Ischaemic bowel disease

Gastroenterology (12%) Core Clinical Conditions

1B The Physician Associate is able to identify the condition as a possible diagnosis: may not have the knowledge/resources to confirm the diagnosis or to manage the condition safely, but can take measures to avoid immediate deterioration and refer appropriately.

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Definition Aetiology Pathophysiology Risk factor Sign and Symptoms Investigations Management

Ischaemic bowel disease, also known as mesenteric ischemia, is a medical condition that affects the blood supply to the intestines, causing inadequate blood flow and subsequent damage to the bowel. This condition can lead to serious complications and requires prompt medical attention.

1. Arterial embolus: A blood clot that forms elsewhere in the body and travels through the bloodstream, blocking blood flow in a mesenteric artery.
2. Arterial thrombus: A blood clot that develops within a mesenteric artery, restricting blood flow.
3. Mesenteric venous thrombosis: A blood clot in the veins that drain blood from the intestines, causing reduced blood flow.
4. Non-occlusive factors: Conditions like low blood pressure, heart failure, or vasospasm can also cause ischaemic bowel disease by reducing blood flow to the intestines.

A reduction or complete occlusion of blood flow to the intestines. This can occur due to a variety of factors, including arterial emboli (blood clots), thrombosis (blood clot formation), mesenteric artery or vein constriction, or systemic hypoperfusion (reduced blood flow throughout the body). These mechanisms disrupt the normal delivery of oxygen and nutrients to the intestinal tissues, leading to tissue ischemia (lack of blood supply), subsequent inflammation, and tissue injury.
The intestines, especially the small intestine, have a high metabolic demand, requiring a significant blood supply to sustain cellular function. Unlike other organs, such as the heart or brain, the intestines have limited collateral blood flow, making them particularly vulnerable to ischaemic injury. The delicate balance between oxygen delivery and metabolic demand is disrupted in ischaemic bowel disease, leading to tissue hypoxia (oxygen deprivation) and subsequent tissue damage.
The reduced blood flow and subsequent hypoxia trigger a cascade of pathological events within the intestines. Initially, the intestinal cells switch from aerobic to anaerobic metabolism to adapt to the reduced oxygen supply. This shift in metabolism results in the accumulation of lactic acid and other metabolites, causing intracellular acidosis and impairing cellular functions.
As the ischaemia progresses, the damaged intestinal cells release inflammatory mediators, including cytokines and chemokines, initiating an inflammatory response. This inflammatory process attracts immune cells to the affected area, further exacerbating tissue damage. The release of reactive oxygen species, such as free radicals, also contributes to the injury by causing oxidative stress and damaging cellular structures.
The tissue damage and inflammation can lead to a range of complications, depending on the severity and duration of the ischaemia. The initial insult may cause reversible injury, with symptoms such as abdominal pain, diarrhoea, and weight loss. However, if the blood flow is not restored promptly, irreversible transmural infarction (death) of the affected intestinal segment may occur. This can result in bowel perforation, peritonitis (inflammation of the abdominal lining), sepsis (systemic infection), and potentially multi-organ failure.

1. Atherosclerosis: Atherosclerosis, a condition involving the buildup of fatty deposits in artery walls, is a major risk factor for ischaemic bowel disease. It narrows the arteries supplying blood to the intestines, reducing their capacity to deliver oxygen and nutrients. As a result, the bowel tissue becomes vulnerable to inadequate blood flow, increasing the likelihood of ischaemic events.
2. Age: Advanced age has been identified as a risk factor for ischaemic bowel disease. With age, blood vessels lose elasticity and become more prone to occlusion or blockage. Additionally, elderly individuals often have multiple comorbidities, such as diabetes or cardiovascular disease, which further enhance the risk of developing ischaemia in the bowel.
3. Cardiovascular disease: Individuals with a history of cardiovascular disease, such as coronary artery disease or peripheral artery disease, face an elevated risk of ischaemic bowel disease. These conditions can reduce blood flow to the bowel due to underlying issues with arterial plaques or blood clots, thereby contributing to the development of mesenteric ischemia.
4. Hypertension: High blood pressure can damage and narrow the arterial walls over time, impeding proper blood flow to the intestines. Hypertension increases the risk of ischaemic bowel disease by directly compromising the health and functionality of blood vessels, making them more susceptible to occlusion or spasm.
5. Smoking and alcohol abuse: Unhealthy lifestyle habits such as smoking and excessive alcohol consumption can significantly impact the risk of developing ischaemic bowel disease. Both smoking and alcohol abuse contribute to the formation of atherosclerosis and plaque buildup in the arteries, which can lead to reduced blood supply to the intestines.
6. Medications: Certain medications can increase the risk of ischaemic bowel disease. Non-steroidal anti-inflammatory drugs (NSAIDs) commonly used for pain relief and the control of inflammation, when taken in high doses or for extended periods, may disrupt the blood flow to the bowel, predisposing individuals to ischaemic events.
7. Abdominal surgeries or interventions: Prior abdominal surgeries, particularly those involving blood vessels, can increase the risk of ischaemic bowel disease. Surgical procedures in the abdominal region may inadvertently damage or disrupt the arterial blood supply to the intestines, leading to subsequent ischaemia.

• Abdominal pain: Typically severe and crampy, usually concentrated in the mid-abdomen.

• Nausea and vomiting: These symptoms may be present due to the reduced blood flow to the intestines.

• Bloody stools: In severe cases, blood may be present in the stools due to damaged blood vessels.

• Diarrhoea: Sometimes accompanied by urgency and tenesmus (feeling of incomplete bowel movement).

• Weight loss: Chronic ischaemic bowel disease can lead to unintentional weight loss over time.

• History and physical examination.

• Blood test: FBC raised WCC, low HB, raised Amylase. Also request LFTs and U&E.

• Imaging tests: abdominal XR, CT scan, angiography, or mesenteric duplex ultrasound to visualise the blocked blood vessels.

• Medications: Blood thinners or medicines to treat underlying conditions, such as clot-busting drugs or vasodilators.

• Surgery: In cases of severe damage, surgery may be necessary to remove the affected part of the bowel or create a bypass to restore blood flow.

• Endovascular procedures: Minimally invasive procedures, such as angioplasty or stent placement, can be performed to restore blood flow.

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