Clinical guidelines suggest adenoidectomy when enlarged adenoids are associated with nasal obstruction and other symptoms. Given that nasal obstruction is the leading symptom of adenoid hypertrophy, it should be thoroughly explored. However, there is no consensus regarding what could be the best approach. This systematic review is designed with the objective of exploring the extent to which adenoidectomy can decrease nasal resistance through rhinomanometry. 3 authors members of the YO-IFOS rhinology study group independently analyzed the data sources (Pubmed, the Cochrane Library, EMBASE, SciELO) for papers assessing the change in nasal resistance and/or nasal airflow in rhinomanometry after adenoidectomy in pediatric patients. A total of 9 studies with a total population of 423 participants (323 patients excluding healthy controls) met the inclusion criteria. All of them found decreased nasal resistance after adenoidectomy. 5 studies could be combined in a metanalysis, which revealed a statistically significant difference of 0.52 Pa in basal conditions, and 0.64 Pa in rhinomanometry under nasal decongestion. 4 authors explored changes in nasal airflow. All of them found a statistically significant increase in nasal airflow after adenoidectomy. However, their results could not be merged in a meta-analysis. This systematic review and meta-analysis demonstrated the existence of a systematic decrease in nasal resistance and increase in nasal airflow with and without nasal decongestant after adenoidectomy. The available evidence suggests that rhinomanometry with nasal decongestant could help in intermediate cases of adenoid hypertrophy, in order to identify the presence of nasal obstruction and, when present, the possibility of other causes for it rather than enlarged adenoids, mainly turbinate hypertrophy. [ABSTRACT FROM AUTHOR]