Key Points

• FAST is POCUS evaluation for trauma patients, whereas FAFF is performed in medical or non-trauma patients, but it shares the objective of evaluation for the presence of free fluid in critically ill patients.

• Renal and Bladder evaluation is a part of POCUS solely for evaluation of obstruction of the urinary system, either by looking for the presence of hydronephrosis, stones or bladder distention.

The Focused Assessment with Sonography for Trauma (FAST) has been an important point-of-care tool for rapidly detecting the presence of haemoperitoneum in blunt-trauma patients. This is done by assessing four different views: perihepatic, perisplenic, pelvic and pericardial (subcostal). Pleural fluid can be assessed rapidly in the perihepatic and the perisplenic views by scanning upward. In trauma, every free fluid is interpreted to be blood given the clinical setting but in non-trauma patients, this becomes an assessment for free-fluid, not for blood, becoming a Focused Assessment of Free Fluid (FAFF). There is no difference in technique between the FAST and the FAFF, the only difference is the group of patients where it is performed.

Indications for performing a FAFF:

• 1. Hemodynamic instability

  2. Peritonitis

  3. Concern for thoracoabdominal free fluid

  4. Sepsis of unknown source

Technique

• Probe: low-frequency - phased-array or curvilinear

• Position: supine

• Some Tips: lateral decubitus or Trendelenburg positions enhance evaluations of upper abdominal spaces; decrease far field-gain to correct for posterior enhancement.

• There are 4 standard windows that need to be examined: Subxiphoid (Sx), Right Upper Quadrant (RUQ), Left Upper Quadrant (LUQ) and Suprapubic (SP).

Right Upper Quadrant - Normal (left) and Abnormal (Right)

Left Upper Quadrant - Normal (left) and Abnormal (Right)

Some abnormal subxiphoid images. Note the pericardial effusions on both images with increased echogenicity likely representing blood and clot formation (right image)

Pathology to look for:

The main indication of the renal ultrasound during POCUS is to identify signs of obstruction of the urinary system, it is NOT intended to evaluate for medical renal disease.

1. Hydronephrosis: its presence is important because it could indicate an obstruction in the urinary system. The visualized image of hydronephrosis varies depending on its severity: mild, minor calyces only dilated (hypoechoic line with bumps); moderate, major and minor calyces are dilated; and severe, parenchymal effacement, displacing the renal cortex.

2. Stones: they are very difficult to visualize. They are echogenic and may or may not shadow, depending on their size.

3. Bladder: its evaluation is focused on the presence of prostate enlargement, masses or stones that may be causing an obstruction. If the bladder is full, the balloon of the Foley must be seen inside the bladder.

Image below, ureterovesical junction nephrolithiasis.