What should you know?
Post-void residual is the urine remaining in the bladder after urination. Ultrasound records the full-bladder volume and repeats measurements promptly after the patient voids.
Urinary tract ultrasound evaluates the kidneys, bladder and, when requested, post-void residual volume. It helps detect obstruction, stones, cysts and structural changes.
Common symptoms and signs
- Measurement should follow urination without a long delay
- A single result can be affected by circumstances
- A substantial residual may indicate impaired emptying
- Causes may be neurologic, functional or obstructive
Diagnosis and the role of ultrasound
The radiologist measures the kidneys and parenchyma, assesses the collecting systems, focal findings and bladder wall. A moderately full bladder is often needed; residual urine is measured before and after voiding.
- Kidney size and parenchyma
- Stones or urinary tract dilatation
- Bladder wall and contents
- Post-void residual urine
Ultrasound findings must be interpreted together with symptoms, examination and, when needed, laboratory or other imaging results. An image alone should not be used for self-diagnosis or self-treatment.
Treatment and next steps
Persistent elevation warrants urology assessment and may lead to urine-flow testing or other studies. Results may guide urinalysis, kidney function tests, urology review or additional imaging.
Management is individual and depends on age, symptoms, imaging findings, other health conditions and pregnancy plans. Medication or a procedure should be selected with the appropriate clinician.
When is urgent care needed?
- Inability to urinate or a marked fall in urine output
- Severe flank pain with fever or chills
- Visible blood in urine with weakness or vomiting
Related reading
- Frequent urination — when is bladder ultrasound needed?
- Bladder wall thickening — what are the possible causes?
- Urinary system ultrasound
When should you consult radiologist Lana Ezieshvili?
Radiologist Lana Ezieshvili performs targeted ultrasound examinations, describes findings using standard imaging criteria and explains the report in clear language.
If you have symptoms, a referral or need follow-up imaging, use the form below to book a visit with Lana Ezieshvili. Timely, appropriately selected imaging can reduce uncertainty and help determine the right next step.
This article is for education and does not replace medical advice. Seek urgent care for severe or rapidly worsening symptoms.