Procedures › Bowel resection

Anaesthesia for bowel resection (including bowel cancer)

This page covers the anaesthetic plan for major bowel surgery, including the spinal block, enhanced recovery pathway, pain relief and the medicines you may need to change before surgery. Your own plan is agreed with you before surgery.

Why is bowel surgery different?

Major abdominal surgery puts stress on the body. It can affect breathing, heart function, and recovery of the gut. Pain, nausea, and tiredness are common in the early days after surgery. Careful anaesthetic planning and modern "Enhanced Recovery" pathways help reduce complications and get you home sooner.

Before surgery

• Fasting: No food for 6 hours before surgery. Clear fluids (water, black tea/coffee without milk, clear apple juice) are allowed until 2 hours before.
• Bowel preparation: Some patients may be asked to complete a bowel prep. Your surgeon and hospital team will provide specific instructions.
• Medications: Most regular medicines should be continued unless advised otherwise. Blood thinners, diabetes medications, and some heart medicines may require changes.
• Pre-operative consultation: I will review your medical history and may organise a phone call to discuss your anaesthetic plan with you before surgery.
• Stopping smoking and alcohol: Stopping well before surgery greatly reduces risks, especially of infection and poor wound healing.

See our fasting guidance and medicines before surgery page for more detail.

Blood pressure medicines to withhold before surgery

If you take any of the following medicines, do not take them on the morning of your operation. Bring them with you to hospital so your team can confirm when to restart them.

ACE inhibitors

• Perindopril (Coversyl, Coversyl Arginine, Reaptan [with amlodipine], Coversyl Plus [with indapamide])
• Ramipril (Tritace, Triapin [with felodipine], Ramipril Sandoz, Ramipril Apotex)
• Lisinopril (Prinivil, Zestril, Lisodur)
• Enalapril (Renitec, Enahexal, Enapine, Renitec Plus [with diuretic])
• Captopril (Capoten, Acenorm, Acehexal)
• Trandolapril (Gopten, Choretensin [with verapamil])
• Fosinopril (Monopril, Fosinopril Sandoz)
• Quinapril (Accupril, Accuretic [with hydrochlorothiazide])

Angiotensin II receptor blockers (ARBs)

• Irbesartan (Avapro, Karvezide [with hydrochlorothiazide], Avalide)
• Valsartan (Diovan, Exforge [with amlodipine], Co-Diovan [with hydrochlorothiazide])
• Telmisartan (Micardis, Twynsta [with amlodipine], Micardis Plus [with hydrochlorothiazide])
• Candesartan (Atacand, Atacand Plus [with hydrochlorothiazide])
• Olmesartan (Olmetec, Sevikar [with amlodipine], Olmetec Plus [with hydrochlorothiazide])
• Losartan (Cozaar, Hyzaar [with hydrochlorothiazide])
• Eprosartan (Teveten, Teveten Plus [with hydrochlorothiazide])

Key instructions

• Do not take these medicines within 24 hours before surgery (especially the morning dose).
• Take your other regular medicines unless your anaesthetist advises otherwise.
• Always bring your medication list or the actual packets to hospital.

Diabetes medications and surgery

If you have diabetes, your medicines may need to be changed around the time of surgery to keep you safe. High or low blood sugars during surgery can cause complications, so your anaesthetist and surgical team will guide you on what to do.

Insulin

• Long-acting insulin (Optisulin, Toujeo): usually take half your normal dose the night before, and half your normal morning dose on the day of surgery.
• Intermediate-acting insulin (Humulin NPH, Protaphane): usually take half the dose the night before and half the morning dose.
• Mixed insulins (Humulin 30/70, Ryzodeg 70/30, Novomix 30/70, Mixtard 30/70): usually reduce the night dose by 20%. Morning dose is often withheld if you are fasting.
• Short-acting insulins (Actrapid, Novorapid, Humalog): these are usually withheld while fasting.
• Insulin pump users: do not stop your pump unless advised. The basal (background) rate usually continues. Sometimes the rate is reduced to 80% overnight. The infusion site may be moved away from where the surgery is taking place.

