Functional Constipation Causes and Diagnosis

Functional Constipation

• Constipation can be attributed to multiple causes, including congenital, acquired behavioral, infectious, or anatomic and physiological abnormalities.

Nonrelaxing Puborectalis

• Failure of puborectalis relaxation or paradoxical contraction leads to pelvic outlet obstruction and failed elimination.
• The anorectal angle is normally straightened during defecation due to relaxation of the puborectalis and external anal sphincter.
• The syndrome of nonrelaxing puborectalis is diagnosed through physical examination and anorectal physiologic testing.

Diagnosis of Paradoxical Puborectalis Syndrome

• Physical examination involves noting increased anal canal tone and mobility of the posterior loop of the puborectalis during squeezing.
• Defecography, manometry, electromyography (EMG), or dynamic pelvic magnetic resonance imaging (DPMRI) confirm the diagnosis.
• The diagnosis should be excluded in patients with anterior rectocele, as paradoxical puborectalis syndrome can instigate this condition in up to 45% of cases.

Associated Factors

• Paradoxical puborectalis contraction can be a manifestation of coping from sexual assault or abuse.
• It can also be a learned response to passage of large painful bowel movements during childhood.

Increased Perineal Descent

• Perineal descent may be a manifestation of weakness of the pelvic floor support structures.
• Patients present with increased perianal and perineal descent upon straining, leading to constipation and symptoms.
• Over time, the anterior rectal wall may prolapse through the anal canal, causing bleeding and irritation.

Treatment and Management

• Treatment is generally conservative, with biofeedback playing a principal role.
• Patient compliance is essential for favorable results.
• Failure of biofeedback may be augmented with botulinum toxin injection for paradoxical puborectalis contraction.
• Increased perineal descent is treated with biofeedback and perineal support maneuvers.
• Surgery has little or no role in these conditions, but may be offered as a last resort in the form of a stoma.