Among the many acute abdominal conditions that confront the general surgeon, disorders involving the vascular system are in the minority. Yet these conditions are often highly lethal if undiagnosed or inappropriately treated. Because operations involving vascular exposure, control, and repair are uncommon in the practice of most abdominal surgeons, a straightforward plan to identify and manage these conditions is required for optimal success. This chapter concerns itself with the general diagnosis of acute vascular abdominal conditions, principles of vascular control and repair, and a discussion of the management of the 3 most common types of vascular emergency: mesenteric ischemia, ruptured abdominal aneurysm, and abdominal vascular trauma. Whenever possible, emphasis is placed on general principles that can be applied to a variety of conditions. Acute pathology of the gastrointestinal tract that results in hemorrhage (eg, bleeding ulcer, esophageal varices, bleeding diverticula) is not considered within this chapter.
GENERAL DIAGNOSTIC CONSIDERATIONS
Acute vascular conditions can be divided into those associated with hemorrhage and those accompanied by vascular thrombosis. The presentation within each of these 2 broad categories is generally distinct. Conditions associated with hemorrhage present with evidence of blood loss including shock. Hemodynamic alterations, for example hypotension and tachycardia, predominate over physical findings. Signs of an “acute abdomen,” specifically peritoneal irritation, are often absent. While abdominal pain is usually present, it is often focal and may be associated with a palpable abdominal mass. Signs of shock in the absence of generalized peritonitis or visceral perforation should prompt the consideration of a vascular emergency. In contrast, vascular thrombosis leads to intestinal ischemia and perforation. The clinical presentation of vascular thrombosis is often identical to that of other acute nonvascular abdominal conditions that cause an acute abdomen. Stigmata of cardiovascular disease, for example peripheral vascular occlusions, history of cardiac disease, atrial fibrillation, vascular bruits, and advanced age, should all increase the clinical suspicion of a vascular event as the underlying cause of symptoms. Nevertheless, thrombotic vascular complications often remain undiagnosed until the time of laparotomy.
While physical examination may help to identify patients with intra-abdominal or retroperitoneal bleeding (signs of hemorrhagic shock, absence of peritonitis), routine laboratory evaluations are less helpful. Acute hemorrhage may not result in changes in hemoglobin in its early stages. Laboratory studies are generally useful in excluding other acute inflammatory states, such as pancreatitis, and acute processes of the biliary tree or intestine. Plain films of the abdomen may reveal vascular calcifications or suggest hemorrhage (loss of psoas shadow) but are often nondiagnostic. Computed tomography (CT) scanning, when available, is the most useful preoperative diagnostic study (Fig. 20-1). With the addition of intravenous contrast, CT angiography (CTA) can identify vascular calcifications, aneurysms, and pseudoaneurysms; localize and quantify blood loss; and often identify thrombosis of major arterial and venous structures. Refinements in CTA, such as 3-dimensional (3D) reconstructions, have markedly reduced the need for diagnostic angiography and streamlined the evaluation of ...