atherosclerotic stenoses of the coeliac , superior mesenteric and inferior mesenteric arteries are common . in a retrospective review of 980 angiographic studies by thomas et al .
however , extensive collateral vessels often form between the territories of these major arteries , such that compensatory blood supply is achieved in the setting of single vessel stenosis .
most cases of symptomatic chronic mesenteric ischaemia therefore occur in the setting of 2 or 3 mesenteric arteries being affected .
mesenteric blood flow normally increases from 25% of total cardiac output to 35% or more after a meal , but in the absence of sufficient perfusion , ischaemia ensues with anaerobic glycolysis and lactate production by intestinal enterocytes .
cell death occurs due to disruption of membrane pumps , leading to reduced epithelial barrier function and translocation of intestinal bacteria into the bloodstream .
this initiates a local inflammatory response that in turn leads to the classic symptoms of post - prandial pain and nausea with subsequent anorexia , avoidance of meals and weight loss .
chronic mesenteric ischaemia is a rare condition , however , with only 13 of 980 patients in the study by thomas et al .  
therefore , it may be overlooked by gastroenterologists in favour of more common luminal or functional differential diagnoses .
we present a case where a diagnosis of chronic mesenteric ischaemia was delayed due to atypical symptomatology , leading to consecutive cognitive errors by the treating clinicians .
a 67-year - old man presented to clinic with 4 months of increasing diarrhoea and weight loss from 74 to 60 kg .
he opened his bowels up to 8 times a day with loose motions , though without associated blood or mucus , and had not improved with trials of gluten - free and lactose - free diets . prior to this
his past history was significant for klinefelter 's syndrome requiring parenteral testosterone replacement , 2 previous lumbar laminectomies , and chronic obstructive pulmonary disease with a 30 pack - year history of cigarette smoking that had ceased 4 years prior .
these included full blood count ; renal function and liver function tests ; serum levels of iron , vitamin b12 , folate and albumin ; erythrocyte sedimentation rate and c - reactive protein ; thyroid function tests ; serology for human immunodeficiency virus hepatitis b and hepatitis c ; stool cultures and parasite screening , and anti - tissue transglutaminase antibodies .
computed tomography ( ct ) scans of his chest , abdomen and pelvis revealed only a 1-cm left adrenal adenoma which appeared benign , uncomplicated cholelithiasis and atheroma within the abdominal aorta .
gastroscopy and colonoscopy were macroscopically unremarkable , with biopsies of the stomach , duodenum , terminal ileum and colon showing no abnormalities . on a second clinic review
2 months later , his symptoms had progressed to include nausea beginning 1 h after meals , persisting for several hours and causing secondary anorexia .
further outpatient tests included a nuclear medicine gastric emptying study with a negative result ; although faecal calprotectin via the quantum blue method was elevated at 145 g / g , indicating a high probability of inflammation in the gastrointestinal tract .
three weeks later , prior to a planned clinic appointment , he was admitted to the hospital with ongoing nausea and diarrhoea which was impossible to be managed at home with anti - emetic and anti - diarrhoeal medications .
new symptoms included cramping lower abdominal pain associated with the nausea , radiating to the back .
due to the elevated calprotectin , ct enteroclysis of the small bowel was performed to assess for crohn 's disease , with a negative result .
further blood tests ensued with negative results including lipase , lactate , anti - nuclear antibodies , rheumatoid factor , complement levels , igg subclasses , vasoactive intestinal peptide and gastrin , cortisol and protein electrophoresis .
urine tests for electrophoresis , 24-hour catecholamines and 5-hydroxyindoleacetic acid were unremarkable , as were faecal elastase and ct of the brain . his symptoms improved significantly during a 14-day hospital admission without any change to medications .
he was highly anxious , and further history revealed recent major psychosocial stressors , as well as several episodes of left leg pain upon mobilising that the patient ascribed to referred pain from his previous laminectomies .
he was therefore given a presumptive diagnosis of a diarrhoeal predominant irritable bowel syndrome with a possible contribution of neuropathic pain radiating from his back .
amitriptyline 12.5 mg daily was started , as well as a diet low in fermentable oligosaccharides , disaccharides , monosaccharides and polyols ( fodmaps ) .
his symptoms improved further over several days , and an outpatient psychiatric review was arranged . however , mild abdominal pain recurred on the evening prior to planned discharge and his abdomen was auscultated by junior medical staff , with a vascular bruit heard in the epigastrium .
mesenteric vessel ultrasound demonstrated > 70% stenoses in the coeliac and superior mesenteric ( fig .
1 ) vessels , though as his symptoms abated again over the next 24 h the significance of these was initially unclear .
he represented several days later with severe abdominal pain , elevated white cell count of 16  10/l and c - reactive protein of 52 , though with normal serum lactate and lipase .
his arterial carboxyhaemoglobin was measured for the first time and was elevated at 5.2% . upon questioning , the patient admitted to having restarted smoking at home 6 months prior , corresponding to the onset of his symptoms , but abstaining whilst in hospital .
mesenteric ct angiography demonstrated short 90% ostial stenoses of the coeliac and superior mesenteric arteries ( fig .
