Author

Stephen J. Birchard DVM, MS, Diplomate ACVS

Tuesday, September 17, 2013

Intestinal Biopsy: When, and How?


Fig. 1: Intestinal segment from a dog with chronic diarrhea.
Note dilated lymphatics and whitish plaques in the mesentery.
Histopathology of biopsy samples revealed lymphangiectasia.

You are in the middle of an abdominal exploratory on a dog with chronic vomiting and diarrhea. You were REALLY hoping to find a foreign body but no such luck. The only abnormality is some thickened intestine with what looks like some dilated lymphatics and a couple of small whitish nodules just under the serosa.(Fig. 1) You know you should obtain a full thickness biopsy of that intestine but how will you do it, will it heal without complications and will you be able to sleep at night worrying about it?

Indications

Biopsy of the intestine is indicated for a variety of reasons. Chronic vomiting or diarrhea of unknown etiology, chronic hypoproteinemia of intestinal origin, and suspected intestinal neoplasia are all disorders that may require a full thickness intestinal biopsy for definitive diagnosis. A classic indication for full thickness biopsy is to differentiate between inflammatory bowel disease and lymphosarcoma in cats. Surgical biopsies were found to be preferred over endoscopic biopsies in one study of 22 cats.1

Instruments

Certain surgical instruments are helpful for performing meticulous and atraumatic intestinal surgery. Suction is mandatory to help prevent spillage of intestinal contents. Use DeBakey thumb forceps to handle the bowel instead of Brown-Adson or Adson forceps.(Fig.2) 
Fig. 2
Handle the bowel very gently and avoid grabbing the full thickness of the intestine to minimize trauma. Be sure to have 4-0 PDS suture with the R-B1 taper needle. Skin biopsy punches, size 4mm-6mm, will also be necessary. One last thing, be sure to have plenty of sterile blue towels just in case you decide to take pictures of the affected area of intestine.  (See Fig. 1; my former students and residents will understand that strange statement.)

Surgical Technique

Isolate the segment of intestine to be sampled with moistened sponges and place stay sutures on the anti-mesenteric surface. Make a small elliptical incision in the antimesenteric aspect of the intestine using a #15 scalpel blade and Metzenbaum scissors. (Fig. 3) 
Fig. 3: Biopsy of the intestine using scalpel.
An initial stab incision can be made and then the tissue sample trimmed out with scissors. Alternatively, my preferred technique is to use a 4, 5, or 6 mm skin biopsy punch to obtain the tissue sample.(Fig. 4-5)
Fig. 4: Intestinal biopsy using a biopsy punch.
Fig. 5
While holding the intestine with one hand gently place the punch on the antimesenteric side of the bowel and twist it while pushing toward the lumen to make the full thickness cut. It is usually possible to feel when the punch has completely cut through the bowel wall and is in the lumen. Take care not to cut the mesenteric side as well. After pulling out the punch sometimes the tissue sample remains attached to the bowel by a small amount of mucosa and will require trimming it out with Metzenbaum scissors. Occasionally the sample may actually drop into the lumen and out of sight. Gently squeezing the bowel will bring the sample back out through the incision.

Close the biopsy site with 4-0 PDS in a simple interrupted or simple continuous fashion taking full thickness bites of the intestine.(Fig. 6)
Fig. 6: Closure of biopsy incision after scalpel incision.
Polypropylene (4-0) can be used in animals that may have delayed healing. Punch biopsy incisions generally require 2 or 3 simple interrupted sutures.(Fig. 7) These small incisions can be closed either longitudinally or transversely depending on surgeon preference.
Fig. 7: Closure of biopsy incision after punch technique.
Perform a leak test by occluding the bowel on both sides of the sampled area and injecting 5-10cc of sterile saline. Massage the segment to see if any saline leaks out through the incision and place additional sutures if necessary.

To provide a thorough evaluation of the intestinal disorder obtain samples from the duodenum, jejunum, and ileum. Obtain the duodenal sample from the distal duodenum to avoid injuring either the major or minor duodenal papillae. 


Postoperative Care

Postoperatively provide the standard care for a GI surgical patient, i.e., analgesics, intravenous fluids until eating and drinking, prophylactic antibiotics given only during the perioperative period, and famotidine and sucralfate. The famotidine and sucralfate can be continued for several days postoperatively.

References

Sarah E. Evans, DVM; Jennifer J. Bonczynski, DVM, DACVS; John D. Broussard, DVM, DACVIM; Eveline Han, VMD, DACVIM; Keith E. Baer, DVM, DACVP
Comparison of endoscopic and full-thickness biopsy specimens for diagnosis of inflammatory bowel disease and alimentary tract lymphoma in cats. J Am Vet Med Assoc November 1, 2006, Vol. 229, No. 9, Pages 1447-1450