Patency capsule before a VCE

If we think you might have some narrowing of your small bowel, we give you a patency capsule. 

The patency capsule is a safe way to check that there is no blockage (obstruction) in your small bowel. It breaks down into smaller pieces, and does not have any harmful ingredients in it. 

This tells us if it's safe to give you a video capsule, which can diagnose any problems you have. 

A video capsule is the same size, but has a camera in. It is used to take images of your food pipe (oesophagus), stomach, small intestine and large bowel (colon). This is a procedure called a video capsule endoscopy (VCE).

If a video capsule was to become stuck in your small bowel, you would need an endoscopy or surgery to remove it. 

This test is mostly done in people who:

  • have had surgery on their small bowel
  • have known narrowing of their small bowel
  • have a medical history of bowel obstruction
  • have symptoms, such as inflammatory bowel disease, which suggests there might be a blockage in the small bowel

How to take a patency capsule

The patency capsule is swallowed with a glass of water. The capsule is about the size of a large vitamin capsule or the end of your small finger. 

After 30 hours, the capsule will break down into smaller pieces so it can pass through you in your poo. You might not notice when you pass the capsule, and it will flush away in the toilet.

You will have an X-ray or a CT scan of your tummy (abdomen) the day after taking the patency capsule. This is to make sure it has moved through your small bowel and passed in your poo. 

On the day you take the patency capsule

The capsule will be sent to you in the post. You will take the capsule at home, and do not need to come to the hospital. 

Swallow the capsule with water. 

If there is no blockage or narrowing, the capsule can move through the small bowel. It will then pass naturally in a bowel movement within 30 hours. You will not feel any pain, or know that you have passed the patency capsule.

If the capsule is held up at a narrowing in the small bowel, you might feel some discomfort, bloating, or feel sick (nausea). This will stop when the capsule breaks down and passes through you in a bowel movement.

You should take your usual medicines with a sip of water. 

The day after you take the patency capsule

You will have an X-ray or a CT scan of your tummy in hospital. This scan looks for the capsule to make sure it has moved through your small bowel.  

If the scan shows the capsule has safely passed, you will be booked to have a video capsule endoscopy. 

If the patency capsule has not passed, and it has been temporarily stuck, it is not safe for you to have a video capsule endoscopy. 

You will be given a follow-up appointment to talk to you about other tests that can be done. 


Complications of this test are very rare. 

The main risk is that the patency capsule might become stuck on a narrowed section of your small bowel. If this happens, you might have some tummy discomfort or bloating, and feel sick or be sick.

These symptoms will stop when the capsule breaks down and passes through you within 30 hours. 

If a narrowed section of the small bowel is found, or the capsule becomes stuck, it would mean you cannot have a video capsule endoscopy.

Let your hospital team know if you have swallowing difficulties or a known narrowing of your food pipe, as we may not recommend you having this procedure.

Useful sources of information

Guts UK is an organisation providing information for people with digestive system conditions. 

Resource number: 5246/VER2
Last reviewed: November 2022
Next review: October 2024

Contact us

To cancel or change your appointment call 020 7188 8887

If you have any questions or concerns, contact the endoscopy unit.

Monday to Friday, 9am to 5pm.

Out of hours, call 020 7188 7188 and ask to be put through to the on-call gastroenterology registrar.

Do you have any comments or concerns about your care?

Contact our Patient Advice and Liaison Service (PALS)

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