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AbdominalBasic 2–3 min

Bladder Volume

Indication: Urinary retention; post-void residual; catheter need assessment

How to Perform

  1. 1

    Patient should not have voided recently. Use curvilinear probe suprapubically.

  2. 2

    Transverse plane: place probe just above the pubic symphysis, marker to patient's right. Measure width (W) and AP depth (D) at the widest point.

  3. 3

    Rotate 90° to sagittal plane. Measure the longest craniocaudal dimension (L).

  4. 4

    Calculate volume: 0.523 × L × W × D. Values >300mL suggest urinary retention.

  5. 5

    Trace the bladder wall continuously in both planes to confirm it is bladder (not an ovarian cyst).

  6. 6

    Assess for wall thickening (>3mm when full = abnormal), intraluminal debris, or masses.

  7. 7

    If post-void residual needed: scan immediately after voiding. PVR >100mL is significant.

Measurement Guide

Bladder Volume / Post-Void Residual

Where:Three orthogonal dimensions measured at maximum bladder dimensions: transverse width (W) in the transverse plane, anteroposterior depth (AP) in the transverse plane, and craniocaudal height (H) in the sagittal plane.
Normal:Pre-void: volume >300 mL suggests retention. Post-void residual: < 50 mL = normal; 50–100 mL = borderline; > 100 mL = incomplete emptying
Tip:Formula: Volume (mL) = 0.523 × W × AP × H. Scan immediately after voiding for accurate PVR. Trace the bladder wall continuously to confirm it is the bladder (not an adnexal cyst).

Bladder Wall Thickness

Where:Anterolateral wall measured in the transverse plane, at a site free of trabeculation, when the bladder is adequately filled.
Normal:≤ 3 mm (when bladder is full/adequately distended); > 3 mm with full bladder = wall thickening
Tip:Wall thickness is dependent on distension — always note the estimated bladder volume at the time of measurement. A poorly filled bladder will appear falsely thick.

Views to Obtain

  • Transverse bladder (max width + depth)
  • Sagittal bladder (max length)

What to Look For

  • 3D dimensions for ellipsoid formula
  • Wall abnormalities
  • Intraluminal pathology

Common Mistakes

  • Ovarian cysts can mimic bladder — trace the bladder wall continuously

Pro Tip

Volume = 0.523 × L × W × H. >300mL suggests urinary retention.

AI Detects

Retention (>300mL)Debris/clotMassThickened wall
Start Scan — Bladder Vol

Protocol pre-selected · AI will use this context for analysis