The Abdominal Exploratory: Surgery as a Diagnostic Tool

Surgical exploration of the abdominal cavity can be a valuable diagnostic tool, particularly when imaging is equivocal in helping discover what is wrong with an animal. Gastrointestinal obstruction is one such clinical example, where surgery can rule-in or rule-out obstruction when less invasive methods are unrewarding. Abdominal exploratory and subsequent organ biopsies are also used to assist in diagnosis of chronic disease and to differentiate between benign and malignant processes. Stomach and proximal intestinal biopsies are commonly performed using endoscopy. However, biopsies are limited to the mucosal surface and are often only representative of those areas. Abdominal surgery allows for complete exploratory and examination of the entire length of the gastrointestinal tract Full-thickness samples can be retrieved from the duodenum, jejunum, and ileum to diagnose diseases such as inflammatory bowel disease, lymphangiectasia, and lymphoma. Routine sampling of the liver and lymph node should be considered when in the abdomen for removal of a possible malignant process (e.g., splenic mass, focal intestinal mass).

What should the length of an abdominal incision be for complete abdominal exploratory?

What should be done with the falciform fat?

What is the value of a surgical safety checklist?

Similar to a physical examination, a routine for abdominal exploration should be developed such that nothing will be overlooked. An exploratory can be performed by system or by quadrant; one approach is “cranial-right-left-caudal”:

• Starting cranially, the diaphragm is observed and then the liver is evaluated. Each lobe of the liver can be gently manipulated such that all surfaces are examined. From left to right, the lobes of the liver are left lateral, left medial, quadrate, right medial, right lateral, and caudate. The gallbladder sits between the quadrate and right medial lobes and can be gently palpated; some prefer to express the gallbladder to ensure patency of the common bile duct, but this is often unnecessary if hepatobiliary disease is not suspected. The stomach is then examined and palpated, starting at the terminal esophagus to the fundus, body, pyloric antrum, and pylorus.
• Heading to the right side of the abdomen, the descending duodenum can be lifted gently out of the abdomen to examine the structures within the mesoduodenum (right limb of the pancreas, common bile duct, and portal vein), and then the mesoduodenum is used to hold back the small intestine to examine the right kidney, caudate lobe of the liver, and the caudal vena cava, often referred to the right gutter. A normal right adrenal gland is not readily visible as it sits under the liver alongside the caudal vena cava. It is difficult to continue to follow the small intestine oral to aboral as the duodenum is tethered at the duodenal flexure by the duodenal-colic ligament.
• Heading to the left side of the abdomen, the spleen is gently examined and palpated from the tail to the head, which is tethered to the greater curvature of the stomach by the short gastric vessels. The descending colon is then lifted to allow the mesocolon to hold back the small intestine and the left kidney and left adrenal gland can be examined (left gutter). The left adrenal gland is identified by the phrenicoabdominal vein coursing back to the caudal vena cava, bisecting the gland into cranial and caudal poles. The gastrointestinal tract is then evaluated from aboral to oral, from the colon to cecum and to the ileum, which is identified by the antimesenteric vessel. Continuing orally, the jejunum is palpated back to the duodenal flexure, taking note of the mesenteric lymph nodes. To examine the left limb of the pancreas, a hole is made in the superficial leaf of the omentum to enter the omental bursa and find the pancreas just dorsal to the greater curvature of the stomach.
• Caudally, the urinary bladder and distal ureters examined. In male dogs, the prostate is palpated by passing a finger dorsal to the urethra. In intact female dogs, the entire reproductive tract is examined from the ovaries to the cervix. In spayed female dogs, the uterine stump can be found dorsal to the bladder on the ventral surface of the distal colon. Medial iliac lymph nodes are found at the bifurcation of the aorta.

Small Intestinal Biopsy

Like the stomach, intestinal biopsies are commonly performed using endoscopy. However, biopsies are limited to the mucosal surface of the duodenum. Segmental disease or abnormalities in the deeper layers of the intestine may be missed with this method, which is of particular concern in cats as the jejunum and ileum are thought to be the most common locations for gastrointestinal lymphoma. Full-thickness samples can be retrieved from the entire length of the small intestine. The large intestine is rarely surgically biopsied due to the poor healing characteristics of the colon and the risk of peritoneal contamination. A recent study examined complications associated with fullthickness biopsies of the small intestine. Twelve percent of dogs died or were euthanized postoperatively due to biopsy site breakdown. Unfortunately, no predictors for risk of dehiscence were identified.

