Food passes from the stomach into the small bowel, where much of digestion and nutrient absorption occurs. The small bowel has three parts: duodenum, jejunum and ileum. The last part, the terminal ileum, meets the caecum at the beginning of the large bowel. The colon absorbs water and helps turn liquid contents into formed stool; the rectum stores stool before it leaves through the anus.

A resection removes a length of bowel. The surgeon may join the remaining ends with stitches or staples, creating an anastomosis, so contents continue along the shortened route. Alternatively, or as well as a join, bowel can be brought to the abdominal wall as a stoma, diverting stool into a bag. The precise route depends on which part is removed and whether the remaining bowel and anus can be used.

An ileocaecal resection removes the end of the small bowel and the beginning of the colon. A segmental colectomy removes a section of colon; a right hemicolectomy removes the right colon and a short part of small bowel. A subtotal colectomy removes most or all of the colon while leaving the rectum. Names describe different operations, not interchangeable amounts of bowel. Ask the team to draw the intended route and identify what will remain.

Location matters as much as length. The terminal ileum absorbs vitamin B12; removing it can lead to deficiency requiring monitoring and treatment. Less colon in the route can mean looser stool or greater fluid loss. Extensive small-bowel removal can make absorption more difficult, so a nutrition plan depends on the bowel remaining and the individual operation.

A surgeon may recommend resection to remove a cancer, take out damaged or narrowed bowel, or treat complications such as a blockage, perforation or severe bleeding. The aim may be to treat disease, relieve symptoms or deal with an immediate danger. The reason, urgency and proposed extent matter more than the general name of the procedure.

In bowel cancer, the location and extent of the tumour guide the operation. For example, sigmoid colectomy can remove the tumour, a margin of bowel and nearby lymph nodes. Tissue analysis helps establish the stage and inform further treatment. Surgery can be offered with different aims, including relief of obstruction; removal alone cannot promise a cure or that further treatment will not be needed.

Crohn’s disease can affect different parts of the digestive tract, sometimes in patches. Surgery may remove a long or severely affected narrowing, or treat a fistula or abscess. It does not cure Crohn’s: inflammation can return near the join or elsewhere. Medicines, monitoring and further treatment may still be needed. Some narrowings may instead be treated with medicine, endoscopic dilatation or bowel-preserving strictureplasty, depending on the findings.

Ulcerative colitis affects the large bowel. Surgery can be considered when medicines are ineffective or unsuitable, or for cancer, precancerous changes or severe complications. A subtotal colectomy may leave the rectum, which can still become inflamed. If the entire colon and rectum are removed, colitis cannot recur in those removed organs, but symptoms outside the gut may persist and a pouch or stoma has its own possible problems.

Planned surgery allows time to discuss alternatives, medical fitness and the possibility of a stoma. Perforation, major bleeding or a severe obstruction can make surgery urgent, leaving less time to prepare. The team may need to make a different decision from the planned operation in order to manage infection or the findings safely.

A primary anastomosis joins bowel ends during the operation. Sometimes a temporary diverting stoma is made as well, directing stool away from a downstream join while it heals. A diversion does not guarantee that the join cannot leak. If a join is not safe or possible, the surgeon may form a stoma without making an immediate connection. Ask what might lead to either decision.

A stoma may be planned as temporary or permanent. A planned temporary stoma needs a later assessment and another operation for reversal; reversal is not guaranteed. Some people need a permanent stoma because the lower bowel or anus is removed or a safe route cannot be restored. The choice may also depend on expected bowel function, health and your preferences.

For selected people with ulcerative colitis, a pouch made from small bowel can be joined to the anus, usually over two or three operations and sometimes with a temporary stoma. This is different from simply restoring the original colon. A pouch can become inflamed and bowel frequency may change. Ask whether a pouch, ileorectal join or permanent stoma is appropriate in your circumstances.

