Is "ischemic" colitis ischemic?

Insights into acute mesenteric ischaemia: an up-to-date, evidence-based review from a mesenteric stroke centre unit

Radiologists play a central role in the diagnostic and prognostic evaluation of patients with acute mesenteric ischaemia (AMI). Unfortunately, more than half of AMI patients undergo imaging with no prior suspicion of AMI, making identifying this disease even more difficult. A confirmed diagnosis of AMI is ideally made with dynamic contrast-enhanced CT but the diagnosis may be made on portal-venous phase images in appropriate clinical settings. AMI is diagnosed on CT based on the identification of vascular impairment and bowel ischaemic injury with no other cause. Moreover, radiologists must evaluate the probability of bowel necrosis, which will influence the treatment options.AMI is usually separated into different entities: arterial, venous, non-occlusive and ischaemic colitis. Arterial AMI can be occlusive or stenotic, the dominant causes being atherothrombosis, embolism and isolated superior mesenteric artery (SMA) dissection. The main finding in the bowel is decreased wall enhancement, and necrosis can be suspected when dilatation >25 mm is identified. Venous AMI is related to superior mesenteric vein (SMV) thrombosis as a result of a thrombophilic state (acquired or inherited), local injury (cancer, inflammation or trauma) or underlying SMV insufficiency. The dominant features in the bowel are hypoattenuating wall thickening with submucosal oedema. Decreased enhancement of the involved bowel suggests necrosis. Non-occlusive mesenteric ischaemia (NOMI) is related to impaired SMA flow following global hypoperfusion associated with low-flow states. There are numerous findings in the bowel characterised by diffuse extension. An absence of bowel enhancement and a thin bowel wall suggest necrosis in NOMI. Finally, ischaemic colitis is a sub-entity of arterial AMI and reflects localised colon ischaemia-reperfusion injury. The main CT finding is a thickened colon wall with fat stranding, which seems to be unrelated to SMA or inferior mesenteric artery lesions. A precise identification and description of vascular lesions, bowel involvement and features associated with transmural necrosis is needed to determine patient treatment and outcome.

Colon ischemia: A comprehensive review

The clinical and endoscopic features of colon ischemia (CI) are non-specific. CI is correctly identified at the time of presentation in only 9% of patients is. The true incidence is likely underestimated because many mild cases resolve spontaneously without medical treatment. Furthermore, since most cases of CI are transient, and no specific cause is detected they are often considered to be "idiopathic". In the setting of severe CI correct diagnosis and prompt recognition and therapy as well as identification of underlying causes are crucial for a favourable outcome. Although less severe, mild cases may present with similar symptoms, the prognosis and management are completely different and managed conservatively rather than with surgery. Unfortunately, data from most studies and current guidelines do not provide recommendations on the long-term management of CI or about the need for endoscopic follow-up to detect the development chronic, recurrent and/or ischemic colonic strictures. In this review, we focus on the definition of CI, its aetiology, and patterns of presentation. We highlight the pharmacological and/or endoscopic management as determined severity of disease that allow for improved outcomes. Prompt recognition and treatment using a multidisciplinary approach are essential for successful management of severe CI because mortality rates are significantly higher when the diagnosis is delayed.

Nonocclusive Ischemic Colitis: Analysis of Risk Factors for Severity

The purpose of this study was to identify risk factors predictive of severe nonocclussive ischemic colitis (IC) requiring operation or resulting in mortality. One hundred seventeen patients with nonocclussive IC were identified and divided into two groups: those with severe disease (n = 24) and those with disease that resolved with supportive care (n = 93). Univariate and multivariate logistic regression models were used. The splenic flexure was the most common involved segment (57.3%), whereas the right colon was involved in 17.9 per cent of patients. Multivariate logistic regression identified three independent risk factors for severe disease: leukocytosis greater than 15 3 109/L (odds ratio [OR], 5.7; confidence interval [CI], 1.5 to 21), hematocrit less than 35 per cent (OR, 4.5; CI, 1.1 to 17), and history of atrial fibrillation (OR, 15; CI, 1.3 to 190). Right-sided IC and chronic renal insufficiency did not affect severity. Special attention should be given to patients with the following risk factors for a severe course: atrial fibrillation, elevated white blood cell count, and anemia. These factors might enable earlier identification of patients who may benefit from early operation. Further prospective studies focusing on subgroups of IC (occlusive and nonocclusive) are required.

