A capsule endoscopy is a non-invasive diagnostic tool that allows medical professionals to visualize the inside of the digestive tract, particularly the small intestine, which is difficult to reach with traditional endoscopic procedures. Unlike conventional endoscopies that involve inserting a flexible tube, the capsule endoscopy relies on a small, disposable camera encased in a vitamin-sized capsule that the patient swallows.
Natural Passage of the Capsule
After swallowing, the capsule endoscopy travels through the digestive system, propelled by natural muscle contractions. The capsule is sealed and designed not to break down in stomach acids. As it moves, the tiny camera inside takes thousands of pictures, transmitting them wirelessly to a recording device worn by the patient. Patients generally do not feel the capsule as it progresses through their digestive tract.
The capsule is eventually excreted from the body in a bowel movement. This process usually occurs within 24 hours, though it can sometimes take several days depending on an individual’s digestive system.
Understanding Capsule Retention
While natural passage is the norm, a less common but concern is capsule retention. Capsule retention is defined as the capsule remaining in the digestive tract for a minimum of two weeks. It can also be suspected if symptoms occur regardless of the time elapsed since ingestion. The overall frequency of capsule retention ranges between 0.3% and 2.5% across various indications.
Symptoms that might indicate a retained capsule include abdominal pain, nausea, vomiting, or abdominal distension. Risk factors for retention often involve conditions that can narrow the digestive tract, such as strictures, inflammatory bowel diseases like Crohn’s disease, or previous abdominal surgeries. Patients with known Crohn’s disease have a higher risk of retention, with reported rates between 2.6% and 13%. Tumors and chronic use of non-steroidal anti-inflammatory drugs (NSAIDs) can also increase this risk.
Interventions for Retained Capsules
If capsule retention is suspected or confirmed, medical professionals will determine the appropriate course of action. An abdominal plain X-ray is often the preferred initial test to confirm retention and locate the capsule if it has not been excreted within 15 days. A CT scan may be performed if a more precise location is needed or if symptoms warrant it.
When natural passage fails, interventions are typically required. Endoscopic retrieval, often using a double-balloon enteroscopy, is a common method for grasping and removing the capsule from the digestive tract. In cases where endoscopic retrieval is not possible, or if there is a complete obstruction or other complications, surgical intervention may be necessary. Surgical approaches are used to remove the retained capsule and address any underlying pathology.
After Capsule Passage
Once the capsule has successfully passed, whether naturally or with medical intervention, there are typically a few follow-up steps. Patients are usually instructed to return the recording device and any associated equipment to their healthcare provider. The medical team will then download and review the thousands of images captured by the capsule to analyze the findings.
The capsule itself is for single use and does not need to be returned to the clinic. It can be safely disposed of by flushing it down the toilet. After reviewing the images, the doctor will discuss the results with the patient, providing insights into any identified issues.