Tonsil and adenoid surgery are among the most commonly performed pediatric procedures in Sweden, yet important knowledge gaps remain regarding indications, outcomes, complication risks, and the associated patient‑reported symptom burden. The overarching aim of this thesis was to examine key aspects of contemporary clinical practice related to pediatric tonsil and adenoidectomy surgery in Sweden, with focus on epidemiology, safety, surgical outcomes, and the development and validation of a Swedish version of a pediatric patient‑reported outcome measure (PROM). The thesis comprises four studies based on register data, clinical outcome analyses, and psychometric validation.

Paper I mapped the national epidemiology of pediatric adenoidectomy between 2004 and 2013 using data from the National Patient Register. Hypertrophy was the most common indication, and combined adenotonsillar surgery was the most common procedure. Adenoidectomy was performed mainly in children aged 2-5 years, with higher incidence among boys.

Paper II examined postoperative morbidity and mortality following adenoidectomy in 51,746 procedures performed between 2007 and 2017. Late postoperative hemorrhage was rare, late bleeding events requiring return to theatre were exceptionally uncommon, and no deaths attributable to adenoidectomy were identified, confirming that the procedure is highly safe in the Swedish context.

Paper III evaluated postoperative bleeding, revision surgery, and caregiver‑reported symptom relief following 1,810 cold steel tonsillotomy procedures with or without adenoidectomy over a 10‑year period. The technique demonstrated low rates of postoperative bleeding, acceptable revision rates, and high caregiver‑reported symptom improvement. At the same time, the technique keeps instrument costs low and reduces environmental impact by avoiding disposable devices and advanced equipment.

Paper IV translated and validated the Paediatric Throat Disorders Outcome Test (T‑14) into Swedish. The instrument demonstrated strong known‑groups validity, an acceptable model fit in confirmatory factor analysis, good internal consistency, and high responsiveness to postoperative changes. The Swedish T‑14 enables structured pre‑ and postoperative assessment of symptom burden and demonstrates potential value for both clinical practice and future research.

Together, the findings demonstrate that pediatric adenoidectomy and cold‑steel tonsillotomy are safe procedures with low complication rates in routine clinical care. The thesis highlights important gaps in national outcome monitoring, particularly the lack of preoperative patient‑reported measures. The findings and the instrument presented may contribute to more informed evaluation, follow‑up, and clinical decision‑making in pediatric adenotonsillar surgery.