title: Monoamniotic twinning and zona manipulation: a survey of U.S. IVF centers correlating zona manipulation procedures and high-risk twinning frequency.
abstract: OBJECTIVE
  An anonymous survey of IVF centers in the United States was employed to calculate frequencies of multiple gestation, monozygotic multiple gestation, and monoamniotic multiple gestation. Rates for zona-manipulated (ICSI, SUZI, zona drilling, mechanical assisted hatching) and non-manipulated pregnancies were compared.
  
  
  RESULTS
  From 42 IVF centers in the United States, a total of 143 pregnancies was ascertained from zona-manipulated cycles. A multiple gestation frequency of 16.1% was reported. Five monoamniotic twin gestations were identified: four from manipulated cycles and one from a nonmanipulated cycle. All monoamniotic twin gestations resulted in live births, although three showed significant intrauterine growth discordance and one newborn was diagnosed with the VATER malformation sequence.
  
  
  CONCLUSIONS
  Monoamniotic multiple gestations may be increased in zona-manipulated cycles. The potential obstetric risks and complications of zona manipulation should be discussed with patients.
authors: Division of Maternal-Fetal Medicine, Eastern Virginia Medical School, Norfolk 23508, USA.
authors: R N
authors: RN
authors: Slotnick
authors: J E
authors: JE
authors: Ortega
mesh_terms: D000328:Adult; D005260:Female; D005307:Fertilization in Vitro / Q000379:methods*; D006801:Humans; D008297:Male; D008846:Micromanipulation; D011247:Pregnancy; D011272:Pregnancy, Multiple / Q000706:statistics & numerical data*; D011795:Surveys and Questionnaires; D014430:Twins, Monozygotic / Q000706:statistics & numerical data; D015044:Zona Pellucida / Q000187:drug effects*