Acute Abdomen, Bowel Obstruction, and Fistula

Acute Abdomen: General Considerations

The surgical approach to a patient with an “acute abdomen” entails evaluation of potentially life-threatening problems and determination of whether emergency surgery is warranted. In patients with cancer, the etiology of acute abdominal pain may arise directly from a malignant process, but it may also stem from a seemingly unrelated process. Problems that require surgical consultation include perforation, hemorrhage, infectious or inflammatory processes, obstruction, and other miscellaneous problems such as fistulae ( Box 52.1 ). In a prospective analysis of more than 1000 consecutive palliative procedures in patients with cancer, more than 50% were performed on the GI system. In this study, obstruction and bleeding made up more than 75% of the manifesting symptoms. The majority of the procedures were surgical, and the vast majority (82%) of patients experienced resolution of their initial symptoms regardless of whether surgical or endoscopic intervention was performed. Not surprising, there was a high complication rate, with 39% of patients experiencing any perioperative morbidity and 10% suffering severe morbidity. Furthermore, there was an 11% operative mortality rate, and the median survival time for the cohort was only 6 months. Therefore, the decision to perform an invasive procedure is often very challenging. This is further complicated by a patient's abnormal physiological response to injury and inflammation, the outcome from previous cancer therapies, and the competing risks of the underlying cancer. Not surprisingly, a multidisciplinary approach often proves most beneficial to the patient. In scenarios when the benefit of surgical intervention is felt to be limited, the use of medical management or minimally invasive palliative interventions is typically preferred. Interactions among the patient, the family, and the surgeon (i.e., the palliative triangle), as well as the patient's primary treating oncologist, are critical in making an individualized plan of care for the patient.

Abdominal pain is the most common symptom in a patient with an acute abdomen. In those patients with an intraabdominal malignancy who are undergoing chemotherapy and/or radiation therapy, the etiology of abdominal pain must be investigated thoroughly. Care must be taken to avoid inappropriately attributing these complaints to cancer progression. Other related symptoms and signs (e.g., emesis, abdominal distention, obstipation, fever) should also raise concern for an emerging problem. On physical examination, tenderness to palpation is the most common finding because peritonitis almost invariably produces localized or diffuse abdominal tenderness. Nonreassuring clinical findings, such as hemodynamic instability or deterioration of symptoms during the course of evaluation, should also be considered seriously. Similarly, patients taking corticosteroids or exhibiting an altered sensorium warrant special attention because their physical examination may be unreliable. In short, there is no substitute for a thorough history and physical examination.

A comprehensive differential diagnosis is important in directing the course of subsequent evaluation and treatment. Laboratory tests and diagnostic imaging studies can help narrow the nature of the problem. Standard laboratory studies should include a complete blood cell count and electrolyte panel. Leukocytosis is often evident if an intraabdominal infection is present. However, chemotherapy-induced neutropenia or immunosuppression might prevent the white blood cell count from adequately reflecting an infectious or inflammatory process. Similarly, patients with acute leukemia may demonstrate a persistent leukocytosis, rendering this test unreliable. Liver function studies and a serum amylase level are helpful in patients with upper abdominal complaints when hepatobiliary or pancreatic etiology is suspected. Patients with evidence of GI bleeding require serial hemoglobin tests to assess the severity and magnitude of the bleeding; thrombocytopenia and coagulopathy should be corrected when possible.

If an intraabdominal process is suspected, diagnostic imaging can aid in making the appropriate diagnosis. The use of “routine” imaging studies, such as plain radiographs and abdominal ultrasonography, can provide safe and timely data to guide care. For a patient who is medically stable, a computed tomography (CT) scan of the abdomen and pelvis can also provide great insight into the etiology of a suspected intraabdominal process. Acute findings (e.g., pneumoperitoneum, ascites, pneumatosis intestinalis, portal venous gas, hemorrhage, GI or biliary obstruction) can quickly narrow the differential diagnosis. At the same time, a CT scan can provide important information about the patient's cancer; identifying a response to treatment vs. progressive disease may impact care. Invasive testing, such as endoscopic evaluation or arteriography, may also be useful in certain circumstances. Despite the increased risk of these procedures, they are often therapeutic and can avoid more invasive or risky surgical procedures.

Ultimately, the surgeon must determine whether a patient has an acute abdominal process that requires surgical intervention. The choice to operate on an acutely ill patient with cancer is difficult and can test the judgment of even the most experienced surgeon. To simplify surgical decision making, the stage and prognosis of a patient's cancer should be main factors because they dictate the intent (i.e., therapeutic versus palliative) of a surgical procedure. When a procedure can simultaneously treat an acute abdominal process and an underlying malignancy, it is a straightforward decision for both the surgeon and patient. On the other hand, a procedure that is only palliative in nature is far more challenging. Even when cure is unrealistic, surgeons can still offer cancer patients relief from symptoms and improved quality of life. As such, it is estimated that between 6% and 21% of cancer operations are classified as palliative in nature. However, attempts at successful palliation must be balanced with inappropriately aggressive attempts, which may carry unacceptable rates of morbidity and mortality or result in ineffective palliation.