Overview of Doppler Liver Assessment, Protocols, and Interpretation of Results
Doppler liver ultrasonography is a safe and non-invasive test used to assess the blood vessels in your liver. By studying the usual and unusual patterns of primary liver vessels, specific diseases can be identified because each disease could influence these patterns in a unique way. Understanding what an abnormal liver artery, vein, or portal vein (the main blood vessels in your liver) looks like on a Doppler ultrasound scan can help your doctor spot or confirm a liver disease.
Anatomy and Physiology of Doppler Liver Assessment, Protocols, and Interpretation of Results
The liver is a really important organ in your body that handles a lot of tasks related to how your body runs, especially around breaking down food and clearing out toxins. The blood supply to the liver comes from a variety of sources. About a quarter of the blood pumped by your heart gets sent to the liver.
The liver itself is divided up into some smaller sections. Each of these little chunks of the liver get their supply from three things – a vein called the portal vein, an artery called the hepatic artery, and a system called the biliary tract. This triple-set is fancy known as the “portal triad”.
The portal vein gives the liver most of its blood (about 75% of it). This blood doesn’t have much oxygen in it, but it is rich in nutrients from the food you eat. The portal vein is basically a collection point for blood coming from parts of the body that handle food, like the intestines and the stomach, as well as the pancreas, gallbladder, and spleen. Inside the liver, it splits into two branches – one that feeds the left side of the liver, and one that feeds the right.
The hepatic veins are a trio of veins that carry blood out of the liver to a large vein called the inferior vena cava (IVC). The hepatic veins get rid of the blood once the liver is done with it, sending it back to the heart via the IVC. Another of the ‘triple-set’, the hepatic artery, brings in the rest of the blood supply (about 25% of it) which is rich in oxygen.
We also mention ‘hepatopetal’ and ‘hepatofugal’ flow. Hepatopetal means blood flow that is going towards the liver and is usually used to describe the normal flow of blood in the portal vein. Hepatofugal is just the opposite; it refers to blood flow going away from the liver. This happens when the pressure in the portal vein is too high, a condition known as portal hypertension.
The pressure can be measured by inserting a thin tube, or catheter, into the vessels of the liver – but this is fairly invasive. There’s another way to monitor the health of the liver’s circulation using a non-invasive ultrasound scan, which can pick up any abnormal behavior in these blood vessels.
Why do People Need Doppler Liver Assessment, Protocols, and Interpretation of Results
If you’ve had a liver transplant operation, it’s essential for your doctor to keep a close eye on how your new liver is doing to make sure there are no issues such as blood clots or signs your body is rejecting the graft. This is typically done using a method called hepatic Doppler, which is an easy, non-invasive way to take a look inside your body and see how your liver is functioning.
The Doppler assessment can also be useful in diagnosing portal hypertension, a condition that can happen as a result of liver disease, where the pressure in the vein supplying blood to your liver gets too high. The scan can help visualize the blood flow and detect the presence of any abnormal blood vessels. Also, Doppler can be essential in diagnosing Budd-Chiari syndrome, a rare disorder that blocks the veins that carry blood from your liver back to your heart. Using Doppler, doctors can check for signs such as blockage or narrowing of these veins.
Another condition called chronic thrombosis, where blood clots form in the blood vessels leading to or from your liver, can also be detected using this imaging method. However, another procedure called angiography is considered the “gold standard” and is usually used to confirm the diagnosis. Doppler is also used to evaluate the performance of a stent placed in your liver blood vessels as part of a treatment called transjugular intrahepatic portosystemic shunt (TIPS), which is used for people with serious liver conditions.
Finally, Doppler scan can be helpful in assessing benign and malignant tumors in the liver by looking at the blood flow around the tumor. In heart failure, the blood flow back to the heart from the liver can be affected, and this can be detected using the Doppler technology as well.
When a Person Should Avoid Doppler Liver Assessment, Protocols, and Interpretation of Results
There are no reasons why you shouldn’t be able to undergo this procedure, as it is non-invasive, meaning it doesn’t involve any cuts or incisions in your body.
Equipment used for Doppler Liver Assessment, Protocols, and Interpretation of Results
Abdominal exams often use a tool called a Doppler ultrasound. There are two kinds: pulsed and color Doppler. The third type, called continuous Doppler, is mostly used for examining blood flow in heart valves and blood vessels. However, continuous Doppler isn’t appropriate for checking the portal vein, hepatic veins, and the inferior vena cava (a large vein that carries deoxygenated blood from the lower and middle body into the heart).
