DUHS FCPS-II entry test (Sindh): format, sessions and specialties

Answer: E — Kleihauer-Betke test

The question is not about diagnosing sensitisation but quantifying fetomaternal haemorrhage so the anti-D dose can be calculated. The Kleihauer-Betke acid elution test does exactly that: fetal haemoglobin resists acid elution while adult haemoglobin washes out of the cells, so fetal cells stand out as dark ghosts and can be counted as a proportion of maternal cells, giving the volume of fetal blood. Flow cytometry for HbF-containing cells is the modern equivalent where available. A standard dose covers a defined volume of fetal red cells, and larger bleeds need more. The direct Coombs test detects antibody already bound to the infant's red cells, diagnosing haemolytic disease rather than measuring bleed volume. The indirect Coombs test screens maternal serum for antibody. Bilirubin and reticulocyte count assess neonatal haemolysis, not transplacental passage.

Answer: B — Chronic hepatitis B, inactive carrier state

This tests interpretation of the hepatitis B serological panel. Surface antigen persisting beyond six months defines chronic infection; anti-HBe positivity with a viral load under 2000 IU/mL, normal transaminases and a normal liver together define the inactive carrier, or HBeAg-negative infection, phase. Here immune control holds replication low with little hepatocyte injury, so no antiviral therapy is needed, but six-monthly ALT and viral load monitoring is required as reactivation can occur years later. Acute infection would show IgM anti-HBc with high transaminases. HBeAg-negative active disease carries a viral load above 2000 IU/mL with raised or fluctuating ALT, absent here. Resolved infection requires loss of HBsAg and appearance of anti-HBs, but her surface antigen is still present. Vaccine immunity gives isolated anti-HBs with negative core antibody.

Answer: B — Propranolol

This is essential tremor, and the first-line drug is propranolol. The tremor is bilateral, postural and kinetic, present holding a cup or writing rather than at rest, progressive over years, and eased by a small amount of alcohol; absence of rigidity, bradykinesia and gait disturbance separates it from parkinsonism. Propranolol reduces amplitude by blocking peripheral beta-2 receptors on muscle spindles, typically halving tremor at 80 to 320 mg daily, with asthma and heart block as contraindications. Levodopa treats Parkinson's disease and does nothing for postural tremor. Primidone is an equally effective alternative, preferred when a beta blocker is contraindicated, but its sedation and first-dose reaction make it second choice here. Diazepam is only an adjunct where anxiety worsens the tremor. Trihexyphenidyl is an anticholinergic for parkinsonian tremor.

Answer: A — Digital block with 1% lidocaine without adrenaline up to 4.5 mg/kg

This tests digital anaesthesia and the safe dose of plain lidocaine. A ring (digital) block at the base of the finger anaesthetises all four digital nerves with a small volume. Infiltrating around or into the nail bed is painful and works poorly because the tissue is tightly bound to bone, which rules out options D and E. Traditional teaching, and the expected exam answer, is to avoid adrenaline in fingers because the digital arteries are end arteries and vasospasm might cause ischaemia, so plain lidocaine is chosen and option B is marked wrong. Modern hand-surgery evidence shows that lidocaine with adrenaline is in fact safe in healthy digits, and many UK units now use it, but the exam still expects the plain solution. The maximum dose of plain lidocaine is about 3 mg/kg (BNF: 200 mg in an adult), quoted up to 4.5 mg/kg in some sources; adrenaline slows absorption and raises the ceiling to about 7 mg/kg, so option C pairs the higher dose with adrenaline.

Answer: C — Emergency tracheostomy

A rapidly enlarging hard thyroid mass in an elderly woman with hoarseness and stridor is anaplastic thyroid carcinoma until proved otherwise, but here the question is airway rescue, not diagnosis. Stridor, accessory muscle use, respiratory rate thirty and saturation eighty-eight per cent signify critical obstruction closing within minutes, taking precedence over all else. Because the obstruction lies at and below the larynx with the trachea deviated and invaded, orotracheal intubation may be impossible, so a surgical airway below it is definitive, performed by someone experienced. Fine-needle aspiration gives histology but does nothing for the airway and risks precipitating obstruction in a patient who cannot lie flat. CT maps extent but needs a supine patient and time she lacks. Chemotherapy and radiotherapy are later, with no immediate effect on obstruction.