Video Blog: Colonoscopy and Colon Cancer Screening

Dr. Michael Kreines, Chief of Gastroenterology at The Christ Hospital, explains the importance of a colonoscopy in detecting and preventing colon cancer. For more information, visit

Call (513) 751-6667 to schedule your colonoscopy today

A colonoscopy is an examination of the lower part of the gastrointestinal tract, which is called the colon or large intestine (bowel). Colonoscopy is performed by an Gastroenterologist, who is a physician with special training in endoscopy/colonoscopy procedures. The colonoscope is inserted into the anus and advanced through the entire colon (to the cecum where the appendix is) and possibly a short distance into the small intestine. The procedure generally lasts between twenty minutes and one hour.

Video Blog: Colonoscopy and Colon Cancer Screening: LINK TO VIDEO


The most common reasons for colonoscopy are to evaluate the following:

  • As a screening exam for colon polyps and cancer
  • Blood in the stool or rectal bleeding
  • Dark/black stools
  • Persistent diarrhea
  • Iron deficiency anemia (a decrease in blood count due to loss of iron)
  • Significant, unexplained weight loss, accompanied by gastrointestinal symptoms
  • A family history of colon cancer
  • To evaluate an abnormal imaging Xray test
  • A history of previous colon polyps or colon cancer
  • Surveillance in people with ulcerative colitis or Crohn’s disease
  • For the medical management of chronic inflammatory bowel disease
  • Chronic, unexplained abdominal pain.


Patients are provided with specific instructions about how to prepare for the examination. There is also a section tab of this website “Preparations” with all the preparation instructions. The instructions are designed to maximize safety during and after the examination, minimize possible complications, and allow the endoscopist to fully view the colon.

It is important to read the instructions ahead of time and follow them carefully; patients who have questions should call us.

The inside lining of the colon must be cleaned of stool to permit the endoscopist to complete a thorough examination. This is accomplished by restricting what is eaten and by using purgatives.

What to eat

As a general rule, patients should not eat any solid food for at least one day before the examination. Only clear liquids (bouillon, ginger ale, or juices without pulp) or clear gelatin (flavored is fine, but without added fruit) are recommended.


Some medications, such as aspirin, blood thinners, and iron preparations, should be discontinued before the examination. Patients taking these types of medication should ask us for specific instructions on whether to take or not take them.

Patients should also ask about medications for diabetes, heart or lung disease, high blood pressure, or seizure disorders. Most medications should not be stopped, and many of them can be taken before the examination.


Patients need to arrange for someone to take them safely home after the examination. Although patients will be awake by the time of discharge, the sedative medications cause changes in reflexes and judgment that cause a person to feel well but can interfere with the ability to make decisions, similar to the effect of alcohol.


Prior to the colonoscopy, a nurse will ask questions to ensure the patient understands the procedure and the reason it is planned. The nurse will ask questions to ensure the patient has prepared properly for the procedure. A doctor will also review the procedure, including possible complications, and will ask patients to sign a consent form.

The nurse will start an intravenous line (insert a needle into a vein in the hand or arm) to administer medications. The intravenous line insertion feels like a pin prick, similar to having blood drawn. The vital signs (blood pressure, heart rate, and blood oxygen level) will be monitored before, during, and after the examination. The monitoring is not painful. Some patients will be given oxygen during the examination.


The colonoscopy will be performed while the patient lies on their left side. Medications will be administered through the intravenous line. Most endoscopy units use a combination of a sedative (to help patients relax), and a narcotic (to prevent discomfort). Many people sleep during the examination while others are very relaxed, comfortable, and generally not aware of the examination.

The colonoscope is a flexible tube, approximately the size of the index finger. It has a lens and a light source that allows the doctor  to see the colon. The scope contains channels that allow obtaining biopsies (small pieces of tissue), remove polyps and to introduce or withdraw fluid or air. Polyps are extra growths of tissue that can range in size from the tip of a pen to several inches (doctors measure them in millimeters and centimeters). Most polyps are benign (not cancerous) but can become cancerous if allowed to grow for a long time. As a result, they are usually removed so they can be analyzed. This does not hurt since the lining of the colon does not sense pain.

Air is introduced through the scope to open up the colon so that the scope can be moved forward and to allow the endoscopist to see. Patients may experience a feeling of bloating or gas cramps from the air as it distends the colon. Try not to be embarrassed about releasing the air/ passing gas; patients should let their physician know if they are uncomfortable


After the colonoscopy, the patient will be observed until the effects of the sedative medication are gone. The most common discomfort after colonoscopy is a feeling of bloating and gas cramps. Patients may also feel groggy from the sedation medications. Patients should not return to work that day. Most patients are able to eat a regular diet after the examination. Patients should ask about when it is safe to restart aspirin or blood thinning medications.


Colonoscopy complications are rare, but can occur:

Bleeding can occur from biopsies or the removal of polyps.

The colonoscope can cause a tear or hole in the tissue being examined, which is a serious but uncommon problem that usually requires emergency surgery.

Colonoscopy can miss important abnormalities such as polyps or even cancer.  Every test has a “miss rate” as no perfect test exists. Colonoscopy is an excellent test but not an infallible one.

Adverse reactions to the medications used to sedate you are possible. The endoscopy team will ask about previous medication allergies or reactions and about health problems such as heart, lung, kidney, or liver disease.

The medications can cause irritation in the vein at the site of the intravenous line. If redness, swelling, or warmth occur, applying a warm wet towel to the site may relieve the discomfort. If the discomfort persists, notify the endoscopy unit.

After a colonoscopy, the following problems should be reported to us immediately:

  • Severe abdominal pain (not just gas cramps)
  • A persistent or increasingly firm, distended abdomen
  • Vomiting
  • Fever
  • Rectal bleeding (greater than a few tablespoons).


Although patients worry about discomforts of the examination, most people tolerate it very well and feel fine afterwards. Some fatigue after the examination is common. Patients should plan to take it easy and relax the rest of the day.

The doctor can describe the result of their examination before the patient leaves the endoscopy unit. Due to the lingering effect of the medication given during colonoscopy, patients often do not remember their discussion with the doctor afterwards. A family member or friend accompanying the patient with whom the doctor can speak after the colonoscopy is recommended. If biopsies have been taken or polyps removed, the patient should call for results in one week.