Continuing Education Activity

Acute mesenteric ischemia (AMI) is a life-threatening condition resulting from an abrupt reduction in mesenteric blood flow, leading to rapid progression to bowel ischemia, necrosis, sepsis, and mortality rates approaching 60% to 80%. This course reviews the challenges of early diagnosis due to nonspecific clinical presentations, most notably severe abdominal pain that is often disproportionate to physical examination findings, as well as the multiple etiologies of AMI, including occlusive causes (arterial embolism or thrombosis) and nonocclusive states, each associated with distinct risk factors and clinical contexts. Participants will gain an understanding of key diagnostic strategies, AMI subtypes, characteristic imaging findings, and evidence-based treatment strategies. This activity for healthcare professionals is designed to enhance the learner's competence in recognizing AMI, performing appropriate diagnostic evaluation, and implementing a coordinated, interprofessional approach to management, with the ultimate goal of reducing morbidity and mortality and improving patient outcomes.

Objectives:

• Identify the clinical features that distinguish occlusive and nonocclusive acute mesenteric ischemia in critically ill patients.
• Apply evidence-based criteria to determine the appropriate intervention for patients with suspected acute mesenteric ischemia.
• Implement strategies to monitor bowel viability postrevascularization to inform further management decisions in patients with acute mesenteric ischemia.
• Develop a coordinated interprofessional care plan that integrates team members to improve outcomes and reduce complications n patients with acute mesenteric ischemia.

Introduction

Acute mesenteric ischemia (AMI) is a condition due to a sudden decline in blood flow through the mesenteric vessels. Without appropriate and timely treatment, necrosis of the small and large intestine results, leading to sepsis and potentially death. Due to the difficulty of diagnosis and the rapid progression, the condition is life-threatening if not identified and treated early. Diagnosis is difficult because symptoms are nonspecific, and the index of suspicion must be high. Mortality rates for AMI range between 60% and 80%. AMI is classified as either occlusive or nonocclusive mesenteric ischemia (NOMI). Occlusive mesenteric arterial ischemia (OMI) is subdivided into acute thromboembolism and acute thrombosis. Please see StatPearls' companion resource, "Mesenteric Venous Thrombosis," for further information on this condition.[1][2][3]

Etiology

Embolic patients commonly have a positive medical history of cardiovascular diseases, including recent myocardial infarction, congestive heart failure, and atrial fibrillation. Causes include peripheral arterial emboli, cardiac emboli, and a ruptured or dislodged atheromatous plaque after surgery.[4][5][6] The typical thrombotic patient experiences a history of postprandial abdominal pain, leading to food avoidance and weight loss. Causes include atheromatous vascular disease (eg, atherosclerosis, aortic aneurysm, aortic dissection) and decreased cardiac output due to a secondary cause (eg, dehydration, myocardial infarction, congestive heart failure).

The NOMI patient is typically critically ill, presents with several severe comorbidities, and is hemodynamically unstable. Causes include drugs that reduce blood flow (eg, vasopressors and ergotamines), hypotension from severe medical conditions (eg, myocardial infarction, sepsis, CHF, and renal disease), and patients who have recently undergone major surgery (eg, cardiac and abdominal surgery). NOMI accounts for approximately 20% of AMI cases but is associated with the highest mortality due to its insidious onset, diagnostic complexity, limited therapeutic window, and frequent association with multisystem organ dysfunction.[7][8][9]

Epidemiology

AMI is an uncommon but highly morbid condition, with an estimated prevalence of approximately 1 per 1,000 hospital admissions. Among all cases, arterial embolism accounts for 40% to 50%, arterial thrombosis for 25% to 30%, and NOMI for approximately 20%. AMI most frequently affects older adults, with a higher incidence observed in women and in patients with significant underlying comorbidities.

Pathophysiology

An acute mesenteric arterial embolism is often cardiogenic in origin and primarily affects the superior mesenteric artery (SMA). Preceding events include atrial tachyarrhythmia, congestive heart failure, myocardial ischemia or infarction, cardiomyopathy, and ventricular aneurysm, which results in thrombus formation that later embolizes to cause ischemia. Patients with acute mesenteric arterial thrombosis commonly have a preexisting atherosclerotic disease. Vasospasm in the SMA often accompanies NOMI secondary to cardiac failure, peripheral hypoxemia, or reperfusion injury. 

Toxicokinetics

In rare instances, vasopressors (eg, cocaine and norepinephrine) and ergotamines may cause NOMI. These agents cause vasoconstriction and reduced blood flow in the mesentery, which may result in bowel ischemia.