Pre-assessment reviews health, medicines, allergies, previous surgery, nutrition and the anaesthetic. Tell the team about prescribed and non-prescribed medicines, supplements and possible pregnancy. Follow your hospital’s specific instructions about medicines, fasting and any bowel preparation; these vary with the operation. Do not stop medicines independently. Ask what help is available for nutrition, smoking cessation and building fitness when time permits.

When a stoma is possible, a specialist may mark a suitable position before surgery, considering folds, scars, clothing, whether you can see and reach it, and your preferences. This planning may not be possible in a rapid emergency. Ask for stoma nursing support even when a stoma is only a possibility.

Bowel resection is usually performed under general anaesthetic. A surgeon accesses the bowel through a larger open incision or by keyhole surgery using a camera and instruments; some centres use surgeon-controlled robotic instruments. The diseased section is removed, and the remaining bowel is joined or a stoma is formed according to the plan and findings. A keyhole operation may need conversion to open surgery for safety.

The anaesthetic team monitors breathing and circulation. Afterwards ask what was removed, whether a join or stoma was made, whether the operation differed from the plan and whether tissue was sent for testing. Agree who will explain results, how follow-up is arranged and which medicines should be restarted.

Resection can remove diseased tissue or relieve the physical cause of an obstruction. In an emergency it may address an immediate threat. Whether pain, diarrhoea, fatigue or other symptoms improve depends on their cause, the disease and what bowel remains. The expected benefit needs to be discussed alongside the consequences of not operating and other available treatments.

Possible complications include bleeding, wound or chest infection, injury to nearby structures, blood clots and anaesthetic complications. A clot in the leg can travel to the lung. Prevention may include early movement, stockings or blood-thinning medication when appropriate. Ask the team about your own risk and what prevention and aftercare are planned.

An anastomotic leak occurs when bowel contents escape from a join. It can cause serious infection and may require antibiotics, drainage or another operation, sometimes with a stoma. A stoma diverting stool can help protect a join but does not remove the need to investigate worsening symptoms. The risk and management depend on the person, the join and the operation.

After surgery bowel movement may temporarily slow, called ileus, causing bloating, nausea and vomiting. A mechanical blockage is a different problem and can also occur later, including from internal scar tissue called adhesions. A hernia may develop at an incision or around a stoma. These problems cannot be distinguished reliably by symptoms alone and should be assessed.

In hospital, staff monitor pain, breathing, hydration, urine, wounds and bowel function. A drip and sometimes a urinary catheter may be used. Pain relief should allow you to breathe, cough and move comfortably; tell the team if it is not working. Walking with assistance and eating or drinking as advised are part of many recovery plans, adjusted to your progress.

Discharge depends on your condition, not a fixed number of days. Before leaving, ask for wound and medicine instructions, a contact number for day and night, the plan for blood-clot prevention and how to obtain test results. If you have a stoma, practise emptying and changing the bag and make sure supplies and community stoma nurse follow-up are arranged.

At home, fatigue and altered bowel habit can persist while recovery progresses. Small meals and gradual activity may be helpful. Ask about lifting, driving, work, caring responsibilities and exercise in relation to your incision and role. You need to be able to control the car and make an emergency stop, and should check your insurer’s requirements. Recovery can be longer after emergency surgery or complications.

Bowel frequency, urgency or looseness can change after resection. Ask for dietitian support if eating is difficult, weight falls or you are restricting many foods. Follow-up may involve pathology and cancer care, inflammation monitoring or nutrient checks, depending on the diagnosis. Persistent symptoms deserve assessment rather than assuming they are inevitable after surgery.

Evidence must be matched to the operation and diagnosis. NICE recommendations for colorectal cancer discuss treatment choices, functional effects and possible changes of plan; Crohn’s and ulcerative colitis pathways differ. Findings from a cancer operation or a particular join do not predict your individual outcome. Discuss your own priorities and uncertainties with the surgical and specialist teams.