Surgery of the spleen (Proceedings)

Surgical procedures performed on the spleen include biopsy, partial splenectomy, and total splenectomy. Techniques employed for each procedure varies with the clinical presentation and, to some degree, surgeon preference. Splenic disease represents an important source of morbidity and mortality in aging dogs. While successful splenectomy is frequently accomplished in dogs and cats, postoperative complications affecting both patient morbidity and mortality still persist.

Anatomy and function of the spleen

The spleen is suspended by the greater omentum and is attached to the greater curvature of the stomach by the gastrosplenic ligament. The left limb (lobe) of the pancreas is associated with the gastrosplenic attachments and should be located and preserved during splenectomy (particularly associated with splenic torsion). The blood supply of the spleen (splenic artery) enters the visceral surface at the hilus. The splenic artery usually arises from the celiac artery and divides into multiple smaller hilar branches before entering the spleen. Veins exit the spleen, parallel the arteries, and enter the portal vein. Dogs have a sinusoidal spleen, while the feline spleen is nonsinusoidal. While not essential for life, splenic functions include erythrocyte conditioning and maintenance, erythrocyte and platelet storage, extramedullary hematopoiesis, and filtration of circulating antigens and clearance of microorganisms.

Splenic biopsy

Methods of sampling the spleen include needle biopsy under ultrasonic or direct visual (i.e., surgical) guidance, use of a skin biopsy punch, wedge resection, and partial splenectomy. Use of a skin biopsy punch (e.g., 6 mm size) enables versatility in the sampling of splenic lesions. The defect is closed by placing a cruciate mattress suture in the splenic capsule and parenchyma. Peripheral splenic lesions can be sampled using the wedge resection technique. Full-thickness horizontal mattress sutures (e.g., 3-0 PDS) are placed through the splenic parenchyma to isolate the area of interest. Metzenbaum scissors are used to excise the splenic tissue distal to the sutures. This portion of the spleen is covered with greater omentum. A partial splenectomy results in larger splenic biopsy samples than the previous techniques. Determine the portion of the spleen to be resected and ligate and divide the hilar vessels supplying the portion of interest. Sharply divide the spleen along the line of demarcation created by the vascular ligations. Place a simple continuous suture line in the splenic capsule on the remaining portion of spleen. Alternatively, a stapling device (e.g., TA 55) may be used to provide hemostasis. Cover the edge of the spleen with greater omentum.

Splenic torsion

Torsion occurs when the spleen rotates around its vascular pedicle. Venous obstruction and subsequent splenomegaly result. This surgical condition is most commonly reported in large- or giant-breed dogs with deep-chested conformation. This condition is most often seen as an isolated event; however, it may occasionally be seen in animals with gastric dilatation-volvulus. Two different clinical presentations have been described for dogs with splenic torsion: acute and chronic. Dogs with splenic torsion that present acutely often exhibit significant abdominal pain and collapse. Dogs that present less acutely exhibit nonspecific signs of intermittent abdominal pain, vomiting, anorexia, abdominal distention, and possibly polyuria and polydipsia. Hemoglobinuria may be noted on urinalysis in the chronically presenting dogs. Hematologic findings for dogs with splenic torsion frequently include leukocytosis, anemia, and thrombocytopenia. Serum biochemical findings are often nonspecific. Imaging modalities for diagnosing splenic torsion often includes abdominal radiography and ultrasonography. Radiographic findings may include a mid-abdominal mass and loss of abdominal detail. Abdominal ultrasonography is an excellent diagnostic tool for dogs with suspected splenic torsion. Findings often include generalized splenomegaly, evidence of splenic infarction, a twisted splenic pedicle, and absence of blood flow through the splenic vessels on Doppler evaluation. Definitive diagnosis may be made on emergency exploratory laparotomy.

After a standard approach to the ventral abdomen, the enlarged, discolored, engorged spleen is evaluated. Total splenectomy is performed with the splenic pedicle in its twisted state. Prior to en masse ligation of the twisted pedicle, confirm the location of the left pancreatic lobe (limb). Use one or two large diameter suture material (e.g., #1 PDS) to ligate the entire splenic vascular pedicle. Remove the spleen from the surgical site and slowly untwist the pedicle. Closely observe the untwisted vascular pedicle for hemorrhage and place additional ligatures, as needed. Delayed hemorrhage is a relatively common postoperative complication after splenectomy to treat splenic torsion. Take care to assure that the vascular pedicle is not bleeding prior to closing the abdomen. Intraoperative peritoneal lavage is often performed due to the presence of a hemorrhagic effusion.

Splenic neoplasia

Primary neoplasms of the spleen are relatively commonly encountered in dogs. Of splenic lesions in dogs, approximately 50% are likely to be neoplastic, while only approximately 37% of feline splenic lesions are neoplastic. Hemangiosarcoma is the most common neoplasm of the canine spleen. Other histological types encountered include leiomyosarcoma, liposarcoma, and histiocytoma. Feline splenic tumors include lymphosarcoma and mast cell tumor. Non-neoplastic causes of splenomegaly (e.g., splenic hematoma) may mimic the clinical presentation of splenic neoplasia (e.g., hemoabdomen). Differentiation of these two very different problems requires histopathologic testing. Clinical signs exhibited by patients with splenic tumors are variable, but may include anorexia, vomiting, cardiac arrhythmias, and collapse. Physical examination findings may include a palpable abdominal mass, abdominal pain, pale mucous membranes, and a distended abdomen. Abdominal radiographs and ultrasound frequently demonstrate a definitive abdominal mass. Presurgical stabilization may be necessary prior to the surgical treatment of the patient with a splenic mass, particularly if the surgery is performed on an emergent basis.

An exploratory laparotomy is performed. Surgical goals include evaluation of extent of disease, removal of gross evidence of disease (especially splenic disease), and biopsy of appropriate tissues (e.g., liver and lymph node[s]). Complete splenectomy can be performed by ligation of individual hilar vessels or ligation of the major splenic vessels (including short gastric vessels). If the latter technique is used, preservation of the blood supply to the left lobe of the pancreas is verified. Greater omental adhesions to the spleen require additional ligation and transection. Location and extent of the splenic mass may complicate the ligation of individual hilar vessels. Hemostatic security is necessary, as coagulopathies may be coexistent.

Splenic trauma

Blunt splenic trauma is most frequently associated with vehicular trauma, although other causes may include kicks from large animals or bite wounds. While hemorrhage secondary to splenic lacerations and blunt parenchymal lesions is not usually a major cause of morbidity in dogs and cats, trauma or laceration to major splenic vessels or traumatic splenic transection injuries can induce life-threatening hemorrhage. Surgical options for treating splenic trauma include using topical hemostatic agents, primary surgical repair (i.e., suturing defects), and partial or complete splenectomy.