Portal Vein Doppler Protocol

Summary

This educational video script covers the protocol for performing a portal vein Doppler ultrasound. It details the step-by-step process, starting with the aorta and moving through the IVC, hepatic veins, and portal vein. The script emphasizes proper technique, including grayscale and color Doppler imaging, spectral Doppler measurements, and understanding normal waveforms. It also touches on additional considerations like hepatic artery imaging and assessing the spleen, providing a comprehensive guide for ultrasound technicians.

Takeaways

• 🩺 The protocol for Doppler ultrasound of the portal vein varies by institution, but the process typically starts with imaging the aorta.
• 📏 Use grayscale and color Doppler to capture images, ensuring the angle is 60 degrees or less when measuring peak systolic velocity.
• 📉 After imaging the aorta, move to the inferior vena cava (IVC) using grayscale, color Doppler, and spectral Doppler for accurate measurements.
• 🫀 There are typically three hepatic veins (left, middle, and right), though variations can occur. Grayscale, color Doppler, and spectral Doppler should be used to analyze them.
• 💡 The normal waveform of hepatic veins includes three to four waves, consisting of an atrial kick, systole, and diastole.
• 🌡️ The main portal vein should be measured for its diameter (typically 1.3 cm), with color Doppler used to confirm hepatopetal flow (toward the liver).
• 🔄 Portal veins, including the right and left portal veins, should be assessed using grayscale, color Doppler, and spectral Doppler to check blood flow and velocity.
• 🩸 The hepatic artery typically shows low-resistance flow and supplies 25-30% of oxygenated blood to the liver, with the remainder from the portal vein.
• 🔍 Additional scout images of the liver are needed to check for fatty liver or hepatomegaly, as well as imaging of the spleen for splenomegaly.
• ✅ In cases of cirrhosis and ascites, the fluid can act as a helpful window for clearer imaging, despite potential complications in other patients.

Q & A

What is the primary focus of the video?

The video focuses on performing a Doppler ultrasound of the portal vein, demonstrating the protocol and the steps involved, including grayscale imaging, color Doppler, and spectral Doppler techniques.

Why does the speaker mention that protocols may vary slightly?

Protocols may vary slightly depending on the institution or place of work, so the speaker is showing how they personally conduct the exam while acknowledging that others may follow slightly different procedures.

What is the importance of the angle in spectral Doppler measurements?

In spectral Doppler measurements, maintaining an angle of 60 degrees or less is crucial to accurately measure the peak systolic velocity, ensuring the reliability of the readings.

What does the normal waveform of the hepatic veins look like?

The normal waveform of the hepatic veins consists of three to four waves, typically showing an atrial kick followed by systole and diastole.

What is the significance of the portal vein diameter measurement?

The diameter of the portal vein is important to measure as its upper normal limit is usually 13 millimeters or 1.3 centimeters. In some institutions, the upper limit may be set at 15 millimeters or 1.5 centimeters.

What does hepatopetal flow indicate in color Doppler imaging?

Hepatopetal flow indicates that blood is flowing towards the liver, which is shown as red on a correctly calibrated color Doppler scale. Hepatofugal flow, on the other hand, indicates flow away from the liver.

What role does the portal vein play in liver perfusion?

The portal vein supplies 70 to 75% of the oxygenated blood to the liver, while the hepatic artery provides the remaining blood flow.

Why might cirrhosis and ascites make imaging easier?

Cirrhosis and ascites can make imaging easier because the ascitic fluid acts as a window, allowing clearer views of the portal vein and surrounding structures during the Doppler exam.

What is a typical blood flow velocity for the main portal vein?

A typical blood flow velocity for the main portal vein is around 36 centimeters per second, which is considered normal.

How does the waveform of the splenic artery and vein appear during Doppler imaging?

The waveform of the splenic artery typically shows a low resistance pattern similar to the hepatic artery, while the splenic vein shows venous flow below the baseline.