Neurodiversity information for parents and young people
A colonoscopy is done to have a look inside the bowel. For this, the bowel must be completely empty.
You must prepare properly
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4 days before
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1 day before
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Day of morning appointment
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Day of afternoon appointment
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About bowel preparation
- taking medicines (called laxatives) to make you poo
- cutting down on how much fibre you eat
- stopping all food in the last few hours beforehand.
Important instructions
The instructions given below are very important. If you do not stick to them, we will probably have to cancel the procedure because we will not be able to see inside your bowel clearly.
Effect of bowel preparation
The laxatives will cause repeated bowel movements and eventually diarrhoea.
These effects can start at any time after taking the laxatives. The urge to open your bowels can be sudden, giving you little time to reach a toilet. So, it is a good idea to stay within easy reach of a toilet.
Wiping your bottom with wet wipes and applying a barrier cream, such as petroleum jelly, may help prevent your bottom getting sore.
The laxatives may also cause nausea, stomach cramps and bloating.
Very rarely, patient have a severe reaction to the laxatives.
It is sensible to have a supply of the drinks you will need before starting your laxatives. See box A, below.
4 days before the endoscopy
Increase how much fluids you drink to 200 mls (one large cup) every hour. This is to make the laxatives work better.
Start eating only low-fibre food (see box B).
Cut down alcohol to no more than one small glass of wine or one small bottle of beer per day.
1 day before the endoscopy
When you start this depends on what time your endoscopy is booked for. The tables, below, set out the details.
Morning endoscopy
(8am to 12.45 appointments)
Day before |
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1pm | Stop all solid food until after endoscopy. For the rest of the day, do not drink just water. Drink at least one additional litre of clear fluids (see box A). It is important you drink sugary drinks for the energy and savoury drinks for the salt. Otherwise, you may feel weak or dizzy and you may even faint. |
3pm to 4pm |
Take the first dose of Plenvu, labelled ‘Dose 1’. See box C. Sip very slowly over 60 minutes. You can alternate between Plenvu and clear fluid if you prefer. |
4pm to 8pm | Continue drinking clear fluids as you wish. |
8pm to 9pm |
Take the second dose of Plenvu, labelled ‘Dose 2 Sachet A’ and ‘Dose 2 Sachet B’. See box C. Also drink a further 500ml of clear fluids. Sip very slowly over 60 minutes. You can alternate between Plenvu and clear fluid if you prefer. |
After 9pm | Continue drinking clear fluids as you wish. |
Day of appointment |
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Continue drinking clear fluids as you wish. | |
2 hours before | Stop drinking until after endoscopy. |
Afternoon endoscopy
(1pm to 5.30pm appointments)
Day before |
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3pm | Stop all solid food until after endoscopy. For the rest of the day, do not drink just water. Drink at least one additional litre of clear fluids (see box A). It is important you drink sugary drinks for the energy and savoury drinks for the salt. Otherwise, you may feel weak or dizzy and you may even faint. |
6pm to 7pm |
Take the first dose of Plenvu, labelled ‘Dose 1’. See box C. Sip very slowly over 60 minutes. You can alternate between Plenvu and clear fluid if you prefer. |
After 7pm | Continue drinking clear fluids as you wish. |
Day of appointment |
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Before 7am | Continue drinking clear fluids as you wish. |
7am to 8am |
Take the second dose of Plenvu, labelled ‘Dose 2 Sachet A’ and ‘Dose 2 Sachet B’. See box C. Also drink a further 500ml of clear fluids. Sip very slowly over 60 minutes. You can alternate between Plenvu and clear fluid if you prefer. |
Continue drinking clear fluids as you wish. | |
2 hours before | Stop drinking until after endoscopy. |
Box A
Clear fluids | Avoid |
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Box B
Low-fibre food you can eat |
Foods to avoid |
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Cereals | |
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Dairy | |
milk, cream |
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Soup | |
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Protein | |
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Fruit and vegetables | |
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Bread and starchy food | |
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Preserves | |
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Snacks and puddings | |
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![]() biscuits containing bran |
Box C
How to take laxatives |
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Contact information
Endoscopy nurses helpline
Telephone:
020 8934 6614 (2pm to 4pm only)