The most conventional method to biopsy the intestine is to make 2, 1 cm, parallel, longitudinal, full-thickness incisions in the antimesenteric aspect of the bowel using a scalpel blade. An alternative to this technique is to use a 4 to 6 mm Baker’s biopsy punch to take a full-thickness sample from the antimesenteric border.

Standard Technique:

• A segment of small intestine is isolated from the rest of the abdominal cavity using moistened laparotomy sponges.
• An assistant’s fingers, Doyen intestinal forceps, Penrose drains, or umbilical tape are used to hold back ingesta.
• Make a full-thickness stab incision into the lumen of the intestine on the antimesenteric border using a #11 or #15 scalpel blade.

• Extend the stab incision 1 to 2 cm using a scalpel blade or Metzenbaum scissors. Make sure all layers of the intestine are sampled.

• Close the biopsy site using a single-layer, full-thickness, simple continuous pattern with 3-0 or 4-0 monofilament absorbable suture (e.g., Biosyn , Monocryl , PDS ).
• Consider augmenting the enterotomy site with omentum or a serosal patch if the animal is debilitated or hypoalbuminemic.

Kidney Biopsy

The kidney can be sampled percutaneously with ultrasound guidance, through a keyhole flank incision, or through laparoscopy or laparotomy. The two most common methods for sampling the kidney include needle biopsy or wedge biopsy. If exploratory laparotomy is performed, a wedge biopsy of the kidney allows a larger, more representative sample to be acquired. Hemorrhage can be controlled using digital pressure or hemostatic agents. A recent study found that wedge kidney biopsies were more likely to be of good quality compared to needle biopsies. The most common indication for renal biopsy was proteinuria while the most common complication was severe hemorrhage that occurred in approximately 10% of dogs and 17% of cats.

Technique:

• If disease if thought to be generalized, locate, and isolate the left kidney from a standard midline abdominal approach as the left kidney is more accessible due to its relative caudal location.
• Using a #15 or #11 scalpel blade, make a 1 cm wedge incision into the renal parenchyma along the dorsolateral surface.
• Place a small piece of moistened Gelfoam into the defect to control hemorrhage.
• Place a horizontal mattress suture (3-0 or 4-0 monofilament absorbable suture) through the renal capsule on either side of the wedge incision to close the defect.
• Confirm that hemorrhage has ceased before closing the abdominal cavity.

References

• Evans SE, Bonczynski JJ, Broussard JD, et al. 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 2006;229(9):1447-50
• Petre SL, McClaran JK, Bergman PJ, et al. Safety and efficacy of laparoscopic hepatic biopsy in dogs: 80 cases (2004-2009). J Am Vet Med Assoc 2012;240(2):181-5
• Radhakrishnan A, Mayhew PD. Laparoscopic splenic biopsy in dogs and cats: 15 cases (2006-2008) J Am Anim Hosp Assoc. 2013;49:41-5
• Rothuizen J, Twedt DC. Liver biopsy techniques. Vet Clin North Am Small Anim Pract 2009;39(3):469-80
• Scott KD, Zoran DL, Mansell J, et al. Utility of endoscopic biopsies of the duodenum and ileum for diagnosis of inflammatory bowel disease and small cell lymphoma in cats. J Vet Intern Med 2011;25(6):1253-7
• Shales CJ, Warren J, Anderson DM, et al. Complications following full-thickness small intestinal biopsy in 66 dogs: a retrospective study. J Small Anim Pract 2005;46:317-321
• Swinbourne F, Jeffery N, Tivers MS, et al. The incidence of surgical site dehiscence following full-thickness gastrointestinal biopsy in dogsand cats and associated risk factors. J Small Anim Pract 2017;58(9):495-503
• Vaden SL, Levine JF, Lees GF, et al. Renal biopsy: a retrospective study of methods and complications in 283 dogs and 65 cats. J Vet Intern Med 2005;19:794-801