NEET PG cheat sheet

Brachial plexus roots C5-T1; Erb palsy (C5-C6) gives waiter's tip, Klumpke (C8-T1) gives claw hand with Horner syndrome.

Coronary arteries arise from aortic sinuses; left main bifurcates into LAD and circumflex; RCA supplies SA node in ~60% of people.

Nerve fibre conduction velocity rises with diameter and myelination; A-alpha fastest (~100 m/s), C fibres slowest (~0.5-2 m/s) and pain-conducting.

GFR = Kf x net filtration pressure; normal GFR ~125 mL/min; filtration fraction = GFR/renal plasma flow ~0.2.

Oxygen-haemoglobin curve shifts right (reduced affinity) with increased 2,3-BPG, CO2, H+, temperature; fetal Hb shifts left.

Rate-limiting enzymes: glycolysis phosphofructokinase-1, gluconeogenesis fructose-1,6-bisphosphatase, TCA isocitrate dehydrogenase, cholesterol synthesis HMG-CoA reductase.

Urea cycle: carbamoyl phosphate synthetase I in mitochondria; rate-limiting step is CPS I; hyperammonaemia treated with lactulose, sodium benzoate, arginine.

Vitamin C is cofactor for prolyl and lysyl hydroxylase in collagen; deficiency causes scurvy with perifollicular haemorrhage and poor wound healing.

Golgi tendon organ senses tension (Ib afferent); muscle spindle senses length change (Ia annulospiral, II flower spray).

Reversible cell injury shows cell swelling and fatty change; irreversible injury shows membrane rupture, mitochondrial permeability transition pore, and nuclear changes (pyknosis, karyolysis, karyorrhexis).

Type I hypersensitivity is IgE/mast cell mediated; Type II is antibody against fixed antigen; Type III is immune complex; Type IV is T-cell mediated and delayed.

Tumour suppressor genes follow two-hit hypothesis (RB, APC, BRCA); oncogenes need single activating hit (RAS, MYC, HER2).

Amyloid is beta-pleated, Congo red positive with apple-green birefringence under polarised light; AA (serum amyloid A) and AL (light chain) are common types.

Nephrotic syndrome: proteinuria >3.5 g/day, hypoalbuminaemia, oedema, hyperlipidaemia; minimal change disease is commonest in children and steroid-responsive.

Rheumatoid arthritis: pannus, symmetric small joint involvement, anti-CCP and RF positive; osteoarthritis shows osteophytes, subchondral sclerosis, joint space narrowing.

Cirrhosis is diffuse nodular regeneration with bridging fibrosis; complications include portal hypertension, varices, ascites, hepatic encephalopathy, HCC.

APACHE and Glasgow coma scale quantify severity; GCS eye 4, verbal 5, motor 6; score 8 or less indicates need for airway protection.

Gram-positive cocci in clusters with catalase positive and coagulase positive = Staphylococcus aureus; coagulase negative = S. epidermidis (novobiocin sensitive) or S. saprophyticus (novobiocin resistant).

Optochin sensitive, bile soluble, alpha-haemolytic diplococci = Streptococcus pneumoniae; bacitracin sensitive, beta-haemolytic = S. pyogenes (group A).

Mycobacterium tuberculosis is acid-fast, grows on Lowenstein-Jensen (slow, rough, buff) or Middlebrook; Ziehl-Neelsen stain detects it.

Hepatitis B serology: HBsAg = infection, anti-HBs = immunity, HBeAg = high infectivity, anti-HBc IgM = acute window.

HIV: p24 antigen appears early, ELISA screening confirmed by Western blot or NAT; CD4 count <200 defines AIDS; Pneumocystis jirovecii prophylaxis below 200.

Malaria: Plasmodium falciparum shows multiple rings, banana-shaped gametocytes, Maurer dots; quartan fever = P. malariae (72 h cycle).

Dengue: NS1 antigen detectable days 0-5, IgM from day 5; thrombocytopenia and haemoconcentration indicate warning signs of plasma leakage.

Rabies post-exposure prophylaxis: wound washing, then vaccine (category II) plus rabies immunoglobulin infiltrated locally for category III exposures.

