Page 555 - Clinical Small Animal Internal Medicine

49 Gastrointestinal Endoscopy 523

starting the evening before the procedure is planned. Patient Positioning
VetBooks.ir The solution is dosed three times (each at 20–25 mL/kg) bence for isolated proctoscopy procedures without
Typically, the patient is placed in right lateral recum-
at 2–3‐hour intervals, starting approximately 18 hours
assessment of the transverse or descending colon and
before the procedure is planned (early afternoon the day
before a planned morning procedure). The solution is ileocolic junction. Right lateral recumbence causes any
administered via either intermittent orogastric intuba- residual fluid from patient preparation to pool into the
tion or by mixing it with plain vanilla ice‐cream (one part transverse colon (which is oriented vertically when the
ice‐cream to two parts solution) and allowing the patient animal is in lateral recumbence), aiding in mucosal
to drink it. Many dogs will readily consume the resulting visualization.
solution. If oral intubation is used, the author considers
nasogastric intubation and trickle infusion to be strongly Equipment Choice
contraindicated, as this is associated with increased risk Proctoscopy can be achieved with either flexible or rigid
of aspiration pneumonia, which can be severe and life endoscopes. Refurbished human flexible colonoscopes,
threatening. up to 11 mm diameter, can be effectively used in most
As the last of the evening doses of oral preparation dogs and cats, although some endoscope manipulations
solution is given, a warm water enema (also 20–30 mL/ such a J‐maneuvers (necessary for effective visualization
kg) is administered. The warm water enema is repeated of some very distal rectoanal lesions) can be challenging
early in the morning on the day of the planned procedure or impossible with this size endoscope in smaller dogs
(around 7am for a 9am procedure), which should result and most cats.
in passage of clear fluid with little to no fecal material or Rigid proctoscopes can be very valuable for these pro-
mucus. If the morning enema continues to produce solid cedures, as they usually feature large endoscope lumens
fecal material, ideally the procedure will be delayed by that allow passage of larger instruments, biopsy and cau-
1–2 hours to allow a second morning enema, followed by tery snares, and rigid forceps.
at least an hour of resting time to allow fluid absorption
and resolution of transient irritation of the colonic General Technique and Landmarks
mucosa. The rigid proctoscope is lubricated well and introduced
An adequately prepared colon will allow easy and rela- through the anal sphincter gently, while an obturator is
tively unimpeded observation of the colonic mucosa in place. When resistance to passage of the proctoscope
over the length of the large intestine. Minor adherent reduces, marking entry of the proctoscope into the rec-
material and mucus can usually be lavaged and flushed tum, the obturator device is removed and the lighting
from the colon using endoscope suction. Specific colo- and visualization system (typically a rigid fiberoptic tel-
noscope irrigation and washing pump systems are avail- escope and accessory camera) are attached. The procto-
able and routinely used in human patients, and may be scope is then gently introduced into the colon lumen,
worth consideration in veterinary practices that carry while the operator closely observes the mucosa. Air
out a large number of large intestinal procedures. While insufflation is used as necessary to inflate and maintain
these pumps and washing systems can assist with final the colonic lumen. Rigid proctoscopes should not be
cleaning and visualization of the colonic mucosa, they advanced if the lumen is not visible, as this increases the
are not a replacement for adequate preprocedural risk of colon wall perforation, which is a major and
preparation. potentially life‐threatening complication.
With the larger lumen of the proctoscope, there is the
potential to use larger, rigid biopsy forceps and instru-
Proctoscopy
ments to collect more substantial pieces of tissue than
Indications with typical biopsy instruments used in flexible endo-
Proctoscopy is a useful technique for the assessment of scopes. Some rigid biopsy instruments feature angled
patients with predominantly or exclusively large intesti- biopsy cups, which make the process of sampling the
nal symptoms, such as tenesmus, excess fecal mucus, mucosa through the rigid lumen somewhat easier. Rigid
fecal urge incontinence, hematochezia, dyschezia, and instruments with straight biopsy cups are still useful, but
visible or palpable anorectal masses. As many of the may require removal of a small amount of insufflated air
mucosal diseases affecting the large intestine tend to be to allow the mucosa to “drape” over the front of the endo-
diffuse throughout the large intestinal lumen, and ano- scope lumen.
rectal diseases are by definition limited to the distal large
intestine and anal canal, proctoscopy may be all that is Normal Findings and Potential Abnormalities
necessary to establish a useful working diagnosis in a Normal findings and potential abnormalities encoun-
large intestinal disease case. tered during proctoscopy are identical to those seen