Study On The Electrothermal Tissue Effects During Transcervical Resection Of Endometrium By Plasma Bipolar Hysteroscopy

Objective:Transcervical resection of endometrium (TCRE) is a common method of treating abnormal uterine bleeding, the best option to avoid hysterectomy. At present, application of the unipolar system is a more popular way for hysteroscopic TCRE both at home and abroad, but it has many deficiencies and sometimes may even lead to fatal complications. New plasma bipolar hysteroscopic system can avoid the occurrence of these adverse reactions, but its clinical application for TCRE is still in the initial stage both at home and abroad, and yet there's no formed experience of damaged tissue and appropriate power settings in such surgeries. This study was aimed to research the condition of thermal damaged of myometrium by different electric powers and work time,then get the experimental data of the best cutting electrode power, the role of time and result, therefore to give a scientific support for bipolar hysteroscopy Tare's possibility and security.Methods:Collect 16 DUB patients (ages from 35 to 50) who desired to undergo hysterectomy in our hospital during the period between December 2008 and January 2010. Let the 16 patients all get preoperative dilatation and curettage 3 days before their surgeries in order to thin the endometrium, and then take the endometrial curettage routine to pathology to rule out endometrial malignancy. Take plasma bipolar hysteroscopic endometrial resection after abdominal hysterectomy. Collect samples by frozen sections and paraffin sections to make NADH-d staining and HE staining to watch the depth of thermal damage and histopathological changes, and measure the endometrial ablation, thermal damage and tissue depth of the actual broken ring.Results:1, Relationship between the uterine electrode power, the work time and the depth of thermal damage(1) For the same power and work time, the depth below coagulation electrode is greater than the cutting electrode (P <0.001);(2) resection: For the same power and work time, the depth of thermal damaged tissue and work time was not correlated (P> 0.05), but was positively correlated with the power(P <0.05);(3) coagulation: for the same power and work time, the depth of thermal damaged tissue was positively correlated with work time in a significant way (P <0.001), and was also positively correlated with electric coagulation power (P <0.05).2, Percentage of the maximum depth of thermal damage in uterus wall's thicknessThe average thickness of these patients'myometrium is (2.09±0.38) cm, and the average endometrial thickness of them is (1.42±0.43) mm. Power setted, the depth of maximum thermal damage on uterine is 17.6% of the uterus wall's thickness, less than 20%, in the safe range.3, Histopathological changes of electric damaged tissuesObserve the full-thickness of uterine wall by light microscopy, and then cut and coagulate the thermal damaged tissue zone under electrode, which showed complete and partial necrosis of part of the smooth muscle layer from the outside to the inside. Seen from the microscope, complete necrosis layer was the colorless zone which showed coagulation necrosis, tissue structure damage and cell structure disappearance. Partial necrosis layer was the narrow light blue transition zone which showed cell swelling, structural fuzzy, membrane rupture, increased eosinophilic cytoplasm, nucleus condensation, some fragmentation, dissolution, and in which normal structured cells can be also seen. Thermal damaged zone is below the coagulation electrode, deeper than the cutting electrode. Normal muscle layer was the dark blue zone, which showed normal cell structure.Conclusion:1, Plasma bipolar hysteroscopic surgery was an effective technology for the treatment of DUB. Its effect was equivalent to unipolar hysteroscopic surgery. In order to reduce the complications to improve safety of operation, the optimal resection cut power is 200W, and coagulation power is 160W ~ 200W;2, Vitro experiment proved that plasma bipolar hysteroscopic surgery for TCRE was safe. The tissue ZTN was shallower than unipolar and other hyperthermia techniques so it can effectively avoid electrical injury, and reduced the incidence of uterine perforation and organ damages;3, Vitro studies show that ZTN bellow the coagulation electrode was significantly greater than the cut electrode; we should particularly pay attention to the select of coagulation power and work time.