Faecal impaction

Long term or chronic constipation can lead to faecal impaction. Chronic constipation means difficulty having a poo that can last for several weeks or longer.

What is faecal impaction?

Faecal impaction means having a large amount of dry, hard poo (stool or faeces) in the back passage (rectum). The diagram shows the parts of the bowel, including the rectum.

Diagram showing the parts of the large bowel

Overflow diarrhoea

One main symptom of faecal impaction is overflow diarrhoea. The constipated poo in your bowel is so hard that you can’t push it out. So your bowel begins to leak out watery stools around the poo. The watery stools pass around the blockage and out of your rectum. The leakage can soil your underwear and appear like diarrhoea.

If you’ve had severe constipation and then develop diarrhoea you should not take anti diarrhoea medicines. You must talk to your doctor or nurse before taking anything.

Causes of faecal impaction

The main causes of faecal impaction are similar to those of constipation. They include:

  • side effects from painkilling medicines
  • lack of exercise over a long period of time
  • a low fibre diet
  • long term use of laxatives
  • depression and anxiety

Symptoms of faecal impaction

The symptoms of impaction are similar to the symptoms of constipation. But other more serious symptoms can occur. These include:

  • back pain due to the mass of poo pressing on the nerves in your lower back (the sacral nerves)
  • a swollen tummy (abdomen)
  • high or low blood pressure
  • a fast heart rate
  • dizziness
  • sweating
  • a high temperature (fever)
  • severe diarrhoea that you have no control over
  • feeling and being sick
  • severe tummy pain
  • dehydration - you may feel dizzy, light-headed, or tired, or have a dry mouth, lips, and eyes, and pass small amounts wee infrequently (less than three or four times a day)
  • swelling around the back passage (rectum)
  • a numb feeling around the anus
  • bleeding around the anus

Treating faecal impaction

Doctors and nurses usually treat impaction by moistening and softening the poo with an enema or suppositories. It is very important that you use enemas carefully and only as prescribed by your doctor. Too many enemas can damage the bowel.

If the enema doesn't move the poo, a trained nurse or doctor might need to physically remove the hard poo from your back passage. You should not do this yourself. Understandably, you may find this procedure uncomfortable and embarrassing. But it is very important to clear the bowel.

Let your doctor or nurse know if you have any changes in your bowel habits. If you think you have an impaction, don’t take any laxatives without first discussing it with your doctor or specialist nurse. Laxatives that stimulate the bowel can cause severe cramping and might damage your bowel.

  • Constipation - Clinical Knowledge Summaries
    National Institute for Health and Care Excellence (NICE), revised March 2022 

  • Diagnosis, assessment and management of constipation in advanced cancer: ESMO Clinical Practice Guidelines

    P.J Larkin and others

    Annals of Oncology, 2018. Vol 29, Supplement 4.

  • Management of Constipation in Adults
    Hull and East Riding Prescribing Committee guidelines, May 2016

  • Managing Constipation in Adults With Cancer

    R J Wickham,

    Journal of Advanced Practioner in Oncology, 2017. Volume 8, Issue 2, Pages 149–161.

  • Chronic Idiopathic Constipation in Adults: A Review on Current Guidelines and Emerging Treatment Options
    G Bassotti, P Usai Satta, and M Bellini 
    Clinical and Experimental Gastroenterology, 2021, Volume 14, Pages 413–428.

Last reviewed: 
13 Dec 2022
Next review due: 
13 Dec 2025

Related links