how to spot a complication after colonoscopy

Colonoscopy is a life saving procedure. Like most procedures, it comes with risks. These risks include bleeding, infection, and tear in the colon (perforation). A serious complication occur in less than one percent of patients.  Complications that occur during colonoscopy are usually addressed by your doctor.

Risk and complication of colonoscopy

Common risks and complications

  • Adverse effects of medications given for sedation. 
  • Redness, pain or bruising at the injection site.
  • Mild abdominal pains and discomfort.
  • Nausea and vomiting.
  • Lightheadedness and dizziness.
  • Headaches.
  • Muscle aches and pains.

Uncommon risks and complications

  • Less than 1 in every 1,000 person accidentally get a hole in the colon. This is called perforation. If detected at the time of colonoscopy, it can be repaired without the need for surgery. Surgery may be needed to repair the perforation. A colostomy may be needed.
  • Less than 1 in every 1000 person experience a significant bleeding. This is usually from a site where a polyp is removed. Bleeding can occur up to 2 weeks after the colonoscopy. The bleeding may stop on its own, require blood transfusion or another colonoscopy to stop the bleeding.
  • Inability to see the entire colon. This may be due to inadequate bowel prep, a tortuous colon, a redundant colon or a blockage. A repeat colonoscopy may be needed.
  • Difficulty breathing.
  • Pneumonia from aspiration.
  • Low blood pressure requiring intervention.
  • Abnormal heart rhythm.
  • Heart attack.
  • A polyp or lesion may be missed. Small polyps are missed 5-10 percent of the time.
  • Sneezing and runny nose. 

Rare risks and complications

  • Anaphylaxis to medications used during the colonoscopy.
  • Infection such as bacteria in the blood stream. An antibiotic can be used to treat the infection.
  • Spleen rupture.
  • Stroke.
  • Death. This is very rare.


Who is more likely to have a complication after colonoscopy?

  • Elderly patients.
  • People with weak immune system.
  • Patients on blood thinners.
  • People that are having emergency colonoscopies.
  • Those that are getting therapeutic colonoscopies instead of diagnostic colonoscopy.
  • Patients with poorly treated heart or lung disease.
  • People with altered anatomy including those with diverticulosis, tortuous colon, and obstruction.

How can you spot a complication after you have been discharged home from your colonoscopy?

  • Abdominal pain: You may have some abdominal cramps following a colonoscopy. This is often due to the air used to inflate the colon during the procedure. You should not hold unto any gas or flatus. You should pass gas as much as possible. If you have persistent abdominal pain or cramps or if your pain is getting worse, you should contact your doctor immediately. This may be a sign of a tear in the colon, also known as perforation.
  • Fever: If you develop fever (temperature above 100.4 F) or chills after your colonoscopy, call your doctor. This may be a sign of infection.
  • Bleeding: A small amount of rectal bleeding may be seen after colonoscopy especially after a biopsy or removal of polyp. If rectal bleeding is severe (large amount) or persistent, you should contact your doctor immediately. This may be a sign of serious bleeding.


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