Introduction Acute appendicitis (AA) is the most common surgical condition of the abdomen in children. The aim of this study was to analyse the possible use of the neutrophil-to-lymphocyte ratio (NLR) in the diagnosis and prediction of AA complications in children. Material and methods We included 170 AA patients under 15 years of age, who were divided into the following groups: Group 1 – non-operated patients with AA, and Group 2 – patients who underwent appendectomy. Based on pathologic grades of AA, Group 2 was subdivided into: Group A – phlegmonous, Group B – gangrenous, and Group C – perforated AA. NLR was calculated as the absolute neutrophil count divided by the absolute lymphocyte count. Results In Group 2 NLR was significantly higher than in Group 1 (5.5 (1.9–9.9) vs. 2.3 (1.2–3.7); p < 0.001). A significant difference in NLR was found between Group C and Group A (p < 0.001), and as well as between Group B and Group A (p = 0.001). The determined optimal cut-off value of NLR in differentiating Group 1 vs. Group 2 was ≥ 3.48 (p < 0.001). In differentiating Group A from Group C the optimal cut-off value of NLR was ≥ 5.61 (p < 0.001). Furthermore, optimal cut-off value of NLR in differentiating Group A from Group B was ≥ 5.45 (p = 0.001). Conclusions The obtained results suggest that NLR could be used as a simple and reliable test in the diagnosis and prediction of AA complications in children. However, to draw definite conclusions on the predictive power of NLR as a marker of AA large multicentric studies are required.

Congenital hypertrophic pilorostenosis is a relatively common illness with an incidence of 2-3.5 on 1000 live-born children. (1,2) Most commonly affects prematuruses, firstborn and male children (male to female ration is 4:1 ) in the period of the 3rd to 6th week of life. (3,4) Etiology is not clear yet, it is assumed to be generated by the interaction of genetic and environmental factors. (5,6) The diagnosis is based on heteroanamnesis, physical finding and ultrasonography. The leading symptom is nonbilious projectile vomiting soon after feeding. There is also opstipation. If vomiting takes a few days, alkalosis, electrolyte disorder, dehydration and malnutrition may be present. The gold standard in diagnosis is ultrasound, which has high sensitivity (97%) and specificity (100%). (7) In certain unclear cases, the contrasting rtg of gastroduodenum is also applied. (8,9,10) The final treatment is surgical incision of the pyloric wall to the mucous membrane with leaving pylorus unstretched. (11,12,13,14) The success of the surgical Abstract