แพทย์หญิงสุรีย์พร แจ้งศิริกุล อายุรแพทย์โรคระบบทางเดินอาหารและตับ - Dr Sureeporn Jangsirikul, A gastroenterologist and hepatologist

Colonoscopy

A colonoscopy is a tool for safeguarding your digestive health. It allows doctors to examine the inner lining of your large intestine (colon) for abnormalities. It is especially beneficial in detecting and preventing severe conditions

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Colonoscopy

A colonoscopy is a tool for safeguarding your digestive health. It allows doctors to examine the inner lining of your large intestine (colon) for abnormalities. It is especially beneficial in detecting and preventing severe conditions like colorectal cancer and inflammatory bowel disease.

For most people, regular colonoscopies should begin at age 45, irrespective of symptoms. Early detection is crucial for successful treatment of these conditions.

What is a Colonoscopy?

A colonoscopy involves employing a long, flexible fiberoptic instrument with a camera attached at the tip and sophisticated imaging technologies to examine the cecum, colon, rectum, and anus. The endoscopist inserts the colonoscope into the colon through the anus. A control knob allows flexing of the end of the colonoscope for directional control and a working channel for the introduction of therapeutic devices, enabling immediate intervention, such as a biopsy or polyp removal to prevent colon cancer.

Why Undergo a Colonoscopy?

Why Undergo a Colonoscopy?

Colonoscopies serve purposes in screening, diagnosis, and therapeutic interventions for conditions affecting the large intestine or rectum. Individuals at risk of colorectal cancer, especially those over 45 years old or with a family history of colorectal cancer, are advised to undergo regular colonoscopies at the specified age and time. The procedure can also aid in the identification and removal of suspicious polyps. 

Colonoscopy for Prevention

Since the risk of developing colorectal cancer increases with age, the American Cancer Society recommends that you should start having a regular colonoscopy at the age of 45, regardless of symptoms. This preventive measure can detect and remove small polyps before they become cancerous or cause symptoms.

Who should be screened for colon cancer by colonoscopy?

  • Individuals aged 45 or older without prior colonoscopies.
  • Those with first-degree relatives are diagnosed with colorectal cancer.
  • Individuals with a history of polyp removal.
  • Those who have not undergone a colonoscopy in the last ten years.
  • Patients with inflammatory bowel disease (IBD).

Diagnostic Colonoscopy

Some have symptoms that require a diagnostic colonoscopy. The detailed images obtained during a colonoscopy assist doctors in diagnosing the underlying causes of these symptoms and guide the endoscopist to biopsy tissue from suspicious lesions for pathological diagnosis. Symptoms requiring a diagnostic colonoscopy include persistent abdominal pain, chronic diarrhea, rectal bleeding, changes in bowel habits, chronic colitis, inflammatory bowel disease, and bowel ischemia.

Therapeutic Colonoscopy

In addition to preventive and diagnostic considerations, colonoscopy allows for therapeutic interventions. Endoscopic treatments include:

  • Polypectomy 
  • Stent placement for colonic obstruction
  • Colonic dilation
  • Foreign body removal
  • Stopping bleeding using mechanical or thermal devices.

Procedure for a colonoscopy

Preparation before undergoing a colonoscopy What are the steps?

Your doctor will provide instructions for dietary changes and medication adjustments. Preparation of the colon before the procedure is essential for optimal viewing and to prevent complications.

You should follow a low-fiber diet for a few days before the procedure by taking only a clear fluid or liquid diet, including plain water, clear broth, and coffee or tea with no milk added. Take at least 2-3 liters of laxative until the bowel movement is clean on the day of the procedure or as directed by the endoscopist.

Patients taking medications for underlying medical conditions, especially blood thinners, antidiabetics, or antihypertensives, should adhere to physician instructions about taking them around the colonoscopy. 

What is the procedure for a colonoscopy?

