[Morphological characteristic of anal canal in patients with dyssynergic defecation and its correlation with anorectal manometry].

To evaluate the diagnostic value of three-dimensional endoanal ultrasound (3D-EAUS) for dyssynergic defecation (DD). A case-control study was performed to retrospectively collectclinical data of 46 DD patients, including 16 males and 30 females with median age of 51 (20 to 70) years, at Nanjing Hospital of Chinese Medicine from February 2012 to April 2015.All the patients met the diagnostic criteria of functional constipation of Rome III. The paradoxical contraction of puborectalis (PR) muscle was found by both rectal examination and anorectal manometry. In the same period,45 healthy volunteers, including 22 males and 23 females with median age of 48 (21 to 72) years, without pelvic operation history, and with normal defecation in recent 6 months, were enrolled as the control group. No significant differences were observed in age and gender between two groups (both >0.05). Cleveland constipation score of DD group was higher than that of control group [15(8-24) vs. 5(1-9), =15.720, <0.001]. 3D-EAUS examination was performed in all the subjects. Thickness and length of internal anal sphincter (IAS) (anterior side and posterior side), thickness of PR muscle, length of external anal sphincter (EAS) plus PR muscle, and puborectalis angle were measured and compared by using student t test between two groups. Correlation between these ultrasound parameters and anorectal manometry was examined by Pearson correlation analysis. Both male and female in the DD group had the greater thickness of IAS, as compared to those in the control group [male: (1.7±0.5) mm vs.(1.5±0.2) mm, =2.516, =0.016; female: (1.9±0.4) mm vs.(1.6±0.5) mm, =2.034,=0.047]. No significant differences between the two groups were observed with respect to the posterior length of IAS, length of EAS plus PR muscle, and thickness of PR muscle (all >0.05). Compared to the control group, male in the DD group had smaller puborectalis angle during straining [(87.0±3.6)° vs. (90.5±1.8)°,=3.502,=0.002];female in the DD group had smaller puborectalis angle both in resting and straining [resting:(86.5±3.8)° vs. (90.1±2.1)°,=4.047, <0.001;straining: (84.1±4.5)° vs. (90.2±2.3)°, 5.938, <0.001]. Correlation analysis showed that anterior length of IAS was positively correlated with anal resting pressure (=0.321, =0.030); the length of EAS plus PR muscle was positively correlated with anal squeeze pressure (=0.415, =0.004). There were no correlations between the thickness and the posterior length of IAS and the anal resting pressure, or between the thickness of PR muscle and the anal squeeze pressure (all >0.05). The 3D-EAUS can accurately assess the morphological features of anal canal in DD patients. There is a certain positive correlation between 3D-EAUS and anorectal manometry.