Lateral Neck X-Ray for Adenoid Pad Evaluation
Use a lateral neck radiograph in the supine position to evaluate the adenoid pad, as it is technically easier to perform and entirely satisfactory for appraising adenoid size. 1
Radiographic Technique
The lateral neck X-ray should be obtained in the supine position rather than requiring both supine and erect views, as the supine film alone is sufficient for evaluating adenoid size and is technically simpler to perform in pediatric patients. 1
The lateral projection is important for visualizing the adenoids and sphenoid sinus in children. 2
Measurement Method: Adenoid-Nasopharynx (A/N) Ratio
Calculate the adenoid-to-nasopharynx (A/N) ratio on the lateral neck radiograph by measuring the adenoid size relative to the nasopharyngeal airway at the level of the choanae. 3, 4, 5
A nasopharyngeal airway obstruction of ≥65% can serve as a clinically relevant cut-off (representing two standard deviations below the mean for "moderately obstructive" adenoids) to indicate that adenoid enlargement is significant enough to warrant intervention. 6
Percent airway obstruction values differ significantly between severely obstructive (mean 94.71%) and moderately obstructive (mean 78.53%) adenoid categories across all pediatric age groups. 6
Important Limitations and Caveats
Lateral neck radiographs do not accurately predict the degree of airway obstruction during sleep, so they should not be used as the sole determinant for surgical decision-making in suspected sleep-disordered breathing. 1
Radiographic findings show poor correlation with clinical symptoms and endoscopic findings in some studies, suggesting that lateral neck X-rays should be used selectively rather than routinely. 3
The sensitivity of lateral neck X-ray for adenoid assessment is 79.41% with specificity of 75%, which is lower than nasal endoscopy (sensitivity 87.10%). 4
When to Use Lateral Neck Radiography
Use lateral neck X-rays on a highly selective basis when clinical findings do not clearly point toward adenoid hypertrophy as the primary cause of nasal obstruction, or when endoscopy is not readily available. 3, 6
Primary care physicians and pediatricians can confidently use lateral neck X-ray for making clinical decisions, but should consider nasopharyngoscopy when the clinical picture remains unclear or more evaluation is needed. 5
Nasal endoscopy remains the more accurate screening method for assessing adenoid size in patients with chronic adenoiditis, though lateral neck X-ray provides useful supplemental objective information. 4, 5