Background Spontaneous bacterial peritonitis (SBP) is a signifcant complication among cirrhotic patients with

ascites and is associated with high mortality. Early diagnosis and treatment of SBP are crucial, as they are associated

with better outcomes and lower mortality. The neutrophil-to-lymphocyte ratio (NLR) and mean platelet volume (MPV)

are routine, inexpensive, easily measured markers readily obtained from a complete blood count (CBC). Several studies have addressed the diagnostic role of NLR and MPV in patients with SBP but with diferent cutof values, sensitivity,

and specifcity. Therefore, we conducted this study to validate the clinical utility of NLR and MPV in diagnosing SBP.

Methods This study included 332 cirrhotic patients with ascites who were admitted to Sohag University Hospitals in

Egypt between April 2020 and April 2022. Of these patients, 117 had SBP, and 215 did not. Both NLR and MPV were

measured in all patients, and the ability of NLR and MPV to diagnose SBP was assessed using the receiver operator

characteristic (ROC) curve analysis.

Results NLR and MPV were signifcantly elevated in patients with SBP compared to those without SBP (P < 0.001).

At a cutof value of 5.6, the sensitivity and specifcity of the NLR in detecting SBP were 78% and 81%, respectively. In

contrast, MPV, at a cutof value of 8.8 fL, had a sensitivity of 62% and a specifcity of 63%. The combination of NLR and

MPV did not provide signifcant additional diagnostic value beyond only using NLR.

Conclusion Although NLR and MPV allow the detection of SBP, the NLR has higher clinical utility and is superior to

MPV in diagnosing SBP