Obstructed Defaecation (ODS) your guide

What is Obstructed Defaecation Syndrome?
Obstructed defaecation syndrome (ODS) is a broad term used to describe having difficulty passing stool through the rectum and anal canal (back passage) and not being able to achieve an adequate bowel movement. ODS can affect both men and women however it is more common in women due to hormonal changes that occur with aging and the effects of childbirth. Symptoms often include:

• A feeling of incomplete emptying of the bowel after stool is passed with a need to return to the toilet several times after to pass further stool to clear the bowel fully. Often it is difficult to wipe clean after a bowel movement.
• Prolonged or excessive straining when passing stool.
• A need to assist the passage of stool either by supporting the perineum or vagina internally with a finger (digitation) or manual evacuation.
• Passage of hard stools/constipation.
• Occasional leakage of stool after a bowel movement.

What causes ODS?
ODS can occur if the anal and rectal muscles that normally relax together enabling the bowel to open, do not work together properly. This lack of co-ordinated function is known as anismus or pelvic dysnergy and can result in excessive straining and increased effort to pass a motion with little result. Similarly, the pelvic floor and rectal wall muscles can become physically weakened as a result of hormonal changes, the effects of childbirth, obesity and chronic straining. This weakness can change both the position of the muscles in the pelvis and how well they work. There are a number of physical changes that contribute to ODS and often symptoms occur due to a combination of the following:

• Rectocele – the fibrous tissue layer that separates the vagina and the rectum becomes weakened. The rectum bulges forward and herniates into the vagina creating a pocket within the rectum. Stool can be pushed into the rectocele with straining resulting in a feeling of incomplete emptying after having a motion.
• Enterocele – a natural cavity called the pouch of Douglas exists between the vagina and rectum. This is a long and narrow space. An enterocele occurs when small bowel falls down into this space pushing down and narrowing the rectum making it harder for the passage of stool.
• Intussusception – the internal rectal wall prolapses down, narrowing the rectum and making it harder for stool to pass.

What tests might I have?
In order to help understand the cause of your ODS and treat you correctly, your specialist may advise that you have certain tests. These may include any or all of the following:

• Blood tests – to check the thyroid gland is working correctly and check your calcium levels.
• Physical examination – your specialist will examine both your abdomen (tummy) and perform an internal finger examination of your anal canal, inserting a gloved finger into your bottom.
• Ano-rectal physiology (manometry) – a catheter probe with a small balloon is inserted into the anal canal (back passage). The other end is attached to a machine which measures the pressure in the balloon as you are asked to squeeze and relax the muscles in your rectum. This gives information as to how toned the muscles in your rectum and anal canal are and how well the muscles and nerves are working together to co-ordinate a bowel motion.
• Endoanal ultrasound – an internal probe is passed into the anal canal and uses ultrasound to image the anal sphincter muscles.
• Defaecating Proctogram – a special barium paste enema, which shows up on x-rays, is inserted into the anal canal. A series of x-rays are then taken as the enema is passed naturally into a specially designed toilet. Although the test can cause embarrassment it may be necessary to provide information to help to understand your symptoms and every effort will be taken to maintain your dignity and privacy.
• Flexible sigmoidoscopy/Colonoscopy/CT Colonoscopy – a fine endoscopic tube is passed into the back passage and examines the inner lining of the bowel. Either the full length of the bowel is viewed (colonoscopy) or the examination is limited to the rectum and last section of the large bowel (flexible sigmoidoscopy). This test is used to eliminate any other problems within the bowel.

What is the treatment for Obstructed Defaecation Syndrome?
For many people it is possible to relieve symptoms of obstructed defaecation through dietary and lifestyle changes such as:

• Increase your daily fibre intake. High fibre foods include fruit, vegetables and high fibre cereals. Gradually increase the fibre in your diet so as to avoid bloating and abdominal discomfort.
• Increase your fluid intake to avoid dehydration, aim for at least 6-8 glasses of fluid a day. Carbonated drinks and caffeine can stimulate the bowel to work and can be helpful if you have constipation symptoms.
• Do not ignore the urge to have a bowel motion. Try to work with your bowel’s own pattern and establish a regular routine for opening the bowel. For many people the urge to pass stool will occur after the first meal of the day when eating stimulates the muscles in the bowel, this is known as the gastro-colic reflex.
• Positioning on the toilet – using a foot stool when sitting on the toilet will lift the height of your knees above your hips. This helps to naturally open up the ano-rectal angle and relax the puborectalis muscle to assist a natural bowel motion with less need for straining.
• Laxatives – Your G.P or specialist may prescribe you laxatives. These work to either soften your motion so that it is easier to pass or stimulate the bowel wall to move the stool through.

Non-surgical management of ODS includes:
Biofeedback
This is a 12 week course of specialist physiotherapy to retrain the pelvic floor and is performed in the physiotherapy department. Biofeedback uses a combination of exercises and specially designed sensors to help stimulate the muscles within the pelvic floor helping you to both locate and strengthen or relax them. Approximately 60% of patients report a significant improvement in their obstructive symptoms with Biofeedback alone. It is also used before any surgery is undertaken to improve the overall outcome.
Rectal irrigation
This involves washing out the anal canal and rectum with water after a bowel motion to remove any stool that has not been passed naturally. A small, soft tube is gently introduced inside the anal canal. The tube is attached to a bag containing water. The water is slowly introduced into the anal canal, the tube is removed and the water passed into the toilet with any stool remaining in the rectum. This can be done after each bowel motion to make sure the rectum is fully clear; on a daily basis or whenever you feel it is needed. If your health professional advises rectal irrigation therapy you will be taught to use the equipment at home by a trained bowel specialist who will visit and support you. Afterwards you will be able to perform the procedure by yourself in the privacy of your own bathroom.

In a small number of cases symptoms of ODS are not improved by non-surgical management. If this is so, your case will be reviewed by the pelvic floor multidisciplinary team.

Online resources/links
For further information please visit:
https://www.nhs.uk/conditions/constipation/
https://gutscharity.org.uk/advice-and-information/symptoms/constipation/