30th April 2024

A 16-year-old female with known sickle cell disease presents to the emergency department with a 2-day history of fever, cough, and shortness of breath.

A 16-year-old female with known sickle cell disease presents to the emergency department with a 2-day history of fever, cough, and shortness of breath. She has a history of two hospital admissions in the past year for vaso-occlusive crises. She is currently taking folic acid supplements.

Investigations:

Temperature: 38.6°C

Respiratory rate: 24 breaths/min

Oxygen saturation: 92% on room air

Haemoglobin: 65 g/L (115–155)

White cell count: 12 × 10⁹/L (4.0–11.0)

Platelets: 180 × 10⁹/L (150–400)

Chest X-ray: Infiltrates in the right lower lobe

Which additional investigation is most appropriate to assess her current condition?