This prospective observational study evaluated the diagnostic performance of serum calprotectin in patients presenting with acute abdominal pain and suspected acute appendicitis. Patients with histopathologically confirmed acute appendicitis were compared with patients diagnosed with nonspecific abdominal pain. Serum calprotectin levels were analyzed and compared with conventional inflammatory markers and the Alvarado score to assess their diagnostic value in acute appendicitis.

Acute appendicitis is one of the most common causes of acute abdominal pain requiring emergency surgical intervention. However, establishing an accurate diagnosis may be difficult, particularly in patients presenting with nonspecific abdominal pain or atypical clinical findings. Conventional inflammatory markers and clinical scoring systems are useful adjuncts, but their diagnostic accuracy remains limited.

This prospective single-center observational study evaluated the diagnostic performance of serum calprotectin in adult patients presenting with acute abdominal pain and suspected acute appendicitis. Patients with histopathologically confirmed acute appendicitis were compared with a control group consisting of patients diagnosed with nonspecific abdominal pain after clinical, laboratory, radiological evaluation, and follow-up.

Serum calprotectin concentrations were measured and compared with white blood cell count, C-reactive protein, ferritin, and the Alvarado score. The relationship between serum calprotectin levels and histopathological severity of appendicitis was also assessed.

The primary objective of the study was to determine the diagnostic accuracy of serum calprotectin in distinguishing acute appendicitis from nonspecific abdominal pain.

Inclusion Criteria:

• Age between 18 and 75 years
• Presentation to the emergency department with acute abdominal pain and suspected acute appendicitis
• Willingness to participate and provide informed consent

Exclusion Criteria:

• Previous abdominal surgery
• Chronic inflammatory or autoimmune disease
• Active infection other than suspected appendicitis
• Use of systemic anti-inflammatory or immunosuppressive therapy
• Pregnancy
• Incomplete clinical or laboratory data

Adult patients presenting to the emergency department with acute abdominal pain and suspected acute appendicitis. Participants were divided into two groups: patients diagnosed with acute appendicitis and patients with non-specific abdominal pain.

individual participant data sharing plans are currently undecided.