The goal of this observational study is to investigate whether the A118G single-nucleotide polymorphism (SNP) in the mu-opioid receptor1(OPRM1) and Catechol-O-methyltransferase (COMT) SNPs influence postoperative pain scores in children between the ages of 8 and 18 undergoing orthopedic, abdominal, thoracic, and plastic surgeries. The main question\[s\] it aims to answer \[is\]: Do OPRM1 and COMT SNPs influence postoperative pain scores in children between the ages of 8 and 18 undergoing orthopedic, abdominal, thoracic, and plastic surgeries? Participants will be assessed for their pain scores, sedation level, the amount of postoperative analgesics received, duration of their stay in the post-anesthesia care unit, and toxicity.