Dr Henry WeiGastroenterology & Endoscopy
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Looking at the small bowel: capsule cameras, scans and enteroscopy

Gastroscopy and colonoscopy do not examine most of the small bowel. I recommend another test when your symptoms or earlier results give us a reason to look there. I choose the test based on what we need to find, such as bleeding, inflammation, a narrowing or an area that needs a biopsy.

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In my practice

Choose the investigation that can answer the question

I review the reason for testing and the quality of any previous gastroscopy and colonoscopy. For low iron, I also check the response to iron treatment and possible causes outside the small bowel. A capsule camera is useful for some patients, but is not automatically the next investigation.

A capsule shows the lining, CT or MR enterography shows the bowel wall and surrounding tissues, and enteroscopy can take biopsies or treat a finding. I may recommend one or more, depending on what we need to investigate. Symptoms of blockage or a known narrowing need assessment before a capsule is considered.

Guidance behind this advice
Explore the explanation

Different questions need different views

Choose a view
Explanatory diagram
The small bowel connects the stomach to the large bowelSimplified front view, not to scale. Your right is image left. The food pipe enters the stomach, which lies mainly on your left. The stomach outlet leads into a C-shaped duodenum on your right. Its distal portion crosses the midline and rises towards the duodenojejunal flexure on your left before continuing into coils of jejunum and ileum. The terminal ileum joins the inner, medial side of the caecum through the ileocaecal valve. Only the caecum, a short ascending-colon segment and the appendix are shown from the large bowel. The rest of the colon, other organs, mesentery and blood vessels are omitted. There is no drawn boundary between jejunum and ileum because their change is gradual and their loops do not have fixed positions. Your rightYour leftFront view Food pipe Stomach Duodenum Stomach outlet Jejunumand ileum Caecum End of the ileum joins the caecum Only the beginning of the large bowel is shown. Bowel loops vary. Their shape and relative lengths are simplified.

Where is the small bowel?

The small bowel starts at the stomach outlet. Its first part is the duodenum, followed by the jejunum and ileum. The end of the ileum joins the caecum, the first part of the large bowel. The loops change position, so the drawing is a simplified map.

Simplified illustrations, not to scale. These show an example, not your own anatomy or test result.

Read every diagram explanation

Where is the small bowel?

The small bowel starts at the stomach outlet. Its first part is the duodenum, followed by the jejunum and ileum. The end of the ileum joins the caecum, the first part of the large bowel. The loops change position, so the drawing is a simplified map.

What do routine scopes see?

Gastroscopy examines the stomach and first part of the duodenum. Colonoscopy examines the large bowel and may include a short section of the terminal ileum when needed. Most of the small bowel lies beyond these routine views.

Capsule or a scan?

A capsule takes pictures from inside the bowel. It cannot take biopsies or treat a finding. CT or MR enterography assesses the bowel wall and surrounding structures. I choose the test for the question, and check for possible narrowing before recommending a capsule.

Reaching a selected finding

If a finding needs a biopsy or treatment, I may recommend referral for specialist enteroscopy. The team chooses a route according to where the finding is and what the earlier tests show.

How the procedures work

See how the test works

How a capsule takes pictures

The capsule is a camera you swallow. Select a step or play the short explanation.

Capsule endoscopy: movement and lining picturesOriginal schematic of one short, curved small-bowel lumen, not whole abdominal anatomy. The bowel wall stays fixed while a capsule marker moves inside it. This represents passive transit, not steering, a measured speed, guaranteed completion or an individual's examination. A dotted line represents image transmission to a body-worn recorder. The separate illustrated camera view contains simplified mucosal folds around a central lumen. It is not a clinical photograph or a diagnosis. Mouth, stomach, colon and capsule exit are omitted.A short section of small bowelThe camera travels inside the open space.Body-worn recorderNo steering. No biopsy. No treatment.Transit varies. The animation is not in real time.Illustrated camera viewPictures of the surface liningAn illustration, not your result.Simplified lumen and mucosal folds. Other organs and actual dimensions are omitted.

Animation paused. Select a step or press Play.

01 / 05

Follow the preparation

Follow the service instructions before the test. You usually swallow the small capsule with water after a short period of fasting. Small-bowel capsule preparation often uses about 2 litres of PEG solution, usually less than the 3–4 litres in a standard Glycoprep colonoscopy course. Other lower-volume colonoscopy products differ and still require additional clear fluids. Use your service’s exact product, fluid and timing instructions. This drawing begins inside a short section of bowel, after the mouth and stomach.

Step 1 of 5: Follow the preparation

The whole recording may be incomplete.

