Hyponatremia as a marker of complicated appendicitis: A systematic review

Acute appendicitis, the most common cause of acute surgical abdomen, is associated with intra-abdominal complications, such as perforation, that increase morbidity and mortality. Early and accurate preoperative diagnosis of complicated appendicitis mandates the identification of new diagnostic markers. This systematic review summarizes current literature on the adoption of hyponatremia as an early diagnostic and predictive marker of complicated appendicitis. Pubmed, Cochrane Library, Scopus, Google Scholar, WHO Global Health Library, System for Information on Grey Literature, ISI Web of Science, EBSCOHost and Virtual Health Library were searched in accordance with the PRISMA guidelines in order to identify original human studies investigating the association between hyponatremia and the presence or development of complicated appendicitis. A total of 7 studies conducted in 6 different countries were identified. A prospective diagnostic accuracy study reported a strong association between hyponatremia and complicated appendicitis in children. The largest sample size study performed in adults reported a significant association between hyponatremia and perforated or gangrenous appendicitis. The admission serum sodium level measurement, a routinely performed, low-cost test, should be taken into account in patients with clinical presentation compatible with acute appendicitis and suspicion of underlying complications. Future well-designed prospective diagnostic accuracy studies are required to further establish the association between hyponatremia and perforated appendicitis.