--- title: Mesenteric ischaemia description: What acute and chronic mesenteric ischaemia (lack of blood flow to the intestine) is, why clots from the heart in atrial fibrillation and atherosclerosis cause it, how it is recognised, which treatment approaches guidelines describe and when to call an ambulance. type: disease aliases: - mesenteric ischemia - acute mesenteric ischaemia - acute mesenteric ischemia - chronic mesenteric ischaemia - chronic mesenteric ischemia - intestinal ischaemia - intestinal ischemia - mesenteric artery thrombosis - superior mesenteric artery embolism - bowel infarction - intestinal angina - abdominal angina sources: - tier: guideline org: esc title: 2024 ESC Guidelines for the management of peripheral arterial and aortic diseases year: 2024 doi: 10.1093/eurheartj/ehae179 url: https://doi.org/10.1093/eurheartj/ehae179 - tier: guideline org: minzdrav-rf title: Расслоение аорты year: 2025 url: https://cr.minzdrav.gov.ru/view-cr/946_1 - tier: reference org: msd-manuals title: Acute Mesenteric Ischemia (MSD Manual Professional Version) year: 2024 url: https://www.msdmanuals.com/professional/gastrointestinal-disorders/acute-abdomen-and-surgical-gastroenterology/acute-mesenteric-ischemia - tier: reference org: msd-manuals title: Abdominal Aortic Branch Occlusion (MSD Manual Professional Version) year: 2024 url: https://www.msdmanuals.com/professional/cardiovascular-disorders/diseases-of-the-aorta-and-its-branches/abdominal-aortic-branch-occlusion - tier: reference org: msd-manuals title: Acute Mesenteric Ischemia (MSD Manual Consumer Version) year: 2024 url: https://www.msdmanuals.com/home/digestive-disorders/gastrointestinal-emergencies/acute-mesenteric-ischemia - tier: reference org: msd-manuals title: Abdominal Aortic Branch Occlusion (MSD Manual Consumer Version) year: 2026 url: https://www.msdmanuals.com/home/heart-and-blood-vessel-disorders/aneurysms-and-aortic-dissection/abdominal-aortic-branch-occlusion - tier: reference org: statpearls title: Acute Mesenteric Ischemia year: 2026 url: https://pubmed.ncbi.nlm.nih.gov/28613722/ - tier: reference org: statpearls title: Chronic Mesenteric Ischemia year: 2026 url: https://pubmed.ncbi.nlm.nih.gov/28613499/ - tier: reference org: statpearls title: Mesenteric Artery Thrombosis year: 2026 url: https://pubmed.ncbi.nlm.nih.gov/30969585/ sources_checked: 2026-10-14 review: null --- Mesenteric ischaemia is a lack of blood supply to the intestine when blood flow through its vessels falls or stops. It can be acute or chronic. Acute ischaemia is a sudden interruption of blood flow due to embolism, thrombosis or too little inflow of blood; without timely treatment part of the bowel dies, which leads to sepsis and can end in death. It is a surgical emergency. In chronic ischaemia the intestine lacks blood when it needs it most, during digestion; it is usually caused by atherosclerotic narrowing of the intestinal arteries and shows itself as pain after eating and weight loss.

The diagram shows the abdominal aorta from the side and the three arteries that leave it for the abdominal organs: the coeliac trunk and the superior and inferior mesenteric arteries. The superior mesenteric artery supplies a large part of the intestine. Blood reaches the bowel, and the bowel is pink.

Acute form: a clot has blocked the superior mesenteric artery. It can form in the artery itself or travel with the blood from the heart, for example in atrial fibrillation. The bowel beyond the blockage gets no blood and, without prompt treatment, dies. The label with the yellow mark on the right and the yellow plaques at the start of the arteries are about the chronic form: atherosclerotic plaques gradually narrow the intestinal arteries.

