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Fetal Kidney Volume Measurement, Renal Ultrasound

Published: August 9, 2026Updated: August 16, 2026

This test uses ultrasound to measure the size of your baby’s kidneys during pregnancy. It helps assess whether the kidneys are developing normally and can detect potential issues early.

Quick summary

["An ultrasound check helps ensure your baby’s kidneys are growing properly."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
12162-4
Short code
Fet Kidney-L Volume der US
Synonyms
Fet Kidney-L Volume der US
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
us-derived
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 healthcare provider may recommend this test if you have a history of kidney problems, high blood pressure, diabetes, or other conditions that could affect fetal development. It may also be done if there are concerns about your baby’s growth or if you’re at higher risk for complications.

What to Expect During the Test

You’ll lie on an exam table while a technician applies a gel to your belly. A handheld device (ultrasound probe) glides over your skin to create images of your baby’s kidneys. The process is painless and usually takes about 15–30 minutes.

What Does the Test Measure?

The ultrasound measures the length and width of your baby’s kidneys to calculate their volume. This helps determine if the kidneys are the right size for your baby’s gestational age or if they appear smaller or larger than expected.

What Are Possible Findings?

If the kidneys are smaller than normal, it could signal potential issues like kidney malformation, chromosomal abnormalities, or other congenital conditions. If they appear unusually large, it might indicate conditions like polycystic kidney disease or other fluid-related problems.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Fetal Kidney Size Check

Frequently asked questions

How often will I need this test?
This test is typically done once during pregnancy, usually between 18 and 22 weeks, but your provider may recommend additional ultrasounds if needed based on your health or pregnancy history.
What if my baby’s kidneys are smaller than expected?
If your baby’s kidneys are smaller, your healthcare provider may recommend further testing, such as additional ultrasounds or genetic counseling, to rule out underlying conditions. They’ll also monitor your pregnancy closely to address any concerns.
Do I need to prepare for this test?
No special preparation is needed, but you may want to wear comfortable clothing and bring your prenatal records if requested. Avoid using lotions or creams on your belly before the test.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

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.

Medical Disclaimer

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