Read the whole explanation without animation

  1. Follow the preparation

    Follow the service instructions before the test. You usually swallow the small capsule with water after a short period of fasting. Small-bowel capsule preparation often uses about 2 litres of PEG solution, usually less than the 3–4 litres in a standard Glycoprep colonoscopy course. Other lower-volume colonoscopy products differ and still require additional clear fluids. Use your service’s exact product, fluid and timing instructions. This drawing begins inside a short section of bowel, after the mouth and stomach.

  2. The bowel moves the camera

    The capsule moves with the normal movement of your bowel. It has no steering wheel or controls to turn it back to a particular spot.

  3. Pictures show the lining

    A light and camera take pictures of the bowel lining. The inset shows what a lining view means. It is an illustration, not a photograph or your result.

  4. A recorder stores the pictures

    Images are sent to a recorder. The recording is reviewed afterwards. The capsule cannot take a biopsy or treat a bleeding point.

  5. Check that it has passed

    The capsule usually leaves the body when you open your bowels. A recording may not show the whole small bowel.

A closer view

This is a still frame of the selected step. Swipe across the picture, or focus it and use the arrow keys. Press Escape to close.

See how the test works

How balloon-assisted enteroscopy reaches further

A longer camera tube and a soft balloon on its outer sleeve help a specialist reach a selected area. This example uses a single-balloon system.

Single-balloon enteroscopy: holding, advancing and gatheringUncoiled device-level cutaway of a short small-bowel segment, not whole abdominal anatomy or a clinical training simulation. B is the single balloon on the outer sleeve, called the overtube. The scope slides inside this sleeve. The sequence begins with B inflated to hold the bowel while the scope advances. B then deflates so the overtube can catch up, before reinflating for the next hold and gentle loop reduction. There is no distal scope balloon in this single-balloon system. During gathering, coloured bands on the bowel wall track the tissue grip point as it moves with the overtube; these are explanatory tracking marks, not lesions. The balloon is not a stricture-dilation balloon. Folds and relative distances are conceptual, and no particular insertion depth or whole-bowel completion is implied.BBalloon on the outer sleeveThe sleeve is called the overtubeToward the entry routeFurther into the bowelABThe sleeve balloon holds the bowel.The balloon holds gently. It is not used here to stretch a narrowing.One illustrative cycle. Distances, folds and device sizes are not to scale.This is not a view of the whole abdomen or a guide for performing the procedure.

Animation paused. Select a step or press Play.

01 / 06

The sleeve balloon holds

A soft outer sleeve fits around the camera tube. Its single balloon is inflated gently to hold the bowel while the camera tube is ready to move forward.

Step 1 of 6: The sleeve balloon holds

Balloon systems differ. Your specialist will explain the route and technique. One examination may not reach the target or see the whole small bowel.

Read the whole explanation without animation

  1. The sleeve balloon holds

    A soft outer sleeve fits around the camera tube. Its single balloon is inflated gently to hold the bowel while the camera tube is ready to move forward.

  2. The camera moves forward

    With the sleeve holding its position, the specialist advances the camera tube a short distance through it. The sleeve balloon remains inflated while the camera moves.

  3. The sleeve balloon releases

    The sleeve balloon is released so the outer sleeve can move forward over the camera tube. The camera remains inside the bowel while the sleeve catches up.

  4. The sleeve catches up

    The sleeve moves forward over the camera tube with its balloon flat. The specialist positions it for the next hold.

  5. The bowel gathers onto the sleeve

    The sleeve balloon is inflated again. The specialist gently draws the sleeve and camera tube together, gathering bowel onto the sleeve and reducing loops rather than stretching them.

  6. Repeat if needed

    The camera tube is advanced again while the sleeve balloon holds. The sequence can be repeated to reach a selected area. How far it reaches depends on the bowel and the reason for the test.

A closer view

This is a still frame of the selected step. Swipe across the picture, or focus it and use the arrow keys. Press Escape to close.

Which part has already been examined?

The small bowel connects the stomach to the large bowel. It has three parts: the duodenum, jejunum and ileum. It absorbs much of the food we digest. A gastroscopy examines the duodenum at the beginning. A colonoscopy can sometimes examine a short section of terminal ileum at the other end. Most of the small bowel lies between these two views.

When is a small-bowel test useful?

Reasons include bleeding not explained by other investigations, iron deficiency anaemia that persists despite treatment or returns after appropriate gastroscopy and colonoscopy, or suspected Crohn’s disease after initial assessment. Not everyone with low iron needs a capsule. I check the likely cause and response to iron treatment first.

Common bloating or abdominal pain alone does not by itself require a capsule camera. Blood tests, coeliac testing, stool tests or assessment for other causes may be more useful. The investigation should be likely to change your care.

