Role of D-Dimer Test in Diagnosing Mesenteric Ischemia

Mesenteric Ischemia is a condition characterised by decreased blood flow to the intestine. It may be acute or chronic. Acute mesenteric ischemia is a rare disease that mainly causes ischemia to the intestine due to obstruction of the mesenteric vessel (blood vessel which supplies blood and nutrient to the intestine) feeding to the intestine. According to a study, the overall incidence of acute mesenteric ischemia (AMI) is 0.63 per 100,000 people.^[1] The incidence of AMI mainly increases with increasing age and reaches up to 18% in patients with age greater than 65.

Acute mesenteric ischemia symptoms include sudden onset of abdominal pain, nausea, vomiting, diarrhea, fever, tachycardia, and rectal bleeding in some cases.

There are mainly four different types of acute mesenteric ischemia present,

• Arterial embolism with a mortality rate of 54.1%
• Arterial thrombosis mortality rate of 77,4%
• Non-occlusive mesenteric ischemia mortality rate 72.7%
• Venous thrombosis mortality rate 32.1%.^[1]

There are various reasons that may contribute to the increased rate of mortality such as late hospital admission, delay in diagnosis, and the presence of some previously existing problems such as atrial fibrillation, heart failure, atherosclerosis, and shock with increasing age.

It was found that emergency intervention has a significant role in the reduction of mortality rate if given within the first six hours. If blood flow is restored to the intestine in the early six hours, then they are known to reduce mortality to 10-20%. So, it is very important to take the patient immediately to the hospital so that better care is given to the patient.

Importance of Accurate Diagnosis in Acute Mesenteric Ischemia:

In acute mesenteric ischemia accurate diagnosis is very crucial as it allows for better treatment and improves patient outcome. Delayed or misdiagnosis can lead to very severe manifestations such as tissue death and systemic infection which are proven to be fatal in some cases. The survival rate exceeds almost 90% if an early diagnosis is done. A large multicenter study was done with 780 ICU patients with acute mesenteric ischemia, the overall mortality rate was observed nearly 58%.^[4] The increase in mortality rate is mainly seen in patients with late diagnosis.

For the accurate diagnosis of the AMI, multidetector computed tomography angiography (MDCTA) should be performed as earlier as possible and for the biochemical diagnosis of acute mesenteric ischemia, different types of markers are used which include intestinal fatty acid-binding protein (I-FABP), α-glutathione S-transferase (α-GST), citrulline, D-dimer, L and D-lactate, white blood cell (WBC) count, and neutrophil/lymphocyte ratio (NLR).^[6] Among these markers in this article, we are going to study the D-Dimer as a marker compound in the diagnosis of acute mesenteric ischemia (AMI).

In the year 1990s use of D-dimer techniques were used. The D-Dimer test is used to evaluate or diagnose the thrombotic events that are happening inside the human body including mesenteric ischemia. It is a simple non-invasive, less costly blood test, that mainly measures the concentration of D-Dimer protein in a blood sample.

As we know when there is clot formation inside the body or clot lysis process in the body, in both cases there is a significant rise in blood D-Dimer levels. During clot dissolution or lysis, it releases various types of small and large fragments, among them two fragments of D-Dimer are also released which are cross-linked together.^[5] And one of the reasons for mesenteric vessel blockage is the formation of a thrombus inside the mesenteric vessel, so due to this phenomenon D-Dimer test is utilised in the diagnosis of acute mesenteric ischemia (AMI).

• Blood Sample Collection: The first step for the diagnosis of AMI by using the D-Dimer technique is the collection of blood samples. Keep in mind that the sample must be collected by a healthcare professional who is compatible with this job and mainly blood is drawn from the vein of the arm.
• Laboratory Analysis: For the analysis of blood samples, it will be sent to the laboratory. Where a lab technician can use specific reagents for the detection of D-Dimer levels in a blood sample.^[7] Mainly ELISA (enzyme-linked immunosorbent assay) test is performed for the detection.
• Results and Clinical Assessment: The laboratory will provide the test results and tell the level of D-Dimer in a blood sample. After that, the physician can analyse the report and condition of the patient and provide the best clinical care to the patient to improve the patient’s outcome.

Several studies have been published until now on the diagnostic role of D-Dimer as a biomarker in acute intestinal disease, generating often controversial reports. Although it was shown to display good diagnostic properties in thrombo embolic occlusion. Its diagnostic efficiency seems overall less satisfactory in the case of non-vascular acute intestinal ischemia.^[5] Mainly its less efficacy is due to liver disease, inflammation, trauma, pregnancy, and recent surgery. Because if any of these conditions it will lead to less satisfactory results and often shows false positive test results.

Cudnik et al. reviewed pooled data from five different studies, and according to that data he concluded that D-Dimer test has a very high sensitivity of up to 96% and a quite lower specificity of almost 40%. So due to this, its accuracy created doubt in the early diagnosis of Acute mesenteric ischemia.^[4]

In this article, we studied that mesenteric ischemia is a condition with a high rate of mortality. So, to decrease the mortality rate and improve patient outcomes early diagnosis has proved a key factor. For the proper detection of the AMI, we mainly use the D-Dimer test. This test concludes that the presence of high D-Dimer levels in the blood may indicate early acute mesenteric ischemia or the presence of a thrombus inside the mesenteric vessel. It offers many advantages over other biomarkers as it is invasive and provides faster results. However it is highly sensitive but on the other side, it has less specificity as we have seen in the clinical studies, because the level of d-dimer may increase in various other conditions such as in the presence of liver disease or inflammation. So, there are future research is necessary which mainly focuses on its accuracy In giving results, and providing minimum false results. Researchers may look forward to coupling this D-Dimer test with other some test to overcome its limitations and provide better results. Scientists may also need to focus on making this test appropriate so that early diagnosis could be possible which helps in decreasing the morbidity rate associated with acute mesenteric ischemia.

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