Role of ultrasound in colorectal diseases

Ultrasound is an undervalued non-invasive examination in the diagnosis of colonic diseases. It has been replaced by the considerably more expensive magnetic resonance imaging and computed tomography, despite the fact that, as first examination, it can usefully supplement the diagnostic process. Transabdominal ultrasound can provide quick information about bowel status and help in the choice of adequate further examinations and treatment. Ultrasonography, as a screening imaging modality in asymptomatic patients can identify several colonic diseases such as diverticulosis, inflammatory bowel disease or cancer. In addition, it is widely available, cheap, non-invasive technique without the use of ionizing radiation, therefore it is safe to use in childhood or during pregnancy, and can be repeated at any time. New ultrasound techniques such as elastography, contrast enhanced and Doppler ultrasound, mini-probes rectal and transperineal ultrasonography have broadened the indication. It gives an overview of the methodology of various ultrasound examinations, presents the morphology of normal bowel wall and the typical changes in different colonic diseases. We will pay particular attention to rectal and transperineal ultrasound because of their outstanding significance in the diagnosis of rectal and perineal disorders. This article seeks to overview the diagnostic impact and correct indications of bowel ultrasound.

[Acute mesenteric ischemia]

BACKGROUND

Acute vascular occlusion within the mesenteric circulation leads to ischemic damage of the corresponding bowel segment, which starts on the mucosal level and progresses transmurally.

OBJECTIVES

Report on pathogenesis, clinical picture and treatment of various forms of intestinal ischemia.

MATERIALS AND METHODS

Analysis of the available literature taking into consideration our own experience.

RESULTS

Frequently, predisposing diseases and risk factors are present (e.g., cardiac diseases, hypercoagulability, status post cardiac surgery, circulatory failure, or administration of vasoconstrictive drugs). Acute small bowel ischemia-caused by either mesenteric embolism, mesenteric artery thrombosis, nonocclusive mesenteric ischemia (NOMI) or mesenteric venous thrombosis-represents an acute emergency. If this condition is suspected clinically, the diagnosis must be established immediately by computed tomography of the abdomen with intravenous administration of contrast medium in order to prevent irreversible damage to the small bowel. Medical treatment is supportive. If possible, occluded vessels may be re-opened either by radiologic intervention or surgically. Irreversibly damaged bowel segments must be surgically removed. Ischemic colitis has a benign course in most cases if limited to reversible mucosal damage. The diagnosis is based mainly on colonoscopy and computed tomography findings, and treatment is symptom oriented. Rarely, severe manifestations with a worse prognosis due to considerable comorbidities occur. In such cases, surgical removal of the ischemic bowel is frequently required.

CONCLUSION

Even today, acute mesenteric ischemia is associated with a poor prognosis. To improve survival and to reduce long-term morbidity, a rapid and systematic diagnostic workup is mandatory.

Ischemic colitis: the ABCs of diagnosis and surgical management

Ischemic colitis (IC) is a rare condition. As ischemia is often transient and clinical symptoms are reversible, its exact incidence is unknown. In current clinical practice, two types of IC are described according to the severity: severe IC, with transmural colonic ischemia and/or multi-organ failure (MOF), and mild IC, without MOF and spontaneous favourable evolution in most cases. Two clinical contexts are encountered: spontaneous IC (SIC) and postoperative IC (POIC), mainly after aortic surgery. As there is no specific clinico-biologic symptom of IC, emergent CT-scan and rectosigmoidoscopy are required for diagnosis confirmation, surgical decision and prognosis analysis. IC surgical treatment is not consensual but can be standardized according to organ function and the degree of ischemia: surgical treatment in case of colonic necrosis with deep ischemia and/or MOF; observation for superficial ischemia without organ dysfunction; systematic medical care. Surgery is required in 20% of cases, and consists in extended colectomy without continuity restoration and prophylactic cholecystectomy. Continuity restoration is feasible in one third of survivors, who are exposed to a high risk of severe cardiovascular events.

