Abdominal POCUS

Abominable Abdominal Ultrasound

POCUS for the Abdomen involves 5 basics locations to image when evaluating the organs within the peritoneum. For POCUS views evaluating vascular structures within the abdomen, such as the IVC, please refer to our page dedicated to Vascular Ultrasound.

The 5 views used for abdominal ultrasound are the Right Hemidiaphragm, the Left Hemidiaphragm, the Suprapubic Area, and both the Right and Left Lower Quadrants (primarily used to assess for tappable pockets of ascites).

Remember, when placing your probe on the patient, you want to keep your marker aimed at either the patient’s head, or the right side of their body, depending on what type of cross-section you’re trying to view.

Right Hemidiaphragm

Seem familiar? Yes! The technique and localization is also used in the Pulmonary POCUS exam. However, for the abdominal exam we are of course, more focused on the abdominal structures.

Clinical questions:
Is there fluid in Morrison’s pouch?
Does the Liver have signs of fatty infiltration or Cirrhosis?
Is the Gallbladder visualized? Is it empty?
Is there Hydronephrosis?
For other clinical questions related to the Lungs, click *here*

Probe Positioning
Use the phase array or curvilinear probe.
Start at the mix-axillary line, looking for the hyperechoic diaphragm.
Aim the marker towards the patient’s head.
Slide inferiorly from diaphragm to identify abdominal structures.

Normal Anatomy

You can see the liver abutting the right kidney, without any hypoechoic area between them, which would be consistent with free fluid in Morrison’s pouch. You can also see on the right, in the center of the oval-shaped kidney, the hyperechoic renal calyces. There is no hydronephrosis seen here, demonstrated by the lack of dilation or hypoechoic fluid in these calyces. Normal kidneys are roughly 10-14cm long-axis, and 3-5cm short-axis.

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By fanning through the liver, you can also find the gallbladder (if present). Normally this should be full of anechoic fluid, without stones or sludge visualized. Size is typically 7-10cm in the long-axis, and 3-5cm short-axis. Post-prandially, it may be contracted with very little fluid inside.

Left Hemidiaphragm

Just like the Right Hemidiaphragm, the Left from an abdominal perspective is the same technically as it is for the Pulmonary POCUS exam. The only difference again is that now we focus on the abdominal structures.

Clinical questions (similar to R Hemidiaphragm):
Is there fluid in the Splenorenal Recess?
Is there Splenomegaly?
Is there Hydronephrosis?
For other clinical questions related to the Lungs, click *here*

Probe Positioning
Use the phase array or curvilinear probe.
Start at the mix-axillary line, looking for the hyperechoic diaphragm.
Aim the marker towards the patient’s head.
Slide inferiorly from diaphragm to identify abdominal structures.

Normal Anatomy

From an abdominal perspective this is still similar to the Right Hemidiaphragm, you expect to see no free fluid in any of the space between the Spleen and Left Kidney. You can also assess for Splenomegaly if the patient has a difficult exam, and you are unable to appreciate it. The typical upper limit of normal Spleen size, from an anterior-posterior dimension, is roughly 12-13cm. The Left Kidney is typically a bit larger than the right, but still roughly 10-14cm in the long axis, and 3-5cm in the short axis!

Lower Quadrants and Paracentesis

The lower quadrants (corresponding to views 3 & 4) are typically used as sites to evaluate for tappable pockets of ascites. This is due to the fact that many organs and other structures are not in these areas, they are dependent, and although bowel is present, it is easily distinguished from free fluid.

Clinical questions:
Is there free fluid in the abdomen, which can be targeted for paracentesis?
How much fluid is there, and what other structures are nearby?

Probe Positioning
Use the phase array or curvilinear probe.
Start at the mix-clavicular line, a few centimeters superior to the ASIS (anterior superior iliac spine). Aim the marker towards the patient’s head.
Explore the area with this probe orientation, keeping mindful of the inferior epigastric vessels, visualization of bowel, and other structures.

It is very important to remember your anatomy for procedures, and paracentesis is no exception. The main structures you want to avoid when performing this are the inferior epigastric vessels (red above), the bowel, and the bladder. The inferior epigastrics are roughly 3-5cm lateral to midline.

While the bowel and bladder can be visualized fairly easily on ultrasound, the inferior epigastrics are small, and harder to see. Without color doppler, you may not be able to see them at all. To avoid them, either operate significantly laterally to this area, or identify the vessels, mark their location, and proceed in another spot.

This is a view in the left lower quadrant of free-flowing ascites. The fluid (black, anechoic) is very distinct from the bowel (white, higher echogenicity). As you can see though, fanning the probe sometimes brings loops of bowel into view, so it’s important to check your target area fully in three dimensions through rotating and fanning the probe.

While we won’t discuss the actual paracentesis procedure here, there is a brief walkthrough in your UCSD IM Handbook (BlueBook), and a quick 2-minute video online *here*. The only modification to this video, is to make sure you do the ‘Z’ technique when inserting your needle.

Pull traction on the skin when inserting the needle, so that the tract is less likely to maintain patency after the procedure, when the skin and subcutaneous tissues relax. This reduces likelihood of leakage afterwards.

Suprapubic Area

The area just above the pubic symphysis (corresponding to view 5) is another area key to abdominal ultrasound. This location allows us to view the bladder, and is another area to assess for free fluid.

Clinical questions:
Is there fluid in the bladder, is it decompressed?
Is a placed Foley visualized in the bladder correctly?
Is there free fluid in the pelvis?

Probe Positioning
Use the phase array or curvilinear probe.
Find the patient’s pubic symphysis with palpation. Place the probe a few centimeters just above this.
You have 2 options for the probe orientation. If you aim the marker towards the patient’s head, you’ll get a longitudinal view of the bladder (cranio-caudal). If you instead aim the marker towards the patient’s right side, you’ll get a transverse view of the bladder (which appears more symmetric).

Normal Anatomy

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Multiple views of the bladder. Longitudial = marker to head. Transverse = marker to patient’s right side. In the transverse view sometimes ureteral jets can be visualized. There should normally be no free fluid around the bladder. Once evacuated, the bladder will shrink in size and it’s walls will look thickened. However, wall thickness <4mm is still considered normal.

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If a patient has a Foley, and either has no urine output or it suddenly stops, you can use ultrasound to check the position of the balloon in the bladder. If working correctly, the balloon should be visualized in the bladder itself, with little urine accompanying it (as it would drain through the Foley). Lots of fluid with a corrected positioned Foley could mean clogging, kinking, or clamping of the tube. Failure to see the Foley balloon in the bladder could mean a badly positioned Foley.

That’s it for now! Normal ultrasound findings in the abdomen, pertinent to the internist! Great work, and check out our other systems!