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Colonoscopy: An Ultimate Guide

Colonoscopy Ultimate Guide

Everyone needs to be screened for colorectal cancer at some point in their lives. For most people, screenings will start at age 45. A colonoscopy is the best screening for colorectal cancer (colon cancer and rectal cancer). Plus, it can prevent cancer too.

For people who have never had one before, the idea can be intimidating. You may not know exactly what the procedure entails or why it’s so important. Plus, it can be embarrassing to discuss with others.

Our practice performs thousands of colonoscopies in San Antonio every month. We’ve created this ultimate guide to colonoscopy to learn all about the procedure – from start to finish.

What is a colonoscopy?

A colonoscopy is a procedure that allows complete examination of the inside of the colon. It’s usually performed as a routine check for colorectal cancer or to diagnose other gastrointestinal conditions. A camera attached to a thin flexible tube, called a colonoscope, is inserted into the colon. A gastroenterologist uses the camera to look at the entire colon and rectum. During the colonoscopy, the doctor looks for any abnormalities. This includes looking for growths called polyps.

The colon is a part of the digestive system known as the large intestines. Each part of the intestinal tract is responsible for different functions. The colon removes water, along with some nutrients and electrolytes, from the digested food that was in the small intestine. At the end of the food’s trip through the colon, it is solid stool. Solid stool is stored in the rectum, which is the very last part of the large intestines, until it is ready to be eliminated during a bowel movement.

Why is a colonoscopy performed?

A colonoscopy is usually performed to check for colon cancer, rectal cancer, colon polyps, or to diagnose other gastrointestinal conditions. Polyps are lumps of tissue that form on the inner lining of the colon. They have a strong potential to turn into cancer over time. If a polyp is found, the doctor will remove it and send it to a laboratory for testing.

Sometimes, during a colonoscopy, a cancerous tumor may be found. Depending on the size, the doctor will remove it or take a sample (biopsy) to be tested. Finding cancer in the colon or rectum as soon as possible leads to better treatment outcomes.

Colorectal cancer is the medical term for cancer found in either the colon or the rectum. Sometimes people refer to colorectal cancer simply as colon cancer. Many people use the terms interchangeably, though doctors will usually say colorectal cancer. Regardless of what you call it, having regular colonoscopies is important in preventing it or finding it early enough to treat.

A colonoscopy is the preferred screening test for colorectal cancer. It is the only test that allows a complete examination of the colon and rectum, and allows for removal of abnormal growths.
There are other screening tests available like stool tests or CT scans. These tests are not as complete. If any abnormalities are found during these tests, a colonoscopy will likely need to be performed.

Who needs a colonoscopy?

For most people, the first colonoscopy should be performed at age 45. Previously, the recommended age was 50. Recently, the American Cancer Society and United States Preventive Services Task Force changed the recommended age to 45.  These recommendations are supported by the United States Multi-Society Task Force  on Colorectal Cancer  , which includes members of the American Society for Gastrointestinal Endoscopy, the American College of Gastroenterology, and the American Gastroenterological Association.

People who have higher than normal risk levels may need to start having colonoscopies at a younger age. Here are some risk factors for colorectal cancer:

  • A family or personal history of colon polyps, colon cancer, or rectal cancer
  • A diagnosis of inflammatory bowel disease (IBS), ulcerative colitis, Crohn’s disease, or a similar disease
  • Genetic conditions like hereditary nonpolyposis cancer (HNPCC) or familial adenomatous polyposis (FAP)
  • Being Black or of Ashkenazi Jewish descent

If a person’s first-degree relative (parents and siblings) has been diagnosed with colorectal, then they will need to start getting colonoscopies 10 years younger than the age their relative was diagnosed. For example, If a person’s sister was diagnosed at age 40, then colonoscopies will start at 30.

How often is a colonoscopy performed?

How often a colonoscopy is performed depends on the person’s risk factor and whether or not polyps were found. Typically, the interval is 10 years if no polyps are present and there is an average risk of colorectal cancer.

If polyps are found or there is a higher risk of developing cancer, then the recommended frequency will be every 2-5 years.

Preparing for a Colonoscopy

Colonoscopy Prep Diet

To make sure your colon is as clean and clear as possible during your procedure, a special diet is required. This prep diet will start a couple of days before your appointment. It’s important to follow the instructions given to you by your doctor.

Two Days Before: In most cases, you will be asked to stop eating nuts, seeds, and raw vegetables two days before your appointment (a low fiber diet).
One Day Before: You should be on a clear liquid diet. That means no milk, milk products, or anything red or purple.

