How to use these GSSE practice questions
The RACS Generic Surgical Sciences Examination (GSSE) assesses generic surgical sciences and their application to common perioperative and acute care scenarios. It is a high-volume written examination, with predominantly single-best-answer questions. The questions below are original practice examples, not questions from the examination. They cover mechanisms and clinical decisions across physiology, anatomy, pathology, pharmacology and critical care.
For each item, choose the best answer before reading the explanation that follows it. Pay attention to what the stem asks you to explain: a physiological response, a calculation, an anatomical deficit or an immediate priority. A useful routine is to identify the key finding, state the mechanism linking it to the problem, then rule out the closest distractor. The MySummaries examples show how these topics can be drawn from a candidate’s revision material and practised as questions.
Questions
1. Haemorrhage and compensation
This question tests the short-term autonomic response to reduced circulating volume.
A patient has acute blood loss. Which change is most likely to occur as an immediate baroreceptor-mediated response?
A patient has acute blood loss. Which change is most likely to occur as an immediate baroreceptor-mediated response?
Reduced arterial stretch increases sympathetic outflow and reduces vagal influence. The resulting tachycardia and vasoconstriction help preserve arterial pressure and perfusion of vital organs.
The best answer is increased sympathetic outflow. Baroreceptors in the carotid sinus and aortic arch respond to reduced stretch; the resulting autonomic response raises heart rate and vascular tone. The first option reverses the direction of the response. Compensation can help maintain pressure temporarily, but it does not replace lost circulating volume or establish that perfusion is adequate.
2. Acute respiratory acidosis
This question tests interpretation of an arterial blood gas using the relationship between carbon dioxide and pH.
An arterial blood gas shows pH 7.25, PaCO₂ 60 mmHg and HCO₃⁻ 26 mmol/L. Which is the best interpretation?
An arterial blood gas shows pH 7.25, PaCO₂ 60 mmHg and HCO₃⁻ 26 mmol/L. Which is the best interpretation?
The low pH indicates acidemia, and the raised PaCO₂ indicates a primary respiratory acidosis. The near-normal bicarbonate is consistent with little metabolic compensation, as expected in an acute process.
The pH establishes acidemia; the raised PaCO₂ points to a primary respiratory cause. The bicarbonate is close to the usual reference range, so substantial renal compensation is not evident. The strongest distractor is metabolic acidosis: that would be supported by a low bicarbonate, not the raised carbon dioxide seen here. Interpret the values together rather than labelling a disorder from one number.
3. Arterial oxygen content
This question tests whether you can distinguish oxygen carried by haemoglobin from oxygen dissolved in plasma.
A patient has haemoglobin 7 g/dL, arterial oxygen saturation 98% and PaO₂ 100 mmHg. Using CaO₂ = (1.34 × Hb × SaO₂) + (0.003 × PaO₂), what is the approximate arterial oxygen content?
A patient has haemoglobin 7 g/dL, arterial oxygen saturation 98% and PaO₂ 100 mmHg. Using CaO₂ = (1.34 × Hb × SaO₂) + (0.003 × PaO₂), what is the approximate arterial oxygen content?
The haemoglobin-bound component is 1.34 × 7 × 0.98, approximately 9.2 mL/dL. The dissolved component is 0.3 mL/dL, giving a total of about 9.5 mL O₂/dL.
The haemoglobin-bound component dominates: 1.34 × 7 × 0.98 is about 9.2 mL/dL, and dissolved oxygen adds about 0.3 mL/dL. The answer is therefore about 9.5 mL O₂/dL. The high saturation does not mean oxygen content is normal when haemoglobin is low. The units matter: this result is expressed per decilitre of blood.
4. Common fibular nerve injury
This question tests whether the pattern of weakness and sensory change localises an anatomical lesion.
After an injury around the fibular neck, a patient develops foot drop and reduced sensation over the dorsum of the foot. Which nerve is most likely injured?
After an injury around the fibular neck, a patient develops foot drop and reduced sensation over the dorsum of the foot. Which nerve is most likely injured?
The common fibular nerve winds around the fibular neck and is vulnerable there. Injury can weaken dorsiflexion and eversion, producing foot drop, with sensory loss over much of the dorsum of the foot.
