RBC fragmentation may be caused by RBCs striking
against abnormal surfaces (aortic stenosis;
atherosclerosis) or artificial surfaces (prosthetic
heart valves; arterial grafts).
Schistocytes secondary to mechanical trauma.
Microangiopathic hemolytic anemia is caused by
RBCs torn apart on fibrin strands strung across small
vessels or on damaged endothelial surfaces of small vessels
(akin to a road under construction causing damage to your
car). This accompanies disseminated intravascular
coagulation (DIC), malignant hypertension, hemolytic uremic
syndrome (HUS), thrombotic thrombocytopenia purpura (TTP),
pre-eclampsia, and some vascular neoplasms.
The numerous RBC fragments are a result of TTP.
Thrombotic thrombocytopenia purpura (TTP) is
caused by fibrin and platelet deposition in small vessels
fragmenting RBCs as they flow past.
Patients with TTP are usually adults with neurologic and
mild renal abnormalities. There may be fever.
Schistocytes and severe thrombocytopenia are classic. PT
and PTT studies are normal
Hemolytic uremic syndrome (HUS) is similar to TTP,
but is more common in children and involves primarily the
kidney. Neurologic abnormalities are absent.
Fibrin and platelet deposition are primarily seen in the
microvasculature of the kidney.
Schistocytes and severe thrombocytopenia are classic.
Again PT and PTT studies are normal.
The prognosis of HUS is better than TTP.
HUS is associated with infection, especially E. coli
which produces verocytotoxin.
Fibrin-platelet thrombi in glomerular and
interstitial vessels. Masson- trichrome staining
Slide thanks to Dr. Kline Bolton, UVA.
"Joggers" or "march" hemoglobinuria results from
trauma to red cells occuring in the feet, usually secondary
to jogging, running, or marching. No RBC changes are seen on
Beginning with the next card we will look at several
"miscellaneous" difficult to classify causes of hemolysis.
Under no circumstances should you share any material downloaded from Student Source course websites with individuals outside the class. Under no circumstances should you repost material downloaded from Student Source to other websites. Some of our pages are restricted to UVa School of Medicine users and require an Oasis account for access.