Medical Oncologist
CION Cancer Clinics
Screening colonoscopy: what happens, step by step | CION Cancer Clinics
A screening colonoscopy is a camera test of the whole colon for people who feel well. You are sedated, the doctor looks for polyps, and most polyps found are removed in the same sitting so they never get the chance to change. This page walks through the preparation, the day itself, the possible results and the worries that stop people booking, and says who should not be screened this way. At CION Cancer Clinics, our specialists help you judge which bowel symptoms need tests and plan screening that fits your risk.
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Medically reviewed by Dr. Naresh GunduConsultant Medical Oncologist · MBBS, DNB (Internal Medicine), DM (Medical Oncology, AIIMS) · last reviewed October 2026, next review due October 2027
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On this page
- What actually happens at a screening colonoscopy?
- What happens step by step, from preparation to going home?
- What can a screening colonoscopy find, and what happens next?
- Is a screening colonoscopy different from a diagnostic one?
- Four worries that keep people from booking, and what is true
- What this page cannot tell you
- Common questions about screening colonoscopy
The short answer
What actually happens at a screening colonoscopy?
A thin, flexible tube with a camera is passed through the back passage while you are sedated, and the doctor looks at the lining of the whole colon. They are looking for polyps, small growths that can slowly turn into cancer over many years. Most polyps found are removed during the same test.
Why do it when you feel fine
Colon cancer usually starts as a polyp and gives no warning in its early years. Removing polyps before they change is the whole point of screening, which is why the test is offered to people with no symptoms, usually from about the mid-forties for someone at average risk. India has no national bowel screening programme, so the decision often starts with you, your family doctor, or a son or daughter who has read about it.
Who this page is not for
If you have bleeding from the back passage, a change in bowel habit that has lasted several weeks, weight loss you cannot explain, or anaemia (a low haemoglobin), you need a diagnostic colonoscopy, not a screening one. The procedure is the same. The urgency is not. Read colonoscopy for diagnosis instead, and do not wait for a routine slot.
A screening colonoscopy looks for polyps. Only the laboratory report on what is removed can say what they are.From the day before
What happens step by step, from preparation to going home?
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A day or two of light food
You switch to low-fibre food such as plain rice, idli, curd rice and white bread, and leave out leafy vegetables, millets, whole dal and fruit with seeds. Tell the unit early if you take blood thinners, diabetes medicines or iron tablets, because some need adjusting.
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The bowel preparation
The evening before, and often again early that morning, you drink a laxative solution that empties the colon. Stay near a toilet. A clean colon matters more than anything else on the day, and the bowel preparation guide explains how to get it right.
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Arrival and sedation
You change into a gown and a small plastic tube is placed in a vein in your hand. A sedative or light anaesthesia is given through it, so most people are drowsy or asleep and remember little. You can ask for a female attendant to be present.
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The test itself
You lie on your left side while the scope is passed gently around the colon. Air or carbon dioxide opens the bowel so the lining can be seen. It usually takes around half an hour. Polyps are lifted off with a small wire loop and sent to the laboratory.
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Recovery and going home
You rest until the sedation wears off. Bloating and cramps from the air are common and pass. Someone must take you home, and you should not drive, ride a two-wheeler or sign important papers until the next day.
Not sure whether this applies to you?
Ask an oncologistPossible results
What can a screening colonoscopy find, and what happens next?
Most screening tests end with one of the first two results. Neither is a cancer diagnosis.
Nothing was found
The whole colon was seen, the preparation was good and there were no polyps. For someone at average risk, the next screening test is usually about ten years away. The page on how often to repeat it explains what shortens that gap.
Small polyps, removed on the spot
This is common, and more so with age. The pathology report, usually ready within a week or two, names the type of polyp. That report, not the photographs, sets the date of your next test.
A large or flat polyp
Some polyps are too big or too flat to remove safely during a screening list. The doctor may take small samples, mark the spot with ink and plan a second, longer procedure with a specialist team.
An area that looks suspicious
Occasionally the doctor sees something that may be cancer. Biopsies are taken, and only the laboratory report confirms what it is. If cancer is confirmed, CION's tumour board reviews the report and scans and plans the next step with you.
Keep these papers
- The procedure report and photographs
- The pathology report when it arrives
- The date written down for your next test
Side by side
Is a screening colonoscopy different from a diagnostic one?
The procedure is identical. Why it is done, and how quickly, is not.
Screening colonoscopy
Diagnostic colonoscopy
For people who feel well
For people with symptoms or an abnormal test
Booked at a convenient time
Arranged without delay
Can be your first screening test
Follows a positive stool test
Looks for polyps before they change
Looks for the cause of a symptom
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One field. No form to fill in, and no charge for the call.
What stops people going
Four worries that keep people from booking, and what is true
"It will be unbearable."
Most people are sedated and remember very little. Cramping and bloating afterwards are common and short-lived. Many people say the preparation the night before was harder than the test itself.
"It is too embarrassing to talk about."
Endoscopy staff do this all day and are not embarrassed by it. You stay covered by a gown and sheet, and you can ask for a female attendant. Talking to a doctor about your bowels is ordinary medicine, in any language.
"A colonoscopy can spread cancer."
Looking at or removing a polyp does not make cancer spread. The real risks are different: bleeding after a polyp is removed or, rarely, a tear in the bowel wall. The full answer is here.
