Syria: An American doctor's experience in Aleppo
Dr Samer Attar is an orthopaedic surgeon. He lives and works in Chicago but has worked in the city of Aleppo, in Syria, several times. He has just come back from his most recent visit.
He told the BBC's Eddie Mair about the difficult decisions he had to make in an underground hospital, with few medical supplies.
This interview was broadcast on PM on Radio 4.