Urinary Pelvic Inlet and Outlet Measurements (Hydronephrosis Assessment)
This test measures fluid movement through the kidneys’ upper collecting system (pelvic inlet and outlet) to assess for blockages or abnormal fluid retention, often linked to conditions like kidney stones or urinary tract obstructions.
["This helps diagnose potential kidney or urinary tract blockages that may cause pain, infection, or reduced kidney function."]
Key facts at a glance
- LOINC
- 30771-0
- Short code
- XR Pelvis Inlet+Outlet
- Synonyms
- XR Pelvis Inlet+Outlet
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- xr
- 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 This Test Is Done
Your doctor may recommend this test if you have symptoms like persistent pain in your side or back, frequent urinary tract infections, or signs of kidney issues. It can also be part of evaluating kidney function before surgery or after trauma.
How the Test Works
A contrast dye is injected into your bloodstream, which travels to your kidneys and is excreted into your urine. Special imaging (like X-rays or ultrasounds) captures how fluid moves through the pelvic inlet and outlet, helping identify blockages or narrowing.
Preparation
You may need to drink extra fluids the day before the test to ensure clear urine. Avoid certain medications (like diuretics) that could affect urine flow. Follow any fasting instructions if imaging involves contrast dye.
What to Expect During the Test
You’ll lie still on an imaging table while the dye is injected. Imaging may take 15–60 minutes, depending on the method. You may feel warmth or pressure where the dye is injected, but it’s usually brief and painless.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Abnormal findings, such as slow fluid flow, dilated areas, or signs of obstruction, may indicate conditions like kidney stones, strictures (narrowing), or reflux (backflow of urine). Early detection can guide treatment, such as medications, lifestyle changes, or surgical intervention.
Short name
Urinary Pelvic Flow Study
Frequently asked questions
What does a ‘blockage’ or ‘narrowing’ in the pelvic inlet/outlet mean?
How long does it take to get results?
Can I eat or drink before this test?
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