"My stool test was negative, so I am clear."
A negative FIT is a good result for someone without symptoms, and it is repeated every year. It can miss polyps that are not bleeding, and it does not rule out cancer if you have symptoms.
Being straight with you
What this page cannot tell you
It cannot tell you whether you need a colonoscopy now, or whether a stool test would suit you better. That depends on your age, your family history, your general health and any earlier tests. A doctor who has asked those questions can usually answer it in one conversation.
It cannot read your report
If you already hold a colonoscopy or pathology report, the exact words on it decide what happens next. Bring it to a doctor rather than searching each term. CION's oncologists can go through it with you, and CION arranges the colonoscopy at an accredited partner endoscopy unit when one is needed.
Who this does not suit
Screening colonoscopy is usually not advised for people who are very frail or have serious heart or lung disease, because the preparation and sedation carry more risk than the screening benefit. Someone whose last clean test was only a few years ago does not need another yet. Pregnant women usually postpone screening. Anyone with symptoms belongs on the diagnostic route.
If you are unsure whether you or a parent is due, describe the situation to the helpline. Someone will tell you honestly.Questions we are asked
Common questions about screening colonoscopy
Do I need to stay in hospital overnight?
No. A screening colonoscopy is a day procedure. Most people arrive in the morning and leave a few hours later once the sedation has worn off. Keep the whole day free, and bring someone who can take you home, because you should not travel back alone.
Will I be awake during the test?
It depends on the unit and on you. Most people receive a sedative through a vein and are drowsy, and many units offer light anaesthesia so you sleep through it. A few people choose no sedation at all. Ask what the unit offers when you book.
Can I eat normally afterwards?
Usually yes, starting with something light such as idli, khichdi or curd rice. Drink plenty of water to make up for the preparation. If polyps were removed, follow the discharge sheet, which may ask you to avoid certain painkillers for a few days.
Is bleeding afterwards normal?
A small streak of blood is common, especially after a polyp is removed. Heavy bleeding, passing clots, severe belly pain, a hard swollen belly or a fever after the test needs the emergency department the same day. Tell them you have just had a colonoscopy.
Does finding a polyp mean I have cancer?
No. Most polyps are not cancer, and removing them is the point of screening. The laboratory report names the type of polyp, and that sets the date of your next colonoscopy. Ask the doctor to explain the report rather than guessing from the photographs.
I take blood thinners and diabetes tablets. Can I still have it?
Usually yes, with planning. Tell the unit when you book. Diabetes medicines often need adjusting while you are on clear fluids, and some blood thinners are paused before polyp removal. Never stop a blood thinner on your own. The doctor who prescribed it must agree first.
What does a screening colonoscopy cost in Hyderabad?
It varies by hospital, by the type of sedation and by whether polyps are removed and sent to the laboratory. Ask for a written estimate that includes pathology. The colonoscopy in Hyderabad page sets out typical costs and what insurance usually covers.
Can CION arrange a screening colonoscopy for me or a parent?
Yes. CION does not perform colonoscopies itself. Its oncologists review the age, family history and any earlier reports, arrange the test at an accredited partner endoscopy unit, and go through the results with you afterwards. One helpline serves every centre.
Your Specialists
Meet CION's colon cancer specialists. Bring your colonoscopy, scan or biopsy report.
Our surgical and medical oncologists plan colon cancer care together: which operation, whether chemotherapy is needed, and the follow-up that comes after.
Medical Oncologist
Dr. C. Raghavendra Reddy
MBBS(Gold Medal), DNB(General Medicine), DM(Medical Oncology)(Gold Medal)
Medical Oncologist
Dr. Bharati Devi Gorantla
MBBS, MD(General Medicine), DM(Medical Oncology)(Adyar,Chennai), ECMO, MRCP SCE(UK)
Medical Oncologist
Dr. Owais Mohammed
MBBS, MD (General Medicine), DrNB (Medical Oncology), ECMO, MRCP SCE (Medical Oncology) (UK)
Medical Oncologist
Medical Oncologist
Surgical Oncologist
Dr. Muralidhar Muddusetty
MBBS (AIIMS), MS (Surgery) (AIIMS), DNB (Surgical Oncology), MRCS (Edinburgh)
Surgical Oncologist
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Sources
- NIDDK (NIH) — Colonoscopy
- NHS — Colonoscopy
- American Cancer Society — Colorectal Cancer Screening Tests
- National Cancer Institute — Screening Tests to Detect Colorectal Cancer and Polyps
This page is general information, not a prescription. Do not change or stop any treatment based on what you read here. If anything is worrying you, contact your own treating team — or call our helpline and we will help you reach the right specialist.
Keep reading
Related pages
How often should you have a screening colonoscopy?When the next one is due after a clean test or polypsScreening options comparedColonoscopy, FIT and the other tests side by sideWhat happens after polyps are removedReading the pathology report and planning follow-upOvercoming embarrassment about bowel screeningFor the parent who keeps putting it off
Talk to us
Is it time for you or a parent to be screened?
Tell us the age, the family history and any earlier reports, and a CION oncologist will say honestly whether screening is due and which test suits. If a colonoscopy is needed, we arrange it at an accredited partner endoscopy unit. One helpline serves every CION centre.