RT Book, Section
A1 Bianchi, Diana W.
A1 Crombleholme, Timothy M.
A1 D'Alton, Mary E.
A1 Malone, Fergal D.
SR Print(0)
ID 1106401884
T1 Trisomy 18
T2 Fetology: Diagnosis and Management of the Fetal Patient, 2e
YR 2015
FD 2015
PB McGraw-Hill Education
PP New York, NY
SN 978-0-07-144201-5
LK obgyn.mhmedical.com/content.aspx?aid=1106401884
RD 2023/09/29
AB Key  PointsSecond  most  common  autosomal  trisomy  in  liveborn  infants.Eighty  to  85%  of  cases  result  from  full  trisomy,  10%  are  mosaics,  and  5%  are  due  to  translocation.Incidence  is  about  1  in  3000  livebirths.  Females  are  more  likely  to  be  born  alive  and  survive  longer.Most  affected  fetuses  have  more  than  one  sonographic  abnormality.  Most  common  sonographic  abnormalities  include  IUGR,  cardiac  structural  anomalies,  choroid  plexus  cysts,  central  nervous  system  anomalies,  and  overlapping  fingers/clenched  hands.Associated  with  low  maternal  serum  screening  levels  of  pregnancy-associated  plasma  protein  A,  estriol,  α-fetoprotein,  and  β  human  chorionic  gonadotropin.Median  postnatal  survival  for  males  is  1  to  2  months,  and  for  females  it  is  9  to  10  months.  The  presence  of  a  heart  defect  (surprisingly)  does  not  affect  postnatal  survival  time.  About  5%  to  10%  of  infants  survive  until  their  first  birthday.All  long-term  survivors  are  profoundly  retarded.  Despite  this,  there  are  increasing  reports  in  the  literature  of  aggressive  postnatal  treatment,  including  mechanical  ventilation,  cardiovascular  drugs,  parenteral  nutrition,  and  surgical  repair  of  congenital  anomalies.Reports  exist  of  adults  with  mosaic  trisomy  18  who  have  normal  intelligence.