AMC MCQ - Australian Medical Council Multiple Choice Questions General Surgery Principles Questions and Answers 1 — Questions and Answers
Question 1: A 70-year-old man is on day one post-sigmoid colectomy. The nursing staff report he is hypotensive with a blood pressure of 90/50 mmHg, a heart rate of 115 bpm, and a urine output of less than 20 mL/hour for the past two hours. There is no evidence of active bleeding. What is the most appropriate initial intravenous fluid for resuscitation?
- 4% Albumin solution
- 0.9% Sodium Chloride (Correct answer)
- Packed red blood cells
- 5% Dextrose in water
Correct answer: 0.9% Sodium Chloride
The patient is exhibiting signs of hypovolemic shock, likely due to third-space fluid losses post-operatively. The immediate priority is to restore intravascular volume. According to resuscitation guidelines, an isotonic crystalloid solution, such as 0.9% Sodium Chloride (Normal Saline) or Hartmann's solution, is the first-line choice for initial volume expansion in non-hemorrhagic shock. 5% Dextrose is rapidly metabolised, leaving free water which does not effectively expand the intravascular space. Albumin is a colloid and not typically used for initial resuscitation. Packed red blood cells are only indicated if there is evidence of significant hemorrhage and a low haemoglobin level.
Question 2: A 58-year-old man with a 40-pack-year smoking history is undergoing a laparotomy. In the context of wound healing, which of the following phases is most directly impaired by the physiological effects of cigarette smoking?
- Haemostasis
- Inflammatory phase
- Remodelling phase
- Proliferative phase (Correct answer)
Correct answer: Proliferative phase
The proliferative phase of wound healing (days 3-14) is characterised by fibroblast proliferation, collagen synthesis, and angiogenesis. Cigarette smoking severely impairs this phase. Nicotine is a potent vasoconstrictor, and carbon monoxide reduces the oxygen-carrying capacity of haemoglobin. The resulting tissue hypoxia directly inhibits fibroblast activity and the synthesis of collagen, which is essential for wound strength. While smoking can have negative effects on all phases, its most pronounced impact is on the oxygen-dependent processes of proliferation and matrix deposition.
Question 3: A 62-year-old man is scheduled for an elective inguinal hernia repair. He has no known drug allergies. According to Australian Therapeutic Guidelines for surgical prophylaxis, what is the optimal timing for the administration of intravenous antibiotics to prevent a surgical site infection?
- In the post-anaesthesia care unit (PACU)
- Within 60 minutes prior to skin incision (Correct answer)
- At the time of skin closure
- Two hours prior to skin incision
Correct answer: Within 60 minutes prior to skin incision
To be effective in preventing surgical site infections (SSIs), prophylactic antibiotics must be present in the tissues at a bactericidal concentration at the time of the initial incision. The standard recommendation is to administer the intravenous antibiotic dose within the 60 minutes preceding the skin incision. This ensures peak tissue levels are achieved when the wound is created and the risk of bacterial contamination begins. Administering it too early (>120 minutes) may lead to sub-therapeutic levels, while administration after the incision is made is not considered prophylactic.
Question 4: A 55-year-old patient develops a fever of 38.5°C on post-operative day 1 following an open cholecystectomy. Chest auscultation reveals decreased breath sounds at the lung bases. Which of the following is the most common cause of fever in the first 48 hours after major surgery?
- Atelectasis (Correct answer)
- Surgical site infection
- Urinary tract infection
- Deep vein thrombosis
Correct answer: Atelectasis
The most common cause of fever within the first 48 hours post-operatively is pulmonary atelectasis (the 'Wind' of the '5 Ws' mnemonic for post-op fever). Inadequate lung expansion due to pain, anaesthesia, and immobilisation leads to alveolar collapse, which can cause a low-grade fever. Surgical site infections ('Wound') typically manifest later, around day 5 to 7. Urinary tract infections ('Water') and deep vein thrombosis ('Walking') are also possibilities but are statistically less frequent causes of fever in this very early post-operative period.
Question 5: A 78-year-old woman with oesophageal cancer is found to be severely malnourished, having lost 15% of her body weight over 3 months. Pre-operative nutritional support is initiated via a nasogastric tube. The initiation of feeding in this patient must be done cautiously to avoid which of the following life-threatening metabolic complications?
- Hypernatraemia
- Metabolic acidosis
- Refeeding syndrome (Correct answer)
- Hypercalcaemia
Correct answer: Refeeding syndrome
This patient is at high risk for refeeding syndrome due to severe malnutrition. This syndrome is a potentially fatal condition caused by rapid shifts in fluids and electrolytes that occur when nutritional support is initiated in a chronically starved patient. The shift from fat to carbohydrate metabolism stimulates insulin release, which drives phosphate, potassium, and magnesium into cells, leading to profound hypophosphataemia, hypokalaemia, and hypomagnesaemia. These electrolyte shifts can cause cardiac, pulmonary, and neurological failure.
Question 6: When closing the fascial layer of a midline laparotomy, a surgeon requires a suture material that provides long-term tensile strength and has a low risk of harbouring bacteria. Which of the following is a non-absorbable, monofilament suture commonly used for this purpose?
- Polyglactin 910 (Vicryl)
- Silk
- Catgut
- Polypropylene (Prolene) (Correct answer)
Correct answer: Polypropylene (Prolene)
Polypropylene (e.g., Prolene) is a synthetic, non-absorbable, monofilament suture. Its non-absorbable nature provides permanent tensile strength, which is crucial for fascial closure to prevent incisional hernia formation. Its monofilament structure presents a smooth surface, which is less likely to harbour bacteria compared to braided sutures. Polyglactin 910 (Vicryl) and Catgut are both absorbable. Silk is non-absorbable but is a braided suture, which increases its potential to act as a nidus for infection.
