Symptoms and diagnosis of functional defecation disorders in adults

Many patients reporting constipation have evidence of evacuatory dysfunction (difficulty or inability to expel stools) without structural obstruction.

In patients with symptoms that are refractory to laxative therapy, consider investigation for a functional defecation disorder. Functional defecation disorders cannot be diagnosed based solely on the presence of symptomsSkardoon, 2017. A thorough medical history and rectal examination may be indicative of the presence of a functional defecation disorder. To make the diagnosis of a functional defecation disorder, further assessment with anorectal manometry or defecography by a gastroenterologist is required.

Diagnosis of functional defecation disorders (based on the 2016 Rome IV criteria) is made if the patient fulfils all of the following criteria:

• symptoms have been present for at least 3 months
• the patient satisfies the diagnostic criteria for functional constipation or irritable bowel syndrome with constipation
• during repeated attempts to defecate, there are features of impaired evacuation, demonstrated by at least 2 of the following tests:
  • abnormal balloon expulsion test
  • abnormal anorectal evacuation pattern with manometry or anal surface electromyography
  • impaired rectal evacuation by imagingRome Foundation Inc., 2016.

Functional defecation disorders are divided into 2 subtypes:

• Inadequate defecation propulsion occurs when there is reduced or absent augmentation of intrarectal pressure during attempted evacuation (measured with manometry)Rome Foundation Inc., 2016.
• Dyssynergic defecation occurs when the pelvic floor muscles or anal sphincters fail to relax normally, or paradoxically contract, during attempted defecation (measured with manometry or anal surface electromyography)Rome Foundation Inc., 2016.