Rh blood group


Also found in: Dictionary, Thesaurus, Encyclopedia.

Rh blood group

See Rh factor.

Rh fac·tor

(fak'tŏr)
A protein substance present in the red blood cells of most people (85%), capable of inducing intense antigenic reactions. A person who has the protein substance is calledRh-positive and a person who does not have the protein substance is called Rh-negative. Under ordinary circumstances, the presence or lack of the Rh factor has no bearing on life or health, except when the positive and negative forms commingle. The Rh factor was first identified in the blood of the rhesus monkey in 1940.
Synonym(s): Rh blood group, Rhesus factor.

Rh blood group

A group of antigens on the surface of red blood cells present to a variable degree in human populations. When the Rh factor (an antigen often called D) is present, an individual's blood type is designated Rh+ (Rh positive); when the Rh antigen is absent, the blood type is Rh- (Rh negative). If an individual with Rh blood receives a transfusion of Rh+ blood, anti-Rh antibodies form. Subsequent transfusions of Rh+ blood may result in serious transfusion reactions (agglutination and hemolysis of red blood cells). A pregnant woman who is Rh may become sensitized by entry of red blood cells from an Rh+ fetus into the maternal circulation after abortion, ectopic pregnancy, or delivery. In subsequent pregnancies, if the fetus is Rh+, Rh antibodies produced in maternal blood may cross the placenta and destroy fetal cells, causing erythroblastosis fetalis.
See: Rh immune globulin
See also: blood group
References in periodicals archive ?
Review: The Rh blood group system: an historical calendar.
The Rh blood group system in review: A new face for the next decade.
The number of alleles in the ABO and Rh blood group systems, and the low antigenicity of all but the D antigen in the Rh system, make it relatively easy to supply blood in virtually unlimited quantities to patients requiring hemotherapy.