 2012 (PMID 22228161)
- Baker ML, et al. Causes and management of a high-output stoma. Colorectal Dis 2011 (PMID 19888956)
- Vonk-Klaassen SM, et al. Ostomy-related problems and their impact on quality of life of colorectal cancer ostomates: a systematic review. Qual Life Res 2016 (PMID 26123983)
- MedlinePlus (NIH) — Ostomy
- MedlinePlus (NIH) — Colorectal Cancer
Medical disclaimer
This content is general education about stoma surgery in stage 4 colorectal cancer. It is not a diagnosis, prognosis, or individual treatment plan.
The choice between a stent, a stoma, or tumour removal, the stoma type, reversal, and drug regimens belong to the surgeon, oncologist, and multidisciplinary team caring for the patient.
Do not stop or change medicines on your own. If any symptom in the red-flag section applies, contact the treating team or go to the emergency department immediately.