Anorectal Manometry To Evaluate Anus Functions In Rectal Cancer After Low Anastomosis Operation

Objective: Employment of anorectal manometry to evaluate anus functions inrectal cancer after low anastomosis operation.Methods: Thirty patients with rectal carcinoma who underwent low anteriorresection were enrolled in the study. The resting pressure of rectum and anus,the maximal squeezing pressure of anus, the rectal volume at senory threshold ,the maximal tolerable volume of rectum and the rectal compliance wereassessed with anorectal manometry before and two weeks after operation. Inaddition, the rectoanal inhibitory reflex and the distance between anastomoticlevel and dentate line were determined. The t test was used to comparepreoperative and postoperative data. The multinomial logistic regression wasused to evaluate the relativity between the anus functions and postoperativemanometry. A P value of less than 0.05 was considered statistically significant(SPSS 12.0 for Windows ).Results: The anal resting pressure ( preoperative and postoperative,respectively:44.33 ± 12.78mmHg vs 28.87 ± 12.50mmHg) decreasedsignificantly after operation(P<0.05) ,the maximal tolerable volume of therectal (106.25±30.87ml vs 55.83±27.17ml) and the rectal compliance(13.65± 6.22ml/mmHg vs 4.76 ± 2.08ml/mmHg ) decreased significantly afteroperation(P<0.01). The rectal resting pressure (6.52±4.26mmHg vs 9.05±5.08 mmHg) increased significantly after operation(P<0.05). There was nosignificant change in the maximal squeezing pressure of anus (128.21±31.04mmHg vs 104.93±32.71 mmHg)and the rectal volume at senorythreshold(22.71±13.75ml vs 16.46±8.40ml)(P>0.05). The analrestingpressureand the distance between anastomotic level and dentateline were in positivecorrelation to the anus function(P<0.01). Postoperative anal resting pressure is inpositive correlation to preoperativeanalrestingpressureandtheformulaisasfollows:predictedpostoperativeanalrestingpressure=-1.497+0.67xpreoperativeanalrestingpressure.Conclution: The anal resting pressure is very important parameter to evaluate theanus functions after rectal cancer operation with low anterior resection . Patientswith the distance between anastomotic level and dentateline <1cm andpreoperativeanalrestingpressure <32mmHg will have poor anus function early afteroperation.