Rigid rectosigmoidoscopy has largely been replaced by the flexible
sigmoidoscope for routine elective screening and diagnostic workups.
The rigid rectosigmoidoscope is superior to the flexible sigmoidoscope
in measuring distances accurately, examining an unprepared patient,
and when trying to work within the bowel lumen, for example when
removing foreign bodies. The larger lumen of the rigid rectosigmoidoscope
allows for a larger biopsy of lesions where pathology is in question.
The cost associated with this examination is less than that for
flexible sigmoidoscopy. The rigid rectosigmoidoscope can be purchased
in a disposable model that performs well. It is important for a
physician who evaluates and treats problems related to the colon,
rectum, and anus to be familiar with rigid rectosigmoidoscopy.
The significant anatomy of the anal canal that is necessary to
understand and to perform rigid rectosigmoidoscopy is covered in
Chapter 59 describing the anatomy for anoscopy (Figures 59-1 and 59-2).
The gross anatomy of the colon is reviewed in Figure 60-1A. It is important to be aware of the
large folds that impinge on the lumen of the colon called the valves
of Houston (Figure 60-1B). These folds
must be gently flattened to advance the rigid rectosigmoidoscope
and clearly see the proximal side of the valve when looking for
pathology. It is also necessary to understand the three-dimensional
path followed by the distal colon, rectum, and anus. The direction
to follow will be towards the patient’s umbilicus for 3
to 5 cm initially. The anus then turns posteriorly as it becomes
the rectum and follows the curve of the sacrum. The rectosigmoid
junction is reached at 10 to 15 cm, at which point the lumen sharply
angulates anteriorly and to the left. Because the scope is rigid
and straight, it is necessary to angle the tip of the rigid rectosigmoidoscope
towards the lumen of the bowel and then gently flatten the haustra
or move the patient’s colon so that the lumen is in a straight
Anatomy of the colon. A. The
gross anatomy. B. Cross-section through
the colon demonstrating the valves of Houston.
Many of the indications for rigid rectosigmoidoscopy are the
same as those for performing flexible sigmoid-oscopy. The rigid
scope is more useful when the bowel is not properly prepared, if
a bigger biopsy is needed, or if a larger instrument needs to be
passed to the last 25 centimeters. The following is a list of such
The rigid rectosigmoidoscope may be used to evaluate the rectum
and sigmoid colon in the office or the Emergency Department. Rectal
bleeding can be evaluated in the unprepared patient. It is particularly
helpful to determine if stool is mixed with blood when evaluating
hematochezia and determining if colonoscopy is indicated. Foreign
bodies in the rectum or sigmoid colon can be removed. The ...