What is Paradoxical Puborectalis Contraction?
Paradoxical puborectalis contraction (also called pelvic floor dyssynergia or anismus) is a defecatory disorder characterized by inappropriate contraction or failure to relax the puborectalis muscle and external anal sphincter during attempted defecation, rather than the normal relaxation that should occur. 1
Pathophysiology and Clinical Presentation
The puborectalis muscle normally relaxes during defecation to allow rectal evacuation, but in paradoxical contraction, this muscle contracts or fails to relax, creating functional obstruction. 1 This results in:
- Obstructed defecation with a sense of anorectal blockage 1
- Excessive straining during bowel movements 1
- Incomplete evacuation sensation 1, 2
- Need for manual maneuvers to facilitate defecation 1, 2
- Prolonged, repetitive straining efforts 2
- Potential anorectal pain 2
The condition represents increased resistance to evacuation from incomplete relaxation or paradoxical contraction of the pelvic floor and external anal sphincters during defecation. 1
Diagnostic Approach
Physical Examination Findings
During digital rectal examination, assess for paradoxical contraction by having the patient simulate defecation—a patulous opening suggests neurogenic dysfunction, while failure to relax or active contraction of the puborectalis indicates dyssynergia. 3 The puborectalis is palpable as a muscular ring approximately 3-5 cm from the anal verge. 4
Objective Testing
Anorectal manometry (ARM) is the first-line diagnostic test, demonstrating paradoxical increase in anal sphincter pressure or inadequate pressure decrease during simulated defecation. 5 A strain/squeeze index >50 on electromyography correlates with impaired rectal evacuation. 6
MR defecography or conventional cystocolpoproctography (CCP) directly visualizes the evacuation process and identifies paradoxical sphincter contraction, impaired evacuation, and abnormal anorectal angle changes. 7 These imaging modalities can also detect coexisting structural abnormalities like rectoceles and intussusception. 7
The combination of ARM and defecography provides complementary information—ARM quantifies pressures while defecography visualizes structural and functional abnormalities. 7, 5
Treatment Algorithm
First-Line Conservative Therapy (Always Required First)
All patients must receive an optimal trial of conservative therapy before considering any surgical intervention. 3
Pelvic floor biofeedback therapy is the treatment of choice, achieving symptom improvement in over 70% of patients who complete the therapy course. 3, 8 Success rates of 55% have been documented in patients who complete biofeedback training. 9
- Biofeedback retrains the pelvic floor muscles to relax appropriately during defecation 2, 8
- Patient compliance is the main determinant of successful biofeedback 9
- Coexisting defecographic findings (rectoceles, intussusception, abnormal perineal descent) do not adversely affect biofeedback outcomes 9
Fiber supplementation (25-30g daily) with adequate fluid intake optimizes stool consistency and reduces straining. 3
Second-Line Interventions for Refractory Cases
For patients who fail biofeedback therapy, botulinum toxin injection into the puborectalis muscle is recommended. 8
Sacral nerve stimulation (SNS) targeting the S2-S4 nerve roots can successfully treat refractory paradoxical puborectalis contraction, with initial test stimulation for 2-3 weeks before permanent implantation. 3, 10 This approach has demonstrated dramatic relief in straining, pain, and need for digital manipulation. 10
Last-Resort Options
In medically refractory cases without associated anatomic abnormalities (rectoanal intussusception, rectal prolapse), diversion with an ostomy should be considered rather than pelvic floor repair, which has historically shown suboptimal results. 8
Important Clinical Pitfalls
Do not confuse normal puborectalis contraction during squeeze maneuvers with paradoxical contraction—the key is observing what happens during simulated defecation, not during squeeze. 3
A normal digital rectal examination does not rule out pelvic floor dysfunction; proceed with objective testing (ARM and/or defecography) when clinical suspicion persists based on symptoms. 3
Paradoxical puborectalis contraction can develop after pelvic pouch surgery, often triggered by events like pouchitis or abdominal trauma—suspect this in postoperative patients with defecation difficulties without anatomic abnormality. 2
Coexisting conditions like rectoceles, intussusception, and abnormal perineal descent are common (present in 23-63% of cases) but do not predict biofeedback failure—still offer biofeedback as first-line therapy. 9