Dr Henry WeiGastroenterology & Endoscopy
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Small-bowel investigation: capsule, imaging and enteroscopy

Choose the investigation for the suspected cause and the need for tissue or treatment. Review previous endoscopy before adding another test.

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Author: Dr Henry Wei. Sources checked 16 October 2026.

In practice

Choose the test that will guide treatment

I review the quality of prior endoscopy, iron treatment response and obstruction history. Capsule examines the lining; enterography assesses the bowel wall and surrounding structures; enteroscopy permits biopsy or treatment.

Guidance behind this advice

1. Clarify the question and previous findings

Before choosing a test, ask what we need to know: Is there ongoing or overt bleeding? Has iron deficiency persisted despite replacement? Is there weight loss, diarrhoea, inflammation or a low albumin? What did the previous gastroscopy and colonoscopy show, including preparation and completion?

The common indications for small-bowel assessment are persistent IDA or overt bleeding despite good-quality negative bidirectional endoscopy, and suspected small-bowel disease such as Crohn’s disease. Review coeliac serology while the patient is eating gluten, medicines, previous surgery and any obstruction risk; arrange renal-tract assessment when the iron-deficiency work-up indicates it.

2. Select the investigation

Discuss the case with us and we would be happy to tailor the small-bowel investigation to the clinical question, urgency and need for biopsy or treatment.

Small-bowel investigations
TestBest suited to
CapsuleMucosal bleeding lesions or selected inflammation; no biopsy or treatment.
CT/MR enterographyStrictures, bowel-wall inflammation, masses and extraluminal complications.
Device-assisted enteroscopyTargeted biopsy or treatment after localisation by capsule or imaging.
CT angiographyAcute active bleeding within hospital assessment.

3. Assess capsule retention risk

Obstructive symptoms or known stenosis require cross-sectional imaging first. A patency capsule can assess passage when retention risk is significant and is recommended before camera capsule in established Crohn’s disease.

Ileocolonoscopy with biopsies is usually the first endoscopic test for suspected Crohn’s disease. Capsule can help when suspicion persists after inconclusive investigations.

4. Set urgency and arrange follow-up

Substantial ongoing bleeding, instability or severe symptomatic anaemia requires hospital assessment. After overt suspected small-bowel bleeding in a stable patient, discuss early capsule; ESGE recommends it as soon as possible, ideally within 48 hours.

Send bleeding dates, iron trends and response, previous reports, medicines and surgery history. Prior localisation guides oral or anal enteroscopy. Reassess recurrent bleeding, persistent IDA, weight loss or obstructive symptoms after a negative study.

Clinical pearls

  • Review NSAID exposure before attributing minor capsule erosions to Crohn’s disease.
  • Routine abdominal CT and dedicated enterography use different protocols.
  • Confirm capsule passage before MRI; pain, distension or vomiting before passage needs urgent assessment.
Diagrams and procedure explanations
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

A swallowed camera records the small-bowel lining as it moves through the bowel.

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.

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01 / 05

Follow the preparation

Review preparation, swallowing, previous surgery and retention risk. Obstructive symptoms or known stenosis need cross-sectional imaging first. Patency testing is recommended in established Crohn’s disease and selected other patients at risk of retention.

Step 1 of 5: Follow the preparation

The whole recording may be incomplete.

Read the whole explanation without animation

  1. Follow the preparation

    Review preparation, swallowing, previous surgery and retention risk. Obstructive symptoms or known stenosis need cross-sectional imaging first. Patency testing is recommended in established Crohn’s disease and selected other patients at risk of retention.

  2. The bowel moves the camera

    The capsule travels passively with bowel motility. It cannot be steered or returned to a lesion.

  3. Pictures show the lining

    The camera records the mucosal surface. Folds, contents, rapid transit and incomplete passage during recording can limit detection.

  4. A recorder stores the pictures

    Images are transmitted to a recorder and reviewed afterwards. Findings may guide targeted enteroscopy, biopsy or enterography.

  5. Check that it has passed

    Check whether the recording reached the caecum and whether the capsule has passed. Confirm passage before MRI. Persistent symptoms or bleeding after a negative study may need further investigation.

Interpreting the capsule result

Review preparation, completeness and the clinical findings. Enterography may be needed for suspected bowel-wall or extraluminal disease, and enteroscopy for biopsy or treatment.

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 single balloon on the overtube helps the endoscope advance, with bowel gathered onto the sleeve to reduce loops.

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.

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01 / 06

The sleeve balloon holds

The single balloon on the overtube inflates to hold the bowel. There is no balloon on the endoscope tip.

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

    The single balloon on the overtube inflates to hold the bowel. There is no balloon on the endoscope tip.

  2. The camera moves forward

    The endoscope advances through the overtube while the overtube balloon remains inflated.

  3. The sleeve balloon releases

    The overtube balloon deflates so the sleeve can advance over the endoscope.

  4. The sleeve catches up

    The overtube moves forward with its balloon deflated while the endoscope stays in position.

  5. The bowel gathers onto the sleeve

    The balloon inflates again. Gentle withdrawal of the endoscope and overtube together gathers bowel onto the sleeve and reduces loops.

  6. Repeat if needed

    The cycle repeats to reach the target. Prior capsule or imaging helps determine whether to approach through the mouth or colon.

Choosing the route and target

Capsule or imaging helps localise the finding and select oral or anal access. Enteroscopy can obtain tissue and treat selected lesions. The distance reached depends on anatomy and the clinical target.

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.

Information to share with your patient

Related clinician articles

References

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