A 75 year old female presents to her GP for an emergency appointment. She describes a six hour history of severe generalised abdominal pain, one episode of rectal bleeding and vomiting. She has type 2 diabetes and atrial fibrillation, and smokes 10 cigarettes per day.
On examination she has a temperature of 37.3°C and a heart rate of 115 bpm (irregular,) and cries out in pain on gentle palpation throughout the abdomen. Rectal examination reveals no masses, but some altered blood on the glove.
Her GP suspects a diagnosis of mesenteric ischaemia and urgently refers her to the emergency department.
Mesenteric ischaemia is injury to the small bowel or colon as a result of an insufficient blood supply. This can occur with an acute or chronic onset, which is dependent on the underlying cause for reduction in blood flow to the bowel.
Acute mesenteric ischaemia carries a high risk of morbidity and mortality, but the prognosis for patients depends on a prompt and early diagnosis. It is important to have a high index of suspicion in any cases with abdominal pain out of proportion to clinical findings, particularly those with risk factors such as atrial fibrillation or smoking or those with pre-existing vascular disease. Early diagnosis and referral can result in successful treatment and improved outcomes.
The causes for mesenteric ischaemic can be broadly classified into four categories:
- Acute mesenteric arterial embolism
- Acute mesenteric arterial thrombosis
- Non-occlusive mesenteric ischaemia
- Mesenteric venous thrombosis
The incidence of acute mesenteric ischaemic is five in 100,000 and chronic mesenteric ischaemia is one in 100,000 per year.1
Table 1: pathophysiology of mesenteric ischaemia3-8
|Aetiology||Site of Pathology||% of cases||Mortality Rates|
|Acute mesenteric arterial embolism||Emboli – e.g. from a cardiac source
|SMA* (most commonly)||50%||50 – 100%|
|Acute mesenteric arterial thrombosis||Pre-existing atherosclerosis
Decreased cardiac output
|In situ thrombus formation – more common in coeliac artery and origin of the SMA||20%||70-100%|
|Non-occlusive mesenteric ischemia||Low flow blood state/vasospasm
An exaggerated normal physiological response to maintain perfusion of vital organs at the expense of mesenteric perfusion
E.g. myocardial failure, septic shock, digoxin toxicity
|Splanchnic vasoconstriction – watershed areas of circulation are more vulnerable e.g. Griffiths point**||20%||50%|
|Mesenteric venous thrombosis||Often secondary to global disease states such as:
Neoplastic disease processes
Abdominal inflammatory conditions
|Infarction when there is occlusion of intramural vessels – normally segmental||10%||44%|
* SMA: superior mesenteric artery
** Griffiths’ point is defined as the site of (a) communication of the ascending left colic artery with the marginal artery of Drummond, and (b) anastomotic bridging between the right and left terminal branches of the ascending left colic artery at the splenic flexure of the colon2
Acute mesenteric ischaemia is more common in the over-70s.1 Acute mesenteric arterial embolism is the commonest type of acute mesenteric ischaemia and patients are most at risk of developing this if they have the following comorbidities:
- Atrial fibrillation.
- Recent myocardial infarction.
- Cardiac thrombi.
- Left ventricular aneurysm.
- Previous embolic disease.2
The classical presentation of acute mesenteric ischaemia is acute, severe abdominal pain out of proportion to the physical examination findings.
Other associated findings include:
- Rectal bleeding.
It is important to take a clear history to establish an underlying cause for the diagnosis.
Diagnosis and Investigations
A high index of suspicion in patients presenting as above is essential for the early diagnosis and treatment of acute mesenteric ischaemia.
A study of acute mesenteric ischaemia showed that 95% of patients presented with abdominal pain, 44% with nausea, 35% with vomiting, 35% with diarrhoea and 16% with rectal bleeding.3 A high index of suspicion should be had in any patients with a combination of these symptoms, or particularly a triad of abdominal pain, fever and rectal bleeding.
- FBC: raised white cell count (often with marked leucocytosis).
- U&Es: occasionally raised amylase and creatinine kinase.3
- Arterial blood gases: raised lactate, elevated anion gap, metabolic acidosis.
- Clotting profile.
- This is usually normal when performed early after the onset of symptoms in acute mesenteric ischaemia, but should not provide false reassurance. If dilated loops of small bowel are seen, then this can often be a reflection of gangrenous or infarcted loops of bowel, which is a late finding in mesenteric ischaemia.
- · Triphasic CT is the current recommended standard for the diagnosis of acute mesenteric ischaemic.9
- CT angiography is now replacing conventional angiography, as increasing numbers of patients can be treated medically, without the need for invasive intervention.
If the patient presents to primary care, they should be urgently sent to A&E via ambulance. Early administration of strong analgesia is encouraged to minimise patient discomfort and fluid resuscitation should be commenced if possible. A urine dip should be performed as well as a full history taken.
In hospital, treatment should always start with initial resuscitation and stabilisation of the patient, with administration of IV fluids, broad-spectrum IV antibiotics and correction of clotting abnormalities.
Further management will be determined by the cause of the mesenteric ischaemia. In occlusive causes, the aim is for revascularisation of the bowel, either through endovascular or radiological methods, or surgical techniques, such as embolectomy or bypass.
In non-occlusive situations, the condition is normally medically managed, through aggressive fluid resuscitation, anticoagulation and close monitoring for associated complications such as bowel ischaemia.
If there is any evidence or suspicion of bowel infarction, then surgery in the form of emergency laparotomy is required. Any infarcted bowel requires immediate resection.
Miss Annabel Shaw and Mr Nigel Day are colorectal research fellows at Croydon University Hospital.
Mr Muti Abulafi is a consultant colorectal and general surgeon at Croydon University Hospital.