Zero-order kinetics: phenytoin, ethanol, salicylates at high dose, warfarin at high dose; constant amount eliminated per unit time, half-life varies with dose.

Competitive antagonists shift dose-response curve right with same Emax; non-competitive reduce Emax; partial agonists give submaximal Emax.

Cytochrome P450 inducers: rifampicin, phenytoin, carbamazepine, phenobarbital, St John's wort; inhibitors: ketoconazole, erythromycin, cimetidine, grapefruit, ritonavir.

Atropine overdose: dry flushed skin, mydriasis, tachycardia, urinary retention, delirium; treat with physostigmine if severe CNS effects.

Organophosphate poisoning: SLUDGE + bronchorrhoea, miosis, bradycardia; treat with atropine plus pralidoxime before enzyme ageing.

Aminoglycosides are bactericidal, concentration-dependent, nephrotoxic and ototoxic, and inactive against anaerobes; monitor trough levels.

Warfarin inhibits vitamin K epoxide reductase; monitor INR; vitamin K and fresh frozen plasma reverse bleeding; target INR 2-3 for most indications.

Digoxin inhibits Na/K ATPase, increases vagal tone; toxicity worsened by hypokalaemia and renal failure; antidote is digoxin-specific Fab fragments.

Rigor mortis begins in small muscles (face, neck) 1-2 h after death, peaks at 12 h, resolves by 24-36 h; cold stiff body with dependent lividity fixed indicates >6-8 h.

Postmortem lividity appears 2-4 h, becomes fixed by 6-8 h; its distribution indicates body position after death.

Hanging: ligature mark is oblique, above thyroid cartilage, incomplete and non-continuous; strangulation mark is horizontal, below thyroid, continuous.

Drowning: fine white froth at mouth/nose, cutis anserina, wassermann test for diatoms; diatom presence in bone marrow supports antemortem drowning.

Livor, algor, rigor and putrefaction estimate time since death; putrefaction starts in right iliac fossa due to caecal gas.

Carbon monoxide poisoning: cherry-red lividity, carboxyhaemoglobin >50% fatal; CO binds Hb with ~200-250 times affinity of oxygen.

Organophosphate poisoning: garlic odour, miosis, frothy secretions; cyanide gives bitter almond odour and bright red lividity.

Section 304A IPC (now BNS 106) covers death by negligence; Section 320 IPC defines grievous hurt; Section 375 defines rape under old code.

Incidence = new cases/population at risk per unit time; prevalence = all cases/population; prevalence ≈ incidence × duration for stable disease.

Sensitivity = TP/(TP+FN); specificity = TN/(TN+FP); positive predictive value depends on prevalence.

Relative risk = incidence in exposed / incidence in unexposed; attributable risk = incidence exposed minus unexposed; odds ratio approximates RR for rare disease.

Herd immunity threshold = 1 - 1/R0; measles R0 12-18 needs ~92-95% coverage; polio R0 5-7 needs ~80-86%.

Crude birth rate = live births per 1000 mid-year population; infant mortality rate = infant deaths under 1 year per 1000 live births.

Maternal mortality ratio = maternal deaths per 100,000 live births; India's MMR has declined to below 100 per 100,000 in recent NFHS/SRS estimates.

Screening test criteria: disease important, detectable early, acceptable test, effective treatment available, cost-effective; Wilson-Jungner criteria.

Randomised controlled trial is best for causation; cohort for incidence and RR; case-control for rare diseases and OR; cross-sectional for prevalence.

Acute MI: ST elevation in contiguous leads; STEMI reperfusion with primary PCI within 120 min or fibrinolysis within 30 min of door if PCI unavailable.

Diabetic ketoacidosis: hyperglycaemia, ketonaemia, metabolic acidosis; treat with isotonic saline, insulin infusion, potassium replacement once K <5.5.

Tuberculosis treatment: 2 months HRZE intensive plus 4 months HRE continuation under NTEP; fixed-dose combinations weight-banded.

Psoriasis: well-demarcated erythematous plaques with silvery scale on extensor surfaces; Auspitz sign, Koebner phenomenon; methotrexate for severe disease.

