Importance: Congenital nasal pyriform aperture stenosis (CNPAS) is a rare cause of nasal airway obstruction in newborns. The decision to operate is made clinically. Although pyriform aperture width is used for diagnosing CNPAS, it does not fully characterize stenosis of the nasal cavity., Objective: To determine the utility of additional metrics for evaluating CNPAS., Design, Setting, and Participants: The medical records of 13 patients with CNPAS treated from 2007 through 2012 at a single tertiary pediatric facility were retrospectively examined. Data on patient demographic characteristics, known genetic abnormalities, and hospital courses were extracted. Computed tomographic images were evaluated for pyriform aperture width; maxillary-nasal angle (MNA), defined as the angle between the anterior maxilla and anterior-posterior nasal axis; and choanal width., Interventions: Medical management and surgical management., Main Outcomes and Measures: Pyriform aperture width, MNA, and choanal width., Results: Six of 13 patients underwent medical management, and 7 patients underwent surgical treatment. For patients who were managed medically as compared with those managed surgically, the evaluation revealed a larger pyriform aperture width (median [interquartile range {IQR}], 5.6 [5.4-6.1] vs 4.6 [4.5-4.7] mm; P = .03) and MNA (median [IQR], 70° [63°-73°] vs 59° [59°-64°]; P = .048) but no significant difference in choanal width (median [IQR], 11.0 [9.6-12.2] vs 11.9 [10.3-11.9] mm; P = .76)., Conclusions and Relevance: The MNA, when used in conjunction with pyriform aperture width, provides additional pertinent information to supplement clinical decision making in the evaluation of patients with CNPAS. These measurements may be helpful in identifying patients who should undergo surgical intervention, although additional studies would be required to allow predictive use of the MNA.