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Doppler ultrasound waveform indices: A/B ratio, pulsatility index and Pourcelot ratio
Author(s) -
THOMPSON ROSEMARY S.,
TRUDINGER BRIAN J.,
COOK COLLEEN M.
Publication year - 1988
Publication title -
bjog: an international journal of obstetrics and gynaecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.157
H-Index - 164
eISSN - 1471-0528
pISSN - 1470-0328
DOI - 10.1111/j.1471-0528.1988.tb09487.x
Subject(s) - waveform , pulsatility index , converse , statistics , doppler effect , doppler ultrasound , mathematics , index (typography) , ultrasound , umbilical artery , medicine , computer science , physics , pregnancy , radiology , telecommunications , biology , fetus , radar , geometry , astronomy , world wide web , genetics
Summary. Three different indices, the A/B ratio, the pulsatility index (PI) and the Pourcelot ratio (PR), are in common use for quantitative analysis of umbilical artery Doppler ultrasound waveforms. A detailed examination of the similarities and differences between these indices, together with the expected errors for each, was undertaken to enable informed comparisons and choices to be made. The indices were calculated from 133 last trimester recordings using an objective and very reliable computer analysis technique. The PI is more difficult to calculate than the other two quantities and the extra computation does not provide any extra information. The A/B ratio appears the simplest index to use but the values are not normally distributed. With the PR a normal distribution of values can be assumed. A theoretical consideration of errors showed that none of the indices is intrinsically less error prone for last trimester waveforms overall. The errors in the A/B ratio increase as the value of the index increase, whereas the converse holds for the PI and PR.