<prompt> Increased acetylcholinesterase in amniotic fluid indicates -Open neural tube defectsOesophageal atresiaDown syndromeEdwards syndrome  <response>: A Open neural tube defects 1998 - Nelson 19th Failure of closure of the neural tube allows excretion of fetal substances a-fetoprotein , acetylecholinesterase into the amniotic fluid, serving as biochemical and markers of a neural tube defects NTD. Prenatal screening of maternal serum of AFP in the 16th - 18th week gestation is an effective method for identifying pregnancies at risk for features with NTDA in utero. Risk factor for neural tube defects william obsi Family history of NTD-First degree relative 2 - 3 Autosomal dominant or Autosomal recessive - 20 - 3 times highter.ii Exposure to certain environmental agents, malnutrition.iii Diabetes Hyper glycemiaMatemal obesity.iv Hyperthermiav Drugs - valproic acid, carbamazepine, Aminopterin and isotretinoin Anacephaly or encephalocelevi Genetic syndrome with known recurrence risk Meckel - Gruber, Roberts - SC, Phocomelia, Jarco Levin and HARDE syndrome.vii Trisomy 13 and 18 and Triploidy all have 1 recurrence risk. Major NTDs include - spina bifida occulta, meningocele, myelomeningocele, encephalocele, anencephaly, caudal regression syndrome, dermal sinus, tethered cord, syringomyelia, diastematomyelia and lipoma involving the conus medullaris and or filum terminale and the rare condition anencephaly.Prevention - The U.S. Public health service has recommended that all women of child bearing age and who are capable of becoming pregnant take 0.4 mg folic acid daily. Nuchal translucency is used for screening of Down syndrome in antenatal USG 