The Experimental Study Of Mechanisms Of Port Site Metastases After Laparoscopic Surgery For Malignant Tumor

Objective: Electrome and Ultracision harmonic scalpel (UHS) are very important instruments used in dissecting tissue and sealing vessel in laparoscopic operation. The purpose of this study was to detect whether application of electrocautery or cut malignant tumors will result in 1 iberat ion of viabl e mal ignant cell wi thin the smoke and whether laparoscopic instrumentation may cause tumor cell exfoliation and spread. It may help to explore the possible mechanisms of port site metastases and to take further measures to prevent port site implantation in operation.Methods: Mouse tumor were produced by inoculation of H22 cancer cell in the right calf of mice. Laparoscopic surgery for malignant tumor were simulated by using electronic, UHS or scissors, respectively. Smoke particles were collected in 10ml tubes containing 8ml PBS during the operation and then performed morphologic investigations of Papanincoloau-stained smears of suspensions, the trypan blue exclusion test and In vivo inoculation in syngeneic mice. At the end of the operation, the cut margin, instrument and trocar washing liquid was collected and rapidly sent for exfol iative cytologic examination and the trypan blue exclusion test. Pathologic examination of the resected specimens was also performed. The main aim is to investigate still-viable aerosolubilized cells in smoke suspensions, the exfoliated cells in the surgical field, instrument and trocar washings as well as the pathological changes of tumor tissue. All the data were analyzed by the SPSS 8.0 software using chi-squared test and one-way ANOVA analysis.Results: A lot of carbonized particles, cell-sized rounded structures and a few morphologically similar cells were found in the smears of smokesuspensions. There were no trypan-blue-excluding cell in the smoke suspensions and no tumor growth in the mice inoculated with smoke suspensions. Exfoliated tumor cells were found in the surgical field, instrument and trocar washings. Exfoliation of tumor cell caused by electrome and UHS and exfoliative cell viability decreased, compared with the control group. The median percentage cell viability of electrome, UHS and scissors was 11.6% 17.2% 20. 6%, respectively. The difference was significant (p<0. 05) .Conclusion: It is possible that malignant cells may be aerosolized by application of cautery and cut tumor tissues and release aerosolubilized cells into the smoke. This indicates that aerosolubilized cells may be a mechanism for port site contamination. However, these aerosolized particles were not viable and cellular aerosolization may play a small role in port site metastases. Manipulations of tumor tissue may cause intraoperative spillage of tumor cells and some exfoliated cells are still viable. A further possibility is that distant port sites may be polluted with free exfoliated tumor cells by contaminated laparoscopic instruments excessively passing in and out during the procedures. Direct implantation of exfoliated cells may be a important mechanism of port site metastases. Exfoliation of free viable tumor cells through laparoscopic instrumentation decreased, compared with conventional instrumentation. Electrome and UHS are capable of killing some exfoliated cells and tumor cells at local tissue to reduce risk of local recurrence or port site metastases after operation. Electrome has more effects on the pathological changes of tumor tissue than UHS.