Visualising small bowel with wireless capsule endoscopy
What is capsule endoscopy?
The small bowel is the most difficult part of the gastrointestinal tract to investigate because of its distinctive anatomy, length, and location. Radiological examination of the small bowel (small bowel barium follow through and enteroclysis) has been used by radiologists in patients with suspected small bowel diseases such as those with obscure gastrointestinal bleeding or malabsorption. An alternative to radiological test is push enteroscopy which is invasive and does not allow examination of the whole small bowel. These conventional techniques, however, often have a poor diagnostic yield.
Wireless capsule endoscopy (WCE) allows noninvasive imaging of the small bowel mucosa. WCE was a major breakthrough in the field of gastrointestinal endoscopy when it was introduced in early 2000’s. WCE consists of a capsule similar in size to usual drug capsule. It houses a battery, miniature camera and image transmitter. It has become the gold standard for imaging the small intestine. It is a safe, noninvasive and pain-free procedure (therefore does not require sedation) that enables the entire small intestine to be visualised, and can be performed in the outpatient or ambulatory setting.
When will my doctor order WCE for me?
WCE is an extremely useful diagnostic tool for doctors who are faced with patients presenting with suspected small bowel diseases, such as obscure gastrointestinal bleeding, malabsorption, unexplained abdominal pain, abnormal findings on CT or MR enterography (CT or MR examination of the small bowel) or barium follow through and for surveillance of polyposis syndromes of small intestine.
How is WCE Performed?
There is minimal preparation required. Patient undergoing the procedure simply has to fast overnight before reporting to the clinic/endoscopy centre in the morning. Sensors will be attached to the patient’s abdomen. These sensors receive signals/images transmitted by the capsule. These sensors are then connected to a Data recorder (same size as handphone) and battery pack worn around patient’s waist.
The capsule is then turned on and swallowed with water by the patient. The patient is allowed to go home and carry on with his usual activity. Clear liquids are allowed after 2 hours; food and medications are permitted 4 hours after ingestion of the capsule. As the capsule passes through the intestine, its in-built camera will take pictures of the intestine, which are then transmitted to and stored in the Data Recorder. After 8 hours of recording (newer version of WCE has battery life span of more than 24 hours), the patient returns to the clinic and the Data Recorder is then removed from the patient. The data is then downloaded into a computer. With special software, video-clip images of the small intestine can be created for viewing. The capsule itself is disposable (for single use only) and passes out in the faeces usually in 2-3 days time.
What are the benefits and risks of WCE?
Since its introduction into clinical use in the year 2000, WCE has been found to be superior to conventional radiology and push enteroscopy in diagnosing small bowel disease. It has been shown to be superior to push enteroscopy and to barium follow through in patients with occult gastrointestinal bleeding, suspected small bowel pathology or Crohn’s disease. This is because WCE has the advantage of visualising directly the entire small intestinal mucosa.
The procedure is safe, noninvasive and painless. Patients find it highly tolerable and convenient. The only risk of WCE is that of capsule retention which occurred in less than 1% of the patients. This is usually due to unsuspected narrowing or stricture in the small intestine, which impede the passage of the capsule. Surgery is required in some of these patients to retrieve the capsule and at the same time to treat the underlying abnormality.
There is no biopsy or therapeutic capability with WCE. If abnormality is detected, your doctor may order specialized endoscopy for the small bowel.
What are the contraindications?
Patients with intestinal obstruction/strictures/fistulae and pseudo-obstruction/motility disorders should not undergo WCE. It is also not recommended for pregnant patients. For patients with swallowing disorders or gastroparesis, the capsule can be placed in the stomach or duodenum respectively with the help of gastroscopy if WCE needs to be performed.