2 ) as well as an occluded left common iliac artery . the inferior mesenteric artery was patent .
his diagnosis was revised to one of chronic mesenteric ischaemia due to two - vessel atherosclerosis , with his left leg pain also being due to arterial insufficiency .
fluoroscopically guided balloon dilatation and insertion of 2 self - expanding stents ( 6-mm and 7-mm diameter ) into the superior mesenteric artery over a guidewire was performed ( fig .
it was intended that collateral vessels from the reperfused superior mesenteric artery would subsequently supplement blood flow to the territories of the stenosed coeliac artery .
immediate relief in abdominal symptoms ensued , and aspirin 100 mg daily and clopidogrel 75 mg daily were commenced to prevent stent thrombosis . at 1 month after discharge ,
he was still free from abdominal symptoms , had stopped smoking and gained 5 kg of weight .
he is planned for open revascularisation of his left leg via femoral bypass in the future .
this patient was subject to diagnostic delay for several reasons , exemplifying common cognitive errors described in clinical medicine .
firstly , his symptoms consisted primarily of diarrhoea and nausea for the majority of his illness , with pain being a very late feature .
this is unusual : in one retrospective review of 54 cases of mesenteric ischaemia , pain was present in 98% of patients , with diarrhoea only in 24.5% and nausea in 2% .
however , this is not specific for inflammatory bowel disease as calprotectin is raised in myriad intestinal conditions such as infections , malabsorptive syndromes and neoplasms .
secondly , the patient 's diagnostic work - up was coordinated by gastroenterologists , which led to two further cognitive errors being applied : the  availability heuristic , whereby clinicians regular experience with intra - luminal aetiologies such as inflammatory bowel disease , rather than vascular aetiologies , biased the initial investigations , and 
ascertainment bias , whereby clinicians investigated for conditions ( such as inflammatory bowel disease ) that they hoped to find due to their familiarity with subsequent treatment .
thirdly , clinicians were falsely reassured by unremarkable previous abdominal imaging including 2 ct scans and ultrasound .
also falsely reassuring was the absence of biochemical markers of malnutrition such as anaemia or hypoalbuminaemia ; as well as frank lactataemia .
however , serum lactate levels are rarely raised in chronic mesenteric ischaemia due to the capacity of the liver to metabolise lactate delivered via the portal vein . as such , serum lactate is elevated only in cases of critical transmural ischaemia .
fourthly , the patient 's improvement during the hospital stay in the setting of psychosocial stressors engendered a diagnosis of a functional gut disorder and the dual cognitive errors of  fundamental attribution error , whereby clinicians frustrated by an exhaustive course of investigation attributed symptoms to the patient 's personal characteristics , as well as 
we retrospectively theorise that his symptoms improved in the hospital due to smoking cessation , leading to a lower blood carboxyhaemoglobin to oxyhaemoglobin ratio and thereby improving tissue perfusion .
the treatment of chronic mesenteric ischaemia centres around revascularisation : lifestyle modifications such as eating small frequent meals , proton pump inhibition and a low - fat diet are only adjuncts , and medical therapy such as long - term anticoagulation is reserved only for patients who can not undergo revascularisation .
the goals of treatment are symptom relief , weight restoration and the prevention of progression to acute mesenteric ischaemia and intestinal infarction .
.   found that endovascular and open surgical revascularisation techniques were associated with statistically similar rates of peri - operative mortality ( odds ratio 0.78 , 95% ci 0.401.50 , p = 0.45 ) .
though associated with longer hospital stays , surgical revascularisation was associated with better long - term patency in 8 studies where this was reported , with a statistically significant odds ratio of 3.57 compared to endovascular revascularisation ( 95% ci 1.836.97 , p = 0.0002 ) . however , in this case it was felt that as the vascular stenosis involved only a short ostial segment , endovascular therapy was the best first - line option especially in a malnourished patient in whom wound healing after open procedures would be theoretically impaired . reported technical success rates of endovascular treatment are high at 85100% with short - term symptomatic relief in 8095% of patients .
though in - stent restenosis may be a future problem in up to 60% of cases over 2 years , several single - centre series describe favourable outcomes when symptomatic restenosis is treated with further endovascular interventions .
peck et al .   reported 13 of 49 ( 28.6% ) patients undergoing endovascular intervention undergoing repeat endovascular procedures at a median time of 15.5 months .
of these 13 patients , 9 remained completely revascularised and asymptomatic at 3 years after initial intervention .
the remaining 4 underwent successful subsequent surgical revascularisation , 3 of whom remained completely revascularised and asymptomatic at 3 years after initial intervention ( 1 died of an unrelated cause ) .
even if surgical intervention were needed for restenosis , this is theoretically associated with a lower risk of peri - procedural complications compared to first - line surgical therapy as the patient will have undergone an intervening period of nourishment and reconditioning .
the choice to combine balloon angioplasty and stenting for our patient is supported by a systemic review of 328 patients undergoing endovascular intervention in 16 studies   suggesting that , while not reaching statistical significance , this approach trends toward higher initial technical success compared to angioplasty alone ( 92 vs 83% , p = 0.09 ) but decreased restenosis rates compared to stenting alone ( 26 vs. 35% , p = 0.10 ) .
this case highlights the importance of recognising atypical presentations of gastrointestinal conditions as well as considering causes for diarrhoea outside the gut lumen .
importantly , it serves as an illustration of multiple cognitive errors to which clinicians may be susceptible in practice .
awareness of the possibility of such errors allows clinicians to reflect critically on their diagnostic reasoning in difficult cases and reduce diagnostic delay .
 chronic diarrhoeal illnesses with nausea and weight loss are a common indication for gastroenterology review . while many such cases have intra - luminal aetiologies , such as inflammatory bowel disease , coeliac disease or other malabsorptive conditions , with many other cases due to functional gut disorders or systemic malignancy , clinicians must also keep vascular disorders in mind . here 
 we report a patient with a delayed diagnosis of chronic mesenteric ischaemia after 6 months of gastrointestinal symptoms strongly mimicking an alternative diagnosis such as inflammatory bowel disease due an atypical predominance of nausea and diarrhoea rather than pain . 
 we briefly review the literature on treatment of this condition but also discuss with particular attention the sequence of cognitive errors made by clinicians that led to a diagnostic delay , inviting readers to thus reflect on how such errors can be minimised in their practice . 