Endoscopy is the examination of internal parts of the body using special instruments known as endoscopes. The simplest method of instrumental examination is that employed for the analcanal and rectum. A 'speculum' (proctoscope) which is in fact a simple tube with a handle, is introduced through the analcanal and the surgeon examines the rectal wall through the tube. To facilitate the introduction of the instrument, there is a shaped conical stopper which is known as the 'obturator.' This same principle of a shaped introducer is used on many instruments which have an open tubular end. Sigmoidoscopy is the examination of the upper regions of the rectum and the sigmoid or pelvic colon with a longer tubular speculum. Because the folds of mucousmembrane fall against the end of the instrument and obstruct the view, air inflation is used for the introduction of the sigmoidoscope so that the lumen of the bowel is distended. The surgeon inserts the instrument under direct vision, inspecting the wall of the bowel as far as 25 cm. from the anus.
The oesophagoscope is a similar instrument passed down the oesophagus through the mouth, thus enabling the surgeon to inspect the whole length of the gullet. The inside of the stomach is examined by the gastroscope, using air inflation. Through a very small incision in the abdominal wall the surgeon may introduce another viewing instrument, the peritoneoscope, and with this he may inspect the inside of the peritoneal cavity and obtain infonnation to enable him to reach a decision without open operation. In order to separate the coils of intestine from one another and allow the satisfactory inspection of the viscera, the peritoneal cavity is inflated with air through a separate cannula. Endoscopic instruments, except for the simpler forms of proctoscope, carry their own miniature lamps which draw electric current either from a battery or the mains through a transformer to reduce the voltage. The bladder and urethra are inspected with the cytoscope and urethroscope. The urinary tract is distended with water instead of air for the inspection, but air inflation is sometimes used for the lower part of the urethra. Various forms of speculum are used for the vagina and these are usually illuminated by direct light, although some forms carry a lamp of their own. Operations for the removal of tissue for microscopic examination (biopsy) are performed through some of the tubular instruments, and for this purpose there are special long forceps and diathermy electrodes. Examinations carried out with endoscopic instruments may be made with local or general anaesthesia and in the case of the rectum and colon, without anaesthesia. Research Endoscopy
Lignocaine is a short-term local anaesthetic injected into tissues or applied to skin. It is effective for brief, invasive procedures such as dental care or insertion of a cannula into a vein. Temporary paralysis (to prevent involuntary movement during eye surgery, for example) can be achieved by injection directly into the nerve serving the region. Rapidly absorbed by mucous membranes, lignocaine may be sprayed into the nose or throat to allow comfortable insertion of a viewing instrument during endoscopy. Its action makes it a potent anti-arrhythmia drug as well: given intravenously during or following a heartattack, it reduces the risk of cardiac arrest. Research Lignocaine
The Probert Encyclopaedia was designed, edited and programed by
Matt and Leela Probert
Abbreviations
Research Cannula
