A 19-year-old woman presented to her local emergency department with acute chest pain and shortness of breath. She denied any cough, haemoptysis, fever or leg swelling.

Her past medical history was significant for premature birth at 28 weeks gestational age. She required surgical correction of a right clubfoot as an infant. In addition, she had intestinal malrotation complicated by caecal volvulus and perforation treated with laparotomy at age 13, and an ovarian cystectomy performed at age 17. There was no family history of pneumothorax or respiratory disease. She was a non-smoker on no medications.

On examination, she was tachycardic, tachypnoeic and had an oxygen saturation in the low 80s. Her respiratory exam demonstrated decreased air entry to bilateral lung bases. A chest radiograph …