Doctor of Philosophy
Department of Nursing
Niknafs, Parvin, Identification of intrauterine growth restricted babies: development of an IUGR index, Doctor of Philosophy thesis, Department of Nursing, University of Wollongong, 2000. http://ro.uow.edu.au/theses/1614
An important goal in contemporary obstetrics is the identification of high risk pregnancies. Early detection of intrauterine growth restriction (IUGR) is an important item in this context. Intrauterine growth restriction as a result of utero-placental insufficiency is an important cause of death and physical and mental handicap. However, the diagnosis of this condition remains a problem. Although, many techniques have been proposed to detect IUGR, most of them have been criticized as having low level of sensitivity, specificity and positive and negative predictive values. The current study conducted to develop an index with the combination of ultrasonographic parameters and risk factors for IUGR to identify IUGR babies as a result of utero-placental insufficiency as defined by nutritional indicators of IUGR. The validity of a few objectives was also evaluated in the process of this study. It included an assessment of the accuracy of single ultrasound parameters in the detection of IUGR, identification of the most important risk factors for IUGR and comparison of some important proposed ultrasound parameters between the Iranian and Australian samples.
The main study samples are composed of two sets of data, data from Iranian fetuses and data from Australian fetuses. The Iranian study was undertaken, prospectively, on 296 Iranian pregnant women in Shahrood, Iran from October 1998 to June 1999. The study conducted in Australia was based on a retrospective sample of 219 pregnant women attending Wollongong Hospital in the Illawarra region in NSW, Australia. Data on ultrasonographic parameters, maternal risk factors for IUGR and neonatal and foetal characteristics were collected. Data on ultarsononographic and maternal risk factors for IUGR from 74 Iranian pregnant women from May 1999 to July 1999 were used in the next stage of study to evaluate the validity of the developed index.
The results of this study showed that abdominal circumference was as the best single ultrasound parameter as an indicator of IUGR with a reasonably high sensitivity of around 88-94% in the Australian sample and 88-84% in the Iranian sample. However, the positive and negative predictive values for all of the proposed ultrasound parameters were low. This was shown by a high number of false positive and false negative cases detected. Thus, single ultrsonographic parameters do not allow one to diagnose IUGR with confidence.
Chi-square analyses of the risk factors for IUGR showed that asthma (ppppppppp
An IUGR Index consisting of abdominal circumference, head circumference-abdominal circumference ratio, amniotic fluid index, hypertension and low maternal weight gain was developed based on Discriminant analysis of all the proposed ultrasonograhic and risk factors parameters. The developed index has a higher ability and accuracy in the prediction of IUGR than single ultrasound parameters. Validation of the developed index also confirms this and also shows that the index has the ability to detect infant mortality and morbidity.