Purple Bag Syndrome and How it Can Affect Urostomy Appliances

Purple Bag Syndrome and How it Can Affect Urostomy Appliances

Wow, this is the 4th segment of the #UnderstandingUrostomy series every Friday and they have seemed to be quite a hit!

So this post is all about Purple Bag Syndrome......

If you have a Urostomy or have had a urethral/supra-pubic catheter you may have seen this on the groups or forums. Yes, this is really a thing!!!

What is Purple Bag Syndrome?

                      Purple Bag Syndrome                     Purple Bag Syndrome 2

Purple Bag Syndrome also called Purple Urine Bag Syndrome (PUBS) is very RARE and quite alarming if you have never seen it before. It occurs when a Urostomy pouch, night drainage system or urinary catheter appear purple in colour.

PUBS was recognised as a condition and was then published in 1978 in a medical context. Some academics would argue that it was first reported as an observation in 1812 when physicians taking care of King George III noted a bluish discolouration in his urinary catheter bag!

Even though there have been many scientific studies and individual case studies on this phenomenon the exact reason for this are still disputable. There are a few possible theories which I will explain later in this post. The studies all involve long-term catheterised patients however I have seen in groups and forums that PUBS can occur in Urostomates. They state they have seen purple discolouration in their pouches and night drainage systems.

Why does this occur?

Again there are a few theories so I will try to cover them.

  1. High-level tryptophan (amino acid needed in our diet) is present in the gut for longer due to constipation, bowel immobility or slow transit could contribute to PUBS
  2. Alkaline Urine helps breaks down the indoxyl into Indirubin and indigo. These pigments dissolve into the plastic of urostomy pouch, night bag or catheter devices then appears purple.
  3. It has been reported that it is more common in females especially if they are older and bedridden. However, I know a few Urostomates who do not fit into this category and have had PUBS.
  4. Most results from urinalysis shows the presence of bacteria.  It is this bacteria that produces enzymes which break down to form the pigments. Some people may find after a course of antibiotics the PUBS may stop but this doesn’t occur in every case. Most people with PUBS that have bacteria present are asymptomatic. Therefore there is a big discussion whether these people are given antibiotics because they do not have any symptoms.
  5. Another theory that is a bit out there is a bit historical. Going back to King George III’s blue/purple urine in 1812 researchers have found his medical records show that he was given a medicine based on the plant Gentian. This plant has deep blue flowers and is still used today in some tonics and maybe this plant could also be a contributory factor but not all scientists agree.

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So chemically how does this happen?

Ok so bare with me as I try to describe chemically how this can happen with the aid of this diagram!

Purple bag syndrome 4

  • Tryptophan is an amino acid found in the diet and is essential to humans. It is broken down by the enzyme Tryptophase in the GI Tract
  • This produces Indole and is absorbed into the blood by the intestines and passes to the liver.
  • In the liver, it is converted to Indoxyl Sulfate which is excreted in urine. If everything was normal indoxyl sulphate might stay as it is and make its way out of the body in the urine.
  • As mentioned for PUBS to occur there is a debate that an infection may be present although usually asymptomatic. Bacteria is present that produce the enzyme sulphatase and phosphatase that shear the indoxyl of its sulphate leaving indoxyl.
  • If the urine is alkaline (pH greater than 7) the indoxyl breaks down into Indirubin and indigo. These pigments dissolve into the plastic of the urostomy/ catheter bags or drainage device to combine and make a purple colour.

Purple Bowel Syndrome 3

How to Manage PUBS if you have it?

  • Talk to your GP and ask about taking vitamin C to get your urine less alkaline. Please see this post for more advice on achieving acidic urine.
  • Make sure you are eating enough fibre and are not constipated.
  • Clean your night drainage bags and other devices thoroughly the more bacteria that is present the more likely PUBS could develop.
  • Make sure you are hydrated by drinking about 2 litres a day. This also helps prevent infections and alkaline urine. Increase your fluid intake in hot weather and situations where you are exerting yourself such as exercising.
  • Maintain good hygiene when changing appliances.


While purple urine bag syndrome may seem harmless it can be quite alarming. As mentioned the exact cause is still not known and there seems to be many factors that can contribute.

It is important your GP is aware so some tests can be carried out. Some people have a course of antibiotics and the colour goes away but some people may have it for years and does not go away.

If anybody has experienced this please let me know I would love to hear from you.

Written by : Rachel Jury

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