Ultrasound Glossary

A condition in which the fetus grows significantly larger than average, increasing the risk of delivery complications.

The earliest visible form of the developing embryo on ultrasound, appearing as a small, thickened area adjacent to the yolk sac.

The part of the fetus that overlies the maternal cervix, most commonly cephalic (head down) — assessed on obstetric ultrasound.

A common, benign tumor of the uterine muscle, also called a leiomyoma, that is one of the most frequent findings in pelvic ultrasound.

A benign tumor made of fibrous connective tissue that can occur in various locations throughout the body.

A non-inflammatory arterial disease that causes abnormal growth of cells in the artery wall, leading to narrowing, and detectable with Doppler ultrasound.

The formation of excess scar tissue in an organ, which increases its stiffness and can be assessed with ultrasound elastography.

The first 12 weeks of pregnancy, during which early ultrasound confirms viability, dates the pregnancy, and screens for certain abnormalities.

A combination of ultrasound measurements and blood tests performed between 11 and 14 weeks to assess the risk of chromosomal abnormalities.

An abnormal connection between two body structures that are not normally connected, which can sometimes be detected or evaluated with ultrasound.

Any abnormal accumulation of fluid within the body, appearing as a dark area on ultrasound that may represent blood, pus, bile, or other fluids.

The depth at which the ultrasound beam is narrowest and lateral resolution is best.

A rapid, bedside ultrasound examination performed on trauma patients to detect free fluid in the abdomen, chest, and around the heart.

A small, fluid-filled sac in the ovary that contains a developing egg, visible on ultrasound as a round, dark structure.

A reproductive hormone that stimulates the growth of ovarian follicles, whose effects are monitored with ultrasound during fertility treatment.

A common, benign ovarian cyst that forms when a follicle fails to release its egg and continues to grow, usually resolving on its own.

A soft spot on an infant’s skull where the bones have not yet fused, used as an acoustic window for brain ultrasound.

The large opening at the base of the skull through which the spinal cord connects to the brain.

A normal opening between the left and right atria of the fetal heart that allows blood to bypass the lungs before birth and usually closes after delivery.

Any object that is not naturally present in the body, such as a splinter, piece of glass, or retained surgical material, which can be located with ultrasound.

A standard ultrasound image of the fetal heart showing all four chambers, used to screen for congenital heart defects during prenatal ultrasound.

The number of complete ultrasound images produced per second, which affects how smoothly moving structures appear on the display.

Fluid that moves freely within a body cavity, such as the abdomen or pelvis, which appears as dark areas between organs on ultrasound.

The number of sound wave cycles per second, measured in megahertz (MHz); higher frequency gives better resolution but less penetration.

A type of aneurysm in which the blood vessel bulges symmetrically outward in all directions, creating a spindle-shaped dilation.

Real-time co-registration of ultrasound with a pre-acquired CT or MRI dataset, allowing simultaneous side-by-side or overlaid display for lesion targeting.

The overall amplification of returning ultrasound signals, controlling the overall brightness of the image.

A small, pear-shaped organ beneath the liver that stores and concentrates bile, one of the most commonly examined structures in abdominal ultrasound.

A relatively rare but aggressive cancer of the gallbladder that may appear on ultrasound as a mass replacing the gallbladder or as irregular wall thickening.

Abnormal distension of the gallbladder caused by prolonged obstruction of the cystic duct, resulting in a markedly enlarged, fluid-filled gallbladder.

A growth projecting from the inner wall of the gallbladder that does not move with position changes and does not cast a shadow, unlike gallstones.

A thick, muddy mixture of bile components that settles in the gallbladder, appearing as low-level echoes on ultrasound.

A sonographic finding of increased gallbladder wall thickness (>3 mm), associated with cholecystitis but also many systemic conditions.

A calcified or cholesterol concretion within the gallbladder, appearing as a hyperechoic focus with posterior acoustic shadowing on ultrasound.

A fluid-filled sac that commonly forms near joints or tendons, especially the wrist, and is easily evaluated and treated with ultrasound guidance.

Cancer of the stomach that can sometimes be detected on abdominal ultrasound as wall thickening or a mass, though endoscopy is the primary diagnostic tool.

A blockage at the exit of the stomach that prevents food from passing into the small intestine, evaluated with ultrasound in infants for pyloric stenosis.

An open sore in the lining of the stomach, which is primarily diagnosed by endoscopy but may sometimes be suggested by findings on abdominal ultrasound.

The large muscle forming the visible bulk of the calf, commonly evaluated with musculoskeletal ultrasound for tears and other injuries.

The backward flow of stomach contents into the esophagus, which can be observed in real time during abdominal ultrasound.

Bleeding from anywhere in the digestive tract, which may prompt ultrasound evaluation of the liver, spleen, and abdominal organs for underlying causes.

The tubular system of organs extending from the mouth to the anus that digests food, which can be evaluated with ultrasound in specific clinical situations.

A birth defect in which the fetal abdominal wall fails to close completely, allowing intestines to protrude outside the body, detectable on prenatal ultrasound.

The age of a pregnancy measured in weeks from the first day of the last menstrual period.

The first ultrasound-visible sign of pregnancy, appearing as a small, round, fluid-filled structure in the uterus at about 4 to 5 weeks of gestation.

A group of rare conditions in which abnormal tissue grows in the uterus after fertilization, including molar pregnancy, with a characteristic ultrasound appearance.

An enlargement of the thyroid gland visible as a swelling in the neck, which is evaluated with ultrasound to determine its cause and characteristics.

A painful form of arthritis caused by uric acid crystal deposits in joints, which produces distinctive findings on musculoskeletal ultrasound.

An ultrasound technique in which the sonographer applies gradually increasing pressure with the transducer to push gas-filled bowel out of the way and better visualize structures like the appendix.

A small area of inflammation caused by the body’s immune response, which can sometimes be detected as a focal lesion on ultrasound.