History and Physical

AMI patients typically present with abdominal pain that does not correlate with physical exam findings. Abdominal tenderness to palpation occurs when the entire bowel wall is involved, which is a later presentation as necrosis begins. Patients with an embolic disease typically have a history of bowel emptying violently, followed by severe pain. The syndrome rapidly advances to ischemia and necrosis because collateral blood flow is limited.

Thrombosis may take days or weeks to progress, with abdominal pain gradually worsening. Patients also may have a combination of diarrhea, distention, bloody stool, and, most importantly, a history of postprandial pain, suggesting chronic mesenteric ischemia. NOMI progresses slowly, and the associated abdominal pain is not localized and varies in severity and consistency. These patients are critically ill (eg, septic shock, cardiac disease, and respiratory failure), hypotensive, and usually on vasopressor agents.

Evaluation

Laboratory values and biomarkers for AMI are nonspecific and lack diagnostic power. Elevated D-lactate and lactate dehydrogenase are seen in late-stage AMI. Computed tomography (CT) angiography is the preferred method for imaging all types of AMI (see Image. CT Angiogram of the Superior Mesenteric Artery. Sensitivities for CT range from 96% to 100%, and specificities from 89% to 94%. While standard CT angiography provides adequate visualization of the visceral vasculature, a biphasic CT angiography protocol, comprising both arterial and delayed phases, offers improved sensitivity by capturing dynamic perfusion of the portal venous system and bowel wall.

Several nonvascular findings on CT imaging can herald AMI. One of these is pneumatosis intestinalis, which is the presence of gas dissecting through the layers of the bowel wall. Pneumatosis intestinalis may extend into the mesenteric venous system and eventually into the portal vein. This can be seen in 6% to 43% of cases; therefore, its presence warrants a detailed clinical examination. Other findings include changes in bowel wall thickness, which is found in 26% to 96% of AMI cases. Luminal dilatation and bowel air-fluid levels are more often seen in arterial AMI.[10] 

Catheter-directed angiography has fallen out of favor during the initial stages of AMI diagnosis because the added surgical stress is a burden on an already critically ill patient when used in conjunction with endovascular interventions to treat AMI. Plain abdominal radiography, duplex ultrasonography, and magnetic resonance angiography have narrow indications in diagnosing AMI.

Treatment / Management

Medical Interventions

Initial medical treatment focuses on fluid resuscitation and correcting electrolyte imbalances. Avoid vasopressors and alpha-adrenergic agents, which may cause vasospasm. If vasopressor support is essential to optimize cardiac output, agents with minimal adverse effects on splanchnic perfusion, eg, low-dose dopamine, dobutamine, or milrinone, are preferred. Broad-spectrum antibiotics should be given before surgery to avoid abdominal sepsis if the necrotic bowel is resected.[11][12][13]

Surgical Interventions

Early surgical exploration is required to assess the level of ischemia and spread of necrosis. Revascularization of the bowel is the primary goal of surgery, and excision of necrotic bowel is necessary. After revascularization, the bowel should be assessed for viability, including checking pulses with continuous-wave Doppler, peristalsis, and normal color. Depending on the type and location of the vessel occlusion, open or endovascular surgical interventions are indicated for the treatment of occlusive mesenteric arterial ischemia.

Bowel resection occurs in 53% of second-look surgeries and 31% during exploratory surgery at the first attempt to revascularize. The difficulty of assessing the extent of necrosis of the bowel warrants a second-look surgery 12 to 48 hours after revascularization. Revascularization options during open surgery include methods, eg, retrograde open mesenteric stenting, wherein the SMA is surgically exposed, and a soft anterior arterial wall segment is punctured, facilitating placement of a stent. The arteriotomy is closed either with interrupted transverse sutures or a patch. One can also consider a traditional SMA embolectomy as well if the embolus is large and organized.[14]

Endovascular Interventions

In patients without peritonitis, endovascular options can be considered. One of them is endovascular aspiration thrombectomy (EVT), in which the SMA is catheterized, and the thrombus is aspirated using a vacuum. Several passes may occur until the clot is sufficiently removed. Risks of this approach include distal propagation of the thrombus into smaller peripheral branches within the mesentery. Closely monitoring the patient is essential to detect clinical deterioration following thrombus aspiration promptly.[15]

As NOMI is secondary to vasospasm rather than occlusion, treatment is medically focused and relies upon reversing the underlying cause of the low-flow state. Catheter-directed papaverine (a phosphodiesterase inhibitor) delivered via a side-hole catheter or thrombolysis catheter is an interventional option.[16][17]

