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