CT scans and MRI (magnetic resonance imaging) can help in diagnosis. X-rays can determine the location and size of the narrowed airway portion. Optical coherence tomography (OCT) can help observe the progression of the injury. Esophageal pH monitoring can help detect any acid reflux, which can worsen the condition. An endoscope can be inserted and used to see the vocal cords, airway, and esophagus. Spirometry is a useful way to measure respiratory function. People affected by<unk>  have a FEV1 of over 10.<unk>  is graded according to the Cotton-Myer classification system from one to four based on the severity of the blockage. Grade 1 is up to 50% obstruction, Grade 2 is 50-70% obstruction, Grade 3 is 70-99% obstruction, and Grade 4 is with no visible lumen. File:Subglottic<unk>  04.Grade 1<unk>  File:Subglottic<unk>  03.Grade 2<unk>  File:Subglottic<unk>  02.Grade 3<unk>  File:Subglottic<unk>  01.Grade 4<unk>
Subglottic stenosis
Laryngotracheal stenosis
Laryngomalacia
Laryngopharyngeal reflux
Meatal stenosis
Tracheoinnominate fistula
Velopharyngeal insufficiency
Tracheoesophageal fistula