Clinical review Diagnosis and management of intestinal ischaemic disorders Jayaprakash Sreenarasimhaiah Although intestinal ischaemia is an infrequent event, early recognition and appropriate treatment can reduce the potential for a devastating outcome Department of Acute or chronic abdominal pain can be the result of Medicine, Division many different pathophysiological processes. Many of Digestive and Summary points Liver Diseases, presentations are due to benign processes, whereas University of Texas others may be life threatening if not recognised swiftly. Southwestern Acute intestinal ischaemia and infarction can result Among the many possible causes, clinicians need to Medical Center at from impaired blood flow within the mesenteric Dallas, 5323 Harry consider the possibility of intestinal ischaemic disor- arterial or venous systems and are most often Hines Blvd, MC ders. The variable vessels involved, location of bowel 8887, Dallas, TX caused by thrombotic or embolic disease 75390, USA affected, and different levels of acuity of illness all result Jayaprakash in multiple possible presentations. The detection of Chronic mesenteric ischaemia is often Sreenarasimhaiah such a serious condition can be a diagnostic and thera- assistant professor, characterised by postprandial abdominal pain, gastroenterology peutic dilemma. This review aims to help clinicians to sitophobia, and weight loss understand the features and management of acute and jayaprakashsree@ hotmail.com chronic mesenteric ischaemia, mesenteric venous Acute, subacute, or chronic mesenteric venous thrombosis, and ischaemic colitis. thrombosis can be the result of primary BMJ 2003;326:1372–6 hypercoagulable disorders or can be secondary to Sources and selection criteria drugs, portal hypertension, paraneoplastic states, or inflammatory abdominal processes The information in this review is based on results of a Medline search for reviews and evidence based studies Ischaemic colitis results from conditions causing in major journals from the disciplines of gastroenterol- colonic hypoperfusion and embolic or thrombotic ogy, surgery, and radiology published between 1966 occlusion of the vascular supply of the colon and 2003. The key words used included “intestinal ischemia,” “mesenteric ischemia,” “ischemic colitis,” Computed tomography angiography and “mesenteric venous thrombosis,” “mesenteric angio- magnetic resonance imaging have developed into graphy,” “diagnosis,” “management,” and “treatment.” highly accurate and non-invasive methods of diagnosing mesenteric ischaemia Clinical features Surgical revascularisation remains the treatment Acute mesenteric ischaemia of choice for mesenteric ischaemia, but The recognition of acute mesenteric ischaemia can be thrombolytic medical treatment and vascular difficult, as most patients present with non-specific interventional radiological techniques have a symptoms, particularly abdominal pain. Classically, growing role pain is disproportionately exaggerated relative to the unremarkable physical findings and persists beyond two to three hours. However, signs of an acute by cardiac arrhythmias or depressed systolic function abdomen with distension, guarding (rigidity), and due to ischaemic heart disease (box 1). hypotension may also occur, particularly when diagno- In 25% of cases, thrombosis of pre-existing athero- sis has been delayed.1 Fever, diarrhoea, nausea, and sclerotic lesions occurs. Many of these patients report anorexia are all commonly reported. Melena or chronic symptoms consistent with previous transient haematochezia occurs in 15% of cases, and occult mesenteric ischaemia. Non-occlusive mesenteric blood is detected in at least half of patients.2 The ischaemia, which accounts for 20-30% of all cases of underlying process can involve emboli, arterial or acute mesenteric ischaemia, presents similarly but venous thrombosis, vasoconstriction from low flow occurs with patent mesenteric arteries. Microvascular states, or vasculitis. Embolic occlusion of the superior vasoconstriction is the underlying process and is mesenteric artery occurs in more than half of all cases.3 precipitated by splanchnic hypoperfusion due to Most emboli originate in the heart and are potentiated depressed cardiac output or renal or hepatic disease.4 1372 BMJ VOLUME 326 21 JUNE 2003 bmj.com Clinical review Mesenteric venous thrombosis Middle colic artery Primary or secondary thrombosis of the superior Right colic artery Superior mesenteric artery mesenteric vein accounts for 95% of cases and 5-15% of all intestinal ischaemic events. Primary thrombosis is most commonly due to hereditary or acquired hypercoagulation disorders. Deficiencies of protein C, protein S, anti-thrombin III, and factor V Leidin are discovered in some