Patients over 50 should have a colonoscopy every 10 years to screen for colon cancer, according to MayoClinic.com. Colonoscopies also assist in determining the cause of gastrointestinal problems such as abdominal pain, chronic constipation or diarrhea and rectal bleeding. The procedure involves inserting a long flexible tube with a video camera at the tip, called a colonoscope, into the patient's rectum to visualize the inside of the colon or intestine. Complications are few but may be serious.
Sedative Reaction
Prior to the colonoscopy, the patient receives intravenous medication consisting of a narcotic painkiller, a benzodiazepine for sedation, or both. Most patients become drowsy and relaxed, and they are unable to remember the procedure afterward. People may remain confused, dizzy and unable to concentrate afterward, increasing their risk of falling or having a motor vehicle accident. In six to seven of every 10,000 colonoscopy cases, the patient will have an adverse reaction to the medication that causes low blood pressure and breathing problems, according to the University of Maryland Medical Center. Severe reactions may include aspiration, irregular heartbeats or cardiac arrest, according to the Merck Manual.
Bleeding
A routine colonoscopy poses no risk of bleeding, according to the Merck Manual. However, if the surgeon performs a biopsy or removes a polyp from the colon during the procedure, that site may bleed heavily. Bleeding occurs about seven times in every 1000 colonoscopies with polypectomy, according to the University of Maryland Medical Center. Larger polyps increase the risk of bleeding.
Bowel Injury
Accidental injury or bowel perforation occurs in approximately one to three of every 1000 colonoscopies, according to the University of Maryland Medical Center. Symptoms of a bowel perforation include abdominal pain, distention, malaise and fever. If the patient was not able to cleanse his bowels thoroughly before the procedure, the contents may leak into the abdominal cavity, causing infection. Surgical repair is the only treatment for a bowel perforation.
Bowel Preparation Side Effects
Patients must cleanse their bowels before a colonoscopy to allow visualization of the colon and to prevent bowel contents from leaking into the abdominal cavity if an accidental injury occurs during the procedure. The medications used for bowel preparation may cause gastrointestinal symptoms, including bloating, nausea, vomiting and irritation of the rectum, according to the University of Maryland Medical Center. The patient may become dehydrated and should drink plenty of fluids after completion of the test. Diabetics may experience hypoglycemia unless they postpone their insulin or oral medication until after the test or take a smaller dose.
