Ultrasound Glossary

The parotid gland is the largest salivary gland, located in front of the ear, and can be evaluated by ultrasound for masses, stones, and inflammation.

Patent ductus arteriosus is a congenital heart condition in which a fetal blood vessel fails to close after birth, diagnosed by echocardiography.

The maximum blood flow velocity measured during systole using spectral Doppler — a key parameter for grading vascular stenosis.

Peak Systolic Velocity (PSV): The highest velocity recorded during systole on a spectral Doppler waveform, used to quantify arterial stenosis severity. Peak systolic velocity (PSV) is the maximum blood flow velocity measured during cardiac systole on spectral Doppler waveform analysis. It is the primary metric used to grade carotid artery stenosis (ICA PSV >125 cm/s…

Pelvic inflammatory disease (PID) is an infection of the female reproductive organs, evaluated by ultrasound for complications like abscess.

Excess fluid in the pericardial sac surrounding the heart, detected on echocardiography.

Pericarditis is inflammation of the pericardium (the sac around the heart), which may produce an effusion detectable on echocardiography.

The pericardium is the protective sac surrounding the heart, visible on echocardiography as a bright, thin line.

Peripheral artery disease is narrowing of the arteries supplying the limbs, assessed by Doppler ultrasound for stenosis and blood flow abnormalities.

Periportal fibrosis is scarring around the portal tracts of the liver, which appears as increased echogenicity along the portal vein branches on ultrasound.

The peritoneum is the membrane lining the abdominal cavity, assessed by ultrasound for fluid, thickening, or masses.

A phased array is a type of ultrasound transducer with a small footprint that produces a fan-shaped image, commonly used in cardiac imaging.

A small-footprint transducer that steers the beam electronically, producing a sector image — the standard probe for echocardiography.

Piezoelectric refers to the property of certain materials to convert electrical energy into sound waves and vice versa, forming the basis of ultrasound transducers.

The property of certain crystals to generate an electric charge when mechanically stressed, and to deform when an electric current is applied — the physical basis of ultrasound transducers.

The placenta is a temporary organ that connects the fetus to the uterine wall, routinely assessed on prenatal ultrasound for location, maturity, and abnormalities.

Placenta accreta is a serious pregnancy condition in which the placenta grows too deeply into the uterine wall, detectable on prenatal ultrasound.

Abnormal placental attachment to the uterine wall — accreta, increta, or percreta — evaluated on ultrasound in high-risk pregnancies.

A condition in which the placenta partially or completely covers the internal cervical os, identified on ultrasound.

Placental abruption is premature separation of the placenta from the uterine wall, which may show as a blood collection on ultrasound.

Placental grading is an ultrasound classification system that describes the maturity of the placenta based on its appearance and calcification.

Plantar fasciitis is inflammation of the thick tissue on the bottom of the foot, diagnosed and evaluated by ultrasound.

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.