Prior to a colonoscopy, you can eat and drink clear foods and liquids. Bouillon, apple juice, coffee/tea with sugar, and ginger ale are examples of what is allowed on the clear liquid diet.

Gelatin and popsicles are examples of foods you can eat, as long as they are not red or purple. Usually, a clear liquid diet is only required the day before, and a low fiber diet is required starting two days before your appointment. View a sample menu / food restrictions.

Colonoscopy Prep Instructions

Your prep instructions will depend on the type of prep your doctor has recommended. Some preps use tablets, sports drinks, or a solution mixed with cool water. Following the instructions your doctor provides is important. For our patients, links to instructions are below:

Colonoscopy Procedure

During the colonoscopy procedure, your doctor will observe the entire colon using the colonoscope. They will record video or take pictures to show you when you wake up. As they scan through the colon, they are looking for any abnormalities, especially polyps and tumors.

If a polyp or tumor is found, it is removed using surgical tools that pass through the tubing of the colonoscope. The procedure is quick and painless.

Any samples collected during the colonoscopy are sent to a laboratory. They are examined under a microscope by a pathologist. This is known as histopathology or “histopath.” Pathologists are doctors that specialize in examining tissue samples with microscopes and other techniques.

The pathologist will send a report back to the gastroenterologist with their findings. Polyps can be categorized as non-neoplastic and neoplastic. Non-neoplastic polyps do not usually become cancerous. Neoplastic polyps have the potential to become cancerous. Sometimes, a polyp will have already turned into cancer, which may lead to the need for colon cancer treatment. Treatment for colon cancer is usually done by oncologists and may entail chemotherapy and radiation therapy.

The entire process of a colonoscopy is usually about 30 – 60 minutes. Preparation for the procedure by the anesthesia team typically starts about 30 minutes before the colonoscopy begins. Because you are asleep for the procedure, it will feel like it is over in the blink of an eye.


Most colonoscopies are done under full anesthesia. That means you’re completely asleep during the procedure. Anesthesia is supervised by an anesthesiologist, a doctor that has received specialized training. They ensure that patients have the safest experience possible, while your gastroenterologist performs the colonoscopy.

In rare circumstances, a patient may request light anesthesia or no anesthesia. This is not recommended, but something you can discuss with your doctor.

Because you will be asleep, you will not feel the scope during the procedure and it will not hurt. Usually, you will not feel any different when you wake up.

Colonoscopy Recovery

Patients may experience cramping or bloating in the hour following the procedure. The anesthetics take time to completely wear off, so patients may need to remain at the clinic for 1-2 hours, or until fully awake and alert.

You will need a ride home after a procedure with anesthesia. We recommend a trusted friend or relative. Taxis, uber/lift, and public transportation are not permitted because they are not able to care for you.

It’s normal to feel tired or have difficulty concentrating due to the medicine given during the procedure. It’s a good idea to relax at home the rest of the day. Full recovery is expected in 24 hours.

Side effects of colonoscopies are rare, but patients should contact their doctor if they experience:

  • Severe abdominal pain
  • Fever
  • Bloody bowel movements
  • Dizziness

If you have more than 1 to 2 tablespoons of blood when using the restroom, this could be a sign of a serious complication; seek immediate medical attention.

Because bowel prep can cause dehydration, it’s important to drink plenty of liquids. The inside lining of the colon may be sensitive following the procedure, so your doctor may recommend mild, soft foods for 24 or 48 hours. Examples:

  • Scrambled eggs
  • White bread/crackers
  • Mashed potatoes
  • Applesauce
  • Pudding

Liquids like water, sports drinks, soups, and herbal tea are also recommended.

You’ll want to avoid high fiber foods like raw vegetables, beans, brown rice, and fatty foods like fried food. Alcohol, carbonated drinks, milk, and coffee with cream may upset your digestive system.


Rarely, a patient may experience tearing or perforation of the lining of the intestine. If this happens, surgery may be needed to repair the injury. Another risk is bleeding, usually at the site of a biopsy or polyp removal. Most cases of bleeding stop without treatment or can be controlled at the time of the procedure.
As with any procedure involving anesthesia, there are certain risks. Often, your anesthesia risk profile depends on your current health status. Your anesthesiologist will discuss your risk factors prior to your procedure.

