Chronic mesenteric ischaemia presenting as possible large bowl malignancy: an easily overlooked differential diagnosis

Abstract

An 80-year-old woman presented to a regional emergency department with postprandial pain, weight loss and diarrhoea for 2 months and a Computed Tomography (CT) report suggestive of descending colon malignancy. Subsequent investigations revealed the patient to have chronic mesenteric ischaemia (CMI) with associated bowel changes. She developed an acute-on-chronic ischaemia that required emergency transfer, damage control surgery and revascularisation. While the patient survived, this case highlights the importance of considering CMI in elderly patients with vague abdominal symptoms and early intervention to avoid potentially catastrophic outcomes.

Background

Mesenteric ischaemia is a less common but potentially life-threatening cause of abdominal pain. Acute ischaemia typically presents with a sudden onset of abdominal pain that is intractable to opioid pain relief. Chronic mesenteric ischaemia (CMI) on the other hand can present with insidious and sometimes vague symptoms such as postprandial pain, diarrhoea and weight loss. This myriad of symptoms can also be seen in patients with large bowel malignancies, which are a more common cause for this type of presentation. This case highlights the importance of keeping mesenteric ischaemia in mind in patients who present with abdominal pain, weight loss and diarrhoea as the consequences of missing this diagnosis can be potentially catastrophic.

Case presentation

An 80-year-old woman presented to a regional emergency department with a 2-month history of postprandial abdominal pain, diarrhoea and 12 kg of weight loss. The patient had presented to a different hospital two times in the previous month with similar symptoms. At the first presentation, the patient had a weakly positive urine culture that was treated with oral trimethoprim and on the second presentation she was treated with 24 hours of triple intravenous antibiotics followed by 5 days of oral amoxiclav. Despite these interventions, the patient’s symptoms continued. In addition to this, the patient was suffering from generalised decline with weakness, lethargy and increasing difficulty performing her usual activities of daily living.

On examination, the patient was pale but normotensive with a heart rate of 84 beats per minute and afebrile. Abdominal examination revealed mild, generalised abdominal pain without peritonism and the digital rectal examination was unremarkable.

The patient’s medical history was significant for triple-bypass surgery in 2009 as well as type-2 diabetes mellitus, dyslipidaemia and asthma. Despite this, she was very independent prior to the onset of symptoms and had only recently moved in with her daughter as she was no longer able to cope on her own. She was a non-smoker and only drank alcohol sparingly.

Given the patients frailty, she was admitted under the surgical team with a plan for slow bowel preparation, dietician input and an inpatient colonoscopy.

Investigations

At the time of presentation, the patient had already undergone two contrast-enhanced CT scans. The first was performed a month prior at a different centre and was reported that no cause for the patient’s symptoms could be found. The second CT arranged by the general practitioner reported the descending colon thickening with no comment on the mesenteric vessels (figure 1). Unfortunately, at the time of presentation, the treating team did not have access to the images.

Figure 1.

Initial portovenous CT demonstrating significant coeliac trunk and superior mesenteric artery stenosis.

Blood tests at time of admission revealed an elevated carcinoembryonic antigen (14 µg/L; reference range <5) and Ca 19.9 (46kU/L; reference range <35). There was also a mild normocytic anaemia with a haemoglobin of 104 g/L and a significant leucocytosis ((WCC) 30.5 ×10⁹/L; reference range <11).

Differential diagnoses

Considering the patient’s age, tumour markers and CT findings, the most likely diagnosis was deemed to be large bowel malignancy. The possibility of an infective colitis was also considered given the elevated WCC; however, ischaemic colitis was not seriously considered initially.

Treatment

The patient’s admission was complicated from the outset. The bowel preparation was causing significant abdominal discomfort and unfortunately her planned colonoscopy at day 3 of the admission had to be postponed as her prep quality was not deemed adequate. When her prep finally reached a fair-to-good quality at day 5, her potassium was noted to be 2.2 mmol/L with an associated arrhythmia that required transfer to the medical unit on telemetry until it was corrected. She underwent her colonoscopy on day 7 of her admission.

