Exploratory laparotomy (celiotomy) is often indicated when a disease process involving a structure within the peritoneal cavity requires diagnosis, prognosis, or therapy. Ideally, exploratory laparotomy provides an opportunity for both a definitive diagnosis and therapeutic intervention. Similar to performing a physical examination, one should be thorough, efficient, and consistent when performing an exploratory laparotomy.^1,2 Biopsy with histologic examination should be a part of essentially every exploratory laparotomy in which a direct surgical diagnosis (e.g., enteric foreign body, intussusception) is not achieved. Basingan interpretation on gross evaluation alone during an exploratory celiotomy assures that an accurate definitive diagnosis will not be reached in too many instances. Tissues biopsied at laparotomy often include liver, intestine, lymph node, kidney, prostate, stomach, spleen, and pancreas. Less commonly biopsied tissues are urinary bladder and greater omentum.

Liver Biopsy

One of the simplest methods is the suture fracture of guillotine technique. This method is limited in that only the periphery of a liver lobe may be sampled, although variably sized samples may be obtained. Use a loop of suture material (e.g., 2-0 polydioxanone) to strangulate liver tissue proximal to the proposed biopsy site. Sharply divide the liver tissue distal to the ligature. Use a wedge resection technique to remove larger biopsy samples. Place two rows of overlapping, full-thickness horizontal mattress sutures through the liver. Excise the specimen distal to the sutures. After either of the above methods, cover the incised edge of liver with greater omentum. Another versatile method of liver biopsy involves use of a skin biopsy punch^a. Any portion of the liver may be sampled using this method; however, smaller, partial thickness samples are obtained. Drill the biopsy punch into the hepatic tissue and twist it to obtain the specimen. Avoid excessively deep penetration into the hepatic tissue to avoid larger vessels. Insert either a topical hemostatic agent (e.g., absorbable gelatin sponge) or omentum into the defect.

Intestinal Biopsy

Principles of intestinal biopsy acquisition include the need to perform multiple biopsies along the length of the small intestine, obtain full-thickness samples, and protect the properly closed biopsy site. Technical considerations include size of the biopsy specimen to acquire, closure technique, and method of protection of the enteric incision. Intestinal biopsies are efficiently obtained using a skin biopsy punch. Use a 6 mm biopsy punch in dogs and a 4 mm biopsy punch in cats^a. Position the biopsy punch at the antimesenteric aspect and exert rotary forces, taking care to avoid trauma to the opposite (mesenteric) aspect of the intestine. Complete the transection by using Metzenbaum scissors at the base. Close the defect transversely in a single layer using a full-thickness appositional suture pattern (e.g., simple interrupted) of synthetic absorbable suture (e.g., 4-0 polydioxanone).³ A wedge resection technique, with the wedge centered on the antimesenteric aspect and oriented transversely, yields larger samples. Techniques for visceral wound protection include use of greater omentum or a serosal patch. Use greater omental coverage of the properly closed biopsy site when uncomplicated wound healing is expected. Place a serosal patch in situations of potential delayed wound healing (e.g., peritonitis or possibly hypoproteinemia).

Lymph Node Biopsy

Abdominal lymph nodes frequently sampled by the author include one or more from the following lymph centers: celiac lymph center (pancreaticoduodenal), cranial mesenteric lymph center (left colic), and iliosacral lymph center (medial iliac). Excisional or incisional biopsies are preferred to simple aspiration to provide morphologic interpretation. Preserve regional blood supply to adjacent tissue during excisional or incisional biopsies. For excisional biopsies, interrupt the blood supply to the lymph node with sutures or electrosurgery, and carefully dissect the lymph node from surrounding tissues. Minimize trauma to avoid tissue distortion.

Kidney Biopsy

Kidney biopsies provide both diagnostic and prognostic information. Biopsy may be achieved using either a needle biopsy technique or a wedge resection technique. For a needle biopsy, insert the needle^b through the renal capsule at the caudal aspect of the kidney and direct it within the cortex toward the cranial pole. Exert digital pressure to achieve hemostasis at the needle exit site. Wedge resection biopsies yield larger, more reliable biopsy specimens, yet have a higher risk of hemorrhage during and following biopsy. Incise the renal capsule and excise a wedge-shaped segment of renal cortex using a #15 scalpel blade. Close the defect using mattress sutures placed through the renal capsule and parenchyma. Hemostasis may be enhanced by incorporating greater omentum into the closure.

