From the Guidelines
An abnormal post-void residual (PVR) on ultrasound is generally considered to be a urine volume greater than 100 mL remaining in the bladder after urination, as suggested by the most recent guidelines 1. This finding suggests incomplete bladder emptying, which can indicate various urological or neurological conditions. For adults, a PVR over 100 mL is typically considered abnormal, while values between 50-100 mL may warrant monitoring. The significance of an abnormal PVR depends on the clinical context and patient symptoms. Potential causes include:
- Bladder outlet obstruction (such as from prostate enlargement or urethral stricture)
- Neurogenic bladder
- Detrusor muscle weakness
- Medication side effects (particularly anticholinergics, alpha-agonists, and some antidepressants) Patients with abnormal PVR may experience:
- Urinary frequency
- Urgency
- Incontinence
- Recurrent urinary tract infections
- A sensation of incomplete emptying Management depends on the underlying cause and may include:
- Addressing reversible factors
- Medication adjustments
- Intermittent catheterization
- Surgical intervention for obstructive causes Persistent elevated PVR can lead to complications such as urinary tract infections, bladder stones, or upper urinary tract damage, making proper evaluation and management important, as highlighted in recent studies 1.
From the Research
Definition of Abnormal Post-Void Residual
An abnormal post-void residual (PVR) is a volume of urine that remains in the bladder after urination. The definition of an abnormal PVR varies depending on the study and population being examined.
Studies on Abnormal Post-Void Residual
- A study published in 2008 2 found that a PVR of 180 ml or greater was associated with a high risk of bacteriuria in asymptomatic adult men.
- However, a study published in 2009 3 found that this cutoff value had only 28% sensitivity and 94% specificity for predicting urinary tract infection, and therefore, it may be premature to recommend a specific cutoff value.
- Another study published in 2022 4 found that a PVR of less than 200 ml did not exclude the possibility of cauda equina syndrome, and that clinical suspicion of the condition should always lead to an MRI scan.
- A study published in 2009 5 found that in healthy kindergarteners, abnormal post-void residual urine could be defined as a PVR greater than 20 ml on repeat micturitions without bladder over distention.
Factors Affecting Post-Void Residual
- Age: PVR decreases as the age of the child increases 5.
- Bladder capacity: PVR increases as bladder capacity increases 5.
- Hydration: Drinking more fluids before voiding may increase the rate of bladder over distention 5.
- Neurological conditions: Certain conditions, such as diabetic neuropathy, Alzheimer's disease, and white matter lesions, can affect bladder function and lead to abnormal PVR 6.