The prone jackknife position provides excellent exposure of the perineum, anus, and gluteal cleft. This position requires the use of a maneuverable table to facilitate exposure. The patient is asked to kneel on the table platform, bending forward and placing their chest on the table with elbows forward, palms on the table, and the back in a slight sway back position. After being appropriately draped, the patient is warned to remain in this position. The table is then raised and tipped forward for exposure and inspection.

Appropriate patient selection for this position is key. Patients with significant cardiopulmonary disease may not tolerate this position for prolonged periods as compression of the chest and abdomen may reduce ventilatory capacity and decrease preload due to compression of the IVC. Furthermore, physical factors that would prevent the patient from lying prone, such as obesity, pregnancy, and tense ascites, may require the use of a different position. Additionally, patients with orthopedic conditions that limit their range of motion including significant osteoarthritis, kyphosis, or have a history of lower extremity joint replacement should be placed in other positions.

The lithotomy position is most frequently used for gynecologic examinations and procedures; however, it may be used for the examination of the perineum and anus. The patient is asked to lie in the supine position on the examination table, place their heels in stirrups, and then move their buttocks to the edge of the table. The advantages of this position include the ability to perform anorectal, pelvic, abdominal, and bimanual examinations. For additional exposure, the table may be placed in slight trendelenburg position. While this position provides some technical advantages for the surgeon, the patient (especially if the patient is male) may feel uncomfortable in this position and appropriate coaching may be necessary. The posterior position of the anus limits the surgeon technically in performing some procedures, including endoscopy.

In the left lateral decubitus position, the patient lays left side down with the buttocks brought to the edge of the table or even a slight bit over the edge of the table. The back is slightly flexed and both arms are extended with the hips and knees flexed. A variation of this is the Sim position where in the patient is similarly positioned with the exception that the left leg is kept straight. This is the most comfortable and well-tolerated position for the patient. Patients who cannot tolerate prone jackknife or knee to chest positions due to significant cardiopulmonary disease are best suited for this position. However, access to the perineum and anus is less optimal. Adequate exposure requires retraction of the buttocks to examine and perform interventions on the perineum and anus. This can be facilitated by the aid of an assistant.

The knee-chest position is accomplished by placing the patient in the prone position, then having them bring their knees to their chest with their arms extended forward. Like prone jack-knife, this position provides excellent exposure to the anus and perineum. This position maybe favorable for pregnant patients as their gravid abdomen may prevent them from comfortably laying in the prone position. However, the cardiopulmonary limitations associated with the prone jackknife position also apply to the knee to chest position.

Anoscopy offers the best means to detect pathology of the anal canal. Anoscopy allows the examiner to visually inspect the terminal 10 cm of the gastrointestinal tract (Fig. 14.2). Additionally, it is essential in the performance of procedures to treat conditions of the anal canal. Numerous anoscopes and specula are available. Anoscopes are either reusable or disposable with some having a light source that fits into the instrument. The use of a fiberoptic light source is optional as a headlamp or a simple gooseneck lamp works well. Once the patient is adequately positioned, a digital rectal exam is performed. The anoscope is lubricated and the instrument is introduced with the obturator in place. When rotating the anoscope around the anal canal circumference, it is helpful to reinsert the obturator to turn the instrument. By doing so, the tendency to drag or pinch the anal canal or perianal skin is minimized. Finally, when pathologic features are noted or treated, the site should be recorded as follows: right anterior, left lateral, and right posterior.

Reusable or disposable rigid sigmoidoscopes are available with or without fiberoptics. Reusable instruments require care and cleansing, with the need for sterilization equipment. Disposable ones are discarded and are treated as medical waste . The decision to utilize disposable versus reusable proctoscopes is dependent upon physician preference and the cost-benefit of having a number of instruments readily available for which the expense of maintenance and cleansing must be justified. These instruments are available in several diameters, ranging from 1.1 to 2.7 cm. In addition to the speculum tube, the instrumentation includes a light source, a proximal magnifying lens, and an attachment for the insufflation of air (Fig. 14.3).

