Diagnostic accuracy of biochemical tests of placental function versus ultrasound assessment of fetal size for stillbirth and small-for-gestational-age infants

This is the protocol for a review and there is no abstract. The objectives are as follows:

The primary objective of this review is to assess and compare the diagnostic accuracy of ultrasound assessment of fetal growth and placental biomarkers alone and in any combination used after 24 weeks of pregnancy in the identification of placental dysfunction as evidenced by either stillbirth or born small-for-gestational age (SGA). Accuracy is described by the proportion of fetuses who are subsequently stillborn or who have a SGA baby detected by a positive test result (the presence of placental dysfunction) (sensitivity) and by the proportion of fetuses that have an uncomplicated pregnancy following a negative index tests result (absence of placental dysfunction) (specificity).

We will investigate the effect of clinical (patient and test characteristics) and methodological factors (study design, threshold used to define SGA) on test performance. The clinical factors include patient group (low-risk or high-risk pregnancies), gestation at measurement, ethnicity, maternal age and method of testing. With regard to methodological variation, studies may include an intervention (delivery or additional fetal surveillance for test positive cases) which will impact on the outcome; therefore we will assess whether this is a source of heterogeneity.