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Intraobserver and interobserver variation in the sonographic grading of placental maturity
Author(s) -
Sau A.,
Seed P.,
Langford K.
Publication year - 2004
Publication title -
ultrasound in obstetrics and gynecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.202
H-Index - 141
eISSN - 1469-0705
pISSN - 0960-7692
DOI - 10.1002/uog.1004
Subject(s) - kappa , medicine , cohen's kappa , grading (engineering) , placenta , obstetrics , reproducibility , nuclear medicine , pregnancy , radiology , gynecology , fetus , statistics , mathematics , civil engineering , biology , engineering , genetics , geometry
Objectives The appearance of Grannum Grade III changes in the placenta at around 34–36 weeks is a predictor of adverse perinatal outcome, which may be reduced by reporting to the clinician. This has led to the suggestion that the placental grade should be noted during any third‐trimester scan. There are no published data on the reproducibility of sonographic Grannum grading of the placenta; the objective of this study was to evaluate intra‐ and interobserver variation. Methods Fifty‐five placental images from normal and complicated pregnancies of several different gestational ages were collected between April and October 2001. Three fetal medicine consultants and three experienced sonographers graded the images as 0, I, II, III or ungradeable. They then regraded the same images, presented in a different order and with different codes, 4–6 weeks later. Observers were blinded to their previous grading and to each others'. Weighted kappa (κ), with linear weights, was used to look for strength of agreement. Results There was good agreement between the two observations of each placental image for five observers (κ = 0.61 to 0.90), and moderate agreement for one observer (κ = 0.56). However, the κ‐values for comparisons between the 15 pairs of observers ranged from 0.24 to 0.69 with six values below 0.41, indicating only fair agreement. This was confirmed by the overall κ‐value of 0.24 between all six observers. The agreement between the observers for Grade III placenta was poor, with an overall κ‐value of 0.09. Conclusions Although intraobserver agreement was generally good, interobserver agreement was only fair for all grades and poor for Grade III placenta. This may be an indication that Grannum grading is not reproducible or it may reflect a need for training in those performing grading. Such variation may limit the effectiveness of reporting Grannum grades in clinical practice. Copyright © 2004 ISUOG. Published by John Wiley & Sons, Ltd.