Exploratory Laparotomy and Oncologic Abdominal Emergencies

Introduction

Emergencies often occur because of an underlying oncologic problem and pose a challenge for the medical and surgical oncologist. Many tumor-related emergencies require immediate surgical intervention but are complicated by the debilitated state of the patient or ethical concerns for the patient’s ultimate prognosis. The acute nature of the problem, the physical status of the animal, and the availability of alternative treatment determine the necessity of immediate surgery. A decision has to be made in which the progression of the disease, general health status of the animal, and experience of the clinician are of extreme importance. All these factors influence surgical morbidity and mortality, the extent of surgery, postoperative management, and overall prognosis. Thus, every oncologic emergency requires a thorough evaluation and individual therapeutic approach.

The surgeon often has a central role in the diagnosis, treatment, and aftercare of the cancer patient in an emergency situation. The first step in managing the emergency is to evaluate the patient’s pathophysiologic status and eliminate immediate threats to the patient’s life. The anamnesis should include previous oncologic diagnoses, procedures, and therapies. At the same time, a cursory physical examination will point out signs of life-threatening complications that should be dealt with immediately to stabilize the patient’s physical functions. After stabilization, a thorough physical examination is performed and a diagnostic and therapeutic plan is formulated. Further diagnostic steps include general tests (complete blood count, biochemistry and clotting profiles, and urinalysis) and cancer-specific tests (fine needle aspiration, radiography, ultrasonography, CT- and MRI scans).

The timing, selection, and purpose of surgical therapy varies with the type of cancer and the site of involvement. Timing depends on whether the emergency involves 1) a patient with stable vital functions and a problem requiring surgical correction, 2) a patient with compromised vital functions and a delayed threat to life, or 3) a patient with an immediate threat to life requiring surgical correction. Immediate surgery is only necessary in life-threatening situations and should be accompanied by adequate supportive care. The goal of surgery may be complete excision of the tumor and cure, palliation, cytoreduction, or histologic confirmation of the tumor type. Regardless of resection type, surgery should resolve the emergency situation. Complete excision of the tumor is the hopeful goal of surgery. Palliative surgery must improve the patient’s quality of life, and perhaps prolong it. The aim of cytoreduction is to decrease tumor bulk to improve the efficacy of adjunctive treatment. Cytoreduction without adjunctive therapy is of no benefit to the patient.^3,4 Biopsy specimens always should be examined to aid in evaluating the prognosis and further therapy.

Postoperative management includes monitoring the return of normal physiologic functions, evaluation of wound healing, the use of adjunctive therapy, and periodic assessment of tumor recurrence and metastasis. Intensive supportive therapy is often necessary after emergency surgery and may include intravenous administration of fluids, blood, or plasma, antibiotic therapy, and nutritional support.

The benefits of surgical intervention in cancer patients must be weighed against the risks of surgery. Operative morbidity and mortality depend on the basic disease process, the surgical procedure, anesthesia, and the patient’s general status and ability to withstand operative trauma. In oncologic patients, the basic disease process and debilitated state of the patient are major determinants of operative morbidity and mortality. Surgery may alleviate clinical signs in an emergency situation but mortality rates can be high. Every emergency cancer patient should be evaluated individually and carefully, and the risks and benefits of therapy should be explained to the client.

Exploratory Laparotomy

The ventral midline approach is the standard access route for almost all of the abdominal contents and should be referred to as celiotomy. A laparotomy strictly refers to flank incisions.

The aim is to incise through the linea alba and to avoid cutting into the rectus abdominal muscles. This is caudally more difficult than cranially, because the width of the linea decreases caudally. The falciform ligament is the first organ that is encountered. To improve the exposure of the abdomen this ligament is normally dissected and ligated cranially. Insufficient ligation may lead to abdominal hemorrhage. The abdomen should always be explored in a standard manner to avoid skipping certain abdominal structures. The author prefers a cranio-caudal method starting with the diaphragm and liver and ending with the caudal GI tract. Closure of the abdomen is performed by a continuous closure pattern of absorbable monofilament suture material.

