Transthoracic single-port assisted laparoscopic five-step maneuver inferior mediastinal lymphadenectomy for Siewert type II adenocarcinoma of esophagogastric junction (AEG) has superiority in lower mediastinal lymph nodes dissection and digestive tract reconstruction. However, the right pleura was probably ruptured in this surgical technique. The aim of this study was to explore whether the infracardiac bursa (ICB) exposed could protect right pleura.We retrospectively collected and evaluated the clinical and pathological data of patients who underwent five-step maneuver of transthoracic single-port assisted laparoscopic lower mediastinal lymphadenectomy for Siewert II AEG at Guangdong Provincial Hospital of Chinese Medicine between May 2017 and February 2022.A total of 49 patients were eligible, including 31 patients in ICB exposed group (group A) and 18 patients in ICB unexposed group (group B). There were no statistically significant differences in baseline characteristics between the two groups. 4 patients (12.9%) had right pleura rupture in group A, while 14 patients (77.8%) in group B, and the difference was statistically significant (p < 0.001). Compared with group B, the extubation time of endotracheal intubation (10.0 (6.0 ~ 12.0) vs. 13.0 (8.0 ~ 15.0) min, p = 0.003) and thoracic drainage tube stay (6.0 (5.0 ~ 7.0) vs. 8.0 (6.0 ~ 10.5) days, p = 0.041) were significantly shorted in the group A. The drainage volume of thorax (351.61 ± 125.00 vs. 418.61 ± 207.86 mL, p = 0.146) was non-significant less and the rate of complications (3.2% vs. 11.1%, p = 0.074) was non-significant lower in group A compared with group B. The postoperative hospital stay (9.0 (8.0,13.0) vs. 9.0 (8.0,12.0) days, p = 0.983) were similar in two groups. No serious adverse event occurred in any patient.The ICB exposed could protect the right pleura and may promote postoperative recovery, which may be used as an anatomical marker in inferior mediastinal lymphadenectomy.© 2022. The Author(s).