Proctoscopy

Equipment

There are numerous rigid sigmoidoscopes available: reusable and disposable; with proximal or distal lighting; with and without fiberoptics ( Figure 42-1-1 ). If only a few examinations a day are performed, the reusable instrument may be most appropriate. If many examinations are undertaken every day, unless one can afford the luxury of having a number of instruments and can justify the labour and expense of cleansing them, the disposable instrument is usually preferred. When using plastic disposable instruments be generous with the lubricant gel – they do not glide like cold steel.

Instruments are available in a number of diameters ranging from 1.1 to 2.7 cm; the 1.9-cm instrument is an excellent compromise. The large-bore instrument is less useful for screening because of greater patient discomfort but may be invaluable for removing large polyps. The narrow sigmoidoscope is a good screening tool and is particularly useful if an anal stricture precludes the use of the larger diameter instrument or if the patient has had a previous anal anastomosis. In addition to the tube itself, the instrumentation includes a light source, a proximal magnifying lens, and an attachment for the insufflation of air. Suction facilities should be available for banding of hemorrhoids and removal of liquid stool.

Method

Bowel preparation is not normally necessary, although a digital rectal examination should always precede instrumentation. The well-lubricated, warmed sigmoidoscope is inserted and passed to the maximum height under vision as quickly as possible without causing discomfort. Air insufflation is of value in demonstrating the lumen and is of even greater benefit in visualizing the mucosa, but it should be kept to a minimum because it tends to cause pain. Most information is obtained as the sigmoidoscope is withdrawn, when the entire circumference of the bowel wall can be inspected.