Overview of Transabdominal Ultrasound
Ultrasound is a technology that has been used in healthcare for around half a century. It began as very large machines, similar to the size of refrigerators, but over time they have become much smaller and more advanced. There are now even ultrasound devices that can be used with smartphones. Ultrasound can produce images of various parts of the body, but this explanation will focus specifically on a type of ultrasound called ‘transabdominal ultrasound’.
Transabdominal ultrasound was first used in the 1960s for pregnancy checks. Now, it’s used to look at various organs in the abdomen, which is the section of the body between your chest and hips. Basically, if an ultrasound is used to look at any part of your body through your abdominal wall, it’s a transabdominal ultrasound. It can check the health of organs like the liver, gallbladder, kidneys, pancreas, intestine, appendix, bladder, uterus, and spleen. It can also look at blood vessels like the aorta and the inferior vena cava (a large vein that carries deoxygenated blood from the lower half of the body back to the heart).
In obstetrics and gynecology (the healthcare specialty that deals with women’s health and pregnancy), this type of ultrasound is often used to safely and non-invasively check for any issues in the pelvic area, or to confirm a pregnancy. In emergency situations, it’s often used to check for certain conditions quickly, such as an ectopic pregnancy (a pregnancy that’s outside the uterus), gallstones, internal bleeding, aneurysms (a bulge in a blood vessel), and hydronephrosis (a condition where one or both kidneys swell because urine can’t drain out properly).
In an emergency setting, the ultrasound exam is usually carried out by an emergency doctor and can be done quickly at the bedside to answer urgent medical questions and help direct immediate care. While ultrasounds performed by sonographers (medical experts trained specifically in carrying out ultrasound exams) can be more detailed, the main goal of an emergency ultrasound exam is to answer immediate questions that can help guide a patient’s care.
Anatomy and Physiology of Transabdominal Ultrasound
In the field of medical imaging, much like in the broader study of the body’s structure, we use certain landmarks and standard methods that were initially established by areas such as pregnancy care and radiology. Take the gallbladder for example, it’s found underneath the liver, but its exact location can differ greatly from person to person.
To correctly identify the gallbladder, we use a reference point known as the sonographic cystic pedicle (SCP). Initially, this was referred to as the main lobar fissure (MLF), because we believed that it matched up to the main passageway in the liver. But, upon further research using cadavers, this was shown to be a structure outside the liver, following along the edge of the main lobar fissure. So, the name was changed to the SCP, inclusive of the cystic duct (the tube carrying bile from the gallbladder), the surrounding fat and the blood vessels.
Each organ we’re interested in has its own unique structure and standard method for ultrasound scanning. These are vital in obtaining the specific images or measurements we need to identify any disease or disorder.
Why do People Need Transabdominal Ultrasound
If you have belly pain, your doctors will run a series of tests to figure out what’s causing it. Here’s what they might look for:
In the upper right part of your belly, they’ll check for fluids building up, gallstones, blockages or stones in the bile duct, liver abscess or unusual masses, and excessive fluid in the kidneys, which can cause swelling and kidney damage.
In the lower right part of your belly, they’ll look for signs of appendicitis, which is a swollen and inflamed appendix. They’ll also look for abscesses in the psoas muscle (a deep muscle in your back), and a condition called intussusception, which happens when part of the intestine folds into itself, like a telescope.
In the upper left part of your belly, they’ll look for fluids building up, damaged spleen (an organ near the stomach), stomach illnesses, and excessive fluid in the kidneys.
In the lower left part of your belly, they might look for an inflammation of small pouches in the walls of the colon called diverticulitis, and blockages in the small intestine.
In the center of your belly, right below your ribs, they might check for abnormal growths in the pancreas or an enlarged or swollen aorta, the main blood vessel that delivers blood from your heart to the rest of your body.
If you have pain in the lower part of your belly, they’ll check for fluids building up, an inability to empty the bladder, pregnancy, tubal pregnancy (a pregnancy where the embryo is outside the uterus), or an unusual mass in your pelvis.
If you’ve been in a major accident – been hit hard in the belly or been stabbed or shot – they’ll look for fluids building up in your belly.
If you are experiencing vaginal bleeding, they will evaluate for possible pregnancy, ectopic pregnancy (a pregnancy where the fetus is growing outside the womb), abnormalities in the uterus, or signs of miscarriage.
If you suffer from low blood pressure, they will look for sources of infection, measure the size of the inferior vena cava (a large vein that carries blood from your lower body back to your heart) as it can give clues about your blood volume status, or look for enlarged aorta.
