Obstructed Defaecation

What is Obstructed Defaecation?

Obstructed defaecation syndrome (ODS) is the medical name given to number of conditions in which there is a normal desire to defaecate, but the ability to evacuate the rectum is impaired.  Often, multiple conditions co-exist and contribute to the overall syndrome of obstructed defaecation.

Symptoms of obstructed defaecation syndrome

Patients with ODS find it difficult to pass bowel motions, often leading to multiple, unsuccessful visits to the toilet.  They perceive a sensation of a blockage and, when they do defaecate, a feeling of inadequate or incomplete emptying.  Patients with ODS may need to use their finger to help them to empty, pushing on the perineum (the skin in front of the anal canal), on the back wall of the vagina or in the anal canal itself.  Paradoxically for patients who struggle to empty their rectum, patients often describe symptoms of anal incontinence.

ODS is usually the result of either a physical or functional problem related to the pelvic floor anatomy during defaecation.  Physical problems can arise due to a weakness or defect in the pelvic floor musculature, and it is therefore more common in women due to changes that occur during childbirth.

Assessment of patients with ODS

A thorough clinical history and examination is essential, usually prior to investigations into the bowel and pelvic floor function.  Investigations can include flexible sigmoidoscopy, endoanal ultrasound, anorectal physiology studies and examination under anaesthetic.  However, most information is usually gained by a proctogram (either conventional or magnetic resonance).

Treatment for ODS

The treatment of ODS depends on the underlying cause.  Sometimes, simple changes in diet or the addition of stool softeners can be helpful.  Supervised pelvic floor retraining can greatly improve symptoms without the need for surgery.  For some patients with structural abnormality of the rectum, surgical treatment, such as laparoscopic ventral rectopexy or STARR procedure may be helpful.  Your surgeon will advise you on the most appropriate treatment, and will discuss with you fully any risks involved.

Laparoscopic ventral rectopexy

Where appropriate, ventral rectopexy can be used to treat ODS.  Using keyhole surgery, the rectum is pulled straight and fixed to the sacrum (low back bone) using a mesh.  This is carried out with the aim to eliminate the internal rectal prolapse that often accounts for ODS.  The procedure is carried out under a general anaesthetic and usually needs 1 or 2 nights in hospital.

STARR procedure

Stapled transanal rectal resection (STARR) employs a stapling devise to surgically remove the redundant rectal tissue (internal rectal prolapse) that causes ODS.

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