This article concerns ischemia of the small bowel. See ischemic colitis for ischemia of the large bowel
Mesenteric ischemia (Mesenteric ischaemia - British English) is a medical condition in which inflammation and injury of the small intestine result from inadequate blood supply.. Causes of the reduced blood flow can include changes in the systemic circulation (e.g. low blood pressure) or local factors such as constriction of blood vessels or a blood clot. It is more common in the elderly.
It is important to differentiate ischemic colitis, which often resolves on its own, from the more immediately life-threatening condition of acute mesenteric ischemia of the small bowel.
Signs and symptoms
Three progressive phases of ischemic colitis have been described:
A hyperactive phase occurs first, in which the primary symptoms are severe abdominal pain and the passage of bloody stools. Many patients get better and do not progress beyond this phase.
A paralytic phase can follow if ischemia continues; in this phase, the abdominal pain becomes more widespread, the belly becomes more tender to the touch, and bowel motility decreases, resulting in abdominal bloating, no further bloody stools, and absent bowel sounds on exam.
Symptoms of mesenteric ischemia vary and can be acute (especially if embolic), subacute, or chronic.
Case series report prevalence of clinical findings and provide the best available, yet biased, estimate of the sensitivity of clinical findings. In a series of 58 patients with mesenteric ischemia due to mixed causes:
abdominal pain was present in 95% (median of 24 hours duration). The other three patients presented with shock and metabolic acidosis.
nausea in 44%
vomiting in 35%
diarrhea in 35%
heart rate > 100 in 33%
'blood per rectum' in 16% (not stated if this number also included occult blood - presumably not)
In the absence of adequate quantitative studies to guide diagnosis, various heuristics help guide diagnosis:
Mesenteric ischemia "should be suspected when individuals, especially those at high risk for acute mesenteric ischemia, develop severe and persisting abdominal pain that is disproportionate to their abdominal findings"
Regarding mesenteric arterial thrombosis or embolism: "...early symptoms are present and are relative mild in 50% of cases for three to four days before medical attention is sought".
Regarding mesenteric arterial thrombosis or embolism: "Any patient with an arrhythmia such as auricular fibrillation who complains of abdominal pain is hghly suspected of having embolization to the superior mesenteric artery until proved otherwise".
Regarding nonocclusive intestinal ischemia: "Any patient who takes digitalis and diuretics and who complains of abdominal pain must be considered to have nonocclusive ischemia until proved otherwise".
In a series of 58 patients with mesenteric ischemia due to mixed causes:
"Surgical revascularisation remains the treatment of choice for mesenteric ischaemia, but thrombolytic medical treatment and vascular interventional radiological techniques have a growing role" .
The prognosis depends on prompt diagnosis (less than 12-24 hours and before gangrene) and the the underlying cause:
venous thrombosis - 32% mortality
arterial embolism - 54% mortality
arterial thrombosis - 77% mortality
non-occlusive ischemia - 73% mortality
^ ab Brandt LJ, Boley SJ (2000). "AGA technical review on intestinal ischemia. American Gastrointestinal Association". Gastroenterology118 (5): 954-68. PMID 10784596.
^ ab American Gastroenterological Association (2000). "American Gastroenterological Association Medical Position Statement: guidelines on intestinal ischemia". Gastroenterology118 (5): 951-3. PMID 10784595. http://www.guideline.gov/summary/summary.aspx?ss=15&doc_id=3069&nbr=2295
^ Greenwald D, Brandt L, Reinus J (2001). "Ischemic bowel disease in the elderly.". Gastroenterol Clin North Am30 (2): 445-73. PMID 11432300.
^ Staunton M, Malone DE (2005). "Can acute mesenteric ischemia be ruled out using computed tomography? Critically appraised topic". Canadian Association of Radiologists journal = Journal l'Association canadienne des radiologistes56 (1): 9-12. PMID 15835585.
^ Pereira JM, Sirlin CB, Pinto PS, Jeffrey RB, Stella DL, Casola G (2004). "Disproportionate fat stranding: a helpful CT sign in patients with acute abdominal pain". Radiographics : a review publication of the Radiological Society of North America, Inc24 (3): 703–15. doi:10.1148/rg.243035084. PMID 15143223.
^ Sreenarasimhaiah J (2003). "Diagnosis and management of intestinal ischaemic disorders". BMJ326 (7403): 1372-6. doi:10.1136/bmj.326.7403.1372. PMID 12816826.
^ Schoots IG, Koffeman GI, Legemate DA, Levi M, van Gulik TM (2004). "Systematic review of survival after acute mesenteric ischaemia according to disease aetiology". The British journal of surgery91 (1): 17-27. PMID 14716789.