eFAST — Suprapubic (Pelvic)

Learning objectives

• Obtain sagittal and transverse suprapubic views using the bladder as a window.
• Identify the rectovesical (male) or rectouterine / Pouch of Douglas (female) space.
• Recognize anechoic free fluid posterior to the bladder.

Maps to

• Resident: ACEP Emergency Ultrasound — FAST: Pelvic acquisition
• Resident: ACEP Emergency Ultrasound — FAST: Free-fluid identification
• Tech: ARDMS Abdomen (AB) — pelvic free fluid

Acquisition — getting the view

Probe

curvilinear

Patient position

Supine; a full bladder improves the acoustic window.

Orientation convention

radiology

Probe placement

Just superior to the pubic symphysis

Marker direction

Indicator cephalad (sagittal), then to patient's right (transverse)

Probe placement (3D)

Structures in the imaging plane (near → far): Abdominal wall · Urinary bladder (acoustic window) · Rectovesical / rectouterine pouch (Pouch of Douglas) · Prostate or uterus

Step by step

1. Place the curvilinear probe just above the pubic symphysis, indicator cephalad, and angle into the pelvis.
   Why: The fluid-filled bladder is the window to the dependent pelvic spaces.
2. Scan through the bladder in sagittal, then rotate to transverse.
   Why: Sagittal is more sensitive for small fluid volumes; two planes avoid missing loculated fluid.
3. Look posterior/superior to the bladder for an anechoic stripe.
   Why: Free fluid gravitates to the most dependent pelvic recess.

Troubleshooting

Empty bladder, poor window.

If feasible, image before catheterization or instill saline; otherwise angle steeply and use whatever bladder volume is present.

Posterior enhancement mimicking pathology.

Recognize the bright signal deep to the bladder as enhancement artifact, not fluid.

Findings: normal

Normal pelvis

A fluid-filled bladder with no anechoic collection in the dependent pelvic space.

Original schematic, dedicated to the public domain (CC0).

Findings: pathology

Pelvic free fluid

An anechoic stripe posterior/superior to the bladder in the rectovesical or rectouterine pouch indicates free fluid (blood in trauma).

Signs: Anechoic fluid in the Pouch of Douglas; Often the most sensitive FAST view when the bladder is full

Original schematic, dedicated to the public domain (CC0).

Interpretation practice

Behind a full bladder you see an anechoic triangular collection in a trauma patient. What is it?

Original schematic, dedicated to the public domain (CC0).

Posterior enhancement artifactFree pelvic fluid (positive FAST)The prostateA bowel loop

Check your understanding

References

• ACEP SonoGuide — FAST · ACEP
• StatPearls — FAST · StatPearls

Related modules

• Cardiac — Parasternal Long Axis (PLAX)
• Cardiac — Subxiphoid (Subcostal) 4-Chamber
• Cardiac — Apical 4-Chamber (A4C)
• eFAST — Right Upper Quadrant (Morison's Pouch)
• Abdominal Aorta (AAA Screening)
• Lung — Anterior (BLUE Protocol)