The common fibular nerve is particularly vulnerable where it winds around the fibular neck. Its deep branch supplies muscles involved in dorsiflexion, while its superficial branch contributes to eversion and sensation over much of the dorsum of the foot. The tibial nerve is the tempting alternative because it is also a major nerve of the leg, but its injury more typically affects plantarflexion and plantar sensation.
5. Wound healing
This question tests the normal change in collagen composition during wound remodelling.
Which collagen change is characteristic of wound maturation?
Which collagen change is characteristic of wound maturation?
Early granulation tissue contains relatively more type III collagen. During remodelling, type III is progressively replaced by stronger type I collagen, although healed tissue does not regain the full strength of uninjured skin.
Early granulation tissue contains relatively more type III collagen. During remodelling, type III is progressively replaced by type I, which contributes greater tensile strength. The first option reverses that direction. This is a useful example of linking a microscopic change to a clinical consequence: remodelling strengthens the wound, but a healed wound does not simply become identical to uninjured skin.
6. Hyperkalaemia and cardiac membrane stability
This question tests prioritisation when an electrolyte disturbance is causing an immediate cardiac risk.
A patient with severe hyperkalaemia has a widened QRS complex on ECG. Which intervention most directly stabilises the cardiac membrane while definitive potassium-lowering treatment is arranged?
A patient with severe hyperkalaemia has a widened QRS complex on ECG. Which intervention most directly stabilises the cardiac membrane while definitive potassium-lowering treatment is arranged?
Intravenous calcium antagonises the membrane effects of hyperkalaemia and is used to stabilise the myocardium when there are ECG changes. Insulin with glucose and salbutamol shift potassium into cells; they lower serum potassium but do not provide the same immediate membrane stabilisation.
Intravenous calcium is the immediate membrane-stabilising choice when hyperkalaemia is associated with ECG changes. Insulin with glucose and salbutamol can shift potassium intracellularly, but they do not directly stabilise the cardiac membrane in the same way. A potassium-binding agent is not the answer to the immediate ECG risk. In practice, urgent monitoring and definitive management are also needed; do not treat the ECG as a reason to delay action.
7. Warfarin-associated major bleeding
This question tests reversal of anticoagulation when rapid correction is required.
A patient taking warfarin has major active bleeding and needs urgent reversal. Which combination is generally used for rapid reversal?
A patient taking warfarin has major active bleeding and needs urgent reversal. Which combination is generally used for rapid reversal?
For major bleeding requiring urgent reversal, four-factor prothrombin complex concentrate rapidly replaces vitamin K-dependent clotting factors, while intravenous vitamin K supports sustained reversal. Local protocols and clinical circumstances guide the precise approach.
Four-factor prothrombin complex concentrate provides rapid replacement of vitamin K-dependent clotting factors; intravenous vitamin K supports sustained reversal. Vitamin K alone is slower, so it is the strongest distractor if the stem stresses urgency. Actual treatment should follow local protocols and account for the patient’s clinical circumstances. The question tests the principle of pairing rapid factor replacement with ongoing reversal, not a one-size-fits-all prescription.
8. Anion gap
This question tests calculation and recognition of a raised anion gap metabolic acidosis.
A patient’s blood results are sodium 140 mmol/L, chloride 104 mmol/L and bicarbonate 12 mmol/L. Using an anion gap that excludes potassium, what is the gap?
A patient’s blood results are sodium 140 mmol/L, chloride 104 mmol/L and bicarbonate 12 mmol/L. Using an anion gap that excludes potassium, what is the gap?
The calculation is sodium minus chloride plus bicarbonate: 140 − (104 + 12) = 24 mmol/L. This is raised against the commonly used reference range, though laboratory ranges vary. Interpret the result with the clinical context and the rest of the acid–base assessment.
Calculate it explicitly: 140 − (104 + 12) = 24 mmol/L. That is raised against a commonly used reference range, although reference ranges vary between laboratories. The tempting answer of 12 is the bicarbonate value, not the gap. A raised gap narrows the acid–base interpretation, but it does not by itself identify the cause; use the clinical context and other results.
9. Oxygen–haemoglobin dissociation
This question tests how changes in pH affect haemoglobin’s affinity for oxygen.
