Fasting Before Stomach Cancer Surgery (Gastrectomy)

Fasting for this procedure

A partial or total gastrectomy is done under general anaesthetic, so you'll be fully asleep with a breathing tube. As an adult, stop solid food (including milk, chewing gum and sweets) 6 hours before your arrival time, and stop clear fluids — water, black tea or coffee, clear juice without pulp — 2 hours before arrival. Because cancer can partly block the stomach outlet, food and fluid may sit in your stomach longer than normal, so your team may ask you to fast a little longer or skip the usual carbohydrate drink; always follow the specific times they give you over the general rule. Many units now follow an ERAS (Enhanced Recovery After Surgery) pathway and may offer a carbohydrate drink up to 2 hours before to ease recovery — only drink it if your surgeon confirms it's safe for you. If your child is having stomach surgery, follow the 6-4-2 rule (food and formula 6 hours, breast milk 4 hours, clear fluids 2 hours) and use our child fasting calculator.

Medicines to check

Blood thinners matter most here. Drugs like warfarin, apixaban, rivaroxaban or clopidogrel raise bleeding risk during this big operation and are usually paused days ahead — never stop them on your own; follow your team's plan and read medications to stop before surgery.

Diabetes medicines need a plan, and the timing differs by drug. SGLT2 inhibitors — the 'flozins' such as dapagliflozin, empagliflozin and canagliflozin — are usually stopped a few days before surgery (often 3–4 days, or at least the day before and the day of, per your team) because, combined with fasting, they can trigger a dangerous diabetic ketoacidosis even when your blood sugar looks normal. Metformin and insulin are instead adjusted or omitted around the day of surgery. Get a dated plan and see diabetes tablets before surgery.

Take your essential daily tablets — heart, blood pressure, thyroid, seizure and reflux medicines — with a small sip of water on the morning of surgery, unless told otherwise.

If you take iron tablets or supplements, ask whether to keep taking them, as many gastrectomy patients are already being treated for anaemia before surgery.

Bring any nutrition drinks or supplements your dietitian started, and check which ones to take before you fast.

Mention herbal remedies, fish oil and high-dose vitamins at your pre-op clinic, as some increase bleeding and are stopped about a week before.

When this surgery may be delayed

A recent chest infection, cough or fever — anaesthetic and a long abdominal operation are riskier when your lungs aren't clear, and good breathing is vital for recovery.

You ate or drank inside the fasting window, or your stomach is found to be holding food because the tumour is partly blocking the outlet — both raise the risk of stomach contents entering the lungs.

Blood tests showing significant anaemia, low albumin or poor nutrition, which are common with stomach cancer and may need correcting first so you heal well.

Blood thinners not stopped on schedule, leaving your blood too 'thin' for safe surgery on the rich blood supply around the stomach.

New scan or staging findings that mean the surgical plan needs rethinking by the cancer team before going ahead.

Reports & documents to carry

Your endoscopy, biopsy and CT or PET scan reports, plus any staging letters from your cancer team.

A current list of all medicines with doses — including blood thinners, diabetes drugs, inhalers and supplements.

Recent blood test results, especially haemoglobin, iron and nutrition markers if you have them.

Your appointment letter, ID and any anaesthetic or pre-assessment paperwork.

A packed bag for several nights — loose clothing, toiletries, phone charger — as a gastrectomy usually means a hospital stay of several days to over a week.

What to ask your anesthesia team

Am I having a partial or total gastrectomy, and is it planned as keyhole (laparoscopic) or open surgery?

Should I drink the ERAS carbohydrate drink, or do you want me to fast longer because of my tumour?

How will my eating and portion sizes change afterwards, and will I see a dietitian before and after surgery?

Will I wake up with drains, a feeding tube (jejunostomy) or a nasogastric tube, and how long do those usually stay in?

How many nights in hospital should I expect, and what extra support is set up for home?

Your prep checklist

Tick things off as you sort them — saved on this device only, nothing is sent anywhere.

A general guide — your hospital's own instructions always come first.

Frequently asked questions

Why might I be asked to fast longer than the usual times?

Stomach cancer can narrow or partly block the outlet of your stomach, so food and fluids empty more slowly than normal. That means contents can still be sitting in your stomach even after the standard fasting window, raising the risk of them entering your lungs once you're asleep. To stay safe, your team may extend your fasting time or ask you to skip the carbohydrate drink. Always follow the exact times they give you.

Will I be able to eat normally after a gastrectomy?

Not straight away, and portions stay smaller for life — especially after a total gastrectomy. You'll start with sips and build up slowly over days to weeks, guided by a dietitian. Most people move to small, frequent meals rather than three big ones, and learn to eat slowly and chew well. Eating too much or too fast can cause 'dumping', with cramps, sweating and loose stools. It improves with time and practice.

What are the drains and tubes I might wake up with?

After a gastrectomy you may wake with one or more abdominal drains to carry away fluid from the operation site, plus sometimes a thin nasogastric tube through your nose to rest the gut. Some patients also have a small feeding tube into the bowel (jejunostomy) to give nutrition while your new join heals. These come out over days as you recover; your team removes each one when it's no longer needed.

Should I keep taking my blood thinner and diabetes tablets?

Not without specific instructions. Blood thinners are usually paused several days before a gastrectomy because of the bleeding risk around the stomach's blood supply, sometimes with bridging injections. Diabetes medicines need a plan that depends on the drug: SGLT2 inhibitors (the 'flozins') are usually stopped a few days beforehand to avoid a dangerous ketoacidosis when you're fasting, while metformin and insulin are adjusted around the day of surgery. Your pre-op team will give you a dated plan — see medications to stop before surgery and diabetes tablets before surgery.