Bà mẹ alpha fetoprotein (AFP) được lấy mẫu xét nghiệm huyết thanh trong phần đầu của tam cá nguyệt thứ hai. AFP cao mức độ so với một giá trị trung bình được hiệu chỉnh về tuổi của người mẹ là tiên đoán của một cơ hội cao hơn của việc có một đứa trẻ với một NTD. Nó nên được công nhận rằng một số lượng lớn các bất thường bẩm sinh | 146 Pediatric Neurosurgery Figure 1. A typical open spina bifida lesion myelomeningocele . The large sac surrounds a midline neural placode. The muscles of the legs are atrophic with bilateral club feet. The anus is protruding or patulous . 8 Management Antenatal Diagnosis and Counseling Maternal alpha fetoprotein AFP is sampled by a serum blood test during the early part of the second trimester. An elevated AFP level compared to a median value corrected for maternal age is predictive of a higher chance of having a child with a NTD. It should be recognized that a large number of other congenital anomalies also result in elevated maternal serum AFP. If the predicted risk is higher than a specific threshold value typically 1 500 then a high-resolution ultrasound is recommended in the middle of the second trimester. The antenatal ultrasound often identifies the level of lesion in approximately two-thirds of patients and the presence of lower extremity deformities and characterizes the severity of associated abnormalities such as the Chiari II malformation and hydrocephalus. Amniocentesis is performed if the maternal AFP and ultrasound are equivocal. Some parents will choose early termination for a fetus with a myelomeningocele. This accounts for some of the reduction in birth incidence of spina bifida in the US in the past 10 to 20 years. For those parents who choose to carry the pregnancy to term the most important concern is long-term functional outcome see below . This discussion should focus on the primary disabilities associated with myelomeningocele and the treatment of hydrocephalus. The specific disabilities include lower extremity dysfunction urinary and fecal incontinence symptoms attributable to a Chiari malformation and cognitive impairment. The lower the lesion is in the spine the more likely the possibility of a favorable neurologic outcome. Quality of life issues are always discussed with the parents at every antenatal visit in order to prepare them for
