Principles of Surgery-in-General Flashcards

According to the WHO Surgical Safety Checklist, which critical step must be completed before the induction of anaesthesia (the 'Sign In' phase)?

Answer: Confirm patient identity, procedure, site marking, and consent

The WHO Surgical Safety Checklist 'Sign In' (before induction) requires confirmation of patient identity, procedure, and site marking; patient consent; pulse oximeter functioning; known allergy status; airway assessment; and anticipated blood loss risk. The 'Time Out' occurs before incision, and the 'Sign Out' before the patient leaves the operating theatre.

A patient develops a surgical site infection 4 days after a colonic anastomosis. Which organism is most commonly responsible for surgical site infections following colorectal surgery?

Answer: Escherichia coli

E. coli is the most common organism causing surgical site infections after colorectal surgery, reflecting contamination with colonic flora. Other common organisms include Bacteroides fragilis (anaerobic), Enterococcus species, and other Enterobacteriaceae. Prophylactic antibiotics for colorectal surgery in the UK typically include a cephalosporin plus metronidazole to cover both aerobic and anaerobic organisms.

In the context of evidence-based surgery, which level of evidence is provided by a well-conducted randomised controlled trial?

Answer: Level 1b

The Oxford Centre for Evidence-Based Medicine hierarchy classifies evidence: Level 1a = systematic review of RCTs, Level 1b = individual RCT (with narrow confidence interval), Level 2a = systematic review of cohort studies, Level 2b = individual cohort study, Level 3 = case-control study, Level 4 = case series, Level 5 = expert opinion. A single well-conducted RCT provides Level 1b evidence.

A patient develops deep vein thrombosis 5 days post-operatively despite receiving prophylactic LMWH. Platelet count has dropped from 250 to 80 x10^9/L. What is the most likely diagnosis?

Answer: Heparin-induced thrombocytopenia type II (HIT)

HIT type II is an immune-mediated prothrombotic condition caused by antibodies against the heparin-PF4 complex. It typically presents 5-10 days after heparin exposure with a >50% drop in platelet count and paradoxical thrombosis (DVT, PE, arterial thrombosis). The 4T score assesses probability. All heparin must be stopped immediately and an alternative anticoagulant (argatroban, fondaparinux, or danaparoid) started.

What is the most appropriate method of sterilisation for surgical instruments that are heat-resistant?

Answer: Autoclaving (steam under pressure at 134°C for 3 minutes)

Autoclaving (moist heat sterilisation) using saturated steam under pressure is the gold standard for sterilising heat-resistant surgical instruments. UK standards require 134°C at 2.2 bar for a minimum of 3 minutes for standard instruments. Prion-contaminated instruments require 134°C for 18 minutes. Ethylene oxide is reserved for heat-sensitive equipment. Gamma irradiation is used for single-use disposable items.

According to the Clavien-Dindo classification, a post-operative complication requiring surgical, endoscopic, or radiological intervention under general anaesthesia is classified as which grade?

Answer: Grade IIIb

Clavien-Dindo classification: Grade I = any deviation not requiring intervention; Grade II = pharmacological treatment needed; Grade IIIa = intervention not under GA; Grade IIIb = intervention under GA; Grade IVa = single organ dysfunction requiring ICU; Grade IVb = multi-organ dysfunction; Grade V = death. Grade IIIb specifically denotes surgical/endoscopic/radiological intervention requiring general anaesthesia.