Pathology Notes

Blood transfusion Updated: 07/28/2025 © Jun Wang, MD, PhD   Blood type ABO Rh Other blood types Commonly used lab tests Forward typing Patient’s RBCs + anti-A or anti-B reagents Agglutination confirm presence of A and/or B antigens Reverse typing Patient’s serum + A or B reagent RBCs Agglutination confirm presence of A and/or B antibodies Screen Identify anti-bodies in patient’s serum Mixing patient’s serum and reagent RBCs with known antigens Agglutination suggest presence of antibodies against one or more antigens on reagent type O RBCs Presence of antibody confirmed by analyzing the agglutination pattern with a panel of reagent cells Cross match Ensure compatibility between recipient’s and donor blood Prevent transfusion reactions Major cross match: mixing patient’s serum with donor RBCs Minor cross match: mixing patient’s RBCs with donor serum Agglutination indicates incompatibility Only compatible blood should be used Direct antiglobulin test AKA direct Coomb...

Anemia Updated: 07/13/2024 © Jun Wang, MD, PhD   General features Decrease in red cell mass Hemoglobin: Levels of hemoglobin in a specific volume of whole blood Hematocrit: Fraction of whole blood composed of red blood cells Red cell count: Quantity of red cell in a specific volume of whole blood Three major groups based on RBC sizes Microcytic Normocytic Macrocytic Three major causes Blood loss: acute or chronic Increased red cell destruction: hemolysis Reduced production: marrow failure due to genetic abnormality or nutritional deficiency Etiology Genetic abnormality Hemoglobinopathies RBC cytoskeletal abomorlities Enzyme abnormalities Fanconi anemia Nutritional deficiencies: iron, VB12, folate, general malnutrition Physical etiologies: trauma, burns, frostbite, prosthetic valves, etc Chronic diseases: chronic infections, neoplasia, autoimmune disorders, kidney or liver diseases, etc Infectious diseases: hepatitis, sepsis , malaria, e...

Infectious gastroenteritis Updated: 01/26/2024 © Jun Wang, MD, PhD   General features Inflammation of GI tract Most commonly caused by viruses May be associated with bacteria, fungi or parasites Fecal-oral transmission: foodborne, waterborne Most important risk factor: poor hygiene and sanitation Presentations: abdominal pain, nausea/vomiting, diarrhea Mild cases Most common Likely self-limited Supportive therapy only Severe cases May cause dehydration and sepsis   Diarrhea vs. Dysentery Diarrhea o    Passage of loose or watery stools o    At least 3 times in a 24-hour period o    Increased water content due to impaired water absorption or active water secretion, with or without mucosa injury or inflammation o    Acute: < 14 days; Persistent: 14-30 days; Chronic: > 30 days Dysentery o    AKA invasive diarrhea o    Diarrhea with visible blood or mucus o    Commonly as...

Shock Updated: 08/08/2022 © Jun Wang, MD, PhD General features Cell/tissue hypoxia Due to circulatory failure Life threatening Reversible at early stage only Need to initiate therapy immediately while rapidly identify underlying etiology Treat underlying etiology Stages Compensation : Perfusion of vital organs maintained Decompensation : Hypoperfusion and lactic acidosis Irreversible : Permanent cell/tissue damage, organ failure, usually leads to death Classification Distributive : Relative hypovolemia due to pathological redistribution of intravascular volume, usually resulted from excessive vasodilation Systemic inflammatory response syndrome Septic shock Neurogenic shock Anaphylactic shock Drug and toxin-induced shock Endocrine shock Cardiogenic : Cardiac malfunctioning associated critical reduction of pumping capacity Cardiomyopathic Arrhythmic Mechanical Hypovolemic : Absolute hypovolemia due to loss of intravascular volume, usu...