Tumours of the small bowel are uncommon. When people use the phrase ‘bowel cancer’, they are usually talking about colorectal cancer; cancers of the stomach and oesophagus are discussed separately. I recommend small-bowel tests when your symptoms, blood results or earlier investigations give us a specific reason to look there.

Which test might I need?

These are complementary options. I choose the test according to your symptoms and results.

Small-bowel investigations
OptionUseful forWhat it cannot do
Capsule endoscopyPhotographing the lining for bleeding sources or selected inflammatory changes.Take biopsies or provide treatment.
CT or MR enterographyAssessing the bowel wall, narrowing and complications outside the lining.Provide a biopsy or show every subtle surface change.
Balloon-assisted enteroscopyTaking tissue or treating a selected abnormal area.Always examine the entire small bowel in one procedure.

Capsule endoscopy: photographs of the lining

You swallow a small capsule containing a camera and light. The bowel carries it along naturally while it sends pictures to a recorder. It is not steered by the doctor and cannot take biopsies, remove polyps or treat bleeding. Swallowing the capsule usually needs no sedation.

It is particularly useful for small areas of inflammation, ulcers or abnormal surface blood vessels. Sometimes the view is incomplete because the bowel is not clear enough or the capsule does not reach the end before recording finishes.

A normal recording does not rule out every small-bowel condition. A small-bowel capsule does not replace a recommended colonoscopy.

CT and MR enterography: the wall and surrounding tissues

Enterography is a scan designed for the small bowel. You usually drink liquid to open up the bowel, and an injection of contrast may be used. These scans assess the bowel wall, nearby tissues, narrowing and complications such as a collection or an abnormal connection between organs.

CT uses X-rays. MRI does not use ionising radiation and can be useful when repeated imaging is needed. The best choice depends on the question and your circumstances.

Tell the radiology service about pregnancy, kidney problems, previous contrast reactions and implanted devices. Scans and capsule pictures provide different information; one may be useful after the other.

Enteroscopy: reaching an area for a biopsy or treatment

A longer flexible endoscope, sometimes using a balloon-assisted system, can reach further into the small bowel. It may pass through the mouth or bottom, depending on where the suspected problem is.

It can take biopsies or treat selected findings, such as a bleeding blood vessel. One procedure does not always examine the whole small bowel. If enteroscopy is needed, I can help arrange the specialist referral.

Before a capsule camera

Capsule endoscopy is generally very safe. Occasionally the capsule is held up at a narrowing. Tell the service about known narrowing, previous bowel blockage or surgery, Crohn’s disease, swallowing difficulty and any pacemaker or other implanted device.

A pacemaker is not automatically a reason to rule out a capsule; the service checks the device and equipment.

If symptoms suggest a blockage or there is known narrowing, imaging comes before considering a camera capsule. If a camera remains appropriate, the service may also check passage with a dissolvable test capsule (a patency capsule).

Established Crohn’s disease usually requires this patency check before a camera capsule. People without these risks do not automatically need it.

Follow the service’s preparation and medicine instructions. These should document whether each blood thinner is continued or withheld and, if withheld, when to restart it. If unsure, call our endoscopy team before changing a dose. Do not stop prescribed medicines from a general online list.

Small-bowel capsule preparation often uses about 2 litres of a PEG bowel-cleansing drink, with food and fluid instructions from the testing service. This is usually less preparation solution than a standard 3 to 4 litre Glycoprep colonoscopy course; lower-volume colonoscopy products differ and still need additional clear fluids.

Afterwards and your results

The capsule normally passes in your poo.

The images need review after recording. I interpret the report with your blood results, symptoms and other investigations. An uncertain finding may need a scan or targeted biopsy, rather than an immediate diagnosis. Follow-up is documented in the investigation report or results letter, and in the histology report when tissue has been taken.

When to get help

After swallowing a capsule, severe or worsening abdominal pain, repeated vomiting, a swollen abdomen or inability to pass wind or poo need urgent medical assessment. Tell the clinician you have had capsule endoscopy.

Heavy bleeding, black tarry stools with faintness, or feeling very unwell also need urgent assessment. If you are unsure whether the capsule has passed, contact the testing service, especially before an MRI.

Call 111 if you collapse or are too unwell to travel safely. Do not wait for a routine appointment or an email reply.

Three things to remember

  • A normal gastroscopy and colonoscopy leave most of the small bowel unseen.
  • Capsule cameras show the lining, scans assess the wall and surroundings, and enteroscopy can obtain tissue or treat selected findings.
  • The next test depends on your symptoms, previous results and whether the finding would change treatment.

Related information

Sources and further reading

English clinical master checked 16 October 2026.

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