The effects of carbon dioxide pneumoperitoneum on seeding of tumor in port sites in a rat model

The use of laparoscopic surgical techniques for the resection of intraperitoneal malignancies has been rapidly increasing in recent years; concomitantly, tumor recurrences at trocar sites have also been reported. These reports bring into question the appropriateness of pneumoperitoneum and laparoscopic techniques for carcinoma removal. We hypothesized that the carbon dioxide pneumoperitoneum and instrumentation used during laparoscopic procedures contribute to a greater incidence of tumor implantation into the ventral peritoneal wall wound sites than seen with laparotomy. This study, which used port placement and carbon dioxide pneumoperitoneum in an animal model, was designed to determine the relative incidences of tumor implantation into wound sites of the ventral peritoneal wall for laparoscopy and laparotomy.Viable MAT B III rat mammary adenocarcinoma cells were injected into the lower right quadrant of the peritoneal cavity of Fisher 344 rats (1 x 10(5) cells/rat). The animals were then divided into 4 groups: 1 group (n = 9) served as a control group and received no further manipulations; another (n = 8) underwent a midline laparotomy; another (n = 8) had four 18-gauge trocars inserted into the peritoneal cavity; and the last (n = 8) underwent induction of a 7- to 8-mm Hg carbon dioxide pneumoperitoneum in addition to the insertion of four 18-gauge trocars. All animals were maintained under surgical conditions for 2 hours. Animals were killed at 7 days, and the ventral peritoneal wall was examined for macroscopic evidence of tumor formation.A total of 32 possible sites of tumor implantation were measured. The control group showed no significant macroscopic evidence of tumor translocation to the ventral peritoneal wall. Among the 32 measured sites the laparotomy group had an overall lower incidence of tumor implantation at the peritoneal wall wound sites (n = 5) than did the group with the trocars alone (n = 20) group (P =.003) and the group with trocars plus carbon dioxide insufflation (n = 29, P <.0001). The group with trocars alone had a lower incidence of tumor implantation than did the group with trocars plus carbon dioxide pneumoperitoneum (P =.02).Trocar use during laparoscopic surgical procedures led to greater translocation of free tumor cells to peritoneal wall wound sites than did laparotomy in this animal model. The addition of carbon dioxide pneumoperitoneum further increased implantation of tumor cells at trocar sites. These results provide evidence that the use of laparoscopic techniques for resection of intraperitoneal malignancy needs further long-term study.