Abdomen

With abdominal ultrasound, POCUS can provide an imense amount of information about your patient. In addition to palpation or checking for CVA tenderness, you can look for hydronephrosis or bladder distention. Look at the IVC and aorta as well as evaluate for bowel obstruction.

Kidneys & Bladder

Kidney & Bladder ultrasound provide a ton of information when evaluating a patient with a genitourinary condition. Whether it is acute kidney injury, pyelonephritis, hydronephritis, within 2-3 minutes you can have an answer.

The left kidney and the right kidney sit differently in the body. The right kidney is more caudal (toward the feet) and lateral, while the left kidney is more rostral and posterior. Also there is lung, liver, spleen and diaphragm in close proximity.

Right Kidney

Patient & probe positioning

Patient is supine. You can use the abdominal or phased array probe. With probe marker facing head, place probe along mid-axillary line approximately 2 inches below the nipple line. In this image, the liver is not shown.

The ultrasound beam will make a longitudinal cut down the center of the kidney. If you rotate this image 90 degrees clockwise, 

Image Interpretation

With the probe marker facing the head, the left kidney can be visualized in the longitudinal plane as seen below. You can see the superior and inferior pole of the kidneys. Fan and slide in every direction and try to center the probe with the renal sinus in view. This is where you can evaluate for hydronephrosis.

Left Kidney

The left kidney is more posterior and rostral. It is also partially covered by the spleen. In this window you should be able to see the spleen, kidney and base of the lung tissue.

Patient & probe positioning

Patient is supine. Probe marker to the head. In contrast to the right kidney, the left kidney is more posterior. this will require you to place the probe almost on the bed and angle towards the right flank. If able, it is helpful to have the patient roll towards their right lateral decubitus position.  

Image Interpretation

On the left side of the body, the acoustic window is through the spleen. As on the right side, the probe marker is facing the head, so the marker in the image is superior. You can see the spleen with similar appearance to the liver. Just below is the right kidney. It can be difficult to see the entire right kidney in one field of view, as the inferior pole is often obstructed by the rib shadow. To combat this you can slide the probe inferiorly, as well as ask patient to take a deep breath in and out.

Bladder

Ultrasounding the bladder is simple and incredibly useful when evaluating a patient with acute kidney injury or concern for urinary retention. While many nurses can do bladder scans at the bedside, this involves blindly placing the bladder scanner on the lower abdomen and waiting for the machine to calculate the volume. This is not useful if the patient has ascites, or if there is a mass in the bladder. 

Transverse View

Patient & probe positioning

Patient is supine.

 

Probe marker to the patient's left to look for the bladder in the transverse plane. Starting just superior to the pubic symphysis scan up towards the head

to look for a round, fluid filled

bladder.

Longitudinal View

Patient & probe positioning

Once you have found the transverse view and the bladder is centered on the screen, rotate the probe clockwise 90 degrees until the probe marker is facing the patient's head.

This will give you a longitudinal view. As you can see the bladder has a more ovoid shape in the anterior to posterior view.

IVC & Aorta

Inferior Vena Cava

The inferior vena cava (IVC) transports unoxygenated blood from the lower body back to the right atrium of the heart. It is a great vessel visible in the abdomen that can provide information regarding volume status and blood flow. If you recall from anatomy, it runs in parallel with the aorta and therefore can be easily mistaken for the aorta. The IVC runs more lateral, goes through the liver, and empties into the right atrium. All these characteristics are useful to confirm you are looking at the IVC and not the aorta.

Patient & probe positioning

Patient is supine. The probe marker is facing towards the head. There are two excellent ways to find the IVC.

 

First, in the abdominal preset, start by placing the probe just below the xiphoid process and angle the probe slightly towards the patient's right side. 

Image Interpretation

In the abdominal preset, the probe marker will be on the left (based on radiology convention). Since we know the IVC travels through the liver and empties into the right atrium, we can use these facts to confirm the IVC. The "sliver in the liver" as it is known, the IVC has thin walls compared to the Aorta and should be seen right next to the liver parenchyma. If you track the IVC superiorly, you should see the movement of the right atrium as the IVC empties into it. 

You can also ask the patient the sniffle, or take a quick inhale, and you should note some respiratory variation if you are in fact on the IVC (unless the patient is very volume overloaded and the IVC has no respiratory variation).

From Cardiac Preset

The second way to find the IVC is to start with the subcostal view of the heart, then turn the probe 90 degrees counter-clockwise. This will move the probe from the patient's right side to their head. Since you will be in the cardiac preset, the image above will appear flipped.

Aorta

Transverse View

Patient & probe positioning

Patient is supine. The probe marker is facing toward patient's right. The Aorta lies parallel and more medial to the IVC. The Aorta also has thicker walls, does not traverse through the liver. Place the probe just under the xyphoid process. and look for two large vessels sitting atop a round, shadowed structure that is the vertebral body. 

Longitudinal View

Patient & probe positioning

Patient is supine. Turn the probe 90 degrees

so the probe marker is pointing to the head.

 

Starting from the IVC you would fan towards the midline looking for the Aorta.

Below is the longitudinal view of the Aorta. The left side of the screen is toward the patient's head. At the top of the image, you can see a portion of the liver. Note that the Aorta is large, with thick walls, and is seperated from the liver parenchyma.

Distinguishing IVC vs Aorta

It can be difficult to differentiate the IVC and the Aorta.  Here are some tips to do so:

  • The IVC is the "sliver in the liver," and transverses through the liver. Look for liver parenchyma around the structure

  • The IVC walls are thinner than the Aorta walls

  • The IVC drains into the right atrium - track the vessel up towards the heart and see if it dumps into the right atrium 

IVC

Aorta

POCUS Med Ed

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