Differential Diagnosis

The early identification of AMI is paramount to reducing the likelihood of debilitating morbidity and high mortality. AMI has a vague presentation, and a high index of suspicion is necessary to diagnose suspected patients because of the life-threatening potential of the disease. Findings of abdominal pain out of proportion to a physical exam and cardiovascular risk factors that predispose a patient to embolism and peripheral thrombosis should alert the clinician to consider AMI. Diseases to consider in the differential diagnosis are those that cause acute abdominal pain and are therefore variable in presentation. These include acute colitis, ruptured abdominal aortic aneurysm, bowel obstruction, diabetic ketoacidosis, gastrointestinal perforation, and malignancy.

Prognosis

The prognosis of AMI is poor, with patients experiencing high morbidity and mortality rates. While a downward trend in mortality rates has occurred since the 1960s, AMI mortality remains high, at 60% to 80%. The specific AMI classification affects the likelihood of mortality, with acute embolism having a better prognosis, followed by NOMI and acute thrombosis. Factors associated with mortality include advanced age, bowel resection during second-look surgery, metabolic acidosis, renal insufficiency, and symptom duration.

A study by Gupta et al found a 30-day morbidity rate of 56%. Major postoperative 30-day complications included ventilator use over 48 hours, septic shock, pneumonia, and sepsis. Follow-up surgical interventions were common, with 30% of patients revisiting the surgical department within 30 days and 14% having a hospital stay longer than 30 days. 

Complications

AMI can lead to significant portions of the small bowel that are nonviable and need to be resected during laparotomy. Depending on how much bowel is resected, patients can end up having short bowel syndrome along with intestinal failure. Short bowel syndrome can significantly diminish quality of life and worsen morbidity. The creation of ostomies during these operations can also lead to difficult-to-manage fluid losses and electrolyte imbalances.[18] 

Consultations

Several specialists should be involved as early as possible in the clinical course to prevent deleterious outcomes. General or acute care surgeons should be included for entry into the abdomen and evaluation of the bowel. Vascular surgeons can assist with revascularization techniques, both open and endovascular. Interventional radiologists parallel this approach with endovascular revascularization.

Clinical pharmacists can provide input on anticoagulation options both in the hospital and on discharge. Lastly, hematology and oncology teams can assist in working up suspected underlying coagulopathies that may have led to the condition. Additional supportive staff can include physical and occupational therapists to assist with mobility and strength recovery following treatment, and social work teams to assist with arranging services to ensure comprehensive patient success following discharge. 

Deterrence and Patient Education

Following successful treatment of AMI, patients should be started on subcutaneous heparin to deter further thromboembolic complications. They may, in fact, need lifelong anticoagulation. Those who suffer from atherosclerotic AMI are recommended to be placed on lifelong platelet antiaggregation medication, eg, low-dose aspirin, in addition to modern medical therapy. In settings where SMA stents are placed, clopidogrel is also added.[19] In older adults prone to falls, shared decision-making should be conducted with the patient and their loved ones to ensure they are properly educated about the risks and benefits of anticoagulation.

Pearls and Other Issues

Maintaining a high clinical suspicion for AMI remains imperative in patients presenting with abdominal pain that is disproportionate to physical examination findings. CT angiography should be pursued whenever AMI is suspected, including in patients with acute kidney injury or compromised renal function, as the consequences of a missed diagnosis far outweigh the risks of contrast-induced nephropathy. Frequent, close monitoring is necessary, incorporating serial abdominal examinations performed by the same clinician, alongside laboratory assessments, eg, serial lactic acid levels, base deficit, anion gap, and bicarbonate, to detect clinical deterioration and guide timely intervention.

Enhancing Healthcare Team Outcomes

AMI represents a life-threatening vascular emergency characterized by a sudden reduction in intestinal blood flow, leading to ischemia, necrosis, sepsis, and high mortality. Diagnosis remains challenging due to nonspecific symptoms and rapid progression, often requiring a high index of suspicion and prompt imaging. Patients frequently present with severe abdominal pain out of proportion to examination findings, and delayed recognition contributes to poor outcomes. Management focuses on rapid hemodynamic resuscitation, early initiation of broad-spectrum antibiotics, and timely surgical or endovascular revascularization, often requiring intensive care support. Many affected individuals are older adults with significant comorbidities, further complicating management and prognosis, while extensive bowel necrosis may necessitate resection and result in ostomy creation or long-term complications such as short bowel syndrome.

