What you may notice
An internal collection is a pocket of fluid seen on a scan. An abscess contains infected material and may cause fever, pain, poor appetite or failure to recover after an operation. Deep collections can produce few local signs, especially in people with reduced immunity.
A localised internal fluid pocket
What could cause it?
Fluid can be pus, blood, bile, urine or a sterile postoperative collection. An infected cyst or an underlying bowel, pancreatic or other organ problem may be responsible. Symptoms, blood tests and imaging help distinguish these causes; a fluid sample may guide antibiotics or other treatment.
When to contact a doctor
Contact the treating team promptly for fever or worsening pain with a known collection or after surgery. Shivering, confusion, fast breathing, faintness or very little urine can signal severe infection and require emergency care: call 108. Do not wait for a routine scan if the person is becoming unwell.
How interventional radiology may help
IR can sometimes guide a needle or drainage catheter through the skin into an accessible collection. A drain carries fluid outside the body into a bag and may stay temporarily. Antibiotics and treatment of the source remain important. Small or inaccessible collections may need medicines, observation or surgery instead; not every fluid pocket needs a drain.
Further reading: detailed assessment and treatment options
Patient information sources
References are in English.
Educational information, not a diagnosis. The causes listed are examples, not a complete list. Tests and treatment depend on your individual assessment.