Acute appendicitis in children: is preoperative hyponatremia a predictive factor of perforation/gangrene? A prospective study.

Purpose: Distinguishing between perforated/gangrenous from uncomplicated appendicitis in children helps management. We evaluated hyponatremia as a new diagnostic marker for perforated/gangrenous appendicitis in children.

Methods: A prospective study including all children with acute appendicitis who underwent appendectomy at our institution from May 2021 to May 2023. Medical history and clinical criteria were analyzed. All blood samples were taken upon admission including serum inflammatory markers and electrolytes. Patients were divided into two groups (Group I: uncomplicated and Group II: perforated/gangrenous), and data between both groups were compared.

Results: The study included 153 patients [Group I: 111 (73%), Group II: 42 (27%)]. Mean serum sodium concentration in children with perforated/gangrenous appendicitis was significantly lower compared to children with uncomplicated appendicitis (131.8 mmol/L vs. 138.7 mmol/L; p < 0.001). The ROC curve of preoperative sodium level to differentiate between perforated/gangrenous and uncomplicated appendicitis revealed an AUC of 0.981. The cut-off-value of sodium level < 135 mmol/L identified perforated/gangrenous appendicitis with a sensitivity of 94% and a specificity of 91% (p < 0.001). Predictive factors of perforated/gangrenous appendicitis were: age less than 5 years (12% vs. 3%; p = 0.02), experiencing symptoms for more than 24 h (100% vs. 58%; p < 0.001), body temperature more than 38.5 °C (52% vs. 13%; p < 0.001), a serum sodium level less than 135 mmol/L (90% vs. 6%; p < 0.001), and a CRP serum level more than 50 mg/L (71% vs. 17%; p < 0.001).

Conclusions: Hyponatremia, upon admission, is a novel, objective biochemical marker that can identify perforated/gangrenous appendicitis in children. We advocate that the assessment of serum sodium level should be added to the diagnostic algorithm in children with suspected acute appendicitis. Surgical intervention in patients with hyponatremia should not be delayed, and non-operative management should be avoided.