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Fetal Bladder Diameter Measurement (Ultrasound)

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

This test measures the size of your baby’s bladder during pregnancy using ultrasound. It helps assess whether the bladder is appropriately filled with amniotic fluid.

Quick summary

["Ultrasound checks help ensure your baby’s bladder is functioning normally and properly filled with fluid."]

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

Key facts at a glance

LOINC
11815-8
Short code
Fet Bladder Diam US.meas
Synonyms
Fet Bladder Diam US.meas
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-measured
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 healthcare provider may recommend this test if you have concerns about your baby’s bladder development, such as signs of polyhydramnios (too much amniotic fluid) or oligohydramnios (too little). It can also be part of routine fetal monitoring to check for any potential issues early on.

How the Test Works

During an ultrasound, a gel is applied to your abdomen, and a transducer sends sound waves to create images of your baby’s bladder. The technician measures the diameter of the bladder to determine its size and fluid content.

What to Expect

You’ll lie on an exam table while the technician moves the transducer over your belly. The procedure is quick and painless, usually taking about 15–30 minutes. You may hear a humming or clicking sound as the ultrasound works.

Preparation

No special preparation is needed. Wear comfortable clothing and bring your pregnancy confirmation (like a positive home test or doctor’s note) if requested.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Fetal bladder size check

Frequently asked questions

Will this test hurt?
No, this test is completely painless. The ultrasound itself doesn’t involve needles or invasive procedures, and you may feel a slight pressure or warmth where the gel is applied.
How soon will I get my results?
Results are typically reviewed by your healthcare provider on the same day or within a few days. They’ll discuss findings with you during your next prenatal visit.
Can I eat or drink before this test?
No restrictions apply. You can eat, drink, or move around normally before the ultrasound. This test focuses on visualizing the bladder, not blood or stool samples.
  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