VIDEOCAPSULE

MEDICAL INFORMATION PRIOR TO VIDEOCAPSULE USE

• WHAT IS IT?

The videocapsule is a miniature camera designed to produce images of the digestive system. The videocapsule is about the size of a vitamin capsule (1.1 x 2.7 cm). It weighs just 4 grams.

Inside is a camera, a light source (a flash), two batteries, a transmitter and an antenna. The capsule is swallowed by the patient and then travels through the oesophagus, stomach and intestine, thanks to the natural contractions of these organs. The capsule takes two photos per second. These images are sent to sensors worn on the patient's stomach. Before the examination, these sensors must be attached to the stomach to receive the images emitted by the capsule. These images are recorded by a device that the patient also wears.

The system is powered by batteries, which are also worn by the patient, and have a lifespan of around eight hours. The passage through the oesophagus is too rapid to gather reliable information. The stomach is much larger in volume, and the capsule can only provide partial information. The real field of application for the capsule is the small intestine. This organ measures four metres and conventional endoscopy techniques do not allow it to be fully examined (except sometimes during an operation).

After passing through the small intestine, the capsule is propelled into the large intestine (or colon), where the presence of faeces prevents reliable interpretation of the data. Finally, after an average of one to two days, the capsule is evacuated naturally.

• HOW DOES THE TEST WORK IN PRACTICE?

The patient does not eat or drink for at least 12 hours. Once the sensors have been attached to the stomach (using self-adhesive stickers), the capsule is swallowed with a little water. Recording begins and lasts 8 hours. The patient remains in hospital or, in some centres, can return home. After eight hours, the sensors and recorder are removed. The recorder is connected to a computer that will process the images (often more than 50,000!) and allow them to be interpreted by the doctor. This reading takes time, but a trained doctor can do it in about an hour. In some centres, a laxative is administered the day before the examination.

• WHY CARRY OUT A VIDEOCAPSULE EXAMINATION?

The main reason for this examination is to detect diseases of the small intestine, and in particular bleeding of obscure origin. In concrete terms, this refers to patients who have lost blood in their stools or who have anaemia, the cause of which cannot be found by conventional endoscopies (gastroscopy and colonoscopy).

The stomach and large intestine are by far the organs most often responsible for such bleeding, and should therefore be examined first before considering a videocapsule examination. In the small intestine, for example, the capsule can detect small abnormalities of the vessels (or angiomas), or small ulcers, or more rarely a tumour. In patients with Crohn's disease, the video capsule may reveal lesions in the mucosa that are undetectable by other methods.

In selected cases, these patients may benefit from video-capsule examination.

• WEAKNESSES OF THE CAPSULE

The video capsule is not suitable for examining the oesophagus, stomach or large intestine. The capsule is only used for diagnosis and cannot perform any treatment. Therefore, if a lesion is discovered, endoscopy using a very long device will often be necessary to treat the lesion. Sometimes, an operation will be necessary. If the examination is negative, it is very likely that there is no lesion in the small intestine. At present, the price of the capsule is still a problem. It is not reimbursed by mutual insurance companies and costs around €650. This is one more argument for rigorously selecting the patients who can benefit from it.

• POSSIBLE DISADVANTAGES

If there is a narrowing in the digestive tract, it may be impossible for the capsule to pass through and obstruction may occur. In practice, this danger arises very rarely. However, it is always wise to inform the doctor of any previous abdominal surgery. Pace-maker wearers should also inform their doctor, although the waves emitted by the capsule do not interfere with normal pace-maker operation. During the examination, the patient must not undergo magnetic resonance or be near intense magnetic fields.