The Predictive Value of Use of Dry Brain Sign as Simple Sonographic Marker of Open Spina Bifida at First Trimester Anomaly Scan

Spina Bifida is the most common congenital abnormality of the central nervous system it was detected during 2nd trimester anomaly scan; it is a congenital defect of neural tube closure that occurs exactly between 24 and 26 days of gestation. But detection of it at first trimester by using dry brain sign which is caused by cerebrospinal fluid leakage and choroid plexus expansion into the lateral ventricles which is could be promising marker for prediction of spina bifda. the use of dry brain sign in first trimester mainly between 11 to 13 weeks as sonographic marker for early detection of spina bifida and reduction of the complications associated with late pregnancy terminations and its costs. Objectives to highlight the role of measuring dry brain sign in 1st trimester scan as fetal sonographic marker for spina bifida Methods This prospective case control study of 50 cases of single tone fetus referred for First trimester scan at fetal unit at the pregnant women tertiary hospital, divided into two groups: 25 control group population had normal first- followed by second-trimester ultrasound findings, 25 case group had positive dry brain sign on ultrasound which show large choroid plexuses with no cerebrospinal fluid around In both groups we measured each CP at its longest length then calculated the mean CP length .and measured biparietal diameter and the largest occipitofrontal diameter .The collected data was correlated with late 2nd trimester and 3 rd trimester scan Results Both mean CP/BPD and mean CP/OFD are increased in cases group with almost choroid plexus filling the lateral ventricle (dry brain sign) with mean CP/BPD ratio Using ROC curve, could be used in diagnosis of SOB (P0.05) at a cutoff level ≥92.6, with sensitivity, specificity, positive and negative predictive value equal to 64% Conclusions between 11-13 weeks with OSB showing choroid plexuses filling the lateral ventricle with reduced fluid in ventricles giving appearance of dry brain sign which could be measured during routine first-trimester ultrasound examination and including it into check list will add value in early detection of open spina bifida