Interprofessional collaboration plays a critical role in optimizing outcomes and ensuring patient-centered care. Emergency physicians and primary care clinicians facilitate early recognition and timely referral, while radiologists expedite diagnosis through advanced imaging. Surgeons and vascular specialists coordinate revascularization and operative management, with support from intensivists skilled in critical care resuscitation. Advanced practitioners and nurses perform continuous monitoring, serial assessments, and patient education, including ostomy care when needed.[1][20][21] Pharmacists guide anticoagulation therapy and medication safety, particularly for long-term management. Gastroenterologists contribute to diagnostic evaluation and follow-up care. Coordinated communication, shared decision-making, and early involvement of specialized services, including stoma care, reduce complications, improve safety, and enhance continuity of care across the treatment spectrum.

Review Questions

• Access free multiple choice questions on this topic.
• Click here for a simplified version.
• Comment on this article.

References

1.

Bath J, Hartwig J, Dombrovskiy VY, Vogel TR. Trends in management and outcomes of vascular emergencies in the nationwide inpatient sample. Vasa. 2020 Mar;49(2):99-105. [PubMed: 31021300]

2.

Khan SM, Emile SH, Wang Z, Agha MA. Diagnostic accuracy of hematological parameters in Acute mesenteric ischemia-A systematic review. Int J Surg. 2019 Jun;66:18-27. [PubMed: 30999055]

3.

Robles-Martín ML, Reyes-Ortega JP, Rodríguez-Morata A. A Rare Case of Ischemia-Reperfusion Injury After Mesenteric Revascularization. Vasc Endovascular Surg. 2019 Jul;53(5):424-428. [PubMed: 30982410]

4.

Franca E, Shaydakov ME, Kosove J. StatPearls [Internet]. StatPearls Publishing; Treasure Island (FL): May 2, 2023. Mesenteric Artery Thrombosis. [PubMed: 30969585]

5.

Mizumoto M, Ochi F, Jogamoto T, Okamoto K, Fukuda M, Yamauchi T, Miyata T, Tashiro R, Eguchi M, Kitazawa R, Ishii E. Nonocclusive Mesenteric Ischemia Rescued by Immediate Surgical Exploration in a Boy with Severe Neurodevelopmental Disability. Case Rep Pediatr. 2019;2019:5354074. [PMC free article: PMC6399550] [PubMed: 30915251]

6.

Stahl K, Busch M, Maschke SK, Schneider A, Manns MP, Fuge J, Wiesner O, Meyer BC, Hoeper MM, Hinrichs JB, David S. A Retrospective Analysis of Nonocclusive Mesenteric Ischemia in Medical and Surgical ICU Patients: Clinical Data on Demography, Clinical Signs, and Survival. J Intensive Care Med. 2020 Nov;35(11):1162-1172. [PMC free article: PMC7536530] [PubMed: 30909787]

7.

Karadeniz E, Bayramoğlu A, Atamanalp SS. Sensitivity and Specificity of the Platelet-Lymphocyte Ratio and the Neutrophil-Lymphocyte Ratio in Diagnosing Acute Mesenteric Ischemia in Patients Operated on for the Diagnosis of Mesenteric Ischemia: A Retrospective Case-Control Study. J Invest Surg. 2020 Sep;33(8):774-781. [PubMed: 30885018]

8.

Kurita D, Fujita T, Horikiri Y, Sato T, Fujiwara H, Daiko H. Non-occlusive mesenteric ischemia associated with enteral feeding after esophagectomy for esophageal cancer: report of two cases and review of the literature. Surg Case Rep. 2019 Feb 20;5(1):36. [PMC free article: PMC6382915] [PubMed: 30788678]

9.

Somarajan S, Muszynski ND, Olson JD, Bradshaw LA, Richards WO. Magnetoenterography for the Detection of Partial Mesenteric Ischemia. J Surg Res. 2019 Jul;239:31-37. [PMC free article: PMC6506857] [PubMed: 30782544]

10.

Yu H, Kirkpatrick IDC. An Update on Acute Mesenteric Ischemia. Can Assoc Radiol J. 2023 Feb;74(1):160-171. [PubMed: 35544414]

11.

Expert Panels on Vascular Imaging and Gastrointestinal Imaging: Ginsburg M, Obara P, Lambert DL, Hanley M, Steigner ML, Camacho MA, Chandra A, Chang KJ, Gage KL, Peterson CM, Ptak T, Verma N, Kim DH, Carucci LR, Dill KE. ACR Appropriateness Criteria^® Imaging of Mesenteric Ischemia. J Am Coll Radiol. 2018 Nov;15(11S):S332-S340. [PubMed: 30392602]

12.