Who is needed to perform Doppler Liver Assessment, Protocols, and Interpretation of Results?
Doppler ultrasound, a procedure that uses sound waves to picture and examine parts of the body, is usually performed by a professional called a sonographer. This person could be a radiologist (a doctor specialized in using imaging technology for diagnosing and treating diseases) or a gastroenterologist (a doctor who focuses on digestive system and its disorders).
Preparing for Doppler Liver Assessment, Protocols, and Interpretation of Results
Before an abdominal examination, it’s often recommended that the patient doesn’t eat or drink anything for 4 to 6 hours. This is intended to reduce the amount of gas and liquids in the stomach, leading to a clearer view of the blood vessels during the exam. Before the examination begins, it’s also important to adjust the settings of the scanning device, including the signal strength (gain), the pitch of the sound waves (frequency), and the depth at which the ultrasound waves will penetrate into the body. These adjustments help to get the best possible image during the examination.
How is Doppler Liver Assessment, Protocols, and Interpretation of Results performed
Using a certain type of ultrasound known as a hepatic Doppler as part of the regular abdominal ultrasound can refine the operator’s skill in managing the ultrasound tool and help them see the liver vessels better. In spite of doing both examinations (the normal abdominal ultrasound and the hepatic Doppler), it won’t take much more time.
During the ultrasound, you might be asked to hold your breath – this can make the images clearer. On the screen, a red color usually represents the blood flow towards the ultrasound probe, while a blue color shows the blood flow away from it. Various vessels can be seen: the portal vein, which has a thick lining that appears as a highlighted line around the vessel, and the thinner walled hepatic veins, which are typically not visible.
The width of these vessels can vary: the portal vein can be between 7 and 15 millimeters wide, the hepatic veins between 5 and 7 millimeters, and the IVC – another type of blood vessel – between 13 and 22 millimeters. Normally, pressure makes the IVC wall collapse.
For the test, you will be positioned on your left side or lying flat on your back. The operator starts the scanning from the right subcostal area (beneath the ribcage) to visualize the portal vein. As they move the ultrasound probe towards the left and towards the midline, they can see the confluence (merging) of the splenic and superior mesenteric veins. When the probe is placed under the sternum (substernal position), the operator can see the IVC and aorta. By facing the probe backwards, the hepatic veins – which drain into the IVC – can be seen. The best way to see these veins is from an intercostal position on the right side (between the ribs) with the probe directed inward.
However, there are a few challenges with this procedure. If someone is obese, it might be hard to get a good image of the blood flow and velocity in the vessels. Eating might increase the pressure in the portal vein and widen it, and the presence of food and gas in the gut can obstruct the view of the vessels. So, it’s recommended to fast for 4 to 6 hours before the exam. Incorrectly adjusting the frequency and gain on the equipment could also produce a false diagnosis of changes in the blood flow of the liver or a clot in the portal vein. Lastly, if someone can’t hold their breath, it might make it difficult to visualize the vessels, but this can be overcome by synchronizing the movement of the ultrasound probe with the patient’s inhalation.
What Else Should I Know About Doppler Liver Assessment, Protocols, and Interpretation of Results?
Hepatic Doppler ultrasound is a test that allows doctors to look at your liver without needing to make any cuts or incisions. Together with an ultrasound of your abdomen, it can provide valuable information to your doctor. This procedure is advantageous as it is not only affordable but also comes without any risks or after-effects.
This type of ultrasound is most often used to check the flow of blood in diseases like:
* Cirrhosis, which can cause increased blood pressure in the vein that carries blood to the liver (portal hypertension).
* Blockages or clots in the portal or liver veins.
* Changes in blood flow around abnormal spots within the liver.
* Monitoring of the liver after specific procedures like TIPS (transjugular intrahepatic portosystemic shunt– a procedure that creates a new connection between two blood vessels in your liver) or a liver transplant.
* Measuring the openness, speed, and direction of blood flow in the hepatic vein and artery.
Based on the results of the Doppler ultrasound, your doctor may decide whether you need further, more invasive tests or treatments. These might include measuring the pressure in your liver veins (hepatic venous pressure gradient or HVPG), angiography (a test that uses X-rays to view your body’s blood vessels), or other procedures.