Ischemic colitis: clinical presentation, localization in relation to risk factors, and long-term results

BACKGROUND

Ischemic colitis is commonly thought to occur most often in the left hemicolon close to the splenic flexure owing to insufficient blood supply near Griffith's point. This study investigates the colorectal localization pattern, the risk factors, and the long-term outcome of histologically proven ischemic colitis.

METHODS

Between 1996 and 2004, a total of 49 patients with a median age of 69 years (range 26-94 years) with colonoscopically assessed and histologically proven ischemic colitis were identified on behalf of the pathology database. Long-term results of 43 patients were evaluated retrospectively after a median interval of 79 months (range 6-163 months).

RESULTS

In 27 patients (55%) more than one location was affected. We found 98 affected locations in 49 patients. The distribution of ischemic colitis in our group shows no significantly preferred location. In an exploratory analysis, the cecum, ascending colon, and right flexure were affected significantly more often if intake of a nonsteroidal antiinflammatory drug (NSAID) is documented. There was no association between the location of ischemic colitis and a history of smoking, peripheral artery occlusive disease, coronary heart disease, diabetes, or malignant tumor.

CONCLUSIONS

Ischemic colitis seems not to have a predisposing site of occurrence in the colorectum, especially Griffith's point which was not afflicted significantly more often than other sites. Frequently, ischemic colitis afflicts more than one colonic location. In patients being treated with NSAIDs, ischemic colitis was observed significantly more often in the right hemicolon. Recurrence of ischemic colitis seems to be rare.

Biopsy interpretation of colonic biopsies when inflammatory bowel disease is excluded

The interpretation of colonic biopsies related to inflammatory conditions can be challenging because the colorectal mucosa has a limited repertoire of morphologic responses to various injurious agents. Only few processes have specific diagnostic features, and many of the various histological patterns reflect severity and duration of the disease. Importantly the correlation with endoscopic and clinical information is often cardinal to arrive at a specific diagnosis in many cases.

Inflammation-induced changes in the chemical coding pattern of colon-projecting neurons in the inferior mesenteric ganglia of the pig

The present study examines the chemical coding of the inferior mesenteric ganglia after chemically induced colitis in the pig animal model. In all animals (n = 6), a median laparotomy was performed under anesthesia, and the Fast Blue retrograde tracer was injected into the descending colon wall. In experimental animals (n = 3), the thick descending colon were injected with formalin solution to induce inflammation. The animals were euthanized and the inferior mesenteric ganglion was harvested and processed for double-labeling immunofluorescence for calbindin-D28k (CB) in combination with either tyrosine hydroxylase (TH), neuropeptide Y (NPY), somatostatin (SOM), vasoactive intestinal polypeptide (VIP), nitric oxide synthase (NOS), Leu-enkephalin (LENK), substance P (SP), vesicular acetylcholine transporter (VAChT), or galanin (GAL). Immunohistochemistry revealed significant changes in the chemical coding pattern of inferior mesenteric ganglion neurons. In control animals, Fast Blue-positive neurons were immunoreactive to TH, NPY, SOM, VIP, LENK, CB, and NOS. In the experimental group, TH, NPY, SOM, VIP, and LENK expressing neurons were reduced, whereas the number of neurons immunoreactive to CB, NOS, and GAL were increased. The increase of so-called neuroprotective neuropeptides suggests that the changes in the chemical coding of inferior mesenteric ganglion neurons reflect adaption under pathological conditions to promote their own survival.