## Why it happens The intestine receives blood through three arteries that leave the abdominal aorta: the coeliac trunk and the superior and inferior mesenteric arteries. The lining of the bowel is very active and receives a lot of blood, so it is very sensitive to a shortage of it. Acute ischaemia is most often caused by embolism and thrombosis of an artery. An embolus is a blood clot or a piece of atherosclerotic plaque that formed in the heart or the aorta, was carried away by the blood and got stuck in an intestinal artery. The risk of embolism is higher with [atrial fibrillation](../atrial-fibrillation/), [coronary heart disease](../coronary-heart-disease/), [heart failure](../heart-failure/), heart valve disease and in people who have had emboli before. In thrombosis the clot forms right in the intestinal artery, most often where atherosclerosis has long been narrowing it. So chronic ischaemia can turn into acute ischaemia. Sometimes the artery is not blocked, but too little blood reaches the bowel: when the heart pumps out little blood, as in heart failure or shock (see [cardiogenic shock](../cardiogenic-shock/)), or because of medicines and drugs that narrow the blood vessels. Less often the cause is thrombosis of the intestinal veins. [Aortic dissection](../aortic-dissection/) can also disrupt blood flow in the intestinal arteries. The risk of acute ischaemia is higher in older people, but many people who develop it have no obvious risk factors. Chronic ischaemia is most often caused by atherosclerosis: plaques gradually narrow the intestinal arteries, especially the superior mesenteric artery. It has much in common with coronary heart disease and [atherosclerosis of the leg arteries](../peripheral-artery-disease/); the main risk factors are smoking, high cholesterol ([dyslipidaemia](../dyslipidemia/)), diabetes, older age and [high blood pressure](../hypertension/). Less often the arteries are narrowed by fibromuscular dysplasia or pressure from a tumour; the renal arteries can narrow in the same way, see [renal artery stenosis](../renal-artery-stenosis/). The small-bowel mucosa has a high metabolic rate and normally receives 20–25% of cardiac output. Ischaemia disrupts the mucosal barrier: bacteria, toxins and vasoactive mediators cause myocardial depression, a systemic inflammatory response, multi-organ failure and death; mediators may be released even before bowel infarction. Territories (MSD): coeliac trunk, the oesophagus, stomach, proximal duodenum, liver, gallbladder, pancreas and spleen; superior mesenteric artery (SMA), the distal duodenum, jejunum, ileum and colon to the splenic flexure; inferior mesenteric artery (IMA), the descending colon, sigmoid colon and rectum. The splenic flexure is a watershed between the SMA and IMA and is at particular risk of ischaemia. Acute mesenteric ischaemia is classified as occlusive (thromboembolism and thrombosis) or non-occlusive (NOMI). Risk factors by type of occlusion (MSD): for embolism, coronary artery disease, heart failure, valvular heart disease, atrial fibrillation and a history of arterial emboli; for arterial thrombosis, generalised atherosclerosis; for venous thrombosis, hypercoagulable states, inflammation (pancreatitis, diverticulitis), trauma, heart failure, renal failure and portal hypertension; for NOMI, low-flow states (heart failure, shock, cardiopulmonary bypass) and splanchnic vasoconstriction (vasopressors, cocaine). In general, patients over 50 are at greatest risk. In acute aortic dissection, intestinal ischaemia is part of the malperfusion syndrome. Chronic mesenteric vascular insufficiency rarely causes symptoms unless both the SMA and the coeliac trunk are substantially narrowed or occluded, because collateral circulation between them is extensive. Acute mesenteric ischaemia should not be confused with ischaemic colitis, which involves only small vessels and causes mainly mucosal necrosis and bleeding. ## Symptoms The main sign of acute ischaemia is severe abdominal pain that usually starts suddenly. What is unusual is that at first the abdomen stays soft and hurts only a little when pressed: the pain seems worse than the examination would suggest. Nausea and vomiting and an urgent need to open the bowels are common, and the abdomen may be slightly swollen. Then blood appears in the stool, blood pressure falls and shock may develop: areas of the bowel are dying. When the bowel starts to die, the abdomen becomes very tender and tense. Chronic ischaemia ("abdominal angina") shows itself as severe, steady pain, usually around the navel, that comes on after eating: during digestion the intestine needs more blood. People become afraid to eat and lose a lot of weight; nausea, vomiting, diarrhoea or constipation can occur. Sudden severe pain in someone who used to have abdominal pain after eating can mean thrombosis of the artery, that is, acute ischaemia. The early hallmark is severe pain with minimal physical findings: the abdomen is soft, with little or no tenderness, and mild tachycardia may be present. As necrosis develops, signs of peritonitis appear: marked tenderness, guarding, rigidity and absent bowel sounds; the stool may test positive for blood, and then shock develops, frequently followed by death. Sudden onset of pain suggests but does not prove arterial embolism; a more gradual onset is typical of venous thrombosis. Chronic ischaemia may cause an abdominal bruit and dark stools; rarely, malabsorption adds to weight loss. Chronic ischaemia often mimics more common gastrointestinal diseases, and the time from onset of symptoms to diagnosis often exceeds a year. ## How it is diagnosed Recognising acute ischaemia early is hard: its signs are non-specific. So the doctor suspects it mainly from the combination of sudden severe abdominal pain and risk factors, such as atrial fibrillation or other heart disease. If the signs are typical or the abdomen is very tender, the person is usually taken straight to the operating theatre, where diagnosis and treatment happen at the same time. In that case there is no waiting for test results: early in