Fine Needle Aspiration of Retroperitoneal Fluid (Guided by CT Scan)
This procedure involves using a CT-guided needle to collect a small sample of fluid from your retroperitoneal space, an area behind the abdominal wall. It helps doctors examine fluid for signs of infection, inflammation, or cancer.
["A diagnostic test to analyze fluid collected from your abdomen under imaging guidance."]
Key facts at a glance
- LOINC
- 44107-1
- Short code
- CT Guided Retroperitoneum FNA
- Synonyms
- CT Guided Retroperitoneum FNA
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Ref low
- 136
- Ref high
- 145
- Critical range
- 120 N/A – 160 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- ct
- CPT
- 84295
- SNOMED
- 110741000
- Specimen volume
- 5 mL
- Stability
- Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 4–24 hours
- Order
- routine
Why Is This Test Done?
Your doctor may recommend this test if they suspect abnormal fluid buildup, such as from conditions like pancreatitis, kidney disease, or tumors. The CT scan helps pinpoint the exact location of the fluid for safer needle placement.
What Happens During the Procedure?
You’ll lie on your back or side while a radiologist guides the needle into your retroperitoneal space using real-time CT images. A small amount of fluid is collected into a sterile vial. The procedure usually takes 30–60 minutes and may cause mild discomfort or bruising afterward.
What Does the Test Involve?
The collected fluid is sent to a lab for microscopic and chemical analysis. This may include checking for cells, proteins, bacteria, or other substances that could indicate underlying health issues.
Preparation and Risks
No special preparation is needed, but you may be asked to fast for 4–6 hours before the procedure. Common risks include bruising, minor bleeding, or infection at the needle site. Rarely, complications like puncturing nearby organs may occur.
Reference range
Adult: 136-145 mmol/LN/A
No special preparation usually required. Stay well hydrated. Inform your healthcare provider of all medications and supplements you are taking.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Short name
Retroperitoneal Fluid FNA
Frequently asked questions
This test helps diagnose conditions like abscesses, tumors, or inflammatory diseases in the retroperitoneal space. Results can guide treatment decisions, such as antibiotics for infections or further imaging or surgery for suspected tumors.
Results are typically available within 1–3 business days, depending on lab processing. Your doctor will discuss them with you during a follow-up visit.
You may experience mild discomfort or pressure, but the radiologist will stop if you feel severe pain. Over-the-counter pain relievers can help manage any post-procedure soreness.
Sources
- 1
- 2Lab Tests OnlineSource
- 3
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy