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Medical ultrasound
1958 (Donald, Glasgow; earlier work 1940s)· Invention or discovery· Medicine & surgery
Mostly agreedGood evidence; some details, dates or numbers uncertain.
Imaging the inside of the body with high-pitched sound waves and their echoes, without X-rays or surgery.
See it on the Technology & Medicine map →How it works
A probe sends pulses of sound, millions of vibrations per second and far above human hearing, into the body. Each boundary between tissues reflects some sound back, and timing the echoes shows how deep it lies. Glasgow obstetrician Ian Donald, with engineer Tom Brown and doctor John MacVicar, adapted an industrial metal-flaw detector and in 1958 published images of abdominal tumours, and soon of unborn babies. Earlier attempts dated from the 1940s.
Why it mattered
Using no ionizing radiation, it became the safe, cheap standard for checking pregnancies, and is now used for the heart and other organs and for guiding needles.
How we know
Donald, MacVicar and Brown's paper in The Lancet, June 1958; Brown's later accounts; preserved early scanners; and decades of clinical studies on its safety.
Still unknown or debated
Who invented it depends on the use: Karl Dussik tried brain scans in Austria in 1942, and John Wild and Douglass Howry made body images in the US in the early 1950s.
Connections (2)
▸Radar shared pulse-echo principles with Medical ultrasoundMostly agreed
The connection
Radar sends out radio pulses and times the echoes to find aircraft. Ultrasound does the same with sound: a probe sends short, very high-pitched pulses into the body and times the echoes from each tissue boundary to locate it. Wartime radar electronics, plus sonar and metal-flaw detectors using the same pulse-echo idea, supplied the hardware.
When and how
Radar in Britain, the US, Germany and elsewhere in the 1930s–40s; Ian Donald, who learned about radar and sonar in the RAF during the war, began ultrasound work in Glasgow in the mid-1950s.
How sure are we?
Donald credited his wartime RAF exposure to radar and sonar, and early ultrasound machines used the same pulse timing and oscilloscope screens as radar.
Debates and open questions
Sonar, which uses sound underwater, is arguably a closer parent than radar; how to split credit among radar, sonar and industrial flaw detectors is a matter of emphasis.
▸Medical ultrasound guides egg collection in In vitro fertilisation (IVF)Well documented
The connection
Early IVF needed keyhole surgery under general anaesthetic to collect eggs. From the 1980s doctors instead used ultrasound to see the ovaries and guide a thin needle into each follicle, the fluid-filled sac holding an egg. Ultrasound also tracks follicle growth before collection and confirms early pregnancy afterwards.
When and how
First ultrasound-guided egg collection by Susan Lenz's team in Copenhagen, Denmark, in 1981; vaginal-probe methods spread from the mid-1980s and are now standard.
How we know
Clinical papers from the 1980s and current IVF guidelines describe ultrasound-guided collection as routine, replacing keyhole surgery.
Debates and open questions
Little is debated; research continues on reducing the number of scans needed and on whether 3D ultrasound improves pregnancy rates.