Medical Dictionary Definitions A-Z List
Medical Dictionary Definitions A - Z - «H»:
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Hydrocele
Hydrocele: Accumulation of fluid in the coat around the testis.
Small hydroceles tend to disappear by a year of age while larger hydroceles may persist
and warrant surgery. ...
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Hydrocephalus
Hydrocephalus: Hydrocephalus is an abnormal buildup
of cerebrospinal fluid (CSF) in the ventricles of the brain. The
fluid is often under increased pressure and can compress and
damage the brain.
Hydrocephalus can arise before birth or any time afterward. It may
be due to many causes including a...
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Hydrocephalus ex-vacuo
Hydrocephalus ex-vacuo: What is termed "hydrocephalus ex-vacuo" occurs when there is damage to the brain caused by stroke or injury, and there may be an actual shrinkage of brain substance. Although there is more CSF than usual, the CSF
pressure itself is normal in hydrocephalus ex-vacuo.
Hydroceph...
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Hydrocephalus, acquired
Hydrocephalus, acquired: Hydrocephalus due to a postnatal cause, something that happened sometime after birth....
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Hydrocephalus, communicating
Hydrocephalus, communicating: Hydrocephalus in which there is no obstruction to the flow of the cerebrospinal fluid (CSF). Specifically, there is no obstruction within the ventricular system of the brain or where the CSF passes into the spinal canal. By process of elimination, the hydrocephalus is d...
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Hydrocephalus, congenital
Hydrocephalus, congenital: Hydrocephalus present at birth....
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Hydrocephalus, Macewen sign of
Hydrocephalus, Macewen sign of: A sign to detect hydrocephalus (and brain abscess). Percussion
(tapping) on the skull at a particular spot (near the
junction of the frontal, temporal and parietal bones)
yields an unusually resonant sound in the presence of
hydrocephalus or a brain abscess.
...
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Hydrocephalus, normal pressure
Hydrocephalus, normal pressure: See: Normal pressure hydrocephalus....
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Hydrocephaly
Hydrocephaly: Also known as hydrocephalus, this is an
abnormal buildup
of cerebrospinal fluid (CSF) in the ventricles of the brain. The
fluid is often under increased pressure and can compress and
damage the brain.
Hydrocephalus can arise before birth or any time afterward. It may
be due to man...
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Hydrogen
Hydrogen: The most plentiful element in the universe and one present in all organic compounds. Hydrogen is a gas with an atomic number of 1 and the symbol H.
Two isotopes of hydrogen -- deuterium and tritium -- have been used as tracers in metabolic studies. Tritium is a long-lived weak emitter of ...
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Hydrogen cyanide
Hydrogen cyanide: See: Cyanide....
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Hydronephrosis
Hydronephrosis: Distention of the kidney with urine. Due to
obstruction of urine outflow (for example, by a stone blocking the ureter, the tube going
from the kidney to the bladder). ...
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Hydrophobia
Hydrophobia: 1. Literally, an irrational fear of water, to drink or to swim in. Someone who is scared of the water is hydrophobic.
2. A term once commonly used for rabies because in the later stages of that disease, the animal (or person) has difficulty swallowing and so fears a drink of water.
Fro...
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Hydrops fetalis
Hydrops fetalis: Gross edema (swelling), usually
with anemia, of the fetus. It can be due to Rh blood group
incompatibility, in which antibodies crossing the placenta from the
mother destroy the red blood cells of the fetus. It can also be
caused by a lethal form of the genetic disorder thalas...
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Hydrostatic weighing
Hydrostatic weighing: See: Underwater weighing....
