Analysis of Major Factors Affecting False Positive Results in Neonatal Screening Test within 3 Days after Birth

Objective: We examined the factors affecting the false positive results in the accidental neonatal screening test (NST) within 3 days after birth and tried to find out the most relevant factors. Methods: From January 2011 to December 2016, we reviewed the electronic medical records of 142 patients with a gestational age of 34 weeks or more who had false positives at the first NST. NST was performed by tandem mass spectrometry. We collected information on gestational age, birth weight, delivery method, Apgar score at the time of birth. Postnatal exam time, body weight, feeding volume and parenteral nutrition, antibiotics, and steroid administration were also investigated at the time of NST. Results: In the first NST, there were 102 cases of congenital adrenal hyperplasia, 27 cases of congenital hypothyroidism, nine cases of galactosemia and one case of homocystinuria. Gender, birth weight, and delivery method were statistically significant (P<0.05) at the time of birth using Pearson Chi-square method. There were significant differences in body weight, feeding volume, parenteral nutrition at the time of NST (P<0.05). In binary logistic regression analysis, the gender and the body weight seemed significant statistically. Conclusion: Male sex and weight were identified as major factors of the false positive results in the NST performed within 3 days after birth, but further studies seemed to be needed. In the case of patients with short admission period or insufficient perinatal information, the first NST after birth should be performed at the time of outpatient department or after precise information collection.