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Medical Author:

Benjamin Wedro, MD, FACEP, FAAEM

Benjamin Wedro, MD, FACEP, FAAEM

Dr. Ben Wedro practices emergency medicine at Gundersen Clinic, a regional trauma center in La Crosse, Wisconsin. His background includes undergraduate and medical studies at the University of Alberta, a Family Practice internship at Queen's University in Kingston, Ontario and residency training in Emergency Medicine at the University of Oklahoma Health Sciences Center.

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Medical Editor:

William C. Shiel Jr., MD, FACP, FACR

William C. Shiel Jr., MD, FACP, FACR

Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.

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In this Article

• Introduction
• What is an ultrasound?
• What is ultrasonography?
• For what purposes are ultrasounds used?
• Diagnostic uses
• Screening uses
• Therapeutic uses
• What are the risks of ultrasound?
• How do patients prepare for an ultrasound?
• How are the results of ultrasound interpreted and communicated to the physician?
• Patient Comments: Ultrasound - Diagnosis
• Find a local Doctor in your town
• Ultrasound Index

For what purposes are ultrasounds used?

Ultrasound is not limited to diagnosis, but can also be used in screening for disease and to aid in treatment of diseases or conditions.

Diagnostic uses

Obstetrics

Ultrasound routinely for assessing the progression of pregnancy. Pelvic ultrasounds can be obtained trans-abdominally where the probe is placed on the abdominal wall, or trans-vaginally, where the probe is placed in the vagina. For example ultrasound in obstetrics is used to diagnose growths or tumors of the ovary, uterus, Fallopian tubes.

Cardiology

Echocardiography

Echocardiography (echo=sound + cardio=heart + graphy=study) evaluates the heart, the heart's valve function, and blood flow through them. It also evaluates the heart wall motion and the amount of blood the heart pumps with each stroke.

Echocardiography can be performed in two ways:

• trans-thoracic: the probe is place on chest wall to obtain images, and
  
  
• trans-esophageal: where the probe is placed through the mouth into the esophagus.

Anatomically, the esophagus sits near the heart and allows clearer images. However, this approach is a little more invasive.

Different groups of illnesses can be assessed by echocardiography:

• Valves in the heart keep blood flowing in one direction when the heart pumps. For example, when the heart beats, blood is pumped from the left ventricle through the aortic valve into the aorta and the rest of the body. The aortic valve prevents blood from back-flowing into the heart as it fills for the next beat. Echocardiography can determine if the valve is narrow or leaking (regurgitating, insufficient). By following how the patient fares clinically, repeated echocardiograms can help determine whether valve replacement or repair is warranted. The same principles apply to the mitral valve which keeps blood flowing from the left atrium to the left ventricle.
  
  
• The heart muscle pumps blood to the body. If the heart weakens, the amount of blood it pumps with each beat can decrease, leading to congestive heart failure. The echocardiogram can measure the efficiency of the heart beat and how much blood it pumps; which assists in determining whether medications are needed. It also is used to monitor how well medications are working.
  
  
• Echocardiography can visualize the heart chambers to detect blood clots in conditions such as atrial fibrillation (an irregular heart rhythm). In other situations, the test can help diagnose endocarditis (an infection of the heart valves) by visualizing "vegetations" (an infected mass) on the valves themselves.
  
  
• Echocardiography also can detect abnormal fluid collections (pericardial effusions) in the pericardium.
  
  
• Echocardiograms are used to diagnose and monitor pulmonary artery hypertension.

Blood vessels

Ultrasound can detect blood clots in veins (superficial or deep venous thrombosis) or artery blockage (stenosis) and dilatation (aneurysms). Some examples of ultrasound testing include:

• Carotid ultrasound is performed in patients with transient ischemic attacks (TIAs) or strokes to determine whether the major arteries in the neck are blocked causing the decreased blood supply to the brain.
  
  
• The aorta is the large blood vessel leaving the heart that supplies blood to the rest of the body. The walls of the aorta are under significant pressure from the force of the heartbeat and over time, may weaken and widen. This is called an aneurysm, and it can be detected in the abdomen by ultrasound (abdominal aortic aneurysm). For those patients with small aneurysm, observation may be recommended and the aneurysm size followed over time by repeated tests.
  
  
• Veins can also be evaluated by ultrasound and it is a common test to assess whether swelling in a leg is due to a blood clot, deep vein thrombosis (DVT) or another cause.

Abdominal structures

Aside from its use in obstetrics, ultrasound can evaluate most of the solid structures in the abdominal cavity. This includes the liver, gallbladder, pancreas, kidneys, bladder, prostate, testicles, uterus, and ovaries.

• Ultrasound is the preferred to test to screen for gallstones or an infected gallbladder. The ultrasound can reveal the stones as well as signs of infection, including thickening of the gallbladder wall and fluid surrounding the gallbladder. The ultrasound may find blockage in the bile ducts.
  
  
• For those patients where the radiation of a CT scan (computerized tomography) is a potential risk (pregnant patients or children), ultrasound may be used to look for diseases like appendicitis or kidney stones.
  
  
• Ultrasound is the test of choice to diagnose testicular torsion.
  
  
• Pelvic ultrasound is used in gynecology to help assess non-pregnancy related issues like lower abdominal pain, ovarian cysts, uterine fibroids, uterine growths, and endometriosis.

The neck

The thyroid gland can be imaged using ultrasound looking for nodules, growths, or tumors.

Knee joint

Ultrasound can be used to detect bulging of fluid from a swollen knee joint into the back of the knee, called a Baker's cyst.