Morphometric and Morphological Analysis of the Pulmonary Auscultatory Triangle in Human Fetuses: Anatomical Insights for Thoracic Surgery

Objectives: The Pulmonary Auscultatory Triangle (PAT) is a bilateral region on the back delimited by the trapezius, latissimus dorsi, and scapula. Beyond its relevance for pulmonary auscultation, PAT also represents an important anatomical window for posterior thoracic approaches. While its anatomy has been extensively described in adults, data on its developmental morphology during fetal life remain scarce. This original morphometric study aimed to characterize the morphometry and morphology of the PAT in human fetuses and to evaluate differences according to sex, side, and gestational age. Methods: A total of 80 PATs from 40 human fetuses (20 male and 20 female) were examined. Using ImageJ software 1.54k, we measured margin lengths (inferior trapezius, medial scapular, and superior latissimus), area, and perimeter. Morphological classification was performed based on internal angles. Associations with sex, side, and gestational age were statistically assessed. Results: The mean gestational age was 28.6 weeks. PAT had a mean area of 103.2 mm2 and a mean perimeter of 49.1 mm. Mean margin lengths were 20.1 mm for the trapezius, 12.4 mm for the scapular margin, and 16.6 mm for the latissimus dorsi. Three morphologies were observed: acute (42.5%), obtuse (25.0%), and rectangular (32.5%). A significant asymmetry in shape distribution was found between sides (p = 0.034). Weak but statistically significant positive correlations with gestational age were found for perimeter and for the trapezius and latissimus dorsi margins, indicating progressive enlargement with fetal growth. Conclusions: This study provides the first detailed morphometric and morphological description of the PAT in human fetuses. The findings establish a developmental anatomical baseline for the posterior thoracic wall and highlight growth-related changes and side-related variability.