Before the colonoscopy

Your doctor will review the procedure and possible complications with you and ask you to sign a consent form. A nurse will start an IV line for administration of sedatives and painkillers.

During the colonoscopy

The staff will monitor your blood pressure, breathing, heart rate, electrical activity, and oxygen saturation of the blood.

The endoscopist will insert the colonoscope through the anus and insufflate carbon dioxide to distend the colon for better visibility. While most patients fall asleep during the procedure, some may experience gas discomfort or an urge to use the bathroom. If discomfort arises, inform the doctor for additional sedation or pain relief.

Polyps found during your colonoscopy can usually be removed right then and there. This removal process is painless. It is important to note that most polyps are harmless but can develop into cancer over the long term. That is why catching them early with a colonoscopy is so important.

How long does a colonoscopy take?

The colonoscopy itself takes about 30 to 60 minutes. You will then rest comfortably in a recovery area while the staff monitor you. It is usual to experience some gas cramps or bloating after the procedure, but these usually improve within 30 to 60 minutes.

Since you will receive sedation for the colonoscopy, it can temporarily affect your coordination and thinking. For your safety, you will need someone to drive you home. However, you should feel well enough to resume your normal activities, including work, the next day.

Possible Complications

Although colonoscopy is a safe test, complications occur in a tiny proportion of cases (1 per 1,000). Possible complications include:

  • Bleedings from the biopsied or polyp removal sites
  • Perforation of the colon: With today’s advanced instruments for colonoscopy, this rare event is treatable endoscopically. Only a small number of patients require surgical treatment.
  • Side effects from the sedatives such as nausea or vomiting.

Seek medical attention immediately if you experience the following symptoms after a colonoscopy

  • Severe abdominal pain that is not gas cramps
  • Rectal bleeding of more than 30 mL (2 tablespoons) or blood clots in stool
  • Fever
  • Vomiting

ผลตรวจส่องกล้องลำไส้ใหญ่ Colonoscopy

Results

You will usually know the results of the procedure right away. If polyps or abnormal tissue are found and removed, the tissue pathology report may require a few days to a week.

Potential Abnormal Findings Discovered by Colonoscopy
A colonoscopy may discover the following conditions:

  • Benign, precancerous, or cancerous polyps
  • Colonic bleeding
  • Ulcers
  • Diverticulosis
  • Colitis
  • Obstruction or stenosis

FAQ

  • What are alternative options to colonoscopy for colon cancer screenings?
    Alternatives to colon cancer screening include:
    • Fecal immunochemical test (FIT): The test aims to detect stool occult blood for suggestive diagnosis of colorectal cancer. A positive test could mean bleeding from a lesion in your digestive tract, like intestinal polyp or cancer. Further diagnostic steps may involve a tissue biopsy. Doctors recommend getting a FIT test every year for colorectal cancer screening.
    • Virtual colonoscopy: This is a 3D reconstruction of a CT scan to view the entire colon for detecting colorectal polyps or cancer. Despite not requiring a colonoscope or anesthesia, you must prep your colon like a regular colonoscopy – by taking laxatives – to ensure a clear, unobstructed mucosal image. A standard colonoscopy is necessary after finding an abnormality during a virtual colonoscopy. Physicians suggest undergoing this test every five years.
      While other screening options exist, conventional colonoscopy remains the gold standard for early detection of colorectal cancer. Uniquely, it combines diagnosis and treatment in one procedure. Polyps or other abnormalities can be identified and removed during the same colonoscopy.
  • What are the benefits of cancer screening with colonoscopy?
    Benefits of a colonoscopy include:
    • Early detection.
    • Useful for diagnostic, therapeutic, and preventive procedures.
    • If your results are negative, you do not need a repeat colonoscopy often; you can have it every ten years.
      A colonoscopy is a valuable tool in safeguarding your colorectal health. If you have any concerns or fall into high-risk categories, consult your healthcare provider to determine the best course of action for your individual needs.

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Published: 01 Apr 2024

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