360: Does first-trimester ultrasound predict obstetrical and neonatal outcomes in monochorionic diamniotic twin pregnancies?

lucency ultrasound with evaluation of the fetal anatomy at 11-14 weeks AND an early second trimester fetal anatomical survey between 15 and 17 weeks. All cases of ONTD diagnosed in our unit were identified using ICD-9 codes, and all MSAFP results over the same time frame were queried. Groups were compared using Fisher Exact test with p 0.05 as significance. RESULTS: Our unit performed 17,656 nuchal translucency ultraounds and 21,436 early anatomical surveys, and sent 11,809 speciens for MSAFP during the study period. 11 ONTD were diagnosed y our unit during this time frame (incidence of 0.56 to 0.67 per 1000). 1/11 ONTD (100%) were diagnosed by ultrasound; 0/11 (0%) were etected after MSAFP screening (p 0.0001). 7/11 cases (64%) were iagnosed during the first trimester; 4/11 (36%) were diagnosed at the arly second trimester anatomy scan. No cases of ONTD were diagosed after 18 weeks’ gestation, and no cases of ONTD were missed by ur unit (sensitivity 100%). CONCLUSION: Ultrasound for fetal anatomical survey during the first and early second trimester detected 100% of ONTD in our population with the majority identified in the first trimester. MSAFP was not useful as a screening tool for neural tube defects in the setting of this ultrasound screening protocol.