Reference — Renal
Bladder Scan & Catheterization Reference
The non-invasive bladder scan confirms retention before you reach for a catheter — and choosing the right catheter (or none) is a core safety decision because of CAUTI.
Educational use only. Catheterization decisions and PVR thresholds follow provider orders and facility policy. This reference is an educational aid. This material supports nursing education and exam review. It is not medical advice and is not a substitute for clinical judgment, institutional policy, or medical direction. Always follow facility protocols and current provider orders.
Bladder Scan & Post-Void Residual (PVR)
A bladder scanner uses ultrasound to estimate bladder volume non-invasively. To measure a post-void residual (PVR), have the patient void, then scan within a few minutes. A normal PVR is small (roughly <50 mL; up to ~100 mL can be acceptable in older adults). A large PVR (often >~200–300 mL, per policy) indicates incomplete emptying/retention and may prompt catheterization. Scanning first avoids unnecessary, infection-prone catheterizations.
Catheter Types & When to Use Them
| Type | Typical use | Notes |
|---|---|---|
| Intermittent (straight) | Preferred for retention and neurogenic bladder; one-time/scheduled drainage | Lowest infection risk over time; can be taught as clean self-cath (CIC) |
| Indwelling (Foley) | Continuous drainage when needed (acute retention, accurate output in critically ill, healing perineal wounds) | Highest CAUTI risk — use only with a clear indication and remove ASAP |
| Suprapubic | Long-term diversion, urethral injury/obstruction | Surgically placed; stoma/site care |
| Condom (external) | Male incontinence without retention | Non-invasive; lower infection risk; check skin |
CAUTI Prevention
Catheter-associated UTI is a major preventable harm. Insert only with a valid indication, use sterile technique, keep the system closed, keep the bag below bladder level and off the floor, maintain unobstructed flow, perform daily perineal/meatal hygiene, and remove the catheter as soon as possible. Prefer intermittent catheterization or external/condom catheters over indwelling when appropriate. (See the urinary catheter care reference.)
NCLEX Pearls
- ✦Bladder scan = non-invasive PVR check; scan BEFORE catheterizing to avoid unnecessary catheter use.
- ✦Normal PVR is small (<~50 mL); a large PVR signals incomplete emptying/retention.
- ✦Intermittent catheterization has a lower long-term infection risk than indwelling — preferred for retention/neurogenic bladder.
- ✦Indwelling catheters carry the highest CAUTI risk — use only with a clear indication and remove ASAP.
- ✦CAUTI prevention: sterile insertion, closed system, bag below the bladder, daily hygiene, early removal.
- ✦Condom (external) catheters suit male incontinence without retention and lower infection risk.
Related Resources
Standards & sources
Fact-checked Jun 21, 2026This page is written to align with KDIGO Clinical Practice Guidelines · National Kidney Foundation (NKF). It is an educational summary, not a citation of any single document — always verify specific doses, values, and protocols against current guidelines and your facility policy. How we source content →