Three is not a crowd: improving the study of chronic constipation

High-definition anorectal manometry (HD-ARM), balloon expulsion test (BET), and magnetic resonance defecography (MR defecography) are important tools in studying constipation. Our aim was to evaluate the prevalence of functional defecation disorders and structural anorectal alterations in patients with chronic constipation and compare the findings of HD-ARM and BET with MR defecography.

Retrospective cohort study including patients with functional constipation or irritable bowel syndrome with constipation (IBS-C), refractory to medical therapy, submitted to HD-ARM, BET, and MR defecography. Patients were divided into three groups: (a) normal anorectal evacuation in HD-ARM and normal BET; (b) abnormal evacuation pattern and abnormal BET; and (c) normal anorectal evacuation pattern and abnormal BET, or abnormal evacuation pattern and normal BET.

A total of 64 patients were included, 49 with functional constipation (76.6%) and 15 with IBS-C (23.4%). In MR defecography, 47 patients had structural alterations (73.4%) and 15 had dyssynergia (23.4%). Overall, 19 patients were diagnosed with dyssynergic defecation (29.7%). Comparing the findings of HD-ARM and BET with MR defecography: in group 1 ( n  = 20), 15 patients had structural alterations (75.0%); in group 2 ( n  = 11), 8 had structural alterations (72.7%); and in group 3 ( n  = 33), 22 patients only had structural alterations (66.7%), 6 only had dyssynergic defecation (18.2%), and 2 had both (6.0%). MR defecography allowed the diagnosis of dyssynergic defecation in 8 patients (24.2%).

One third of patients with functional constipation and IBS-C had dyssynergic defecation and three quarters had relevant structural anorectal alterations. Therefore, it is important to combine MR defecography with HD-ARM and BET in the study of constipation.