From the Guidelines
Urinary retention is diagnosed by a bladder scan when the post-void residual bladder volume exceeds 500 cm3 in asymptomatic patients or 300 cm3 in symptomatic patients. This criteria is based on the most recent guidelines from the International Journal of Infectious Diseases 1. The diagnosis of urinary retention should consider both the volume of urine retained in the bladder and the presence of symptoms such as bladder pain or fullness, persistent urge to void, new incontinence or leaking, or being only able to have frequent small voids.
Key considerations for diagnosing urinary retention include:
- Post-void residual bladder volume: volumes greater than 500 cm3 in asymptomatic patients or 300 cm3 in symptomatic patients indicate urinary retention 1.
- Symptoms: patients with symptoms such as bladder pain or fullness, persistent urge to void, new incontinence or leaking, or being only able to have frequent small voids should be evaluated for urinary retention, regardless of the post-void residual volume.
- Patient population: certain populations, such as the elderly or those with neurological disorders, may have higher baseline residual volumes and require individualized assessment.
The use of bladder scanners to assess post-void residual volume is a recommended non-invasive method for diagnosing urinary retention 1. Regular reassessment is essential to prevent complications such as bladder distension, infection, or upper urinary tract damage. The most recent guidelines from 2025 should be prioritized when making decisions about urinary retention diagnosis and management 1.
From the Research
Criteria for Urinary Retention
The criteria for urinary retention as diagnosed by a bladder scan (ultrasound) are not explicitly defined in the provided studies. However, the following points can be considered:
- Post-void residual urine (PVR) volume is a key factor in diagnosing urinary retention 2, 3, 4.
- A PVR volume > 200-300 mL may indicate marked bladder dysfunction 2.
- A PVR volume > 400 mL may result in intermittent urinary catheterization (IC) 3.
- A PVR volume ≥ 150 mL is commonly recommended for catheterization or close follow-up 4.
- The interval between voiding and post-void residual measurement should be short, and ultrasound bladder volume measurement is preferred to urethral catheterization 2.
Key Findings
- Urinary retention is a common medical problem that can lead to serious conditions if left untreated 5.
- Chronic urinary retention is often difficult to identify due to its asymptomatic nature 5.
- Measurement of PVR is recommended in guidelines for the management of lower urinary tract symptoms (LUTS) and urinary incontinence, but the level of evidence is not high 2.
- A bladder scan protocol using a portable ultrasonographic device can be useful in managing urinary retention in subacute stroke patients 3.
- Urinary retention is common in hospitalized older adults, but measurements of PVR do not have definite clinical utility 4.
Diagnosis and Management
- Diagnosis of urinary retention involves measuring PVR volume using ultrasound or urethral catheterization 2, 3, 4.
- Management of urinary retention depends on the cause and may include conservative treatment, drug therapy, and surgery 5, 6.
- Alpha-blockers may be effective in reducing the symptoms of benign prostatic hyperplasia (BPH) and improving the success rate of a trial without catheter (TWOC) 6.