Anatomical variations of the pulmonary hilum in Nepalese population: a contrast CT scan study

Abstract

Introduction: The pulmonary hilum is a critical anatomical region where bronchi, pulmonary vessels, and lymphatics converge. Variations in hilar anatomy can influence thoracic surgery, bronchoscopy, and radiological interpretation. This study aimed to document the prevalence and types of pulmonary hilar anatomical variations in a Nepalese population using contrast‑enhanced chest CT scans.

Method: This descriptive cross-sectional study was conducted from Jan 2025 to Jan, 2026 in the Department of Radiology and Imaging at Patan Academy of Health Sciences, Patan Hospital, Nepal. with ethical approval obtained from Institutional Review Board (IRC) of Patan Academy (Ref no: ). A stratified random sampling technique was employed, and a sample size of 369 was calculated based on prevalence data from prior studies. Adults aged ≥18 years undergoing contrast-enhanced chest CT for diagnostic purposes were included, while those with prior thoracic surgery, pregnancy, or contraindications to CT were excluded. CT images were reviewed by radiologists to identify variations in bronchi, pulmonary arteries, and veins. Data were analyzed using R software with descriptive statistics

Result: Of the 369 participants, 219(59.35%) were female and 150(40.65%) were male with a mean age of 56.81±15.82. On the right side, Type B among 133(36.04%) and Type E 84(22.76%) were more common, while on the left side, Type A 128(34.69%) and Type E 113(30.62%) were most frequent. Bilateral symmetry was observed in 86(23.31%) of cases.

Conclusion: Contrast CT scans revealed diverse pulmonary hilar variations in the Nepalese population, with Type B on the right and Type A on the left most common. These findings underscore the importance of population‑specific anatomical knowledge for surgical planning and radiological interpretation.