Diagnosing acute appendicitis in children remains a clinical challenge, with delayed or incorrect diagnosis potentially leading to serious complications or unnecessary surgery. Prostaglandin E urinary metabolites (PGE-M) have been found elevated in various inflammatory conditions, but their diagnostic value in pediatric appendicitis is not well established. This study aims to assess the potential of PGE-M as a biomarker for acute appendicitis in children.

The study will be conducted over 12 months and will include 100 children aged 5 to 17 years presenting with acute abdominal pain. In addition to routine laboratory tests, urinary PGE-M levels will be analyzed. The study involves minimal risk to participants

The diagnosis of acute appendicitis in children remains a challenge, even for experienced clinicians. Failure to recognize this acute condition may result in perforation and subsequent peritonitis, whereas misdiagnosis can lead to unnecessary (negative) appendectomies. Elevated levels of prostaglandin E urinary metabolites (PGE-M) have been observed in other inflammatory conditions such as inflammatory bowel disease, acute mesenteric ischemia, and necrotizing enterocolitis.

The aim of this study is to determine whether PGE-M levels are elevated in children with acute appendicitis and whether this biomarker could be used in the diagnosis of acute appendicitis.

The planned duration of the study is 12 months, with a projected sample size of 100 participants.

Inclusion criteria: Children aged 5 to 17 years presenting with acute abdominal pain and signs and symptoms suggestive of acute appendicitis, without significant comorbidities.

Exclusion criteria: Children outside the specified age range, those with a previously diagnosed chronic or malignant disease, a history of abdominal surgery, or pregnancy.

For each child included in the study, demographic data, clinical characteristics, laboratory and diagnostic test results, intraoperative findings, and discharge diagnoses will be recorded. Since the child is already indicated for surgery or hospital admission regardless of study participation, there are no significant risks associated with participation in this study-apart from potential, but rare, complications related to peripheral venous blood sampling (e.g., hematoma or discomfort).

For the purposes of the study, a peripheral venous blood sample will be collected (on the day of surgery or hospital admission) to analyze laboratory parameters including leukocyte count, C-reactive protein, and neutrophils. Additionally, a urine sample will be collected to determine the levels of prostaglandin E urinary metabolites (PGE-M) and creatinine

Inclusion Criteria:

• children of age 5 -17 years with acute abdominal pain
• children with clinical signs of acute appendicitis

Exclusion Criteria:

• previous diagnosis of chronic and/or malignant disease
• children who had previous abdominal surgery
• pregnancy

Patients from 5 to 17 years of age, presenting with acute abdominal pain consistent with diagnosis of acute appendicitis, to Emergency Surgical Department at the University Hospital of Split