Prevalence and anatomical characteristics of subsuperior segment in lung lower lobe

The subsuperior segment is an atypical pulmonary segment of the lung lower lobe. With the increased application of segmentectomy, it has received increased attention from thoracic surgeons. Studies of the subsuperior segment are scarce and mostly on the basis of small-sample autopsy studies, whose described characteristics are inconsistent with intraoperative observations. Our objective was to accurately define the subsuperior segment and elucidate its prevalence and anatomical characteristics in detail.

A total of 2194 chest computed tomography images were obtained using separate random sampling on the basis of the amount of data available to each of the 6 thoracic surgery institutions in different provinces covering various regions of China. All of the images were reconstructed in 3 dimensions. Subsuperior segments were screened according to their new definition and statistically analyzed for their prevalence and anatomical characteristics.

The prevalence of subsuperior segments was 32.04%, with 413 on the right (18.79%); the value was higher than that on the left (347; 15.81%). The average volume of the subsuperior segment was 52.81 ± 21.96 cm³. Only 1 bronchus was detected in the unilateral subsuperior segment, with an average diameter of 2.53 ± 0.61 mm. Only 1 pulmonary artery was observed in most of the subsuperior segments (89.34%), but 81 cases (10.66%) had 2 in our study. One intersegmental vein of the subsuperior segment was the most common situation on both sides.

Using a multicenter large-sample study, we calculated a 32.04% prevalence and systematically detailed the anatomical characteristics of the subsuperior segment in the lung lower lobe, corrected previous reports, and supplemented pulmonary anatomical studies.