Pemphigus vulgaris: intraepidermal IgG against desmoglein 3, flaccid bullae, positive Nikolsky; bullous pemphigoid is subepidermal with tense bullae.

Schizophrenia: first-rank symptoms (thought insertion, broadcasting, third-person auditory hallucinations); treat with atypical antipsychotics, monitor metabolic effects.

Neonatal jaundice: physiological after 24 h, peaks day 3-5; pathological if within 24 h, direct hyperbilirubinaemia, or rise >5 mg/dL/day.

Nephrotic syndrome in children: prednisolone 60 mg/m2/day for 6 weeks then alternate-day for 6 weeks; biopsy if steroid resistant or age <1 or >12.

Acute appendicitis: migration of pain to right iliac fossa, McBurney point tenderness, Alvarado score; appendicectomy is treatment of choice.

Shock: classify as hypovolaemic, cardiogenic, distributive, obstructive; initial crystalloid bolus 20 mL/kg in children, 500-1000 mL in adults.

Fracture healing: haematoma, fibrocartilaginous callus, bony callus, remodelling; open fractures need antibiotics and debridement within 6 h.

Compartment syndrome: pain out of proportion, pain on passive stretch, paraesthesia; pulselessness is late; treat with urgent fasciotomy.

Spinal anaesthesia: level depends on baricity and position; hypotension from sympathetic blockade; post-dural puncture headache treated with blood patch.

Malignant hyperthermia: autosomal dominant ryanodine receptor mutation triggered by volatile agents and succinylcholine; treat with dantrolene 2.5 mg/kg IV.

Acute otitis media: bulging erythematous tympanic membrane; amoxicillin first line; mastoiditis is a complication with postauricular swelling.

Primary open-angle glaucoma: raised intraocular pressure, cupping, field loss; first-line prostaglandin analogue (latanoprost) increases uveoscleral outflow.

Estimated date of delivery = last menstrual period + 280 days (Naegele rule); gestational age by ultrasound crown-rump length is most accurate in first trimester.

Preeclampsia: BP ≥140/90 after 20 weeks with proteinuria or organ dysfunction; severe features include BP ≥160/110, platelets <100,000, transaminitis, pulmonary oedema.

Eclampsia: magnesium sulphate 4-6 g IV loading then 1-2 g/hour; monitor reflexes, respiratory rate, urine output; calcium gluconate is antidote.

Postpartum haemorrhage: >500 mL after vaginal or >1000 mL after caesarean delivery; uterine atony commonest cause; give oxytocin, then tranexamic acid 1 g IV.

Antepartum haemorrhage: placenta praevia painless bleeding, avoid digital examination; abruption painful with board-like uterus.

Contraception: combined oral pills contraindicated in migraine with aura, smokers over 35, and hypertension; copper IUCD is emergency contraception up to 5 days.

PCOS Rotterdam criteria: two of oligo/anovulation, hyperandrogenism, polycystic ovaries; first-line ovulation induction is letrozole or clomiphene.

Cervical cancer screening: Pap smear from age 21 or 25; HPV testing every 5 years; HPV 16 and 18 cause most cases; vaccine is prophylactic.

Informed consent requires capacity, adequate disclosure, comprehension, and voluntariness; document discussion of risks, benefits, and alternatives.

Confidentiality may be breached when legally mandated (notifiable diseases, court order) or when there is serious risk to a third party.

Emergency exception: treat without consent when immediate life-saving intervention is needed and the patient cannot consent.

Research ethics: Institutional Ethics Committee approval, informed consent, risk-benefit assessment; vulnerable populations need extra protection.

Medical negligence requires duty, breach of duty, causation, and damage; res ipsa loquitur shifts burden when the injury could not occur without negligence.

Never events (wrong-site surgery, retained instrument, wrong patient) are reportable patient safety incidents requiring root cause analysis.

Euthanasia and physician-assisted dying are illegal in India; withholding futile life support with documented family and ethics committee discussion is permitted.

Professional boundaries: avoid dual relationships; gifts and referrals must not influence clinical decisions; maintain accurate medical records.