Blood Group Applications
- Emergency transfusion: O-negative is given when blood type is unknown (trauma patients)
- Pre-natal Rh screening: All pregnant women are tested for Rh status; Rh-negative mothers monitored for anti-Rh antibody development
- RhoGAM injection: Given to Rh-negative mother within 72 hours of first Rh-positive delivery to prevent erythroblastosis fetalis
- Cross-matching: Done before every elective transfusion to confirm compatibility beyond just ABO/Rh typing
ECG Clinical Applications
- First-degree AV block: Prolonged PR interval (>0.20 s) — slowed AVN conduction; often benign
- Second-degree AV block: Some P waves not followed by QRS — incomplete AVN conduction
- Third-degree (complete) AV block: Complete AVN block; P and QRS are dissociated; requires pacemaker
- Myocardial infarction: ST-segment elevation indicates myocardial cell injury; Q waves indicate infarction
Cardiac Disorder Applications
| Disorder | Key Clinical Sign | Treatment Principle |
|---|---|---|
| Hypertension | Often asymptomatic ("silent killer") until organ damage | Lifestyle changes, antihypertensives |
| Angina Pectoris | Chest pain during exertion, relieved by rest or nitroglycerin | Vasodilators, beta-blockers |
| CAD | Atherosclerosis narrows coronary arteries | Statins (lower LDL), revascularization |
| Heart Failure | Breathlessness, edema, fatigue | Diuretics, ACE inhibitors, digoxin |
| Erythroblastosis Fetalis | Foetal jaundice, anaemia, foetal hydrops | RhoGAM prevention; phototherapy for newborn |
Blood Count Applications
- Neutrophilia: Elevated neutrophils → bacterial infection
- Lymphocytosis: Elevated lymphocytes → viral infection (EBV, CMV)
- Eosinophilia: Elevated eosinophils → allergy or parasitic infection
- Thrombocytopenia: Low platelets → dengue fever, ITP; bleeding risk
- Anaemia: Low RBC/Hb → iron deficiency, B12 deficiency, haemolysis