From the Guidelines
A bladder volume of more than 500 cm3 on bladder scan indicates acute urinary retention in a patient with urinary retention, particularly if symptomatic, as indicated by a postvoid residual bladder volume > 500 cm3 for asymptomatic patients or > 300 cm3 for symptomatic patients 1. When evaluating a patient for acute urinary retention, it's crucial to consider both the bladder volume and the presence of symptoms such as bladder pain, fullness, persistent urge to void, new incontinence, or only being able to have frequent small voids.
- Key factors in diagnosing acute urinary retention include:
- Bladder volume on scan
- Presence of symptoms
- Inability to void The normal adult bladder capacity ranges from 300-500 mL, and volumes exceeding this capacity without the ability to empty can lead to detrusor muscle overstretching, potentially causing bladder decompensation if not addressed promptly 1. Management of acute urinary retention typically involves immediate bladder decompression via catheterization to relieve symptoms and prevent complications such as bladder damage, urinary tract infections, or kidney injury.
- Post-management steps include:
- Investigating the underlying cause
- Addressing potential causes like prostatic enlargement, medication side effects, neurological disorders, or urethral obstruction It's essential to prioritize the patient's clinical presentation and symptoms when determining the need for intervention, as indicated by the guidelines for managing acute urinary retention 1.
From the Research
Definition of Acute Urinary Retention
The definition of acute urinary retention is not clearly established, but it is characterized by a sudden and painful inability to pass urine 2.
Volume of Urine on Bladder Scan
There is no consensus regarding a postvoid residual (PVR) volume-based definition for acute urinary retention 3. However, a study suggests that a urinary volume ≥500 mL in ultrasound can be considered urinary retention 4. Another study defines chronic urinary retention as a PVR volume greater than 300 mL measured on two separate occasions and persisting for at least six months 3.
Key Findings
- A high postvoid residual urine volume may help identify patients at risk of an unfavorable outcome 2.
- The American Urological Association recommends that chronic urinary retention be defined as PVR volume greater than 300 mL measured on two separate occasions and persisting for at least six months 3.
- Ultrasound showed to be accurate in establishing urinary volume, with a strong correlation between ultrasound and bladder catheterization 4.
Factors Affecting Urinary Retention
- Baseline prostate volume and postvoid residual urine volume were independent factors predicting treatment failure 5.
- A high prostate-specific antigen level and postvoid residual urine volume may help identify patients at risk of an unfavorable outcome 2.