You have now learned how to answer the focused questions in focused ultrasonography of the abdomen relevant in emergency medicine.
Sweep of Morison’s pouch
To evaluate the entire area at the sub diaphragmatic level, Morison’s pouch and anterior liver tip, sweep the transducer from the anterior to posterior position.
Here exemplified at the Morison’s pouch level.
Looking for free fluid in the longitudinal pelvic view
Obtain the longitudinal pelvic view.
Look for free fluid around the intestines.
In men: Look for free fluid between the bladder and the rectum.
In women: Look for free fluid between the bladder and the uterus and between the uterus and the rectum.
Tilt the transducer to view the lateral side of the bladder on both sides and look for free fluid.
Looking for free fluid is a dynamic process – not a question of getting THE ONE right image – tilt the transducer and do the sweep.
Image B: Pelvic view with intraperitoneal fluid
B: Bladder, F: Fluid, U: Uterus
Looking for free fluid in the transverse pelvic view
Obtain the transverse pelvic view.
Look for free fluid to the sides, below and posterior to the bladder.
Sweep the transducer from top to bottom to look for fluid at all levels.
Looking for free fluid is a dynamic process – not a question of getting THE ONE right image – move the transducer and do the sweep.
Image B: Pelvic view with peritoneal fluid
B: Bladder, F: Fluid, U: Uterus
Video showing free fluid in the perihepatic view
The video shows a recording of a perihepatic examination from a trauma patient with free fluid in the abdomen.
Free fluid is seen in the hepatorenal recess (Morison’s pouch).
A normal perihepatic view recording is shown for comparison.
Looking for free fluid in the perisplenic view
Obtain the perisplenic view.
Look for free fluid between the diaphragm and the spleen (subdiaphragmatic) – remember the sweep at this level.
Look for free fluid between the spleen and and the kidney (splenorenal recess) – remember the sweep at this level as well.
Intraperitoneal fluid appears as a black anechoic (black) stripe.
Looking for free fluid is a dynamic process – not a question of getting THE ONE right image – move the transducer and do the sweep.
In the top image free fluid (marked with white arrows) is seen between the diaphragm and the spleen and around the spleen.
Video showing free fluid in the perisplenic view
The video shows a recording of a perisplenic examination from a trauma patient with a ruptured spleen and free fluid in the abdomen.
Free fluid is seen between the diaphragm and the spleen.
A normal perisplenic recording is shown for comparison.
Identification of free fluid
Free fluid is seen as anechoic (black) areas in locations where fluid is not normally found.
Free fluid often collects in specific locations in the abdomen – these include:
Perihepatic:
Measuring the abdominal aorta
Always find the largest diameter.
When measuring the abdominal aortic, the largest diameter should be found.
An intramural thrombus is often seen with abdominal aortic aneurisms.
Thus, it is essential to measure the entire aorta – from outer edge to outer edge.
Tips
When a mural thrombus is present, the lumen of the aorta is narrowed (and is most often irregular and not circular) – remember to measure the entire aorta not just the lumen.
The correct measurement from outer edge to outer edge is displayed at the bottom.
Notice the intramural thrombus and the irregular lumen.
Is an abdominal aortic aneurism present?
A maximum abdominal aortic diameter of <3.5 cm makes rupture very unlikely.
In a patient with the relevant symptoms and an abdominal aortic diameter >3.5 cm, a ruptured abdominal aortic aneurism is possible.
Most ruptures (90%) do however occur at maximum abdominal aortic diameters >5 cm.
Other findings supporting a clinical suspicion of ruptured abdominal aneurism:
– Free intraperitoneal fluid on focused ultrasonography of the abdomen (this is covered later in this lesson).
Rupture into the peritoneum is only seen in 20% of patients with rupture – rupture into the retroperitoneum is much more frequent (>75% of cases), but is difficult to asses using ultrasonography.