Medical Term Glossary
Plain-language explanations of the medical terms that appear on CT, MRI and X-ray reports — what each one means, when it matters, and what to ask your doctor.
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Adrenal gland
A small, triangular hormone-producing organ sitting on top of each kidney. It releases stress hormones such as cortisol and adrenaline, along with chemicals that help the body manage salt, water, and blood pressure. Small spots found here by chance on a scan are extremely common and the vast majority turn out to be harmless.
Also: adrenal, adrenals, gland above the kidney
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Ascites
Extra fluid that has collected inside the belly, in the space surrounding the bowel and organs. A small amount can be normal in some situations, but larger collections almost always point to a problem with the liver, heart, kidneys, or the lining of the abdomen itself. The cause matters far more than the fluid.
Also: abdominal effusion, abdominal fluid, fluid build-up in the belly
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Biliary dilatation
A widening of the small tubes that carry bile from the liver to the bowel. It usually means something downstream is slowing or blocking the flow — a stone, a narrowing, an inflamed pancreas, or, less often, a mass. The location and degree of the widening tell the medical team where to look next.
Also: bile duct dilation, biliary dilation, biliary tree dilation
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urgent
Bowel obstruction
A blockage that stops food, fluid, and gas from moving through the intestines as they normally would. The gut above the block stretches and fills with fluid and air, which is what shows up on a scan. It is almost always a problem that needs prompt medical attention, sometimes urgent surgery.
Also: blocked bowel, blocked intestine, gut blockage
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D
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normal
Diverticulosis
Small pouches that bulge outward from the wall of the large intestine, most often in the lower-left part. They are extremely common after middle age, usually cause no symptoms, and are typically found by chance on a scan or colonoscopy. They only become a concern if one of the pouches becomes inflamed or bleeds.
Also: bowel pouches, colon pouches, colonic diverticulosis
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Duodenum
The first, C-shaped part of the small intestine, just past the stomach. It receives food from the stomach and mixes it with juices from the pancreas and gallbladder to start digestion. Its name comes from a word for twelve fingers, its rough length. Reports often name it to locate a finding in the upper belly.
Also: C-loop of small bowel, duodenal loop, duodenal segment
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Gallbladder
A small pear-shaped sac tucked under the liver that stores and concentrates bile, the greenish fluid the liver makes to help break down fats. It releases that bile into the small intestine after a fatty meal. People can live normally without it if it has to be removed, which is one of the most common abdominal surgeries.
Also: bile sac, bile storage pouch, biliary sac
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Gallstones
Small, hardened deposits that form inside the gallbladder — the little pear-shaped sac that stores bile beneath the liver. Many people have them without ever knowing, and a quiet stone often needs no treatment. They only become a medical problem when one moves, blocks a duct, or sets off inflammation.
Also: biliary stones, cholecystolithiasis, cholelithiasis
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Gastric
Anything to do with the stomach. It is simply the medical adjective for 'relating to the stomach', from the Greek word for stomach. On its own it carries no good or bad meaning — it just tells you which organ a finding involves. The noun attached to it, like wall or folds, is what actually matters.
Also: of the stomach, pertaining to the stomach, relating to the stomach
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normal
Hepatic cyst
A small, fluid-filled pocket sitting inside the liver. The vast majority are harmless, present from birth, and stay quiet for life. Many people have one without ever knowing — they tend to be found by chance on a scan ordered for something completely unrelated, and they rarely cause symptoms.
Also: benign liver cyst, biliary cyst, cyst in the liver
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Hepatic flexure
The sharp bend in the large bowel in the upper right belly, just under the liver, where the colon turns from heading up to running across. Hepatic means relating to the liver, its near neighbour. Reports often name it to locate a finding at this corner of the colon.
Also: colon bend near liver, hepatic colonic flexure, right colic flexure
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Hepatic steatosis
Extra fat stored inside the cells of the liver. It is very common, often has no symptoms, and is usually picked up by chance on imaging done for other reasons. The amount of fat and the reason behind it — diet, weight, alcohol, or certain medications — guide how much it matters.
Also: MASLD, NAFLD, fat in the liver
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Hydronephrosis
A swelling of one or both kidneys caused by urine that cannot drain away properly. The backed-up fluid stretches the kidney's collecting system, which shows up clearly on imaging. The cause matters more than the swelling itself — kidney stones, narrowed tubes, and an enlarged prostate are typical reasons.
Also: dilated renal pelvis, kidney backup, kidney swelling
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urgent
Pneumoperitoneum (free air)
Air sitting inside the belly cavity where there should be none. Normally air stays inside the stomach and intestines; finding it loose in the surrounding space usually means a hole somewhere in the gut wall has let it escape. It is almost always treated urgently because the underlying leak needs prompt attention.
Also: free abdominal air, free air, free air in the belly
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Psoas muscle
A long, deep muscle on each side of the lower spine that runs down into the top of the thigh. It is a main hip flexor, lifting your knee toward your chest when you walk or climb stairs. Reports often name it as a landmark in the lower belly or to confirm it looks symmetric and normal.
Also: hip flexor, iliopsoas, psoas
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Rectum
The final straight section of the large bowel, sitting low in the pelvis just before the anus. It holds stool until you are ready to go, then signals the urge to pass it. Reports often name it to locate a finding in the lowest part of the bowel or to confirm it looks normal.
Also: back passage, final bowel section, lower bowel end
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normal
Renal cyst
A small, fluid-filled sac inside the kidney. Most are harmless, develop quietly with age, and are picked up by chance on a scan done for something else. The radiologist's job is to tell the simple, benign kind apart from the rare more complex variety that needs a closer look — and most of the time it is the simple kind.
Also: benign kidney cyst, cyst on the kidney, fluid-filled kidney lesion
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Sigmoid colon
The S-shaped final loop of the large bowel in the lower left side of the belly, just before the rectum. It stores formed stool until it is ready to pass. Its name comes from the Greek letter sigma because of its curve. Reports often name it to locate a finding in this part of the colon.
Also: S-shaped colon, pelvic colon, sigmoid
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Splenomegaly
An enlarged spleen — the small, fist-sized organ tucked under the ribs on the left side. It is a sign, not a diagnosis: the spleen grows in response to many different things, from a recent viral infection to long-standing liver disease or a blood disorder. The reason behind the enlargement is what matters.
Also: big spleen, enlarged spleen, spleen enlargement
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