Re: Pathology 16
TheOne - 10-15-06 15:53

Explanation: The correct answer is C. Simply put, schistocytes are fragments of red blood cells of different shapes and sizes. They are derived from mechanical damage to circulating erythrocytes, which results in a form of anemia referred to as microangiopathic hemolytic anemia. There are two main causes of this form of anemia: disseminated intravascular coagulation (DIC) and prosthetic valves. DIC is due to widespread and uncontrolled activation of the coagulation cascade, leading to formation of microthrombi throughout the circulation. Erythrocytes become fragmented as they squeeze through narrowed arterioles and capillaries. Acute blood loss (choice A) is followed by reduced circulating blood volume. In the acute phase, a sample of blood may appear entirely normal. Only following hemodilution does a normocytic normochromic anemia becomes apparent. Chronic autoimmune gastritis (choice B) is associated with autoantibodies that block the binding of intrinsic factor to vitamin B12, leading to deficient B12 absorption and megaloblastic anemia. Abnormally large (macrocytic) red blood cells and hypersegmented neutrophils are the diagnostic features of this form of anemia. Immune-mediated hemolysis (choice D) is due to agglutinins that can be classified as warm (IgG type) or cold (IgM type) according to whether the Coombs test is positive at 37 C or 0-4 C. Agglutinins binding red blood cells may cause acute or chronic anemia by intravascular or extravascular coagulation. Unconjugated hyperbilirubinemia is usually present, and the anemia is normochromic and normocytic. Schistocytes are not observed. Any form of iron-deficiency anemia (choice E), whether due to decreased absorption or to chronic blood loss, is characterized by small (microcytic) and pale (hypochromic) erythrocytes. Thalassemia (choice F) is a genetic condition caused by mutations of the genes coding for the globin chains. Patients homozygous for mutations in the ?-globin genes are affected by a severe form of chronic anemia, referred to as thalassemia major, because of severely reduced or absent ?-globin synthesis. Heterozygous individuals have the ?-thalassemia trait and manifest a clinical picture known as thalassemia minor. They are usually asymptomatic, but the peripheral blood smear shows microcytic erythrocytes, similar to those observed in iron-deficiency anemia.

Re: Pathology 16
galaxy - 05-27-10 19:12

A hospital laboratory is sent blood samples from six patients with six different diagnoses. A blood smear from one sample shows a reduced number of normochromic, normocytic erythrocytes, with numerous schistocytes. This blood sample has been probably drawn from the patient with?

D. immune-mediated hemolysis

Re: Pathology 16
babbu5508 - 06-21-10 14:56

C. disseminated intravascular coagulation...schistocytes are RBC of different sizes and shapes seen in mechanical damage to the erythrocytes

Re: Pathology 16
bingousmle - 06-30-10 22:25

CCCC.DIC is due to widespread and uncontrolled activation of the coagulation cascade, leading to formation of microthrombi throughout the circulation.

Re: Pathology 16
leenamathew1 - 07-04-10 07:07

c

Re: Pathology 16
dinmenace - 06-30-11 23:45

c