If you have blood in your urine, they’ll check for masses in your urinary system, kidney stones, or swelling in your kidneys.
When a Person Should Avoid Transabdominal Ultrasound
There aren’t any strict rules saying when a transabdominal ultrasound – a scan of the stomach area – can’t be done. However, doctors will avoid doing a scan over a cut or a surgical wound to keep it clean and prevent any possible infections. Also, two specific types of ultrasound, Color and Pulsed Doppler, should not be used on an unborn baby because there’s a chance, even if it’s just a theory, that the radiation could harm the baby.
Equipment used for Transabdominal Ultrasound
If your doctor needs to examine your tummy (abdomen), they’ll use a special tool called an ultrasound with a low-frequency probe. This tool will most likely have a large curved surface for better imaging. There are many different types of probes, but the most commonly used ones are curvilinear or phased array probes.
The probe needs to be cleaned before and after use to prevent the spread of infections. The type of cleaning equipment and disinfectant wipes used can vary from hospital to hospital. Usually, the department that deals with infectious diseases in the hospital decides what type to use.
Who is needed to perform Transabdominal Ultrasound?
A healthcare professional who has received special training can carry out an ultrasound scan of your abdomen. This professional, known as a Registered Diagnostic Medical Sonographer (RDMS), has different training and qualifications than your regular doctor who could also perform a basic ultrasound at your bedside. For instance, emergency room doctors must carry out and understand at least 25 to 50 heart ultrasound scans before they finish their training.
Preparing for Transabdominal Ultrasound
Before going into a patient’s room, it’s important to make sure that the ultrasound machine and its probe are clean. The right probes need to be attached to the machine. Ideally, the patient should be lying flat (supine position) on a stretcher with their stomach area visible. To keep the patient comfortable and maintain their privacy, towels can be placed around the edges of their gown and underclothing. This also helps in keeping areas that aren’t being scanned clean from the ultrasound gel.
If you’re right-handed, you should place the ultrasound machine on the patient’s right side near the head of the bed. Make sure it’s plugged in (if needed) and switched on. If possible, dim the lights. This helps to see the ultrasound images better. If the ultrasound is for the gallbladder, it’s better if the patient hasn’t eaten for a while. This helps the gallbladder swell up, making it easier to see. But, if you’re looking at the uterus, the patient should have a full bladder. This is because the liquid in the bladder creates a ‘window’ that allows the ultrasound waves to reach deeper structures, providing a clearer image.
How is Transabdominal Ultrasound performed
An ultrasound scan is usually performed using a device called a convex probe. This device produces low-frequency sound waves that let us see inside your body, like a camera that peers through the skin. This type of probe is particularly helpful for exploring the abdomen. But don’t worry, if we don’t have this probe, another kind called a phased array probe can be used.
The details we need to look at can vary depending on what part of your body we’re scanning, so we have to adjust the ultrasound machine settings accordingly. These settings help us get the best quality images.
To guide the probe, we aim it either towards your head or towards your right, depending on what we’re looking at. When scanning certain areas, For instance, if we need to look at your gallbladder, we will typically place the probe in line with your body, just below your ribs on your right side. After that, we move the probe side to side along your ribs. We might ask you to take a deep breath and hold it; this moves your diaphragm (the muscle used in breathing) so your liver and gallbladder shift position and it makes it easier for us see these organs.
Another way to get a good view of your gallbladder is by placing the probe on your side, below your armpit, and angling it towards your head. We then move it back and forth. We use these techniques to check for things like gallstones, thickened walls in your gallbladder, pain on touch (known as Murphy’s sign), and any fluid around the gallbladder.
All these techniques and settings are pretty standard for an ultrasound scan. But remember, the approach can change according to which part of your body we need to investigate, and what exactly it is we’re looking for.
Possible Complications of Transabdominal Ultrasound
Ultrasound scans that look into your abdomen, similar to other kinds of ultrasound scans, are generally safe and don’t pose much risk. However, some discomfort might be felt when pressure is applied during the scan.
What Else Should I Know About Transabdominal Ultrasound?
Transabdominal ultrasound is an affordable, quick, and safe method often used by doctors to diagnose various health issues. This technique can efficiently confirm or rule out certain conditions like cholecystitis (inflammation of the gallbladder), and in many instances, it can make other imaging tests unnecessary. This can speed up the diagnosis and treatment process while also lowering your exposure to harmful radiation.
