Clinical Study Of Precise Resection Of Proximal Margin In Low Rectal Cancer

Objective:To explore the imageology foundation of pubic symphysis as a reference of the proximal margin in low rectal cancer.On this basis,the imageology line was used to guide the localization of the proximal margin in Low Anterior Resection operation,which to evaluate the feasibility of this method.The contractility of rectal specimens was also studied to excise the rectal intestine accurately.Methods:1.The clinical data of 120 patients with rectal cancer from August 2017 to May2018 in Sichuan Cancer Hospital were retrospectively analyzed,with male and female cases 60 each.Pelvic dimensions were measured on preoperative CT or MRI image,including Sacropubic diameter(A),Sacral-to-anal diameter(B),Rectal curve(C).The shortest length(B minus A)and optimal length(C minus A)were also calculated and compared.2.Sixteen patients with rectal cancer treated in Sichuan Cancer Hospital from April2017 to October 2018 were enrolled.Preoperative imageology line were used as guidance to locate the proximal margin.Observed the tension of the intestinal after anastomosis,the pathological margin,and the complications after operation.At the same time,the corresponding intracorporal lines were measured,including the Sacral-to-anal straight line,Sacral-to-anal curve and Sacral-to-proximal margin line.The consistency analysis between the imageology line and theintracorporal lines was compared.Results:1.The sacropubic diameter(A)value was shorter in male than in female(10.18±0.82 Vs 10.87±1.00,P<0.05).The Sacral-to-anal diameter(B)was longer in male than in female(13.00±0.92 Vs 12.50±0.96,P<0.05).The shortest length was longer in male than in female(2.81±0.75 Vs 1.63±0.83,P<0.05).No significant difference was observed between two groups in terms of optimal length(5.50±1.40 Vs5.03±1.57,P>0.05).2.The study included 16 patients,including 10 males and 6 females.The averagedistance from the lower edge of rectal tumors to the anus was 5.16 cm.Four patients received preoperative radiotherapy,and the other 12 patients were not.Sixteen patients successfully completed the operation,including 7 cases of conventional LAR operation and 9 cases of NOSES radical operation.The tension of intestinal tract after anastomosis was good,including 14 cases of intestinal relaxation and 2 cases of intestinal tract tension-free.Postoperative complications occurred in 2 cases,all of which were recovery after reoperation.No anastomotic fistula,anastomotic bleeding and intestinal obstruction complications occurred in the remaining 14 cases.Postoperative pathology of 16 cases showed that the proximal and distal margins were negative.The consistency analysis between imageology lines of sacroanal diameter(B)and Sacral-to-anal straight line was good(12.38±1.39 Vs.12.48±1.32),ICC=0.651,p=0.002);the consistency analysis between Rectal curve(C)and Sacral-to-anal curve was general(15.97±1.24 Vs.16.46±1.67),ICC=0.469,p=0.029);The Rectal curve(C)and Sacral-to-proximal margin line was poor(15.97±1.24 Vs.17.27±2.23,ICC = 0.299,P = 0.122).For the results of intestinal tract contraction,the mean length of delayed specimens was significantly different from that of fresh specimens(12.78±3.09 Vs.16.78±2.82,P <0.001);the mean length of pathological specimens was significantly different from that of fresh specimens(10.91±3.01 Vs.16.78±2.82,P < 0.001);the mean length of pathological specimens have no significantly different from that of delayed specimens(10.91±3.001).01 Vs.12.78±3.09,P = 0.08).The average contraction rate from fresh to delayed specimens is 24.27%,from fresh specimens to pathological specimens was35.72%,and from delayed specimens to pathological specimens was 14.79%.There have significant difference in the length between the fresh and pathological proximal margins(12.46±2.69 Vs.6.43±2.25),P < 0.001);there have significant difference in the length between the fresh and pathological distal margins(2.37±0.64 Vs.0.86±0.65),P <0.001).Conclusion:1.Male pelvis is funnel-shaped,deeper and narrower than female,therefore,in order to ensure reliable anastomosis,the shortest length of proximal bowel needed to retain is slightly longer in male than in female.2.For the optimal length,it is recommended that 5 cm beyond the pubicsymphysis is appropriate,regardless of men and women.3.The imageology line is basically consistent with the intracorporal lines.The preoperative imageology line can guide the precise locate of proximal margin intestine.4.The length of the intestinal will change obviously under different conditions.When measuring the adequacy of the proximal and distal cutting edges of the intestinal,the contractility of the intestinal should be fully considered.