Non-insulin injectable medications

• GLP-1 receptor agonists (Ozempic, Trulicity, Rybelsus, Byetta, Victoza): They slow stomach emptying, which can increase the risk of vomiting or aspiration during anaesthesia. Please follow the instructions on our medicines before surgery page.

Tablets

• Metformin (Diabex, Glucophage): usually stop on the day of surgery. If your kidney function is reduced or you are having contrast dye, metformin is stopped the day before and for 48 hours after surgery.
• DPP-4 inhibitors (Trajenta, Onglyza, Januvia, Galvus): usually stop on the day of surgery.
• Sulfonylureas (Diamicron, Minidiab, Amaryl): usually stop on the day of surgery. These medicines can cause low blood sugar when you are fasting.
• SGLT2 inhibitors (Forxiga, Jardiance, Steglatro, Invokana): must be stopped 3 days before surgery. These drugs carry a risk of "euglycaemic ketoacidosis" (a dangerous complication) if continued.
• Thiazolidinediones (Actos): usually stop on the day of surgery.

What you can do

• Bring a full list of your diabetes medications and insulin types with you to hospital.
• Check your blood sugar as instructed the night before and the morning of surgery.
• Tell the staff if you feel unwell, shaky, or think your sugar is too low or too high.

After surgery, your blood sugar will be monitored regularly. You may need temporary insulin injections or a drip, even if you don't normally take insulin.

Anaesthetic plan - summary

For major bowel surgery, anaesthesia is tailored to keep you safe and provide effective pain relief:

• General anaesthetic (GA) - You will be fully asleep with a breathing tube in place.
• Spinal block - For most patients, a spinal block is used to provide pain relief during and after surgery.
• Local anaesthetic infiltration - Your surgeon may also inject local anaesthetic into the wound at the end of surgery.
• Arterial line and monitoring: Extra lines may be used for continuous blood pressure monitoring and frequent blood tests.

Spinal block

For many operations, including major abdominal surgery such as bowel resections, a spinal anaesthetic can be used in combination with a general anaesthetic. This is not something that is offered randomly. It is part of an enhanced recovery pathway designed to reduce the stress response to surgery, improve safety, and provide excellent pain relief afterwards.

What is a spinal anaesthetic?

A spinal anaesthetic is given by injecting local anaesthetic and pain relief into the fluid that surrounds the nerves in your lower back. This numbs the nerves from the waist down to the toes. The numbness usually lasts between 4 and 8 hours. A longer-acting pain relief medicine (such as morphine) can also be injected at the same time. This extends the pain relief for 16-48 hours and means you need far fewer strong opioids and anaesthetic medicines.

Why have a spinal for bowel surgery?

There are clear advantages to adding a spinal anaesthetic to your anaesthetic plan:

• Reduced stress response: Surgery triggers hormonal and inflammatory changes which can put strain on the heart, lungs, and other organs. A spinal helps dampen this response.
• Less need for opioids: Because the spinal provides strong pain relief, you need far fewer strong pain medicines like morphine, which reduces side effects such as sickness, drowsiness, constipation, and breathing problems.
• Better pain relief: The spinal provides reliable pain relief immediately after the operation.
• Enhanced recovery: With less pain and fewer side effects, you can breathe more deeply, mobilise earlier, and recover faster.

How is the spinal performed?

• You will have your spinal in theatre (operation room), just before going off to sleep for your general anaesthetic.
• You will meet the anaesthetic assistant, who helps with monitoring and support.
• A cannula (drip) is inserted in your hand or arm to give fluids and medicines.
• You will be positioned sitting up or curled on your side.
• The skin is numbed with local anaesthetic, then a fine needle is used to inject the spinal medicine.
• You may feel tingling or a brief electric shock sensation in one leg, this is common and passes quickly.
• The numbness comes on within a few minutes. Your legs will feel warm, heavy, and difficult to move.