the disease they tell little, and delay is dangerous. If the diagnosis is unclear, CT angiography is done: a CT scan with a contrast agent injected into a vein, which shows where the artery is blocked. It is also recommended when chronic ischaemia is suspected; ultrasound of the vessels and angiography through a catheter are used as well. Before looking for chronic ischaemia, the doctor rules out other causes of abdominal pain. ESC 2024: in suspected acute or chronic mesenteric ischaemia, CTA is recommended (I C); the patient should be assessed by a vascular team (I C). MSD: with clear peritoneal signs, straight to the operating theatre for diagnosis and treatment; for others, selective mesenteric angiography or CTA, with MRA if there is a contraindication to standard intravenous contrast. Plain radiographs are mainly for ruling out other causes (for example, perforation); markers (creatine kinase, lactate) rise with necrosis but are non-specific and appear late, so clinical diagnosis takes precedence over tests that may delay treatment. Chronic ischaemia: CTA is the preferred initial non-invasive test; duplex ultrasound and digital subtraction angiography (DSA) are also used, with DSA the gold standard in equivocal cases. ESC 2024 algorithm (Figure 20): exclude other causes → CTA; with multi-vessel stenosis, atherosclerosis, a multidisciplinary meeting, endovascular or surgical revascularisation and secondary prevention of atherosclerosis; with isolated stenosis of the coeliac trunk or SMA, or with no stenosis, a functional test that distinguishes median arcuate ligament syndrome (MALS), atherosclerosis and chronic non-occlusive ischaemia; in MALS and NOMI the underlying condition is treated. ## How it is treated Acute blockage of an intestinal artery is a surgical emergency. The person is given fluids and antibiotics into a vein. The key is to restore blood flow as fast as possible: remove or dissolve the clot, widen the artery from inside through a catheter (angioplasty, sometimes with a stent) or bypass the blockage with a graft during surgery. For acute blockage of the superior mesenteric artery, the European guideline recommends restoring blood flow endovascularly, that is, from inside the vessel with a catheter. Dead sections of bowel are removed; sometimes a second operation is needed to check whether doubtful sections are still viable. Whether the person survives and whether the bowel can be saved depend on how fast blood flow is restored. If the diagnosis is made and treatment started early, people usually recover well; once the bowel has died, mortality is high. After recovery many people need medicines that prevent blood clots. Which medicines are needed is decided by the doctor. Preventing clots in atrial fibrillation is covered in the article on [atrial fibrillation](../atrial-fibrillation/). In chronic ischaemia with symptoms, blood flow is restored: from inside the artery with a balloon, sometimes with a stent, or by open surgery, a bypass from the aorta to the artery beyond the narrowing. After a successful procedure the pain may go away quickly and weight may be regained. Atherosclerosis itself is also treated: risk factors are modified and medicines that prevent clotting are prescribed. Without treatment, chronic ischaemia with symptoms is life-threatening. If a narrowing is found by chance and causes no symptoms, widening the artery is not recommended: usually lifestyle changes and medicines prescribed by the doctor are all that is done. The European guideline recommends that a person with acute or chronic mesenteric ischaemia be assessed by a vascular team. ESC 2024: in acute mesenteric ischaemia due to acute occlusion of the SMA, endovascular revascularisation is recommended (I B); the 2017 ESC guidelines suggested considering both endovascular and open surgery for acute embolic occlusion of the SMA (IIa B). MSD: intravenous fluids to improve visceral perfusion and broad-spectrum antibiotics; if the diagnosis is made at laparotomy, embolectomy, revascularisation and resection, with a second-look laparotomy if needed; peritoneal signs at any time call for immediate surgery. When the diagnosis is made by angiography, intra-arterial vasodilator infusion in NOMI and thrombolysis in arterial occlusion are options. For patients after arterial embolism or venous thrombosis, MSD suggests considering long-term anticoagulant and antiplatelet therapy and surveillance of graft or stent patency. If diagnosis and treatment come before bowel infarction, mortality is low; after infarction it is high and depends on the cause. Chronic ischaemia: revascularisation of asymptomatic atherosclerotic visceral artery stenosis is not recommended (ESC 2024, III C). Symptomatic chronic mesenteric ischaemia requires revascularisation, open or endovascular. MSD: with severe symptoms, bypass from the aorta to the visceral arteries beyond the occlusion; in selected patients, especially older people at high surgical risk, percutaneous transluminal angioplasty with or without a stent. ## When to call an ambulance Sudden severe abdominal pain is a reason to call your local emergency number straight away (112 in the EU, 911 in the US and Canada, 999 in the UK), especially in someone with atrial fibrillation, other heart disease or atherosclerosis. Do not wait to see whether the pain goes away, even if the abdomen is soft: without blood flow the bowel dies quickly. Also call an ambulance for severe abdominal pain with nausea and vomiting, an urgent need to open the bowels or blood in the stool, if the person suddenly gets worse and their blood pressure falls during the pain (these are signs of shock), and for sudden severe pain in someone who used to have abdominal pain after eating. Pain after eating, fear of eating and weight loss without sudden severe pain are a reason to see a doctor soon: chronic ischaemia needs to be recognised and treated in time. As with any heart or blood vessel condition, call an ambulance for fainting, chest pain or severe breathlessness: this is the site's general safety rule, repeated at the bottom of every page.