Daoud H, Abugroun A, Subahi A, Khalaf H. Isolated Superior Mesenteric Artery Dissection: A Case Report and Literature Review. Gastroenterology Res. 2018 Oct;11(5):374-378. [PMC free article: PMC6188040] [PubMed: 30344810]

13.

Luther B, Mamopoulos A, Lehmann C, Klar E. The Ongoing Challenge of Acute Mesenteric Ischemia. Visc Med. 2018 Jul;34(3):217-223. [PMC free article: PMC6103345] [PubMed: 30140688]

14.

Tolonen M, Vikatmaa P. Diagnosis and management of acute mesenteric ischemia: What you need to know. J Trauma Acute Care Surg. 2025 Aug 01;99(2):151-161. [PubMed: 40107963]

15.

Lendzion RJ, Frahm-Jensen G, Keck J. Acute Mesenteric Ischemia. Clin Colon Rectal Surg. 2022 May;35(3):227-236. [PMC free article: PMC9374525] [PubMed: 35966379]

16.

Bala M, Kashuk J, Moore EE, Kluger Y, Biffl W, Gomes CA, Ben-Ishay O, Rubinstein C, Balogh ZJ, Civil I, Coccolini F, Leppaniemi A, Peitzman A, Ansaloni L, Sugrue M, Sartelli M, Di Saverio S, Fraga GP, Catena F. Acute mesenteric ischemia: guidelines of the World Society of Emergency Surgery. World J Emerg Surg. 2017;12:38. [PMC free article: PMC5545843] [PubMed: 28794797]

17.

Salsano A, Salsano G, Spinella G, Palombo D, Santini F. Acute Mesenteric Ischemia: Have the Guidelines of the World Society of Emergency Surgery Analyzed All the Available Evidence? Cardiovasc Intervent Radiol. 2018 Feb;41(2):358-359. [PubMed: 29086055]

18.

Bala M, Catena F, Kashuk J, De Simone B, Gomes CA, Weber D, Sartelli M, Coccolini F, Kluger Y, Abu-Zidan FM, Picetti E, Ansaloni L, Augustin G, Biffl WL, Ceresoli M, Chiara O, Chiarugi M, Coimbra R, Cui Y, Damaskos D, Di Saverio S, Galante JM, Khokha V, Kirkpatrick AW, Inaba K, Leppäniemi A, Litvin A, Peitzman AB, Shelat VG, Sugrue M, Tolonen M, Rizoli S, Sall I, Beka SG, Di Carlo I, Ten Broek R, Mircea C, Tebala G, Pisano M, van Goor H, Maier RV, Jeekel H, Civil I, Hecker A, Tan E, Soreide K, Lee MJ, Wani I, Bonavina L, Malangoni MA, Koike K, Velmahos GC, Fraga GP, Fette A, de'Angelis N, Balogh ZJ, Scalea TM, Sganga G, Kelly MD, Khan J, Stahel PF, Moore EE. Acute mesenteric ischemia: updated guidelines of the World Society of Emergency Surgery. World J Emerg Surg. 2022 Oct 19;17(1):54. [PMC free article: PMC9580452] [PubMed: 36261857]

19.

Kärkkäinen JM. Acute Mesenteric Ischemia: A Challenge for the Acute Care Surgeon. Scand J Surg. 2021 Jun;110(2):150-158. [PMC free article: PMC8258713] [PubMed: 33866891]

20.

Scali ST, Ayo D, Giles KA, Gray S, Kubilis P, Back M, Fatima J, Arnaoutakis D, Berceli SA, Beck AW, Upchurch GJ, Feezor RJ, Huber TS. Outcomes of antegrade and retrograde open mesenteric bypass for acute mesenteric ischemia. J Vasc Surg. 2019 Jan;69(1):129-140. [PubMed: 30580778]

21.

Yang S, Zhao Y, Chen J, Ni Q, Guo X, Huang X, Xue G, Zhang L. Clinical Features and Outcomes of Patients With Acute Mesenteric Ischemia and Concomitant Colon Ischemia: A Retrospective Cohort Study. J Surg Res. 2019 Jan;233:231-239. [PubMed: 30502253]

Disclosure: Salmaan Zafer declares no relevant financial relationships with ineligible companies.

Disclosure: Richard Lopez declares no relevant financial relationships with ineligible companies.

Disclosure: Ali Kimyaghalam declares no relevant financial relationships with ineligible companies.