About Colorectal Cancer

Nearly 150,000 people are expected to be diagnosed with colorectal cancer in 2021. Colorectal cancer is the second leading cause of cancer-related deaths. The 5-year survival rate is only 65% – meaning 35 out of 100 people with colorectal cancer will die. Fortunately, when diagnosed early, the survival rate jumps to 90%.

New cases and deaths from colorectal cancer have been dropping over the recent years. This is likely because when people have a colonoscopy performed as recommended, polyps are removed before they can turn into cancer. And if there is cancer, it is found early enough to have a good prognosis.

Colonoscopy Cost

A screening colonoscopy is covered by insurance as required by the Affordable Care Act. What each person pays out of pocket depends on their particular insurance plan. You may need to pay a co-pay or deductible. Additionally, not all insurance companies will cover the cost of a colonoscopy if you are between ages 45 – 50. It is best to check with your individual insurance provider to find out how much a colonoscopy will cost.

A colonoscopy may not be covered by insurance if it is considered to be a diagnostic colonoscopy. This typically happens if a different colon cancer screening test was positive and now a colonoscopy is required.

Alternatives to Colonoscopy for Colorectal Cancer Screening

There are some alternatives to colonoscopy for colorectal cancer screening. The most common ones are stool tests and virtual colonoscopy.

There are several different stool tests on the market. Each of them are designed to look for markers that could indicate there is colon cancer, like blood or DNA. Cologuard is an example of a brand-name stool test. If a stool test is positive, a colonoscopy is usually recommended as a follow-up. (Related: How Cologuard May End Up Costing You Thousands)

Virtual colonoscopy is done with a CT-scanner. CT-scanners are a special type of x-ray machine that produces a series of pictures of the colon and surrounding organs. If any polyps or growths are identified, a colonoscopy needs to be performed to remove them. There is also a chance that small polyps will be missed with this method.

A colonoscopy is considered the gold standard of screening tests for colorectal cancer and is the test most commonly recommended by gastroenterologists.


How much does a colonoscopy cost? The cost of a colonoscopy depends on your insurance coverage. While insurance companies cover screening colonoscopies, there may be some out-of-pocket costs like a co-pay or deductible.

How do I prepare for a colonoscopy? The most important thing is to follow all of your doctor’s instructions and take the prescribed prep as directed. Check out these helpful tips to prep for your colonoscopy and make sure you don’t make these mistakes when prepping.

Will I be up all night with colonoscopy prep? After the first round of evening prep, most patients are able to sleep through the night.

How do I drink colonoscopy prep without throwing up? Nausea and vomiting (throwing up) may happen during prep. To avoid this, try taking small sips of the liquid over time. If you’re taking a prep solution, you may also sip on chilled water, a sports drink (no red, purple, or blue), or Pedialyte. You can also pause the prep for one hour. If vomiting continues for several hours, please contact your doctor.

What can you eat before a colonoscopy? Two days before your colonoscopy, you will stop eating raw vegetables, nuts, and seeds. The day before your colonoscopy, you will typically need to stick to a clear liquid diet of water, sports drinks, tea, or broth.

Does a colonoscopy hurt? No – because you are under anesthesia and asleep, you will not feel anything during a colonoscopy.

What is a gastroenterologist? A gastroenterologist is a doctor that specializes in conditions of the stomach and intestines. They receive additional training after medical school through a residency in internal medicine and then a fellowship in gastroenterology.

What is the easiest colonoscopy prep to tolerate? If you’ve had problems with prep in the past, or are worried about the prep, talk to your doctor about options that may be easier for you to tolerate.

What should I eat after a colonoscopy? Foods and drinks that are gentle on the stomach are best after a colonoscopy. Some examples are scrambled eggs, white bread/crackers, soups, and herbal teas.

What is the difference between endoscopy and colonoscopy?  Click here to learn more about the differences.

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6 Dangers of Putting Off Your Colonoscopy

According to the American Cancer Society, one in three people who should get tested for colon cancer has never had a colonoscopy. They may not know that testing can save their lives! If you’re putting off your colonoscopy, you should be informed about the dangers of doing so.

1. Not Preventing Cancer Before it Happens

Regular colon cancer screenings are the most powerful tool for prevention. Colonoscopies don’t just check for cancer, they prevent it! During a colonoscopy, your gastroenterologist is checking for any abnormalities, signs of cancer, or polyps. Polyps are growths on the wall of the large intestine. Many polyps are precancerous. If polyps are found during a colonoscopy, they will be painlessly removed, which stops them from turning into cancer.

One reason that colon cancer deaths have decreased in recent decades is that precancerous polyps are more often found and removed during colonoscopies.

