Ultrasound Glossary

Focal thickening of the arterial wall due to atherosclerosis, detected on carotid or peripheral vascular ultrasound.

Fluid in the pleural space between the lung and chest wall, appearing as an anechoic or echogenic collection on thoracic ultrasound.

A pneumothorax is a collection of air between the lung and chest wall, which can be rapidly detected by point-of-care ultrasound.

Ultrasound performed and interpreted at the bedside by the treating clinician to answer a focused clinical question in real time.

Polycystic kidney disease is a genetic condition that causes numerous cysts to develop in the kidneys, clearly visible on ultrasound.

Polycystic ovarian syndrome (PCOS) is a hormonal condition that may cause enlarged ovaries with many small follicles, identified on ultrasound.

A hormonal disorder characterized on ultrasound by enlarged ovaries containing 20 or more follicles per ovary.

Polyhydramnios is an excess of amniotic fluid during pregnancy, measured by ultrasound using the amniotic fluid index.

A polyp is a growth projecting from a mucous membrane surface, identifiable on ultrasound in locations like the gallbladder and endometrium.

The popliteal artery is the main artery behind the knee, evaluated by ultrasound for aneurysm, stenosis, and entrapment.

A popliteal cyst (Baker cyst) is a fluid-filled swelling behind the knee, well visualized by ultrasound.

The popliteal vein is the main vein behind the knee, routinely evaluated during venous duplex ultrasound for blood clots.

Portal hypertension is abnormally high blood pressure in the portal venous system, detectable by Doppler ultrasound through characteristic flow changes.

The portal vein is the major vessel carrying nutrient-rich blood from the digestive organs to the liver, routinely assessed on abdominal ultrasound.

Portal venous gas is the presence of air in the portal venous system, appearing as bright, moving echoes on ultrasound, often indicating a serious condition.

Post-void residual is the amount of urine remaining in the bladder after urination, measured by ultrasound to assess bladder function.

Increased brightness seen deep to a fluid-filled structure on ultrasound, caused by less attenuation through fluid than surrounding tissue.

Posterior acoustic shadowing is a dark area behind a dense structure on ultrasound, commonly seen behind gallstones and calcifications.

A bright area that appears on the ultrasound image behind a fluid-filled structure because sound waves travel through fluid more easily than through tissue. This helps identify cysts and fluid collections.

A Doppler mode that displays the amplitude of the Doppler signal rather than velocity, making it more sensitive to slow flow.

The prostate is a male reproductive gland located below the bladder, commonly evaluated by transabdominal and transrectal ultrasound.

A contained rupture of an artery forming a pulsatile hematoma connected to the vessel lumen, showing characteristic to-and-fro Doppler flow.

A pseudocyst is a fluid collection enclosed by a wall of fibrous tissue rather than a true epithelial lining, most commonly associated with the pancreas.

A psoas abscess is an infection within the psoas muscle, appearing as a fluid collection on ultrasound, often requiring image-guided drainage.

The pulsatility index is a Doppler measurement that reflects the resistance to blood flow in a vessel, calculated from systolic and diastolic velocities.

The number of ultrasound pulses transmitted per second; affects maximum imaging depth and the Nyquist limit in Doppler.

Pulse wave Doppler is an ultrasound technique that measures blood flow velocity at a specific depth using a sample volume gate.

A Doppler mode that samples blood flow velocity at a specific depth by sending and receiving short ultrasound pulses.

Pyelonephritis is a kidney infection that may show as enlarged, swollen kidneys with increased blood flow on ultrasound.

Pyloric stenosis is a thickening of the pylorus muscle in infants that causes projectile vomiting, diagnosed by ultrasound.

The quadriceps tendon connects the quadriceps muscles to the kneecap and is evaluated by ultrasound for tears and tendinopathy.

The radial artery is a major artery of the forearm, palpable at the wrist, and evaluated by ultrasound for patency and suitability for vascular access.

Registered Diagnostic Cardiac Sonographer — an ARDMS credential for cardiac sonographers (echocardiographers).

Registered Diagnostic Medical Sonographer — a credential awarded by ARDMS to sonographers who pass specialty examinations.

Ultrasound images that update continuously as you move the transducer, allowing you to see live movement of organs and structures. This is what makes ultrasound useful for watching how things move.

A refractive artifact occurs when the ultrasound beam bends at a tissue boundary, causing structures to appear duplicated or displaced.

The renal artery supplies blood to the kidney and is evaluated by Doppler ultrasound for stenosis and flow abnormalities.

Narrowing of the renal artery, evaluated with Doppler ultrasound by measuring peak systolic velocity and acceleration time in the renal vessels.

A kidney stone appearing as a hyperechoic focus with posterior acoustic shadowing on renal ultrasound.

Renal cell carcinoma is the most common kidney cancer in adults, often detected incidentally as a solid mass on ultrasound.

A renal cyst is a fluid-filled sac in the kidney, one of the most common incidental findings on abdominal ultrasound.

The renal parenchyma is the functional tissue of the kidney, assessed on ultrasound for thickness, echogenicity, and disease.

The renal pelvis is the funnel-shaped collecting area at the center of the kidney, evaluated by ultrasound for dilation indicating obstruction.

A renal transplant is a surgically placed donor kidney, monitored closely with Doppler ultrasound for vascular and parenchymal complications.

The renal vein drains blood from the kidney and is assessed by ultrasound for thrombosis and flow abnormalities.

A Doppler-derived ratio reflecting downstream vascular resistance, calculated as (PSV − EDV) / PSV.

The ability of an ultrasound system to distinguish two closely spaced structures as separate — includes axial, lateral, and temporal resolution.

Retained products of conception refers to tissue remaining in the uterus after pregnancy, diagnosed by ultrasound showing a thickened, echogenic endometrium.

Repeated parallel lines on ultrasound caused by sound bouncing back and forth between two highly reflective surfaces.

Rhabdomyolysis is the breakdown of muscle tissue that can cause kidney damage, with ultrasound used to evaluate both the affected muscles and kidneys.