The purpose of this study was to examine differences in the way Britain and the United States invest in and deploy a new medical technology.

We used structured interviews to obtain information on the technical sophistication and approximate replacement value of all hospital-based obstetrical ultrasound machines in every maternity hospital in Washington state and Wales.

The supply of hospital-based ultrasound machines-approximately two machines per 1,000 births-was similar in both countries.

Wales had fewer advanced ultrasound machines than Washington state, and they were based exclusively in high-volume district general hospitals ; there were no obstetric ultrasound machines in the private sector.

In Washington state, the majority of advanced machines were in small and medium-sized hospitals, and many private offices had ultrasound machines.

The approximate replacement value of hospital-based machines was three times as high per birth in Washington state as in Wales.

In the case of obstetrical ultrasound, centralization of facilities, a relatively small private sector, and global budgeting lead to lower expenditures per patient within the National Health Service without compromising access to care.