Faecal incontinence (soiling)

It is difficult to know how common this problem is, but various research studies suggest that 2–15% of adults soil their underwear regularly (Gastroenterology 2005;129:6).

Causes of faecal incontinence
Diet is the first thing to check. Anything that makes the consistency of the faeces more runny, such as a heavy intake of beer, will make it more difficult for you to hold them in.

In the USA, the ‘non-fat fat’, called olestra (Olean), used in some ‘slimming’ foods has gained unwelcome publicity for this reason. It is an artificial mixture of fats, none of which can be digested or absorbed. Instead, it goes straight along the gut and is passed out at the other end. This means that the faeces are runny and slippery with fat, and soiled underwear can result. Some snack foods (for example some crisps) contain olestra, but the amount in the snacks is too small to cause a problem.

Anything which makes you pass more wind makes leakage more likely. This is because the anus has to relax to let the wind out, and some faecal material may be propelled out at the same time.

Irritable bowel syndrome is the other common cause. In irritable bowel syndrome (also known as IBS), the bowel muscle squeezes strongly, so that it may be difficult to hold the faeces in. If you have abdominal pain as well as leakage of faeces, then IBS is a strong possibility. The pain of IBS can occur anywhere in the abdomen, but is usually felt low down on the right or left side. Passing wind or opening the bowels often relieves it. People with IBS often have to rush to the lavatory, and some leakage is common. There is also often a ‘morning rush’ – the bowels have to be opened urgently several times on rising and after breakfast.

Childbirth. After having a baby, more than 1 in 10 women finds that she has difficulty in controlling wind or faecal leakage. It is most likely if you were an older mother (over 35 years of age) or had a large baby. The reason may be that the anal muscle is damaged by a tear, or by the episiotomy cut made during childbirth. Damage to the pudendal nerve can also occur during childbirth, and result in incontinence. The problem is likely to improve somewhat, but if you first noticed faecal incontinence after having a baby, do see your doctor – a surgical operation to repair the damage often gives good results even if you have had the problem for years.

It is quite common to have both faecal leakage and leakage of urine. A study of women with incontinence of urine found that almost 1 in 4 also had some leakage of faeces (Obstetrics and Gynecology 2002;100:719–23). The connection is that both are related to childbirth, especially if the baby was large.

Ageing. Faecal leakage is also quite common in older people, because the anal muscle becomes weaker with age. This is something that you should definitely discuss with your doctor, because a lot can be done to help. The real reason may be constipation – if you have hard faeces in the lower bowel, some watery faeces can leak round them and be difficult to control. Doctors are very familiar with this problem (called ‘overflow incontinence’) and should know how to deal with it.

Medications. Some medications make the faeces looser and therefore more difficult to hold in. Check that you are not taking a laxative from habit. If you are taking an indigestion remedy, check that it does not contain magnesium trisilicate, because this can cause diarrhoea. Misoprostol (a medication for stomach and duodenal ulcers that is sometimes prescribed for elderly people) is another possible culprit.

Orlistat (Xenical) is a diet pill that works by blocking the enzymes that digest fat. This means that the fat cannot be absorbed from the gut. With the correct dose, a third of the fat that you eat is blocked, and is excreted in the faeces instead of ending up as part of your spare tyre. By the time it reaches the lower part of the gut, this extra fat has the consistency of light machine oil. As a result, it can cause oily anal leakage, and the problem gets worse with the more fat that you eat. To stop it happening, you have to eat less than 70 g of fat a day.

What your doctor can do
Your doctor will try to work out what the cause is. Before seeing the doctor, you may wish to keep a bowel diary for a week (look at the Bowel Control website listed in the useful contacts section). In difficult cases, an ultrasound scan can tell if the anal muscles have been damaged (for example, by childbirth). Medications such as loperamide can be used to prevent the bowel muscle squeezing too strongly and to make the faeces more solid.

Recently, a form of treatment called ‘behavioural treatment’ has proved to be helpful. This teaches you how to resist the urgent need to rush to the lavatory. Look at bowel retraining in the self-help section of the Bowel Control website in the useful contacts section.

If the anal muscles are weak, injections of ‘bulking agents’ into the wall of the anus may help, but these have to be done by a specialist doctor and it is uncertain how effective the treatment is (British Journal of Surgery 2005; 92: 521–7). For major incontinence, a surgical operation is a last resort and may not be successful.

Other useful sections

• How the anus works
• Anal bleeding
• Anal itching
• Anal pain
• Piles
• Seeing your doctor about an anal problem
• Useful contacts

Dr Phil’s poem on Irritable Bowel Syndrome