OBJECTIVE: We determine the main physical effects of pneumoperitoneum on tumour dissemination and port-site metastases occurrence. DESIGN: A prospective randomised study in rats. METHODS: A human ovarian cancer cell line (IGR-OV1) was xenografted in nude rats. Seven days after cancer inoculation, surgery was performed. Rats were randomised in two main groups and underwent either: gasless laparoscopy (n = 20) CO2 laparoscopy with pneumoperitoneum pressure at 4 mmHg (n = 20), or 8 mmHg (n = 20) with in each case, increasing operative duration: 30,60,90 or 120 minutes (five rats for each time). Animals were killed seven days after the intervention. MAIN OUTCOME MEASURES: Tumour dissemination and frequency of port-site metastases. RESULTS: Tumour dissemination was not influenced by gas pressures or duration of procedure. The rate of rats with at least one port-site metastasis (one or two) was similar in all groups: gasless: n = 10/20; 4 mmHg CO2: 5/20; 8 mmHg CO2: 7/20,(P = 0.26). The number of port-site metastases were significantly higher in the gasless group compared with the 4 mmHg CO2 group (15/40 (37.5%) vs 5/40 (12.5%), P = 0.01). Difference was not significant between the 8mmHg group and the gasless group (9/40(22.5%) vs 15/40(37.5%), P = 0.14) or the 4mmHg group (9/40(37.5%) vs 5/40 (12.5%), P = 0.24). Duration of procedures had no significant influence on port-site metastases rate (P > 0.05). CONCLUSIONS: Unlike previous animal studies, port-site metastases were more frequent with gasless laparoscopy than with CO2 pneumoperitoneum. Local peritoneal factors could play an important role in port-site metastases mechanism.
OBJECTIVE: We determine the main physical effects of pneumoperitoneum on tumour dissemination and port-site metastases occurrence. DESIGN: A prospective randomised study in rats. METHODS: A humanovarian cancer cell line (IGR-OV1) was xenografted in nude rats. Seven days after cancer inoculation, surgery was performed. Rats were randomised in two main groups and underwent either: gasless laparoscopy (n = 20) CO2 laparoscopy with pneumoperitoneum pressure at 4 mmHg (n = 20), or 8 mmHg (n = 20) with in each case, increasing operative duration: 30,60,90 or 120 minutes (five rats for each time). Animals were killed seven days after the intervention. MAIN OUTCOME MEASURES: Tumour dissemination and frequency of port-site metastases. RESULTS:Tumour dissemination was not influenced by gas pressures or duration of procedure. The rate of rats with at least one port-site metastasis (one or two) was similar in all groups: gasless: n = 10/20; 4 mmHg CO2: 5/20; 8 mmHg CO2: 7/20,(P = 0.26). The number of port-site metastases were significantly higher in the gasless group compared with the 4 mmHg CO2 group (15/40 (37.5%) vs 5/40 (12.5%), P = 0.01). Difference was not significant between the 8mmHg group and the gasless group (9/40(22.5%) vs 15/40(37.5%), P = 0.14) or the 4mmHg group (9/40(37.5%) vs 5/40 (12.5%), P = 0.24). Duration of procedures had no significant influence on port-site metastases rate (P > 0.05). CONCLUSIONS: Unlike previous animal studies, port-site metastases were more frequent with gasless laparoscopy than with CO2 pneumoperitoneum. Local peritoneal factors could play an important role in port-site metastases mechanism.