Colonoscopy

A colonoscopy is an exam of the inside of your large intestine (the colon) and rectum. A doctor uses a long, thin, flexible tube with a small camera on the end, called a colonoscope. You are sedated, so most people feel comfortable and remember little or nothing of the exam. If you live in Los Angeles and have been told you need a colonoscopy, this page explains what happens before, during and after.

Why do people have a colonoscopy?

There are three common reasons. Knowing which one applies to you helps you understand your results and when you will need another exam.

Screening

Screening means checking for colorectal cancer, or the polyps that can turn into it, before you have any symptoms. Most adults at average risk are advised to start at age 45. Colonoscopy is the one screening test that can find polyps and remove them in the same exam, which can prevent cancer from developing. Read more about your options on our colorectal cancer screening page.

Surveillance

If you have had polyps before, or you have a strong family history of colorectal cancer or long-standing inflammatory bowel disease, you will usually need colonoscopies more often. These follow-up exams are called surveillance.

Symptoms or abnormal tests

A colonoscopy is also used to find the cause of a problem. Common reasons include:

• Blood in the stool or bleeding from the rectum (see rectal bleeding)
• A change in bowel habits that lasts, such as new constipation or diarrhea
• Iron-deficiency anemia (a low red blood cell count from low iron) without a clear cause
• A positive stool test for colorectal cancer, such as a FIT or stool DNA test
• Ongoing belly pain or unexplained weight loss

When you have symptoms, the exam is called a diagnostic colonoscopy rather than a screening colonoscopy. The exam itself is the same; the reason for it, and sometimes the billing, is different.

Key facts

The exam itself

Usually about 30 to 60 minutes

Time at the center

Plan on a few hours, including check-in and recovery

Sedation

Medicine through an IV so you are relaxed or asleep

Ride home

You need an adult to take you home

Back to normal

Most people return to usual activities the next day

How do I prepare for a colonoscopy?

The most important part of a colonoscopy happens before you arrive. Your colon must be empty and clean so Dr. Pimienta can see the lining clearly. Small or flat polyps can hide behind leftover stool, and a poor prep can mean repeating the exam.

In short, preparation usually means:

• Reviewing your medicines with our office about a week ahead, especially blood thinners, diabetes medicines, iron, and GLP-1 medicines such as semaglutide and tirzepatide
• Eating lower-fiber foods for a few days before
• Drinking only clear liquids the day before
• Taking a bowel prep laxative, usually split into two doses: one the evening before and one the morning of the exam
• Arranging a ride home

Our step-by-step preparation guide covers each day, and the article a practical guide to colonoscopy prep has tips that make the prep easier. Your written instructions from our office always come first.

What happens during a colonoscopy?

Dr. Pimienta performs colonoscopies at Specialty Surgical Center of Beverly Hills, on Wilshire Boulevard less than a mile west of the office.

1. Check-in

   You arrive at the surgery center at the time you were given. Staff confirm your identity, your medicines, when you last ate or drank, and who is driving you home. You change into a gown.

2. Getting ready

   A nurse places a small IV (a thin tube in a vein, usually in your hand or arm). You can ask any last questions, and Dr. Pimienta checks in with you before the exam.

3. Sedation

   You lie on your left side. Medicine given through the IV makes you relaxed and sleepy, and many people sleep through the entire exam. Your breathing, heart rate, blood pressure and oxygen are watched the whole time.

4. The exam

   Dr. Pimienta gently passes the colonoscope through the rectum and around the colon to where it meets the small intestine. Air or carbon dioxide gently opens the colon so he can see. He then looks carefully at the lining as he slowly withdraws the scope.

5. Polyp removal and biopsies

   If he finds a polyp (a small growth on the lining), he usually removes it during the same exam with tiny tools passed through the scope, often a small wire loop called a snare. If an area looks unusual, he may take a biopsy, a tiny piece of tissue. You do not feel either one, because the lining of the colon does not sense cutting. The tissue goes to a lab for a pathologist to examine under a microscope.

6. Recovery room

   You wake up in the recovery area, usually within minutes. You may feel full of gas or a little crampy. Once you are alert, Dr. Pimienta or the staff will tell you what was seen and give you written discharge instructions. Then your ride takes you home.

Because the sedation can affect your memory and judgment for the rest of the day, it helps to have the person picking you up listen to the discharge instructions with you.

What happens after a colonoscopy?

The rest of the day

Plan to rest at home. Do not drive, work, sign important papers, or drink alcohol until the next day. Gas, bloating and mild cramping are common for a few hours as the air leaves your colon. Walking around and passing gas help.

Eating

Most people can eat soon after the exam. Start with something light, then go back to your usual diet unless you were told otherwise. Drink plenty of fluids, since the prep can leave you a bit dehydrated. If polyps were removed, you may get specific instructions about food or blood-thinning medicines.

Your results

You usually hear what Dr. Pimienta saw before you leave. If he removed polyps or took biopsies, the lab results usually come back within about one to two weeks. Dr. Pimienta goes over the results with you, explains what they mean in plain language, and tells you what comes next.

When is my next colonoscopy?

That depends on what was found. After a normal screening colonoscopy, most adults at average risk do not need another for 10 years. If polyps were removed, the timing depends on how many there were, their size and their type under the microscope. A family history or other conditions can also change the interval. Dr. Pimienta tells you when your next exam is due. Learn more about colon polyps.

Is a colonoscopy safe?

Colonoscopy is a common and generally safe procedure, but like any procedure it carries some risk. Serious problems are uncommon. Dr. Pimienta will review them with you before you sign a consent form.

• Bleeding: most likely when a polyp is removed. It is usually minor and stops on its own. Rarely, bleeding happens days later and needs another look with the scope.
• Perforation: a tear in the wall of the colon. This is rare. It may need treatment in the hospital, and sometimes surgery.
• Reactions to sedation: such as changes in breathing, heart rate or blood pressure. You are monitored throughout so these can be treated right away.
• Missed findings: no test is perfect, and a small polyp can be missed, especially when the prep is not clean.

Colonoscopy or a stool test?

For people at average risk with no symptoms, stool tests such as FIT (done every year) or a stool DNA test (every one to three years) are reasonable screening choices. They are done at home and need no prep. But they cannot remove polyps, and if a stool test is positive, you need a colonoscopy to find out why. A colonoscopy is also the right test if you have symptoms, a personal history of polyps, or a strong family history. Compare the options on our colorectal cancer screening page. Your plan depends on your health; Dr. Pimienta will talk with you about what fits you.

Medicare and self-pay

Dr. Pimienta accepts Medicare, including patients with a secondary (supplemental) plan. Medicare covers screening colonoscopy and colonoscopy for symptoms; what you owe can depend on whether the exam is a screening or a diagnostic one, and whether a polyp is removed. For other insurance, the practice is out of network and visits are self-pay. Our team explains pricing, and how out-of-network benefits may work, before anything is booked. See insurance and payment.

Questions patients ask

References

1. National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). Colonoscopy.
2. American Cancer Society. Colonoscopy.
3. Gupta S, et al. Recommendations for Follow-Up After Colonoscopy and Polypectomy: A Consensus Update by the US Multi-Society Task Force on Colorectal Cancer. 2020.
4. US Preventive Services Task Force. Colorectal Cancer: Screening. 2021.