To investigate the correlation between senile constipation and puborectal muscles by three-dimensional ultrasound.

From January 2015 to September 2017, forty-three cases of senile constipation (observation group) and 43 healthy volunteers (control group) were collected from outpatient and Anorectal Department of Qianfushan Hospital Affiliated to Shandong University. The pelvic floor was examined by three-dimensional ultrasonography in resting period, forced drainage period and anal contraction period respectively. The size of posterior angle of puborectal muscle and the thickness of puborectal muscle at 3, 6 and 9 points of anal lithotomy were measured.

The posterior horn of puborectalis muscle of the observation group and the control group was at rest [(83.556±2.110)°, (83.804±2.485)°], anal contraction period [(86.836±1.453)°, (86.557±1.375)°], there was no significant difference between the two groups (t=-0.499, -0.915; P>0.05). At the time of force release [(79.905±2.381)°, (89.214±1.916)°], the difference was significant (t=-19.985, P<0.05).The difference of posterior angle of puborectalis muscle between resting period and force-displacement period was [(3.275±1.236)°, (-6.569±1.209)°], there were significant differences between the two groups (t=-37.147, P<0.05). The puborectal muscle thickness at 3, 6 and 9 points of lithotomy in the observation group and the control group was [(3.274±0.134) mm, (3.307±0.101) mm; (3.476±0.127) mm, (3.461±0.141) mm; (3.281±0.103) mm, (3.327±0.121) mm] during the rest period. During anal contraction was [(3.282±0.154) mm, (3.376±0.113) mm; (3.982±0.214) mm, (4.117±0.173) mm; (3.275±0.134) mm, (3.327±0.119) mm], there was no significant difference between the two groups (t=-0.407, 0.519, -1.901, -1.168, -3.214, -1.898; P>0.05).There were significant differences in the duration of force release [(3.731±0.129) mm, (3.216±0.087) mm; (4.271±0.169) mm, (3.596±0.134) mm; (3.724±0.112) mm, (3.221±0.089) mm] (t=20.924, 20.517, 23.073; P<0.05). The difference of puborectal muscle thickness between the observation group and the control group at 3, 6 and 9 points of lithotomy was [(-0.426±0.091) mm, (-0.217±0.089) mm; (-0.589±0.137) mm, (-0.289±0.109) mm; (-0.431±0.111) mm, (-0.247±0.091) mm], the difference was statistically significant (t=-10.773, -11.236, -2.659; P<0.05).

The posterior angle of puborectalis muscle in elderly patients with defecation disorder was smaller than that in healthy volunteers in force-displacement period, and the thickness of puborectalis muscle at 3, 6 and 9 points of anal lithotomy was thicker than that in healthy volunteers. And the greater the difference between resting period and forced expiration period, the more severe the degree of constipation.