Prior to the examination, a small-volume enema may be used unless otherwise contraindicated. Suction should be available to remove any residual liquid stool or fluid. Regardless vigorous catharsis, the day before the examination and dietary restrictions are unnecessary. Once the patient is positioned, a digital rectal examination precedes instrumentation. In addition to providing valuable information, this procedure permits the sphincter to relax sufficiently to accept an instrument. A well-lubricated rigid proctosigmoidoscope is then inserted and passed to the maximal height as quickly as possible while causing minimal discomfort to the patient. Successful insertion of the proctosigmoidoscope requires familiarity with the anatomy of the rectum and sigmoid colon. When the proctosigmoidoscope is inserted, the low rectal and mid-rectal areas are midline structures. As the upper rectum is reached, the bowel bends slightly to the left.

Minimal air insufflation is used to visualize the mucosa while the instrument is carefully withdrawn viewing the entire circumference of the bowel wall and flattening mucosal folds to be certain that no lesions are missed. The valves of Houston are rectal folds on the lateral aspect of the rectal wall. The upper and lower folds are located on ipsilateral walls while the middle fold is located on the contralateral wall. The valves can serve as useful sites for performing rectal biopsy when the mucosa is grossly normal because of technical ease as well as the limited risk for perforation.

Flexible sigmoidoscopy inspects more bowel surface area than is possible with the rigid proctosigmoidoscope. The flexible sigmoidoscope evaluates the terminal 60 cm of the colon and rectum as well as the anus during retroflexion of the scope in the rectal canal (Fig. 14.4a). The flexible fiberoptic sigmoidoscope is available through several companies and though the specifications of the instruments vary somewhat among the manufacturers the channel size ranges between 2.6 and 3.8 mm, the instrument diameter varies from 12.2 to 14.0 mm, and lengths range from 60 to 71 cm. The working channel allows the passage of biopsy forceps, cytology brushes, snares, and electrocautery as well as a number of other specialized instruments (Fig. 14.4b). Additionally, the working channel permits suction and irrigation. The tip of the instrument is deflected by rotation of the larger dial in each direction, while the smaller dial deflects the tip from side to side. If both dials are turned maximally, it produces a tight bend producing retroflexion of the tip of the instrument (Fig. 14.4c).

Prior to flexible sigmoidoscopy, bowel preparation with small volume enemas assists with the clearance of the majority the stool burden within the distal colon and rectum. Dietary restrictions and oral laxatives are generally unnecessary. In some cases, however, oral bowel prep preparations may be beneficial. Once the patient is placed in the left lateral (or Sims’ position), a digital rectal exam is performed and the instrument is inserted. The endoscopist maneuvers the dials with one hand and guides the instrument with the other. While insufflating air rather than redirecting the tip, the examiner passes the instrument to a depth of 10 or 12 cm. This will permit the visualization of the rectal ampulla. The instrument is then passed with the lumen seen either under direct visualization or with the mucosa seen sliding past. If further passage is impeded, the instrument is withdrawn slightly, the lumen is searched out by dial manipulation and rotation, and the instrument is advanced again. Negotiation of the sigmoid colon is the most difficult part of the procedure. Sedation may be required to accomplish this, but this may not be available for office examinations. After the instrument has been passed to its full length or as far as is possible, it is carefully and slowly withdrawn. Suction, irrigation, and air insufflation are alternately employed as indicated to obtain clear visualization of the entire mucosa. Biopsy, with or without electrocoagulation , is obtained if appropriate. The scope is withdrawn to the distal rectal canal and retroflexed. The tip of the sigmoidoscope is then placed in the neutral position and the instrument is removed.

Flexible sigmoidoscopy is a great tool for in office evaluation, diagnosis, and management of colorectal disease; however, there are some disadvantages to this examination, including cost in the form of capital expense, maintenance, and repairs as well as the risk of complications including the transmission of communicable disease, perforation, and hemorrhage. The cost of equipment may exceed $15,000, including light source and accessories (Fig. 14.5). In addition to the outlay for the capital expense and repairs, there are the costs of personnel (patient preparation as well as instrument cleansing and maintenance). This procedure comes at a considerable higher cost to the patient, ranging from 25 % more than for rigid proctosigmoidoscopy to as much as 200 % more.