During intense exercise, increased hydrogen ion concentration in tissue has which effect on the oxygen–haemoglobin dissociation curve?
During intense exercise, increased hydrogen ion concentration in tissue has which effect on the oxygen–haemoglobin dissociation curve?
Increased hydrogen ion concentration lowers haemoglobin’s affinity for oxygen and shifts the curve to the right, facilitating oxygen unloading in metabolically active tissue. The first option gives the opposite shift and consequence.
Increased hydrogen ion concentration shifts the curve to the right, reducing haemoglobin’s oxygen affinity and favouring unloading to active tissue. The first option reverses both the shift and its effect. In a full answer, connect the direction of the shift to the tissue’s needs rather than memorising a list of curve modifiers without explaining what they do.
10. Positive end-expiratory pressure
This question tests a haemodynamic consequence of changing ventilator settings.
A patient becomes hypotensive after an increase in positive end-expiratory pressure (PEEP). Which mechanism can explain the fall in blood pressure?
A patient becomes hypotensive after an increase in positive end-expiratory pressure (PEEP). Which mechanism can explain the fall in blood pressure?
Higher intrathoracic pressure can impede systemic venous return, reducing right ventricular preload and, in turn, cardiac output. The effect depends on the patient’s physiology and volume status, so it is a plausible mechanism rather than an inevitable response.
Higher intrathoracic pressure can impede venous return, reducing right ventricular preload and potentially cardiac output. The effect depends on the patient’s physiology and volume status; it is not inevitable in every patient. The third option is too absolute and gives the wrong general mechanism. In a clinical response, connect the ventilator change to the haemodynamic observation, then reassess the patient and other possible causes.
Short written-answer practice
Single-best-answer practice is useful, but written responses also demand a clear explanation. This sample is a platform-marked practice response, not an official GSSE marking scheme. Notice how the marker identifies a correct calculation and a missing clinical implication.
A patient has Hb 7 g/dL, SaO₂ 98% and PaO₂ 100 mmHg. Estimate CaO₂ using CaO₂ = (1.34 × Hb × SaO₂) + (0.003 × PaO₂), then state one implication.
3/4CaO₂ = (1.34 × 7 × 0.98) + (0.003 × 100) = about 9.5 mL/dL. Most oxygen is carried bound to haemoglobin, so low Hb reduces oxygen content despite the high saturation.
Correct calculation, units and main clinical implication. The answer could make the small dissolved component explicit and avoid implying that saturation alone measures total oxygen delivery.
Missed
−State that the dissolved oxygen contribution is approximately 0.3 mL/dL and is small compared with the haemoglobin-bound component.
Model answerCaO₂ = (1.34 × 7 × 0.98) + (0.003 × 100), or about 9.5 mL O₂/dL. Approximately 9.2 mL/dL is haemoglobin-bound and 0.3 mL/dL is dissolved. The low haemoglobin therefore reduces arterial oxygen content despite a saturation of 98%. Oxygen delivery also depends on cardiac output, so CaO₂ alone does not describe total tissue oxygen delivery.
That is a MySummaries paper, filled with GSSE material. Yours is written from your own notes. Start free
Review the errors, not just the score
A useful review separates knowledge gaps from calculation slips and misread stems. Rework missed questions by stating the mechanism in one sentence, then add the clinical consequence. If you chose a distractor because it was partly true, identify the word or detail in the stem that makes it less suitable as the single best answer. Keep calculations visible, including units and the formula used.
A weak-area summary should guide what you revisit, rather than serve as a prediction of what will appear in the examination. In this practice example, the candidate’s lower result is in acid–base interpretation, while anatomy is comparatively secure.
If the same error recurs, turn the missed point into a short retrieval prompt. Keep the prompt specific enough that a correct answer must include the mechanism or number, not a vague topic label.
You missed this twice: calculate CaO₂ for Hb 7 g/dL, SaO₂ 98% and PaO₂ 100 mmHg. Include the haemoglobin-bound and dissolved components, with units.
How MySummaries helps
Build a revision board from your own GSSE notes, then use it to generate question practice, flashcards and marked written answers. Review the topics where your answers lose marks and revisit the source material behind them. Open MySummaries.