Can Puborectalis Muscle and Abdominal Subcutaneous Adipose Tissue Thickness Indicate Dyssynergic Defecation?

Abstract

Introduction: Chronic constipation (CC) is a common issue in primary care and gastroenterology. Defined variably by patients and clinicians, CC per Rome III criteria requires symptoms for six months, present three or more days per month for three months. Dyssynergic defecation (DD), a functional constipation type, involves the failure of pelvic floor muscles to relax during defecation. This study examines the relationship between DD, puborectalis muscle thickness, and subcutaneous adipose tissue thickness via MR defecography. Material and Method: After ethical approval, MR defecography images of 110 patients from Ankara Bilkent City Hospital were analyzed retrospectively. Exclusions included pelvic floor descensus, rectal mass, cystocele, rectocele, or movement artifacts. The study comprised 52 DD patients and 52 matched controls. Measurements of subcutaneous adipose tissue at L5-S1 and puborectalis muscle thickness were performed on T2-weighted images. Results: DD patients had significantly higher abdominal subcutaneous adipose tissue and puborectalis muscle thickness than controls (p=0.021, p=0.001). No significant gender differences were noted. ROC analysis revealed cut-off values of 23 mm for adipose tissue and 4.8 mm for puborectalis muscle thickness. Positive predictive values for DD were 62% for adipose tissue >23 mm, 74% for puborectalis muscle thickness >4.8 mm, and 90% for both criteria. Discussion: MR defecography is essential for diagnosing DD. This study is the first to investigate the link between DD and puborectalis muscle thickness. Increased abdominal subcutaneous adipose tissue suggests a connection between DD and obesity, possibly due to increased intra-abdominal pressure leading to higher puborectalis muscle tone. Conclusion: Puborectalis muscle thickness >4.8 mm and abdominal subcutaneous adipose tissue thickness >23 mm are key parameters for diagnosing DD in MR defecography. These findings underscore the importance of MR defecography in diagnosing and understanding DD, leading to more precise and individualized treatments.