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Z ‐velocity in screening for intrauterine growth restriction
Author(s) -
Mondry A.,
Pengbo L.,
Loh M.,
Mongelli M.
Publication year - 2005
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.2598
Subject(s) - medicine , percentile , gold standard (test) , receiver operating characteristic , gestational age , intrauterine growth restriction , fetus , nuclear medicine , obstetrics , ultrasound , abnormality , predictive value , growth velocity , radiology , pregnancy , statistics , mathematics , genetics , psychiatry , biology
Abstract Objectives Ultrasound scans provide the basis for detection of intrauterine growth restriction (IUGR) but often fail to distinguish IUGR from small‐for‐gestational age (SGA) fetuses. This study introduces the concept of Z ‐velocity, calculated as changes in Z ‐scores over time, as an additional criterion in the diagnosis of IUGR. Methods A computer program simulated 50 000 fetal abdominal circumference (FAC) scans based on published growth formulae. False‐positive rates were calculated to determine optimal scan time and scan intervals. Using an independent simulation of 32 500 FAC scans, the two methods were compared using receiver–operating characteristics (ROC) curve analysis. Results ROC showed areas under the curve of > 0.74 over the complete range of scan intervals. The positive predictive value of growth arrest as the only diagnostic criterion was, however, too low to recommend it as an exclusive or the first diagnostic criterion. Conclusions Z ‐velocity can be used to decide whether further investigations for growth abnormality are required in fetuses that fall below the 10 th percentile. The gain of combined diagnostic approaches should be calculated from large databases that include the neonatal ponderal index as the gold standard. Copyright © 2005 ISUOG. Published by John Wiley & Sons, Ltd.