Brief Commentary on the Article “Diagnostic Value of Plasma Pentraxin-3 in Acute Appendicitis”

Keywords::

• Pentraxin-3
• Appendicitis
• Emergency Surgery
• Acute abdomen

This article is referred to by:

Diagnostic Value of Plasma Pentraxin-3 in Acute Appendicitis

Appendicitis has always remained the major subgroup among patients suspected of acute abdomen in emergency departments all over the world. Due to the potential catastrophic events that might ensue if left unattended, surgical removal of the vermiform appendix is the ideal treatment in a case of diagnosed appendicitis. However, there are a large number of clinical conditions which can mimic the clinical features of acute appendicitis, especially in the paediatric population. To diagnose a case of acute abdomen as appendicitis requires astute clinical examination skills as well as an array of investigations in the form of blood counts and imaging modalities like Ultrasonography and Computed Tomography(CT). In spite of all the preoperative investigations, a significant percentage of people(as high as 10%) who undergo emergency appendicectomy still turn up negative histology.¹ Also, the adverse effects associated with CT scan preclude its routine prescription in all suspected cases, especially in the younger population. Over the years, clinicians have been on the hunt for the right blood marker that can differentiate a case of acute appendicitis from other causes of acute abdomen which don't mandate surgical treatment.

Conventional white blood cell count (WBC) count is neither sensitive nor specific in the diagnosis of acute appendicitis as the count is found increased in up to 70 per cent of patients with other causes of right lower quadrant pain.² Other markers used in evaluation of acute appendicitis include C-reactive protein(CRP) and Pro-calcitonin. CRP, although more specific than leucocytes count, is found to be less sensitive in the early stages of acute appendicitis and may be more sensitive in detecting appendicular perforations and abscess formation.³ Pro-calcitonin, a precursor of calcitonin, is normally undetectable and is stimulated by endotoxin or inflammatory cytokines to be produced rapidly by most parenchymal tissues all over the body. It does not respond to sterile inflammations or viral infections unlike CRP. However, pro-calcitonin has been found to have little value in diagnosing acute appendicitis, with diagnostic accuracy lower than CRP and WBC count and hence has diagnostic value in identifying complicated appendicitis only.⁴ Blood level of fibrinogen is another new diagnostic acute-phase reactant claimed to have possible role in reducing negative appendectomy rates.⁵

Pentraxin-3(PTX-3) is a secretory protein classified as a long pentraxin member of the pentraxin family. This protein is structurally found to be related to CRP, but distinct in that pentraxin-3 subunits are approximately twice as large as CRP subunits (46 kDa molecular mass vs. 23 kDa). Hence, the smaller CRP could be lost from the vascular compartment due to leakage, while the larger pentraxin-3 could be protected from such a loss. Pentraxin-3 is produced by a wide variety of cells including macrophages and endothelial cells, in response to primary inflammatory stimuli like Tumour Necrosis Factor-alpha (TNF), interleukin-1(IL-1), and microbial products like lipo-polysaccharides and lipo-arabinomannans. Plasma levels of pentraxin-3 are usually measured using sandwich enzyme-linked immuno-sorbent assay (ELISA) technique and are expressed as nanograms per milliliter (ng/ml), the normal levels in healthy persons being 2 ng/ml.

Many studies have found association between infective and septic pathologies and pentraxin-3. Pentraxin-3 levels have been proven to correlate well with the severity of bacterial infection in patients who are critically ill.⁶ Systemic levels of pentraxin-3 have been found to have prognostic value in patients with SIRS and sepsis, complementing various disease-severity classification systems.⁷ Persisting high plasma levels of circulating pentraxin-3 over the first days from onset of sepsis may be associated with mortality as well as with sepsis associated coagulation and fibrinolysis dysfunction.⁸ Part from septic situations, studies also indicate that pentraxin-3 is a better marker of infection than C-reactive protein in patients with dengue.⁹ Interestingly,pentraxin-3 has also been reported to increase in plasma in patients with acute myocardial infarction.¹⁰

The current case-control study was carried out to measure serum levels of pentraxin-3, in patients admitted to the emergency department with right-lower quadrant pain and investigate whether it will be helpful in diagnosing acute appendicitis.¹¹ The authors took blood samples for pentraxin-3 at the time of admission from these patients. The patients also underwent abdominal CT scanning and based on the findings, patients were classified. At the end of the study, they analyzed 89 patients of which 39 formed the cases. After analysis, pentraxin-3 levels were significantly higher in patients with acute appendicitis than in the control group and patients with non-specific abdominal pain. Based on this, the authors recommend using pentraxin-3 as a routine marker for suspected cases of appendicitis.

Nevertheless, this study does have some drawbacks of its own. The comparatively small sample size reduces the external validity and significance provided by the study results. Also, the varying times of presentation to the emergency might interfere with proper assessment of the plasma levels of pentraxin-3. In spite of that, the novelty of the idea should throw open many opportunities for future research in this aspect. Further research in this area in the form of randomized controlled trials on a larger scale might throw up other interesting applications for this inflammatory marker. As a conclusion, the use of pentraxin-3 as a diagnostic marker for acute appendicitis can definitely be recommended for wider research and subsequent adoption in clinical practice.

Declaration of interest

The author reports no conflicts of interest. The author alone is responsible for the content and writing of the paper.