Abdominal Ultrasound Scanning Techniques and Scan Windows

Subxiphoid Approach: Start with the probe subxiphoid to image the left lobe of the liver.
Sweeping Technique:
- Sweep through the entire left lobe, starting laterally and moving medially.
- First image: Lateral left lobe.
- Second image: More medial, including the aorta.
- Third image: Even more medial, showing the IVC and caudate lobe. Use color Doppler on the IVC to ensure complete filling.

Oblique Approach: Slightly oblique the probe following the rib, pushing in and angling up under the rib.
Sequential Imaging: Start at the dome of the right lobe and take sequential pictures moving down.
- First image: Parenchyma (above hepatic and portal veins).
- Second image: Hepatic veins coming into view. Note that hepatic vein walls are less echogenic than portal veins and drain directly into the IVC.
- Third image: Portal veins. This is the level to assess for ductal dilatation.
Sweeping Technique: Sweep all the way out of the liver.

Subxiphoid Approach: Start subxiphoid again, grabbing the top of the probe.
Sweeping Technique:
- Sweep up through the left lobe until the heart is visualized, then come down.
- First image: Top of the left lobe with the parenchyma.
- Second image: Hepatic veins.
- Third image: Portal veins. Sweep completely through the left lobe.

Angling Technique: From the left lobe position, angle slightly over to visualize the right lobe.
Sweeping Technique:
- Angle up through the dome of the right lobe and come down.
- First image: Parenchyma.
- Second image: Hepatic veins.
- Third image: Portal veins. Sweep all the way out of the liver.

Oblique Probe Position: Angle the probe to fit between the rib spaces.
Sweeping Technique:
- Start at the top of the liver and sweep through the top rib space.
- Move down a rib space and sweep again.
- Images to capture: Dome of the right lobe, hepatic veins, main portal vein (which splits into right anterior and right posterior).
Lower Rib Space: At the last rib space, visualize the upper pole of the kidney against the liver surface to compare echogenicity and assess for liver enlargement.
Coronal View: Turn coronal to evaluate liver enlargement. The right kidney and liver tip should align.
Sweeping Technique: Sweep through the liver completely.

Subcostal Window
- Probe Position: The probe might be slightly oblique to the patient's body.
- Technique: Open up the gallbladder completely.
- Views: Obtain both sagittal and transverse images by rotating the probe 90 degrees.
Intercostal Window
- Use Case: Especially useful for larger or gassy patients.
- Probe Position: Angle up towards the anterior abdomen.
- Technique: Open up the gallbladder to get the widest portion.
- Views: Obtain sagittal and transverse views by rotating the probe 90 degrees.
Decubitus Position
- Purpose: To check for stones in the neck of the gallbladder.
- Patient Position: Have the patient turn onto their left side (left decubitus).
- Technique:
  - Sweep through the gallbladder in sagittal and transverse planes.
  - Stones should drop into the fundus.
  - Good for opening up the neck of the gallbladder.
- Additional Views: The porta hepatis and CBD can also be seen in this position.
  - Technique for CBD Visualization: Elongate the main portal vein and look for tubular structures next to it.
  - Differentiation between Hepatic Artery and CBD: Use color Doppler; the hepatic artery will light up, while the CBD will not.

Subxiphoid Approach:
- Probe Position: Come up high and angle down, using the left lobe of the liver as a window.
- Angulation: Oblique the transducer slightly counterclockwise for a sagittal image.
Landmarks
- The splenic vein is a key landmark indicating proximity to the pancreas.
Sweeping Technique:
- Sweep through the entire pancreas to avoid missing pathology.
- Include the head, uncinate process, and tail (though the tail may be difficult to visualize).
Key Structures to Identify:
- Pancreatic Duct: Runs through the body of the pancreas. A normal measurement is $2$ mm or less.
- Head and Uncinate Process: Angle towards the patient's right side.
- Gastroduodenal Artery (GDA): Located in the anterior head of the pancreas.
- Common Bile Duct (CBD): Located in the posterior head of the pancreas. Can be elongated in a sagittal plane.
Transverse Imaging:
- Probe Position: Sagittal plane to the patient's body.
- Landmarks:
  - Aorta posterior to the pancreas indicates the pancreatic body.
  - IVC indicates the pancreatic head.

Patient Position: Scan from the patient's left side.
Probe Position: Scan in the rib space, angling the probe slightly obliquely.
Sweeping Technique:
- Sweep through the entire rib space.
Measurements:
- Measure the length of the spleen at its maximal dimension.
Transverse Imaging:
- Angle to avoid rib shadows and sweep through as much of the spleen as possible.

Patient Position: Have the patient turn into a right decubitus position (facing you).
Probe Position: Position the probe below the rib spaces with an oblique angle, keeping in mind that the upper pole of the kidney is more posterior, and the lower pole is more anterior.
Sweeping Technique:
- Sweep through the kidney in its entirety, lateral to medial.
Transverse Imaging:
- Rotate the probe 90 degrees from the sagittal image.
- Sweep from the upper pole to the lower pole.
- Utilize intercostal spaces if needed to get a clear image.

Window: Use the intercostal window on the right side.
Advantage: Good for pulse wave Doppler measurements because the main portal vein is usually at a $60$ degree angle.
Technique:
- Elongate the main portal vein, identified by its echogenic walls.
- The hepatic artery and CBD are located next to the portal vein.
- Adjust the probe to elongate the CBD.
Differentiation: Use color Doppler to differentiate between the hepatic artery (which will fill with color) and the CBD (which will not).