2. Waiting Until You have Symptoms Could be Too Late

Colon cancer usually doesn’t have symptoms right away. Waiting until you have symptoms might cost valuable treatment time. These are the most common symptoms of colon cancer:

  • Change in bowel habits that last for more than a few days
  • An urge to have a bowel movement that isn’t relieved by having one
  • Rectal bleeding with bright red blood
  • Blood in the stool (this may make the stool look dark brown or black)
  • Cramping or abdominal pain
  • Weakness
  • Fatigue
  • Unintended weight loss

These symptoms can be caused by other conditions, like an infection, hemorrhoids, or irritable bowel syndrome (IBS). If you are experiencing any of these symptoms, make an appointment with your gastroenterologist so the cause can be found and treated.

3. Finding Cancer Once It’s Difficult to Treat

Having regular colonoscopies allows for cancer to be found when it’s small and easy to treat. Treatment for colon cancer is determined partially by spread. If colon cancer hasn’t spread, it’s easier to treat. Some patients may need chemotherapy.

If colon cancer has spread outside of the colon, treatment is more drastic. It may include removal of sections of colon or other tissues, chemotherapy, radiation, and immunotherapy. If the cancer has spread too far or progressed too much, treatment may be recommended to improve quality of life and relieve cancer symptoms instead of having a goal of remission.

4. Finding Cancer After It’s Spread to Other Organs

If you have colon cancer and delay your colon cancer screening, the cancer will have time to grow.

If colon cancer is found before it has spread, the prognosis is good. The five-year survival rate is 90 percent. However, only 40 percent of colon cancers are found at this early stage. After cancer has spread, the survival rates are lower.

When cancer has spread outside of the colon to nearby structures, the five-year survival rate decreases to 71 percent. When cancer has spread to distant parts of the body, like the liver or lungs, the survival rate drops to 41 percent.

5. The Risk of Colon Cancer Increases with Age

One of the biggest risk factors for colon cancer is age. Though younger adults can be diagnosed, it’s more common for people older than 50 to have colon cancer. The American Cancer Society recommends that people begin colon cancer screening at 45.

Delaying your colonoscopy means that you will be older when you get one. If you’re 45 or older, never had a colonoscopy, and are delaying getting one now, you’ll be beyond the recommended age to begin getting colonoscopies.

6. Premature Death

Colon cancer is the third leading cause of cancer death in the United States. The American Cancer Society estimates that over 40,000 people will die of colon cancer in 2020. Many of those people did not receive colon cancer adequate screening per the American Cancer Society’s guidelines for timing and frequency.

Why You Shouldn’t Put Off Your Colonoscopy

You may be nervous about an upcoming colonoscopy, especially if it’s your first one. It’s understandable! But don’t let that fear stop you from getting this life-saving procedure. Here are the reasons to not delay your colonoscopy.

A Colonoscopy is the Best Way to Detect Cancer Early…

During a colonoscopy, your gastroenterologist uses a colonoscope to check your entire colon and rectum for signs of colon cancer. Early detection leads to a greater chance of surviving colon cancer, which is important because of how prevalent it is. If colon cancer isn’t detected early, treatment is more difficult and surviving cancer is less likely.

AND Prevent It

Colon cancer is preventable! During your colonoscopy, your gastroenterologist is also checking for polyps. Polyps found during a colonoscopy are removed to prevent them from turning into colon cancer. A colonoscopy is more effective than other screenings that only detect cancer; this one actually removes the precancerous polyps. Prevention leads to a greater chance of surviving colon cancer.

Colon Cancer Incidences Didn’t Slow during the Pandemic

Current estimates are that nearly 105,000 new cases of colon cancer will be diagnosed in 2021. This number didn’t change because of the pandemic. Our gastroenterologists diagnose many cases of cancer each month. Some patients who delayed their colonoscopies due to the pandemic may have precancerous polyps or colon cancer that needs treatment. If you delayed your colonoscopy because of the pandemic, it’s time to reschedule.

Prepping for the Procedure has Improved

A lot of people who have had colonoscopies say that the procedure itself isn’t bad, but the prep is! Improvements have been made to the prep process. Prep still involves cleaning out your bowels, but the liquids now taste better and the amount of liquid you need to drink is far less.

A Colonoscopy Doesn’t Hurt

During your colonoscopy, you’ll be under anesthesia. You won’t feel the scope during the procedure. You most likely won’t feel any different when you wake up.

Do you live near San Antonio and need a colonoscopy? Schedule an appointment today.

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