The palatine tonsils, pharyngeal tonsils (adenoids) and lingual tonsils together comprise a ringed, lymphoid tissue complex within the naso- and oropharynx known as Waldeyer's ring. This structure is known to be involved in inducing secretory immunity and regulating secretory immunoglobulin production. Both the adenoids and the tonsils are subject to infection. They can be potential contributors to upper airway obstruction due to hypertrophy. The number of adenotonsillectomies has been decreasing over the last 60 years. Historically, recurrent tonsillitis was the most common indication for adenotonsillectomy. Though this remains an indication for surgical intervention, airway obstruction secondary to adenotonsillar hypertrophy is currently the most common indication. Manifestations of such obstruction fall within the spectrum of sleep-disordered breathing ranging from primary snoring (PS) to upper-airway resistance syndrome (UARS) to obstructive sleep apnea syndrome (OSAS).

Depending on the extent of adenotonsillar hypertrophy, obstructive symptoms can include loud snoring, chronic mouth breathing, hyponasal speech, frequent night-time awakenings, enuresis, parasomnias, daytime somnolence, poor school performance, dysphagia, failure to thrive, and witnessed apneic episodes. On physical exam, adenotonsillar visualization should be performed as well as a speech evaluation to assess for the presence of hyponasality secondary to nasal obstruction. In addition, craniofacial structures should be noted to assess for the stigmata of adenoid facies associated with chronic mouth breathing. The need for preoperative polysomnographic testing to diagnose OSAS should be based primarily on the history and physical examination. Patients with adenotonsillar hypertrophy, clinical stigmata of OSAS, and a history of loud snoring with witnessed obstructive apneic events may be considered for polysomnographic testing. However, this may not always be necessary before proceeding with surgery, and such symptomatology should warrant overnight hospital observation. If the physical examination is inconsistent with the patient's history, preoperative testing should be performed. In addition, polysomnographic testing should be strongly considered for patients with high perioperative risks, including children less than 3 years of age; obese patients; patients with craniofacial anomalies, neuromuscular, or neurologic disease; and patients with other medical conditions (e.g., bleeding diatheses, sickle cell disease, or substantial pulmonary disease) that may complicate postoperative management. The apnea–hypopnea index (AHI), peak end-tidal CO2 and severity of oxygen desaturation are useful data recorded during testing. Based on polysomnography, an AHI of ≥ two events per hour with a clinical history consistent with sleep-disordered breathing is appropriate evidence to proceed with adenotonsillectomy.