The colonoscopy demonstrated discontinuous areas of non-bleeding ulcerated mucosa with no stigmata of recent bleeding that were present throughout the ascending colon. Several small, shallow ulcers of the ascending colon, hepatic flexure and the descending colon were also noted. The treating consultant reviewed the previous CT images and noted significant stenosis of the superior mesenteric artery (SMA) and coeliac trunks. This combined with the colonoscopic findings were considered suggestive of CMI. The plan was to observe the patient over the course of the next 3–4 days with allied health input, a CT angiogram (CTA) prior to discharge and outpatient vascular surgery follow-up.

The patient’s course was largely uneventful for 3 days after her colonoscopy. However, in the evening of the third night, she developed her usual postprandial pain but this time, it would not resolve. The following morning, she underwent her CTA which demonstrated near-critical SMA stenosis with pneumatosis of the distal small bowel concerning for acute ischaemia (figure 2). The patient was transferred to the tertiary referral centre for ongoing management under the care of the vascular and general surgical teams.

Figure 2.

Computed Tomography Angiography again demonstrating critical stenosis.

Outcome and follow-up

On arrival to the tertiary referral centre, a laparotomy was performed by the general surgeons with the vascular team in attendance. Findings as laparotomy included necrosis of the distal small bowel affecting approximately 1.5 m from mid small bowel to 10 cm short of the ileocaecal valve. Patchy necrosis of transverse colon from mid-to-splenic flexure was also noted. The entire 1.5 m of affected small bowel including the terminal ileum and transverse colon were resected and a negative-pressure dressing placed over the laparostomy with a plan for relook in 2 days. The vascular team stented the SMA via the femoral artery endovascular (ER) approach and the patient was transferred to the intensive care unit (ICU).

Relook laparotomy revealed some patchy ecchymosis but otherwise viable bowel. A side-to-side ileocolic anastomosis was performed and a transverse colostomy with mucous fistula was brought up. The patient’s abdomen was closed, and she returned to ICU.

Despite the high risk of mortality, the patient made an uneventful recovery and was discharged from ICU on day 3 postoperatively. She continued to improve and was discharged into her daughter’s care day 34 after her initial presentation.

The patient’s follow-up has been largely uneventful to date. She has not required any further vascular intervention and is currently undergoing 6-monthly reviews with yearly CTA. From a general surgical perspective, the patient has been discharged from ongoing follow-up as stoma reversal was not recommended and the patient was managing well with it.

Discussion

While CMI is very uncommon, the predisposing mesenteric vessel atherosclerosis is quite common and even comparable to peripheral vascular disease, cerebrovascular disease and ischaemic heart disease.^1–6 Recall the mesenteric circulation is comprised of three main vessels—the coeliac axis, SMA and the inferior mesenteric artery with each supplying the embryological foregut, midgut and hindgut, respectively. These vessels share collateral networks to mitigate the potential catastrophic consequences should a single vessel become blocked.⁷

Like the above-mentioned conditions, the pathophysiology of CMI most commonly involves atherosclerosis of one or more of the mesenteric vessels, with the most commonly affected vessel being the SMA.⁸ Regardless of the vessel or vessels affected, atherosclerotic mesenteric stenoses usually are focal and most often are located at the ostium or the very proximal portion of these vessels. It shares the same risk factors as the other vascular diseases that is, hypertension, dyslipidaemia, smoking and obesity. Less common causes include vasculitis, fibromuscular dysplasia and compression of the coeliac axis by the median arcuate ligament. These conditions result in gradual narrowing of the arterial lumen with symptoms typically starting once there is at least 70% stenosis.

