Abdominal Lymphatic System Response on Endosurgical Pneumoperitoneum

Objective. To examine morphological changes in the abdominal lymphatic system after the placement of carbon dioxide pneumoperitoneum and laparoscopic cholecystectomy. Material and methods. The study was performed on laboratory animals involving the modeling of carbon dioxide pneumoperitoneum and laparoscopic cholecystectomy. Morphological assessment was done on the 1st, 3rd and 5th days after surgery using macroscopic analysis, light microscopy and morphometric methods. The condition of the lymphatic vessels, their endothelium, regional lymph nodes, the severity of lymphostasis, edema, inflammatory infiltration of the abdominal organs and signs of tissue reparation were studied. Results. Signs of reactive inflammation of the lymphatic system, including interstitial edema, destruction of the lymphatic vessel endothelium, swelling of the regional lymph node sinuses, and lymphostasis, were detected in the early postoperative period. By the 3rd day, a tendency towards a decrease in the severity of inflammatory changes and lymphostasis was noted. The median severity of inflammatory infiltration decreased from 3.0 [3.0; 3.0] points on the 1st day to 2.5 [2.0; 3.0] points on the 3rd day (p=0.059), the severity of lymphostasis — from 3.0 [2.5; 3.0] to 2.7 [2.5; 3.0] points (p=0.071), and the destruction of the lymphatic vessel endothelium — from 2.5 [2.0; 3.0] to 2.0 [2.0; 2.5] points, respectively (p=0.058). By the 5th day, a partial restoration of the lymphatic system architecture and a predominance of reparative processes were observed. The number of functioning lymphatic capillaries increased from 70.0 [64.0; 75.0] to 84.0 [79.0; 89.0] units/field of view (p=0.001), and the density of lymphatic collectors rose from 7.0% [6.5%; 7.8%] to 8.9% [8.5%; 9.3%] (p=0.024). Signs of lymphostasis on the 5th day remained compared to the 1st day of observation: 3.0 [2.5; 3.0] and 2.5 [2.0; 3.0] points, respectively (p=0.064). Conclusion. Morphological changes in the lymphatic system after the creation of carbon dioxide pneumoperitoneum and laparoscopic cholecystectomy reflect a gradual transition from reactive inflammation to reparation. Restoration of the functional activity of the lymphatic bed is accompanied by an increase in the number of functioning lymphatic capillaries and the density of lymphatic collectors, but signs of lymphostasis persist for up to 5 days of observation.