Endometrial dating images
The early bistable oscilloscopic B-scan image at the level of the BPD and the A-scan tracing showing cephalic (P and D) and midline echoes (M).
The distance between the 2 cephalic echoes is the BPD.
It was not until 1979 that Margi Mantoni and Jan Fog Pederson in Copenhagen first described the visualization of the yolk sac, using the static B-scan.
Also read a brief discussion on the historical aspects of the fetal trunk circumference measurements.
In 1975, the Campbell group introduced the measurement of the abdominal circumference which has since then remained the most important single parameter to assess fetal weight and nutrition.
Circumference measurements of the fetal trunk is considered superior to diameter measuements as the former is less affected by the change in shape of the fetal body.
In 1971, with improvements in the caliper system, Campbell and Newman published normograms for the biparietal diameter from the 13th weeks of gestation and has made cephalometry a standard tool for the assessment of fetal growth and maturity.
Many early paper in cephalometry followed in the late 1960s such as those from Boog in France, Khentov in the USSR, Zacutti and Brugnoli in Italy, Kratochwil in Austria and Pystynen and Ylostalo in Finland.
The measurements were done 'blindly' without actually seeing the structures under study.
Without scan converters on-screen (oscilloscope) measurements on the B-mode image are not possible.
Very accurate measurements can however be made using the A-scan calipers.
Both had appeared as landmark papers in the Lancet.
They were the first cases of these conditions in which a correct diagnosis by ultrasound had effectively led to a termination of pregnancy.
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Two years later in 1973, measurement of the fetal crown-rump length was described by Hugh Robinson in Glasgow who was then a research registrar.