Kolon ve Rektum Hastalıkları

    Bowel Preparation Before Colonoscopy: A Step-by-Step Patient Guide

    Good bowel preparation prevents polyps from being missed and improves the diagnostic value of colonoscopy. Preparing well is as important as the procedure itself.

    All posts
    Op.Dr.Gökhan ATEŞ Medically reviewed: Op.Dr.Gökhan ATEŞ11 July 2026 7 min read

    Colonoscopy is inspection of the inner surface of the large bowel (colon) with a lighted, camera-tipped device. The success of the procedure depends directly on how clean the bowel is. Insufficient preparation can cause polyps and early cancer lesions to be missed and can require repeat procedures.

    What to eat and avoid

    TimingDiet
    3 days beforeCut out whole grains, seeds, dried fruit, raw vegetables, corn, sesame
    2 days beforeMove to low-fibre foods: white bread, rice, eggs, chicken, potato, banana
    1 day beforeClear liquids only: water, unsalted broth, weak tea, strained apple juice
    Procedure dayContinue clear liquids; stop drinking 4–6 hours before as advised

    How to use the preparation

    Your doctor's prescribed preparation is usually taken in a 'split dose': part the evening before, the remainder about 4–6 hours before the procedure. The 2023 ESGE update highlights this approach as preferred, improving diagnostic accuracy.

    Procedure day

    • You should not drive after sedation — arrange for someone to accompany you
    • Avoid jewellery and heavy make-up
    • Bring a list of your regular medications
    • Tell your doctor beforehand if you take diabetes, blood-thinner or blood pressure medication

    Notes for patients on medication

    • Blood thinners (aspirin, clopidogrel, warfarin, DOACs) — plan with your doctor
    • Iron tablets — may need to stop 5–7 days before
    • Diabetes medications — doses may need to be adjusted during fasting

    This content is for general information only. For personal diagnosis and treatment decisions please consult your doctor. For emergencies, contact the nearest medical facility.

    Frequently Asked Questions

    What happens if the bowel is not fully cleaned?
    Image quality drops, polyps may be missed and the procedure may need to be repeated. That is why the preparation steps should not be skipped.
    Is drinking water also forbidden?
    Usually clear liquids are allowed until about 4–6 hours before the procedure. Your doctor will confirm the cut-off time.
    Will I feel pain during colonoscopy?
    In most centres the procedure is performed under sedation so the patient does not feel it.

    Yararlanılan Kaynaklar

    1. ESGE — Bowel Preparation for Colonoscopy Guideline Update 2023
    2. ASCRS — Clinical Practice Guidelines (Colorectal)
    3. NHS — Bowel cancer, Diverticular disease, IBS
    4. Sağlık Hizmetlerinde Tanıtım ve Bilgilendirme Faaliyetleri Hakkında Yönetmelik

    Bu içerik genel bilgilendirme amacıyla hazırlanmıştır. Tanı ve tedavi yerine geçmez. Şikâyetlerinize uygun yaklaşım, muayene ve gerekli tetkikler sonrası belirlenir.

    Related

    Related Content

    Other patient information articles and service pages on this topic.

    Related Service Pages

    WhatsApp'tan Yaz