title: Ultrasonographic development of the fetal sheep stomach and evaluation of early gestation ultrasound-guided in utero intragastric injection.
abstract: OBJECTIVE
  Safely targeting the fetal gastrointestinal tract during early gestation is essential to develop effective prenatal gene therapy for gastrointestinal diseases. In this study, we aimed to characterize the development of the fetal sheep stomach sonographically and to determine the optimum gestational age, as well as the shortterm morbidity and mortality of early-gestation ultrasound-guided intragastric injection.
  
  
  METHODS
  In experiments investigating ultrasound-guided prenatal gene therapy, we studied the size and development of the stomach of 185 sheep fetuses (33-144 days' gestational age [GA]; term is 145 days). Ultrasound-guided intragastric injection was performed in 12 fetuses at 55-62 days' GA and postmortem examinations were performed 48 hours later.
  
  
  RESULTS
  The stomach was not visible at or before 40 days' GA, but it was seen in all fetuses at 55 days' GA or more. The anteroposterior, transverse and longitudinal diameters of the stomach increased in a quasi-linear fashion throughout gestation. Intragastric injection was successful in 10 out of the 11 fetuses (91%) injected at 60-62 days' GA, with nine fetuses (91%) surviving this procedure.
  
  
  CONCLUSIONS
  In the early-gestation sheep fetus, ultrasound-guided intragastric injection has a good success rate with a low short-term mortality and morbidity.
authors.affiliation: Fetal Medicine Unit and Prenatal Cell and Gene Therapy Group, EGA Institute for Women's Health, University College London, London, UK.
authors.forename: Anna L
authors.initials: AL
authors.lastname: David
authors.forename: Khalil N
authors.initials: KN
authors.lastname: Abi-Nader
authors.forename: Boaz
authors.initials: B
authors.lastname: Weisz
authors.forename: S W Steven
authors.initials: SW
authors.lastname: Shaw
authors.forename: Michael
authors.initials: M
authors.lastname: Themis
authors.forename: Terence
authors.initials: T
authors.lastname: Cook
authors.forename: Charles
authors.initials: C
authors.lastname: Coutelle
authors.forename: Charles H
authors.initials: CH
authors.lastname: Rodeck
authors.forename: Donald M
authors.initials: DM
authors.lastname: Peebles
mesh_terms: D000256:Adenoviridae; D000818:Animals; D005260:Female; D015316:Genetic Therapy / Q000379:methods*; D005865:Gestational Age; D007267:Injections; D011247:Pregnancy; D012756:Sheep; D013270:Stomach / Q000000981:diagnostic imaging* / Q000196:embryology*; D018084:Ultrasonography, Interventional; D001616:beta-Galactosidase / Q000235:genetics
chemical_list: D001616:beta-Galactosidase