Hemorrhagic Abdominal Emergencies

Pathophysiology

Hemorrhagic abdominal emergencies develop secondary to direct extension and ulceration of various malignant tumor types into the peritoneal cavity, or to rupture of an organ enlarged from tumor invasion. Abdominal hemorrhage is most frequently associated with splenic or hepatic tumors. The most common canine splenic tumor is hemangiosarcoma. It usually affects older animals and metastasizes in more than 50% of cases to other organs including lungs, heart, liver, kidney, omentum, and peritoneum. Mast cell tumor and malignant lymphoma occur most frequently in the spleen of cats. Any enlarged spleen may rupture, resulting in internal blood loss and hypovolemic shock.

Primary hepatic tumors occur in older dogs and cats but are rare. Hepatocellular carcinoma is most common and it frequently metastasizes to regional lymph nodes, lung, and peritoneum. More common than primary hepatic tumors, metastatic tumors include malignant lymphoma, pancreatic adenocarcinoma, and hemangiosarcoma. Massive hemorrhage can occur from any hepatic tumor and may require emergency laparotomy.

Clinical Presentation and Diagnosis

Abdominal hemorrhage results in abdominal enlargement, pale mucous membranes, lethargy, abdominal pain, tachycardia, tachypnea, and vomiting. Clinical signs vary with the severity of bleeding. In patients with exsanguinating hemorrhage, clinical signs of hypovolemic shock will predominate.

Once a diagnosis of abdominal effusion is made, little additional information is obtained by radiographic examination. The presence of fluid decreases the value of radiography but enhances the use of ultrasonography. Radiography after removal of fluid by abdominal paracentesis may improve visualization of intra-abdominal structures and assist in diagnosis. Fluid obtained should be examined cytologically. Neoplastic cells may be identified in aspirated fluid but neoplastic disease should not be excluded on basis of negative findings. To differentiate hemorrhage from serosanguinous exudate, the packed cell volume and white blood cell counts are compared to those of peripheral blood. The packed cell volume of serosanguinous exudates rarely exceeds 5%. An increase in packed cell volume in sequential samples may indicate continuing intraabdominal bleeding.

Alternatively, intraabdominal masses can be diagnosed by ultrasonography and guided fine needle aspiration. Non-diagnostic samples are relatively common because of sampling errors and because little material is obtained from some tumor types. Definite diagnosis may require histologic examination of a surgical biopsy specimen. In patients with abdominal hemorrhage, clotting ability should be investigated before surgery since disturbances can be caused by the tumor. In up to 50% of dogs with splenic hemangiosarcoma there is diffuse intravascular coagulation.

Surgical Therapy and Aftercare

The clinical status of the patient dictates the type of treatment. An initial period of medical stabilization prior to surgical intervention may improve prognosis. Supportive therapy consists of intravenous fluid, hypertonic saline, or colloid therapy, blood transfusions, and pressure wraps. Blood transfusions are often necessary in dogs with exsanguinating abdominal hemorrhage. Autotransfusion, rather than heterologous blood transfusion, is contraindicated in tumor-induced abdominal hemorrhage, because it can spread tumor cells. Increased intraabdominal pressure by application of an abdominal pressure wrap may help control hemorrhage. Compressive abdominal and pelvic bandages are the practical alternative for seldom available antishock garments.

Emergency laparotomy is indicated if, despite fluid and blood replacement, the animal deteriorates. The abdomen should be thoroughly explored to locate the source of bleeding and search for signs of metastases. Total splenectomy often is life-saving in hemorrhaging splenic malignancies, but a cure is rarely obtained. The prognosis for dogs with a ruptured hemangiosarcoma after splenectomy is poor, because of the tumor’s aggressive metastatic behavior. An average survival time of 2 months without and 6 months with adjuvant chemotherapy has been reported. In contrast to malignant tumors, benign splenic tumors have an excellent prognosis after surgical removal. The use of ligating-dividing staplers (LDS) allow expedient and safe surgical removal of hemorrhaging splenic neoplasms.