GCPS Primary Exam common mistakes
GCPS Primary Exam · Understand the traps and how to avoid them.
Answering basic-science items (physiology, pharmacology, pathology) from ward-level clinical intuition instead of stating the underlying mechanism, so the chosen option describes what one would do rather than why it happens.
Candidates who have done clinical rotations default to management thinking; basic-science stems often ask for the mechanism or the single most likely pathophysiological explanation, and the clinically familiar option is deliberately offered as a distractor.
What to do instead
Before selecting, underline the interrogative in the stem (mechanism, most likely cause, initial step, best next test) and reject any option that answers a different question. Build a one-page mechanism map per high-yield topic (e.g. Starling forces, countercurrent multiplication, cytochrome P450 induction) and rehearse explaining each in one sentence.
Choosing the most sensitive test or the most advanced imaging modality when the item asks for the first-line or most appropriate initial investigation.
Exam stems reward appropriate resource use; candidates equate 'best' with 'most accurate', forgetting that in Family Medicine and Internal Medicine the initial test is often simple, cheap and bedside.
What to do instead
Memorise a short hierarchy per presentation: bedside test → basic laboratory → plain imaging → cross-sectional imaging → invasive. Practise items by writing the first-line test before reading the options, then matching.
Misreading arterial blood gas and acid–base items by calculating only the primary disorder and ignoring compensation, the anion gap, or the delta ratio.
Time pressure leads to a single-step calculation; mixed disorders are common in exam items and the 'expected compensation' option is usually present as a trap.
What to do instead
Use a fixed four-step routine every time: pH → primary disorder → expected compensation (Winter's formula, expected pCO2 change) → anion gap and delta-delta. Write the routine on the scratch sheet at the start of the paper and apply it mechanically.
Treating every abnormal laboratory value as the diagnosis rather than interpreting it against pre-test probability, specimen handling and reference ranges.
Laboratory Medicine items test understanding of sensitivity, specificity, predictive values and pre-analytical error; candidates who memorise cut-offs miss items about haemolysis, fasting status, or post-test probability.
What to do instead
Revise pre-analytical variables (tourniquet time, haemolysis, EDTA contamination, fasting), then practise converting a 2×2 table into sensitivity, specificity, PPV and NPV at two different prevalences. For each common test, state one situation where a normal result does not exclude disease.
In Oncology and Radiotherapy items, selecting a treatment option without first staging the tumour or identifying performance status and intent of treatment (curative versus palliative).
Candidates jump to the named drug or the named operation; modern items hinge on stage, histology, molecular markers and patient fitness, and the option list contains treatments appropriate to a different stage.
What to do instead
Answer in a fixed order: histology → stage → prognostic/molecular features → patient fitness → intent → modality. Learn one staging system per major cancer (e.g. TNM for breast, colorectal, lung) and the emergency indications for radiotherapy (cord compression, superior vena cava obstruction, bleeding).
Managing paediatric items with adult doses, adult fluid volumes, or adult vital-sign thresholds.
Most clinical exposure is adult; paediatric assessment depends on age-specific normal ranges and weight-based calculations, and items deliberately include the adult value as a distractor.
What to do instead
Memorise weight-based formulae (4-2-1 maintenance fluids, 10/20 mL/kg boluses, adrenaline 10 mcg/kg, paracetamol 15 mg/kg), age-specific respiratory and heart rates, and the paediatric assessment triangle. Rehearse one calculation per system daily in the final month.
In Psychiatry items, choosing pharmacotherapy when the stem describes a situation requiring risk assessment, capacity assessment, or a safeguarding/legal step.
Candidates focus on diagnosis and drug choice; many items test the immediate safe action - suicide risk assessment, Mental Health Act provisions, delirium screening, or recognition of organic causes of psychosis.
What to do instead
For every psychiatric stem, first ask: is there risk to self or others, is this delirium or a physical cause, and is there a legal framework involved? Learn the criteria for capacity and for detention, and the first-line management of acute agitation and alcohol withdrawal.
Answering Public Health items with clinical reasoning instead of epidemiological measures - confusing incidence with prevalence, or relative with absolute risk.
Screening, outbreak and study-design items use precise terminology; candidates who do not compute numbers from the given data choose the plausible-sounding statement rather than the arithmetically correct one.
What to do instead
Practise calculating attack rate, incidence density, attributable risk, number needed to treat and vaccine efficacy from short vignettes. Learn the bias typical of each study design and the criteria for a screening programme, and always do the arithmetic on paper before reading the options.
In Surgery and the surgical subspecialties, giving the definitive operation when the item asks for resuscitation and initial management, or missing the time-critical diagnosis (e.g. tension pneumothorax, compartment syndrome, ectopic pregnancy, testicular torsion).
Candidates recall the named procedure but not the sequence; emergency items reward the first 30 minutes, and the definitive option is included as a distractor.
What to do instead
Learn a resuscitation-first rule for every surgical emergency: ABCDE, then the single immediate intervention, then definitive care. Build a table of 'can't-miss diagnoses' by region with their bedside confirmation and immediate action, and revise it weekly.
In Obstetrics and Gynaecology, Radiology and Otorhinolaryngology items, ignoring the pregnancy status or the radiation dose when selecting an investigation or drug.
These domains overlap heavily with general medicine; candidates choose the best test in a non-pregnant adult, forgetting that pregnancy and lactation change the acceptable imaging pathway and formulary.
What to do instead
For any female of reproductive age, state pregnancy status before choosing. Memorise the safe imaging sequence in pregnancy (ultrasound, then MRI; CT only if justified) and the drugs contraindicated in pregnancy and breastfeeding, and apply this check to every relevant item across domains.