The adrenal glands, those tiny but very important glands, can be tricky to find and evaluate during an ultrasound exam.
However, having a system and knowing where to look can make your job much easier.
There are many reasons you want to visualize the adrenal glands on every scan, including checking for neoplasia and other masses and looking for any changes that could be associated with Cushing’s or Addison’s disease.
Here are some tips to help save you time and allow for a clearer view of these small glands…
Have a repeatable system
When you perform an abdominal ultrasound, it’s important to have a systematic approach to look at everything. And that includes keeping small structures like the adrenal glands and abdominal lymph nodes on your list, so they don’t get overlooked.
Do your scan in the same order every time—whether that’s cranial to caudal, clockwise, or some other system that works for you—and it’s much less likely that anything will be missed or any abnormalities overlooked.
Adrenal gland landmarks
The right and left adrenal glands are respectively located near the right and left kidneys. However, the kidneys are relatively large, whereas the adrenal glands are small. So, the kidneys can overshadow these small glands.
The kidneys are the first things you’ll locate because they’ll point you in the right general direction. After that…
Vascular landmarks are most helpful when it comes to locating the adrenals.
Specifically, the aorta, caudal vena cava, renal vessels, and mesenteric artery are what you’re going to be looking for.
Color Doppler can help you visualize the vessels.
Also note, if the patient allows you to apply gradual pressure, it helps to minimize the distance between your probe and the glands as much as possible.
Finding the LEFT adrenal gland
The left adrenal gland is located ventrolateral to the aorta and cranial to the left renal artery.
Start by scanning the left dorsal mid-abdomen and visualizing the aorta in a long view.
Find the spot where the left renal artery branches off from the aorta, and just cranial to that you’ll see the left adrenal gland.
Finding the RIGHT adrenal gland
The right adrenal gland is dorsolateral to the caudal vena cava, and just cranial to the cranial mesenteric artery. It’s also more cranial and dorsal compared to the left adrenal gland.
Scan the right cranial abdomen, with the caudal vena cava in long view.
Apply some pressure with the transducer which will cause compression of the caudal vena cava and help you visualize the right adrenal gland. The gland is right next to the vessel, slightly oblique to it.
Are the adrenal glands normal?
Evaluate the qualitative properties of the gland, and then measure the glands from their cranial pole to caudal pole. Also, measure the thickness of each pole.
Normal adrenal glands are hypoechoic to surrounding fat, and have a characteristic “peanut” shape (although the right adrenal may have more of an “arrowhead” appearance). Typically, adrenals are 4-7mm thick in dogs and 3-4mm thick in cats.
Abnormalities may include…
Evidence of hyperadrenocorticism.
If pituitary-dependent, the adrenal glands may be normal in appearance, or they may be “plump” (symmetrically enlarged). An ultrasound exam alone is not enough to diagnose Cushing’s, but may be helpful in context with additional diagnostic tests.
If adrenal-tumor related, you may be able to visualize a mass.
Evidence of Addison’s disease or hypoadrenocorticism.
You may notice smaller or thinner adrenal glands. As with Cushing’s, you’ll want to use this information in conjunction with clinical symptoms and other diagnostic tests.
Adrenal masses.
Many are incidental findings only.
Pheochromocytoma is a possibility.
Malignancies are possible and may lead to invasion of adjacent tissues, especially blood vessels.
You’ll use your clinical judgment and the patient’s clinical signs to help you determine whether more diagnostics are needed, or to start by monitoring the growth with repeat ultrasound exams over time.
Age-related changes.
Nodular changes and remodeling may be normal in old adrenal glands. Practice will help to develop clinical judgment of what’s normal and what’s not.
The ability to find the adrenal glands quickly will come with experience, and knowing the right tips and techniques will make it easier to get the information you need even when you’re first learning.
Written by: Dr. Tammy Powell, DVM