cases, but these proteins may be 5 falsely low in patients with acute thrombosis. A variety Jejunal arteries of malignancies and inflammatory disorders, such as inflammatory bowel disease or pancreatitis, should also Ileocolic artery be considered as secondary causes. Mesenteric venous thrombosis can also occur postoperatively or as a result of trauma, cirrhosis, portal hypertension, previous Appendix endoscopic sclerotherapy for varices, or use of oral Ileal arteries contraceptives.6 Clinically, thrombosis can present acutely, subacutely, or chronically as a segmental disease, usually affecting the small intestine rather than the colon. The recognition of acute venous thrombosis Fig 1 Distribution of blood supply to the small intestine and colon is essential, because of the risk of bowel infarction or from the superior mesenteric artery, branches of which include the peritonitis. middle, right, and ileocolic arteries as well as jejunal and ileal arteries and arterioles Box 1: Causes of acute mesenteric ischaemia Chronic mesenteric ischaemia Chronic mesenteric ischaemia, also known as “intesti- Arterial occlusion (50%) nal angina,” should be considered when a patient • Emboli to superior mesenteric artery: reports generalised abdominal pain occurring usually Mural thrombi from cardiac hypokinesia or atrial in the postprandial state and persisting for one to three fibrillation hours. Pain may be minimal at the onset but can Cardiac vavular lesions Cholesterol embolisation progress over weeks or months into an incapacitating • Thrombotic occlusion: condition. Weight loss and sitophobia, the fear of 3 Pre-existing atherosclerotic vessel disease eating, are often reported. Severe stenosis or complete Acute obstruction of chronic mesenteric ischaemia obstruction of at least two of the three major splanch- • Dissecting aortic aneurysm nic arteries usually occurs before symptoms are • Vasculitis or arteritis evident, because of the formation of a rich collateral • Fibromuscular dysplasia vascular supply. One of the most feared complications • Direct trauma is acute thrombosis and the consequent development 7 • Endotoxin shock of bowel infarction. Recognition of this can be difficult, as many patients are asymptomatic owing to Non-occlusive mesenteric ischaemia (20-30%) extensive collateral veins. When thrombosis involves • Systemic hypotension the portal or splenic veins the initial presentation may • 8 Cardiac failure be variceal bleeding, splenomegaly, or ascites. • Septic shock Ischaemic colitis • Mesenteric vasoconstriction (sympathetic response) The most common form of ischaemic injury to the Venous occlusion (5-15%) gastrointestinal tract is ischaemic colitis.9 The blood • Primary mesenteric vein thrombosis: supply to the colon and small intestine comes from Deficiency of proteins C and S, antithrombin III, branches of the superior and inferior mesenteric factor V Leiden arteries (fig 1 and fig 2). The rectum also receives blood Antiphospholipid syndrome from the inferior and middle haemorrhoidal arteries, Paroxysmal nocturnal haemoglobinuria which arise from the internal iliac artery.10 Colonic • Secondary mesenteric vein thrombosis: ischaemia may be precipitated by several conditions, Paraneoplastic Pancreatitis although the cause is not clearly identified in most Inflammatory bowel disease cases (box 2). Cirrhosis and portal hypotension Mesenteric artery emboli, thrombosis, or trauma Previous sclerotherapy of varices may lead to occlusive vascular disease and impaired Splenomegaly or splenectomy colonic perfusion. Many patients have underlying Postoperative state 11 atherosclerosis. Hypoperfusion states due to conges- Trauma Oral contraceptives tive heart failure, transient hypotension in the perioperative period, and shock due to a variety of Extravascular sources causes such as hypovolaemia or sepsis can result in • Incarcerated hernia ischaemic colitis.12 In younger patients, vasculitis, • Volvulus oestrogens, cocaine and methamphetamine misuse, • Intussusception psychotropic drugs, use of pseudoephedrine, sickle cell • Adhesive bands disease, and heritable disorders of coagulation should be considered.13 Most patients experience a sudden BMJ VOLUME 326 21 JUNE 2003 bmj.com 1373 Clinical review onset of mild, left sided lower abdominal pain. Mild haematochezia without haemodynamic instability may Box 2: Conditions that predispose to ischaemic occur within 24 hours. The most susceptible areas of colitis the colon to ischaemic damage are the “watershed • Thrombosis: regions,” which include the splenic flexure and the Inferior mesenteric artery thrombosis 14 descending and sigmoid colon. Short segments of • Emboli: involved colon may suggest embolic or focal arterial Mesenteric arterial emboli disease, and longer