This paper analyzes the cause of false signallings that result in abnormal ex-change disconnection, abnormal user off - hook, some ways against them is showed.
Considering MRA as the standard, the sensibility of diagnosing abnormal vessels by TCD was 78.10%, specificity 94.22%, false positive 7.46%, false negative 23.31%, and the coincidence rate 89.36%.
Objective To determine the sensitivity and false-positive rate of maternal serum pregnancy associated plasma protein a (PAPP-A) screening for abnormal fetal karyotype.