Evaluation of the Mechanical Properties of Anorectal Tissues and Muscles by Shear Wave Elastography in Anal Fıssure Disease.

OBJECTIVE

To evaluate the mechanical properties of the tissues and muscles in the anal region with the shearwave elastography for anal fissure etiology.

STUDY DESIGN

Descriptive study.

PLACE AND DURATION OF STUDY

Adana City Training and Research Hospital, Turkey, from March2019 to March 2020.

METHODOLOGY

In this study, 30 patients (fissure group), who were diagnosed with anal fissure in the outpatient clinic; and 20 patients (control group), who did not have any problem in anal examination were included. The anorectal tissues and muscles mechanical properties(elasticity,compliance and stiffness) were compared with the shear wave elastography values.Fissure area,internal anal sphincter,external anal sphincter and levator ani muscles elastographic measurements was performed with 5-18 MHzin lithotomy position, at rest and with Valsalva maneuver.

RESULTS

In elastographic measurement of fissure area (fissure) and normal anorectal tissue (control, AFE); control group values were significantly higher than the fissure group values (p<0.001, and padj <0.001, respectively). Control group valuesof internal anal sphincter in rest and Valsalva maneuver (IAS-R, and IAS-V, respectively) were significantly higher than the fissure group values (p<0.001, padj< 0.001, and p<0.001,  padj <0.001, respectively). There was no significant difference between the elastographic measurement values in rest and valsalva maneuver of the external anal sphincter (EAS-R and EAS-V) (p>0.05). Elastographic measurement values of levator ani muscle (LAM) resting state; were significantly higher in thefissure group than the control group (p<0.001, and padj <0.001, respectively). Elastographic cut-off values that differentiate the fissure group from control group were found to be ≤1kPa forAFE group, ≤44 kPa forIAS-R, ≤0.4kPa forIAS-V,and >11kPa for LAM,respectively. Conclusıon: In anal fissure disease, tissues mechanical properties measured by shear wave elastography showed increased tissue stiffness, which may be added to etiology of this disease. Key Words: Anal fissure, Ultrasonography, Shear wave elastography, Anal sphincter, Tissue elasticity, Tissue stiffness.