Hospitals in Afghanistan and the UK are being stretched by the large number of troops needing treatment after being injured in the Helmand province, the National Audit Office (NAO) has said.
Though the treatment of those badly wounded is highly effective, the government needs to plan more carefully for a rise in casualties in Afghanistan, according to the NAO.
About 4,000 British soldiers are expected to take part in the joint Nato and Afghan army operations.
The hospital in Helmand is now operating at almost full stretch and it is predicted it will come under even greater strain, the NAO said.
Any big increase in military patients at the Selly Oak centre in Birmingham could lead to more civilians being moved elsewhere.
Rates of minor injury and illness among troops deployed to Afghanistan nearly doubled between 2006 and 2009, increasing from 4% to 7% of the total.