During your operation

• The spinal is given in addition to a general anaesthetic, so you will be fully asleep.
• The spinal works in the background, providing pain relief and reducing the amount of anaesthetic and opioid you need.
• This is a planned part of your anaesthetic, not a "random" decision.

After the operation

• The numbness wears off gradually over 4-8 hours.
• You may notice tingling as sensation returns.
• As the spinal wears off, regular pain relief (paracetamol, and stronger tablets if needed) will already be started.
• You may feel some weakness in your legs until the block has fully worn off. Please ask staff for help when you first get out of bed.

Risks and side effects

Spinal anaesthesia is very safe, but all medical treatments carry some risk.

• Common short-lived effects: Drop in blood pressure; tingling, heaviness, or warmth in the legs; difficulty passing urine until the block wears off.
• Uncommon: Headache afterwards (usually treatable, very rarely persistent); temporary backache.
• Rare: Nerve injury (temporary or permanent); infection or bleeding at the injection site.

Your anaesthetist will discuss what risks apply in your case and answer any questions.

Summary

A spinal anaesthetic is an important part of the anaesthetic plan for major bowel surgery. It:

• Reduces the stress response to surgery.
• Provides excellent pain relief.
• Reduces the need for large doses of opioids and anaesthetic drugs.
• Supports faster mobilisation and recovery.

It is part of a carefully planned enhanced recovery pathway - not something done at random.

Patient-controlled analgesia (PCA)

This is a form of pain relief that you control yourself. A pump containing a strong painkiller is connected to your cannula. You are given a handset with a button that activates the pump. When you press the button, a small dose is given. The pump has safety settings to prevent you accidentally getting too much.

Blood transfusion

Blood transfusion is a possibility during all major surgery. Blood is given only if absolutely necessary. If you do not wish to have a blood transfusion, you must discuss this with your doctors well before the day of your operation.

Wound catheters

This is sometimes performed for 'open' procedures. That is surgery that is not keyhole (laparoscopic). Local anaesthetic is administered into the area around your wound via one or more small plastic tubes. The aim is to produce a numb area around the wound. The surgeon or anaesthetist places these tubes during the operation. They are connected to a pump that continuously delivers local anaesthetic. Wound catheters can stay in place for several days after your operation.

For some people, the planned form of pain relief may need to be altered after the operation. Some people need more pain relief than others or respond differently to pain-relieving drugs. Feeling anxious can increase the pain that people feel. If you have pain, the dose of pain relief you are prescribed can be increased, given more often or given in different combinations.

After the operation

Most people will wake up in the recovery area after surgery. A recovery nurse will be with you at all times. Some people may go straight to an ICU or HDU. The recovery nurse will:

• Monitor your blood pressure, oxygen levels and pulse rate.
• Give you oxygen through a mask or soft plastic prongs placed inside the nose.
• Assess your pain level and give you more pain relief if necessary.
• Give you anti-sickness drugs if you feel sick.
• Cover you with a warming blanket if you are cold.
• Return your dentures, hearing aids and glasses/contact lenses when you are awake.

If you have had a spinal for pain relief, the recovery nurse will check to see how effective it is. If you are uncomfortable, your nurse can give you additional pain relief.

• Pain relief: Most patients receive regular intravenous paracetamol and a PCA (patient-controlled analgesia) pump. Some also have a wound catheter.
• Breathing and oxygen: You may need oxygen, especially while using strong pain medicines.
• Eating and drinking: Enhanced Recovery encourages you to start drinking, and then eating, as soon as it is safe.
• Tubes and drains: You may have a urinary catheter and sometimes drains in the abdomen. These are usually removed after a few days.
• Monitoring: Some patients go to a high-dependency or intensive care unit for closer monitoring after surgery.

