Puborectalis syndrome, also known as paradoxical puborectalis contraction or non-relaxing puborectalis syndrome, is a specific form of pelvic floor dysfunction. This condition involves an uncoordinated response of pelvic floor muscles during defecation. Instead of relaxing to allow stool to pass, the puborectalis muscle either fails to relax fully or paradoxically contracts, leading to an obstruction of bowel movements. This muscular incoordination impacts an individual’s ability to empty their bowels effectively.
The Puborectalis Muscle and Its Role
The puborectalis muscle is an integral component of the pelvic floor, belonging to the levator ani muscle group. It originates from the posterior surface of the pubic bones and forms a U-shaped sling that wraps around the lower part of the rectum, just above the anal canal. This anatomical arrangement is crucial for maintaining normal bowel function.
Normally, the puborectalis muscle maintains a tonic contraction, which pulls the rectum forward. This action creates a sharp bend, known as the anorectal angle, which is fundamental for preserving fecal continence. During defecation, this muscle reflexively relaxes, causing the anorectal angle to straighten. This straightening allows for the unobstructed passage of stool from the rectum into the anal canal, facilitating a complete bowel movement.
Symptoms of Puborectalis Syndrome
Individuals experiencing puborectalis syndrome often present with symptoms primarily related to obstructed defecation. Chronic constipation, characterized by infrequent or difficult bowel movements, is a predominant complaint. Patients frequently report excessive straining during attempts to pass stool, often without successful evacuation.
A persistent feeling of incomplete evacuation is also common, where individuals feel their rectum has not fully emptied even after a bowel movement. This sensation can lead to repeated, unproductive trips to the restroom. Some individuals may resort to manual maneuvers, such as pressing on the perineum or within the vagina, to assist in the passage of stool. Some patients may experience pelvic pain or discomfort, or a sensation of “pushing against a closed door” during defecation efforts.
Causes and Risk Factors
The precise reasons why the puborectalis muscle malfunctions are not always clear, but several contributing factors have been identified. One common element is the development of dysfunctional defecation habits, where individuals may have learned improper ways to coordinate their muscles during bowel movements. Chronic straining to pass stool, often due to longstanding constipation, can also contribute to this muscle discoordination over time.
Damage to nerves, such as the pudendal nerve, or injury to the pelvic floor muscles can predispose individuals to the syndrome. Childbirth, particularly vaginal deliveries, can cause trauma to the pelvic nerves and muscles, increasing the risk. Prior pelvic surgeries, including back or pelvic floor procedures, are also considered potential risk factors. Psychological factors, such as anxiety, depression, or a history of sexual trauma, may also play a role in some cases.
Diagnosis and Treatment Strategies
Diagnosis
Diagnosing puborectalis syndrome involves patient history and specialized physiological tests to assess pelvic floor muscle function. A physical examination, including a digital rectal exam, allows a clinician to assess anal canal muscle tone and observe for paradoxical puborectalis contraction during straining. This manual assessment indicates whether the muscle is tightening instead of relaxing.
Several specialized tests are used to confirm the diagnosis and rule out other potential causes of constipation:
- Anorectal manometry measures pressures within the rectum and anal canal during rest and simulated defecation. This test helps identify if the puborectalis muscle fails to relax or contracts inappropriately when a patient attempts to push, providing objective data on muscle coordination.
- Defecography, which can involve cinedefecography or dynamic pelvic MRI, visually tracks stool movement and changes in the anorectal angle during defecation. It can reveal a persistent indentation of the puborectalis muscle and a lack of angle straightening, confirming outlet obstruction.
- Electromyography (EMG) measures the electrical activity of the pelvic floor muscles, offering insights into muscle tone and coordination during various maneuvers.
- A balloon expulsion test assesses the ability to expel a simulated stool, providing a functional measure of obstructed defecation.
Treatment
Treatment for puborectalis syndrome focuses on retraining the pelvic floor muscles. Biofeedback therapy is a primary approach, where patients learn to coordinate their abdominal and pelvic floor muscles using visual or auditory feedback. This therapy helps individuals consciously relax the puborectalis muscle during defecation. Pelvic floor physical therapy complements biofeedback by teaching exercises and relaxation techniques to improve muscle flexibility and coordination.
Lifestyle modifications are also advised, including increased dietary fiber intake, adequate hydration, and regular bowel habits to promote softer, easier-to-pass stools. Medications like stool softeners may be used to manage symptoms. For challenging cases, botulinum toxin injections into the puborectalis muscle or external anal sphincter can temporarily reduce muscle tension, helping the muscle relax. This effect lasts for approximately 4.8 months, and injections are often combined with biofeedback therapy for long-term muscle retraining.