Prostatic Biopsy

Prostatic biopsies may be performed by either needle biopsy or wedge resection (incisional) techniques. Exposure of the prostate gland is aided by exteriorizing and applying cranial traction on the urinary bladder with a stay suture. Incisional biopsies provide more tissue for interpretation; however, they have more potential for complications, such as hemorrhage, infection, or urine leakage. Techniques of needle and incisional biopsy of the prostate gland are similar to those used for the kidney. Take care to avoid penetrating the prostatic urethra during biopsy.

Gastric Biopsy

Gastric biopsies are usually performed in association with gastrotomy. Obtain the specimen by excising an elliptical section of full-thickness gastric wall from one side of the gastrotomy wound edge. Close the stomach wall in two layers (mucosa/submucosa and seromuscular) using a simple continuous pattern of synthetic absorbable suture material (e.g., 3-0 polydioxanone).

Splenic Biopsy

One technique for splenic biopsy is the wedge resection technique. After placement of a row of overlapping, full-thickness horizontal mattress sutures, excise the specimen by sharp dissection distal to the sutures. Oversew the edges with a simple continuous pattern of synthetic absorbable suture material (e.g., 4-0 poliglecaprone 25). Greater omentum also may be incorporated. Alternatively, a biopsy punch may be used to obtain splenic tissue. Larger splenic samples may be obtained by performing a partial splenectomy.

Pancreatic Biopsy

A partial pancreatectomy is used to perform a pancreatic biopsy. Carefully bluntly dissect the pancreatic parenchyma near the end of one lobe of the pancreas to expose pancreatic ducts and blood vessels. Doubly ligate vessels and ducts with monofilament synthetic absorbable (e.g., 4-0 polydioxanone) or nonabsorbable (e.g., 4-0 polypropylene) sutures and transect the tissue distal to the ligatures.

Biopsy of Other Tissues

Urinary bladder biopsies are usually taken at the time of cystotomy. Obtain an elliptical shaped full-thickness specimen from one edge of the cystotomy wound margin. Microbiologic sampling of a part of the excised tissue may be indicated. Close the cystotomy incision in one (normal bladder wall thickness) or two (thickened bladder wall) appositional suture lines using synthetic absorbable suture material (e.g., 4-0 polydioxanone). Greater omental biopsies are achieved by excising a section of omentum isolated by sutures. Preserve the greater omentum whenever possible, as its functions benefit the healing of visceral wounds.

Wound Closure Considerations

Sutures in the body wall should incorporate the linea alba and external fascial sheath of the rectus abdominis muscle only, being placed to incorporate 6 to 8 mm of fascia on each aspect of the incision. Closure of a paramedian body wall incision is accomplished by suturing the external fascial sheath only. Peritoneum, muscle, and internal fascial sheath are not sutured, as fewer complications result. Achieve apposition of wound edges. Either continuous or interrupted suture patterns using either synthetic absorbable (e.g., polydioxanone) or nonabsorbable (e.g., polypropylene) suture material is acceptable. Close the subcutaneous tissue and skin routinely.

Summary

Biopsy of abdominal tissues is an important part of an exploratory laparotomy whenever a direct surgical diagnosis is not achieved. Efficient and effective methods for sampling most abdominal tissues are available. Goals of biopsy include obtaining representative sample(s), maximizing information to the veterinary pathologist, and minimizing patient morbidity.

Endnotes

a. Baker's biopsy punch, Baker Cummings, Key Pharmaceuticals, Miami, FL 33169, USA
b. Tru-Cut^® disposable biopsy needle, Travenol Laboratories, Inc., Deerfield, IL 60015, USA

References

1.  Pastore GE, Lamb, CR, Lipscomb V. Comparison of the results of abdominal ultrasonography and exploratory laparotomy in the dog and cat. J Am Anim Hosp Assoc. 2007;43:264.

2.  Boothe HW, Slater MR, Hobson HP, et al. Exploratory celiotomy in 200 nontraumatized dogs and cats. Vet Surg. 1992;21:452.

3.  Matz BM, Boothe HW, Wright JC, et al. Effect of enteric biopsy closure orientation on enteric circumference and volume of saline needed for leak testing. Can Vet J. 2013;55:1255.