Hemorrhage: Causes and Effects

Hemorrhage is the escape of blood from a blood vessel or the heart. In rupture of the wall of a vessel, hemostatic mechanisms start to control the hemorrhage. A small hemorrhage may have no bad effect but an acute massive hemorrhage threatens the life.

Chronic blood loss produces an iron-deficiency anemia. Hemorrhage may be local or systematic. Systematic hemorrhages occur in hemorhhagic (bleeding) disorders.   

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Causes of Acute Hemorrhage

  • Trauma, eg. Penetrating wounds involving large vessels, bleeding during labour;
  • Erosions of blood vessels in chronic peptic ulcer, typhoid ulcer, tuberculosis;
  • Varicose veins, eg. oesophageal varices;
  • Hypertensions-hemorrhage at sites of arterial weakness;
  • Blood vessel diseases, eg. Atheroma, aneurysm;
  • Invasion of cancers in blood vessels;
  • Hemorrhagic infarction, eg. pulmonary infarction;

Effect of Acute Hemorrhage

The effects depend on the amount and rate of blood loss. A loss of 500 ml (about 10%) of blood has practically has no effect. Sudden acute massive hemorrhage of 1250 ml (about 25%) blood causes shock and a loss of 500 ml may be fetal unless treated. Outcome of a sudden hemorrhage is shown in the following diagram:

image of Outcome of sudden hemorrhage

Diagram Showing Outcome of Sudden Hemorrhage

Response after Acute Hemorrhage


  • Immediate syncope may occur;
  • Peripheral vasoconstriction with raised blood pressure and rapid pulse;
  • Redistribution of blood to vital organs;
  • Haematological values: (i) Hb is normal; (ii) PCV-normal, (iii) WBC total count may be raised (iv) platelets may increase;


  • Extravascular fluid passes into capillaries;
  • Fluid is retained by kidneys;
  • Blood volume may be restored;
  • Hematological Values: (i) Hb is decreased; (ii) PCV is decreased ;


  • Lost red blood cells are replaced;
  • Reticulocytes increases 5-15%;

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