Recovery and what you can do

• Pain is expected but is well managed with the combination of medicines and techniques described.
• Get moving early: Walking, sitting out of bed, and physiotherapy reduce the risk of clots and chest infections.
• Good breathing: Deep breaths, coughing, and using an incentive spirometer if given help prevent pneumonia.
• Nutrition: Eating small meals with protein helps healing.
• No smoking or alcohol: These directly increase the risk of leaks at the bowel join (anastomosis).
• Report problems: Tell staff if you feel new pain, fever, bloating, or difficulty breathing.

Helping your join (anastomosis) heal

Your bowel has been joined back together with stitches or staples. This join needs time and the right conditions to heal well. There are things you can do that make a real difference:

1. Nutrition and eating

• Try to eat small, frequent meals as recommended by your surgical team.
• Good protein (meat, fish, eggs, beans) helps your body build new tissue.
• Drink enough fluids, but avoid overloading with large amounts in one go.

2. Smoking and alcohol

• Stop smoking completely - even a few cigarettes can lower blood flow to the bowel and triple the risk of leaks.
• Avoid alcohol for several weeks after surgery - it slows healing and weakens your body's defences.

3. Blood sugar and anaemia

• If you have diabetes, keep your blood sugar well controlled with medicines and diet.
• Treating anaemia (low blood count) before and after surgery helps oxygen reach the healing tissue.

4. Movement and activity

• Gentle walking improves circulation, lung function, and helps your bowel "wake up".
• Follow advice from physiotherapists or nurses on when and how to mobilise safely.

5. Preventing infection

• Take any antibiotics exactly as prescribed.
• Tell staff quickly if you notice new pain, fever, diarrhoea, or pus in your wound/drain.

6. Weight and general health

• If overweight, even small amounts of weight loss before surgery reduce strain on the join.
• Stick to the recovery plan (Enhanced Recovery After Surgery, or ERAS) - early eating, moving, and normalising body temperature all help healing.

Remember: Most leaks happen from problems inside the body that you cannot control. But by avoiding smoking and alcohol, keeping good nutrition, staying active, and controlling diabetes, you give your bowel the best chance to heal.

Waterworks (bladder and kidneys)

• It's common to have a urinary catheter (a thin tube into the bladder) during and after major abdominal surgery.
• This allows accurate measurement of fluid balance and prevents problems while the spinal is still working.
• The catheter is usually removed within a few days once you are mobile and safe.
• Kidney function is monitored with blood tests and fluid balance charts.

Arterial line

For major operations, I will need to insert an arterial line. This is a thin plastic tube placed into an artery, usually at the wrist. It allows very accurate and continuous monitoring of your blood pressure during surgery, as well as easy blood sampling.

Why is an arterial line used?

• Continuous blood pressure monitoring: More accurate than a standard cuff, especially for long or complex operations.
• Frequent blood tests: It allows us to check oxygen levels, carbon dioxide, and blood chemistry without repeated needle pricks.
• Safety: Helps me detect and treat changes in your circulation quickly.

How is it inserted?

• Usually placed under local anaesthetic in the operating theatre, before or just after you go off to sleep.
• The most common site is the wrist, but sometimes the line is placed in the arm, groin, or foot depending on your surgery and anatomy.
• Once in place, the line is connected to a monitor which displays your blood pressure continuously throughout the operation.

What will I notice afterwards?

• You may have a small bandage on your wrist or arm.
• Sometimes there is mild bruising, tenderness, or a small lump which settles within a few days.
• The line is normally removed soon after surgery, unless you require intensive monitoring in the high-dependency or intensive care unit.

Risks and side effects

Arterial lines are very safe, but as with any procedure there are some risks:

• Bruising or tenderness at the insertion site.
• Temporary reduced blood flow if the artery spasms (rare, usually resolves quickly).
• Infection or damage to the artery (very rare).

I will weigh up the benefits and risks in your case and discuss any particular issues that may arise with you.

Risks and safety

• Anaesthetic care is tailored to your health, medicines, and the type of surgery.
• Common side effects include nausea, drowsiness, and constipation.
• More serious risks (such as chest infection, heart strain, or anastomotic leak) are closely monitored for and managed promptly.