Post-Void Residual Volume

Definition

Post-void residual volume (PVR) refers to the amount of urine that remains in the bladder after urination. It is an important measurement in evaluating bladder function and lower urinary tract symptoms.

5 Must Know Facts For Your Next Test

1. Elevated post-void residual volume can indicate an underlying medical condition, such as benign prostatic hyperplasia (BPH), neurogenic bladder, or diabetes mellitus.
2. Measurement of post-void residual volume is commonly performed using ultrasound imaging or catheterization, and it is an important parameter in the evaluation of lower urinary tract symptoms.
3. Chronic high post-void residual volume can lead to complications like urinary tract infections, bladder stones, and kidney damage if left untreated.
4. Medications that have anticholinergic effects, such as some antispasmodics and antimuscarinics, can contribute to increased post-void residual volume by impairing bladder contractility.
5. Urinary stimulants, such as bethanechol, may be used to improve bladder emptying and reduce post-void residual volume in patients with detrusor underactivity.

Review Questions

• Explain the relationship between post-void residual volume and urinary antispasmodics, antimuscarinics, and anticholinergics.
  • Medications with anticholinergic effects, such as urinary antispasmodics, antimuscarinics, and anticholinergics, can contribute to increased post-void residual volume by impairing bladder contractility. These medications block the action of acetylcholine, a neurotransmitter that is essential for proper bladder function. As a result, the bladder may not be able to contract effectively, leading to incomplete emptying and a higher post-void residual volume. Clinicians must carefully consider the potential impact of these medications on bladder function when prescribing them to patients.
• Describe how post-void residual volume is related to the use of urinary stimulants.
  • Urinary stimulants, such as bethanechol, may be used to improve bladder emptying and reduce post-void residual volume in patients with detrusor underactivity, a condition characterized by diminished bladder muscle contractility. Urinary stimulants work by directly stimulating the muscarinic receptors in the bladder, which enhances the bladder's ability to contract and expel urine. By improving bladder contractility, urinary stimulants can help to decrease the post-void residual volume, reducing the risk of complications associated with incomplete bladder emptying, such as urinary tract infections and kidney damage.
• Analyze the clinical significance of measuring and monitoring post-void residual volume in the context of managing lower urinary tract symptoms.
  • Measuring and monitoring post-void residual volume is crucial in the evaluation and management of lower urinary tract symptoms (LUTS). A high post-void residual volume can indicate an underlying condition, such as benign prostatic hyperplasia, neurogenic bladder, or diabetes mellitus, that is causing incomplete bladder emptying. Chronic high post-void residual volume can lead to serious complications, including urinary tract infections, bladder stones, and kidney damage. By assessing post-void residual volume, clinicians can identify the root cause of LUTS, guide appropriate treatment decisions (e.g., the use of urinary antispasmodics, antimuscarinics, or stimulants), and monitor the effectiveness of interventions in improving bladder function and reducing the risk of complications. Regular monitoring of post-void residual volume is, therefore, an essential component of comprehensive LUTS management.

Related terms

Urinary Retention: Urinary retention is the inability to completely empty the bladder, leading to a high post-void residual volume.

Detrusor Underactivity: Detrusor underactivity is a urodynamic finding characterized by a diminished ability of the bladder muscle to contract, resulting in incomplete bladder emptying and increased post-void residual volume.

Bladder Outlet Obstruction: Bladder outlet obstruction is a condition where there is a mechanical or functional blockage at the bladder neck or urethra, leading to increased post-void residual volume.