Obstructed Defecation Syndrome

Original Editor - Khloud Shreif
Top Contributors - Khloud Shreif, Temitope Olowoyeye, Kim Jackson and Aminat Abolade

Introduction

Obstructed defecation syndrome (ODS) is a pelvic floor disorder characterized by constipation with straining during defecation, incomplete evacuation and the need for digital support. It consists of structural disorders such as rectocele rectal mucosal intussusception, solitary rectal ulcer syndrome, rectocele, enterocele, or descending perineum syndrome and functional disorders such as dysynergy defecation.ODS occur significantly more frequently in women than in men. Increases with advancing age in both sexes.

Clinical Anatomy and Physiology

Pudendal nerve

The levator ani muscles as a component of pelvic floor muscles ( the iliococcygeus, the pubococcygeal, and the puborectalis muscles) in addition to its role as a supportive structure and keeping visceral and internal organs in place, levator ani muscles specifically puborectalis have a role to maintain the urinary and fecal continence, contraction, and relaxation of puborectalis, lower abdominal muscles, and anal sphincter work synchronically for normal and smooth defecation.

The pudendal nerve innervates the external anal sphincter and part of the puborectalis muscle, with frequent and prolonged straining that may stretch the pudendal nerve causing pudendal neuropathy.

While we have voluntary control over the external anal sphincter the internal anal sphincter muscles are involuntary muscles affected by the rectum, it is relaxed if the rectum filled with stool and vice versa, so the sensitivity of the rectum is important for normal physiology.

During normal defecation, the relaxation of the anal sphincters and the puborectalis muscle allows the anorectal angle to widen and the perineum to descend. Concurrently, the voluntary effort of bearing down increases the intra-abdominal pressure. These movements (mixed voluntary and involuntary movements) enable the development of a stripping wave which moves the stool from the rectum and causes the relaxation pelvic floor muscles and the anus, resulting in stool evacuation.

Mechanism of Injury / Pathological Process

In general the pathogeneses of ODS varying from:

• Neurological origin (multiple sclerosis, spinal cord lesions, and pudendal neuropathy that impairs rectal sensitivity cause excess distension and stretch of the rectal wall, paradoxical rectal contractions and overflow incontinence can happen.

• Muscular origin such as (pelvic floor dyssynergia, anismus)

• Psychological origin (anxiety and spastic colon).

• Organ/ mechanical origin, cases of rectocele, outlet rectal obstruction, or intussusception obstruction is defined as overlapping of a part of intestine to the adjacent part blocking the passage of food and fluid.

Cases of rectal prolapse, rectocele most common in female. and internal rectal mucosal prolapse are most common associated and found in patient with ODS.

Clinical Presentation

The patient will have symptoms of the need to strain with bowel movement, episodes of incomplete evacuation, fragmented stool, pelvic heaviness, and sometimes accidental bowel leakage.

Frequent, prolonged straining becomes the prime mover. may cause stretch on the pudendal nerve and pudendal neuropathy causing rectal hypo sensation, internal organ descends (prolapse), muscle weakness, and spending too much time than usual in toilet.

Lower abdominal/rectal pain, feeling of incomplete evacuation of the rectum. The patient will tend to use perineal manipulation to help with the evacuation.

Patients with ODS will have a small, more hard stool and difficulty to evacuate, responses to laxatives and enema, and less effective to trigger the peristaltic reflex.

Fecal incontinence one of the symptoms of ODS. 

Diagnosis

Diagnosis of ODS is essentially based on detailed evaluation of patient's clinical history and the use of some imaging techniques.

Defecography: This imaging technique is particularly used prior to surgery to confirm rectal prolapse, excessive perineal descent, a significant rectocele, an enterocele, or internal rectal intussusception. It measures and records the anatomy of the rectum and pelvic floor functions at rest, during coughing, squeezing, and straining to expel barium from the rectum.

The colonoscopy: rule out rare causes of obstructive defecation tumors for example.

Anorectal manometry: a primary diagnostic test to assess rectum hyposensitivity, use inserted balloon into rectum fill with water or air to trigger the need for evacuation.

Electromyography (EMG): Used to assess the strength and coordination of pelvic floor muscles around the anus, vagina, and the movement of rectum during defecation.

Outcome Measures

Obstructed Defecation Syndrome score: consists of 5 items each item graded from 0-5, as 0 no symptoms and 20 sever symptoms.

Symptoms	0	1	2	3	4
Excessive straining Rarely Sometimes Usually Always	Never	rarely	sometimes	usually	always
Incomplete rectal evacuation	Never	rarely	sometimes	usually	always
Vaginal/Perineal digital pressure	Never	rarely	sometimes	usually	always
Abdominal discomfort/pain	Never	rarely	sometimes	usually	always
Use of enemas/laxative	Never	rarely	sometimes	usually	always

Management / Interventions

Conservative treatment

Change in dietary regimen

The patient advised to stop foods that increase stool viscosity like chocolate, drink plenty of water, and concentrate on food rich in fibers as it affects on consistency of stool and help in digestion of other types of food. Psyllium: another form of fibers was introduced in diet, according to a RCT found that diet rich in psyllium reduces the conscious rectal sensitivity threshold than fiber diet after rehabilitation of ODS.

Is the first step in the treatment of patient with ODS mainly for patients with pelvic floor dyssynergy, some RCT show it is effect is superior to patient education and laxatives.

Before start explain to the patient the defecation problems result from un voluntary and unconscious contraction of anus, a rectal manometry (balloon inflated with air or water) and a screen in front of patient to give feedback of performance and how to correct.

In patient with pelvic floor dyssynergia, train the patient to try to relax the pelvic floor muscles during stimulated defecation and instead tighten the abdominal muscles and lower the diaphragm to increase the intra-abdominal pressure and push the stool

Surgical intervention

surgical interventions should be carried if the conservative treatment failed and there is structural or organ origin for the problem such as in some cases of rectocele, rectal obstruction, or intussusception.

Rectocele can be managed via pelvic floor rehabilitation as long it isn’t significant and don’t become larger.

Surgical interventions divided into: transvaginal, transabdominal and transanal. Transanal procedures. Surgers show short term effect and resolve of the problem,but long-term results are still under discussion.