Patients with CMI often present with a variety of abdominal symptoms including postprandial pain, early satiety, altered bowel habits and weight loss. Unfortunately, these symptoms can also be related to wide range of differential diagnoses including pancreatitis, biliary pathology, diverticulitis and colorectal malignancy. These patients have often been extensively investigated for these pathologies with negative results. A possible pearl in the history is abdominal pain 30–60 min after eating⁹ lasting for 30–120 min. Associated with this pain is a fear of eating, leading the patients to take smaller meals more frequently and avoiding fatty meals.¹⁰

If CMI is suspected, CTA remains the gold standard of investigation to confirm the diagnosis. CTA allows for a rapid assessment of the relevant vessels while also allowing for assessment for the complications of CMI, as was seen in this case. CTA also has a 95%–100% accuracy in correctly diagnosing significant stenosis (ie, >70%) in the mesenteric vessels.¹¹ This case does highlight the importance of adequate reporting of CT as the correct diagnosis may have been reached earlier. This case also highlights the importance of treating clinicians being able to view and have some level of skill in imaging interpretation as no radiology report is infallible and should be treated as such. Had the treating team reviewed the initial CT images it is possible the patient could have avoided a laparotomy, although given the level of stenosis at time of presentation this is by no means certain.

Magnetic resonance angiography (MRA) is another highly accurate cross-sectional modality that provides accurate imaging of the mesenteric vessels. In CMI, MRA can be used as a reasonable substitute to CTA, especially in the context of iodine allergy. The sensitivity and specificity of three-dimensional contrast MRA is approximately 95%–100%. The limitations of MRI are the current inability to scan patients with pacemakers, the issue of claustrophobia, availability, lengthy examination time and the inability to assess patients with mesenteric stents.¹¹ The American College of Radiology released guidelines in 2013 comparing the appropriateness of CTA versus MRA in mesenteric ischaemia and it was concluded that while MRA has a high sensitivity and specificity for diagnosing severe stenosis or occlusion at the origins of the coeliac axis and SMA, it has a limited role in diagnosing distal stenosis as well as non-occlusive mesenteric ischemia, and its use may delay therapeutic options in acute settings because it is a long examination that is not readily available in most practices.¹²

Should CTA or MRA be contraindicated, duplex ultrasonography provides a highly sensitive and specific test that allows for satisfactory assessment of the proximal vasculature, although comprehensive assessment of the distal vessels is more difficult.¹³

Once a diagnosis of CMI has been established, revascularisation becomes the primary goal of treatment. Previous open repair (OR) surgeries have largely been replaced by ER techniques¹⁴ with the fact most stenoses are at the proximal part of the vessel making them highly amenable to such approaches. Furthermore, while mortality rates are comparable, morbidity in OR is higher compared with ER, with OR patients more likely to suffer from cardiac and pulmonary complications in the first 30 days after intervention.¹⁵ This has resulted in an increase in the use of ER in CMI. Angioplasty alone results in relatively poor long-term symptom relief,^{15 16} and therefore angioplasty with stenting is typically performed, as was the case here.

In the case of this patient, an acute-on- chronic Mesenteric Ischaemia resulted in a change in the primary goal of care. While revascularisation was still a critical component of management (one which necessitated transfer), damage control surgery was required first and foremost to not only assess if the patient had a survivable insult, but also to remove any necrotic bowel to minimise intra-abdominal sepsis. A ‘clip-and-drop’ technique was employed, removing the necrotic bowel without performing an anastomosis and leaving the abdomen open. This allowed the vascular team to stent the patient’s SMA and give the remaining bowel a chance to revascularise, which indeed happened and allowed for anastomosis and stoma formation 2 days later.

While this case did not end in a mortality, it highlights the importance of not missing CMI in patients presenting with vague abdominal symptoms, especially in those with known cardiovascular issues affecting other vascular beds. Early recognition in this case may have avoided the need for damage control surgery and ultimately the need for a stoma.

Learning points.

• Chronic mesenteric ischaemia (CMI) is an uncommon but potentially life-threatening presentation of abdominal pain.

• CMI can present with a wide range of abdominal symptoms making it difficult to differentiate from more common causes of abdominal pain.

• Key components of the history include postprandial pain lasting 30–120 min, food avoidance and weight loss.

• CTA is the gold standard of imaging.

• Early revascularisation with angioplasty and stenting will avoid many of the complications of CMI.