Normal distribution Non-normal distribution a. Positive skew: Longer or fatter tail on right b. Negative skew: Longer or fatter tail on left 2X2 tables Disease present Disease absent Test positive TP FP Test negative FN TN Event Non-event Exposed or Treatment a b Non-exposed or Placebo c d Formulae Incidence…
PGMEE, MRCS, USMLE, MBBS, MD/MS 
Phases of Clinical Trial : Mnemonic
Clinical trials conduct ‘human experiments’. Three fundamental principles apply: Blinding: Phases: Mnemonic: I SWIM Phase Purpose Name Sample Blinding and control 0 Initial (Pharmacokinetics and Pharmacodynamics) Microdosing studies Healthy volunteers (smaller) No I Safe? (Safe maximum dose and tolerability) Human pharmacology and safety Healthy volunteers (larger) No II Works? (Efficacy)…
PGMEE, MRCS, USMLE, MBBS, MD/MS 
Medial and Lateral Plantar Nerves
Origin: Tibial nerve (both medial and lateral plantar nerve) Similar to: Course and innervation: Medial plantar nerve Lateral plantar nerve Origin Larger branch of tibial nerve Smaller branch of tibial nerve Course Deep to abductor hallucis muscleBetween 1st and 2nd plantar layers Deep to abductor hallucis muscleBetween 1st and 2nd…
PGMEE, MRCS, USMLE, MBBS, MD/MS 
Clavipectoral Fascia
Extent: Function: Structures piercing the clavipectoral fascia: Mnemonic: CLAP Surgical relevance:
PGMEE, MRCS, USMLE, MBBS, MD/MS 
Meckel’s Diverticulum : Rule of 2
General description Rule of 2s 1. Occurs in 2% population 2. Symptomatic cases are 2 times more common in males 3. Located within 2 feet proximal to ileocecal valve 4. 2 inches long and 2 cm diameter 5. 2 types of ectopic mucosa: gastric and pancreatic 6. Symptomatic only in…
PGMEE, MRCS, USMLE, MBBS, MD/MS 
Electrosurgery Notes
Terminologies Electrosurgery modalities Modality Electrode configuration Waveform Indications Remarks DC Electrocautery Patients with ICDs and pacemakers No current passes through patient (direct heat transference to tissue) AC Unaltered sine wave a. High voltage, Low ampere Can be tolerated in patients with pacemakers at low dosage Electrodessication Monoterminal Markedly damped Superficial…
PGMEE, MRCS, USMLE, MBBS, MD/MS 
Bile duct injuries – Mnemonic
Strasberg and Bismuth classification A – bile leak from part ATTACHED to biliary tree (cystic duct or duct of Luschka) B – BLOCK in part of biliary tree C – bile leak from CUT-OFF duct (not in communication) with the biliary tree D – DEFECT (<50%) in common hepatic duct…
PGMEE, MRCS, USMLE, MBBS, MD/MS 
Femoral Hernia : Mnemonic
Mnemonic: FEMORAL Females (4 times more common) Elderly McEvedey operation (incision above inguinal ligament – preferred in emergency intervention due to easy access to compromised bowel for any resection if required) Obstruction/incarceration/strangulation risk is higher (rigid walls of femoral ring) Richter’s hernia – most common location Above inguinal ligament –…