Farrell, R.N., M.S.N., Mary E. Dabrowiak, R.N., M.S.N., Leslie N. Sutton, M.D., Nalin Gupta, M.D., Ph.D., Noel B. Tulipan, M.D., Mary E. D’Alton, M.D., and Diana L. Farmer, M.D. For the MOMS Investigators: A Randomized Trial of Prenatal versus Postnatal Repair of Myelomeningocele Spina bifida may be the most common of congenital anomalies of the central nervous program that are compatible with life. The most frequent type is myelomeningocele, characterized by the extrusion of the spinal-cord into a sac filled with cerebrospinal fluid, leading to lifelong disability.The analysis was conducted according to the protocol, available with the full text of this article at NEJM.org. Efficacy Assessments Serum HCV RNA amounts were measured by using the COBAS AmpliPrep/COBAS TaqMan HCV Test, edition 2.0 , with a lower limit of quantification of 43 IU per milliliter and a lower limit of detection of 15 IU per milliliter. Serum HCV RNA levels were measured at the next points during the study: at screening; at baseline; at 6, 12, 24, 48, and 72 hours following the first dose; weekly through the entire 8-week or 12-week treatment period; and at 2, 4, 8, 12, and 24 weeks after treatment.