title: Invasive procedures in multiple gestations.
abstract: OBJECTIVE
  The incidence of multiple gestations has increased significantly with advances in assisted reproductive techniques resulting in a concomitant increase in invasive procedures in these pregnancies. Commonly performed invasive procedures include amniocentesis, chorionic villus sampling, multifetal pregnancy reduction, and selective termination. Amniocentesis and chorionic villus sampling are also performed in singleton pregnancies, while multifetal pregnancy reduction and selective termination are procedures that are unique to multiple gestations.
  
  
  RESULTS
  With increased operator experience, pregnancy loss rates after chorionic villus sampling, multifetal pregnancy reduction, and selective termination have decreased to acceptably low levels. Amniocentesis and chorionic villus sampling continue to have similar loss rates in experienced hands. A recent study suggests that amniocentesis in twins may have a higher post-procedural loss rate than in singletons; this may be due to the higher background loss rate of twins. There has been a recent increase in multifetal pregnancy reduction to a singleton with a trend towards improved outcomes over reduction to twins; future studies should focus on whether this confers a definitive advantage. Newer data suggests that selective termination after 20 weeks gestation in experienced hands does not increase loss rates over those procedures performed before 20 weeks. Newer techniques, such as cord coagulation, continue to be developed for selective termination in monochorionic pregnancies, though still with considerable morbidity and mortality.
  
  
  CONCLUSIONS
  In summary, invasive procedures in multiple gestations are now commonly performed with. It is our hope that primary prevention of high order multiple pregnancies by optimization of assisted reproductive techniques will decrease the need for these procedures.
authors.affiliation: Department of Obstetrics, Gynecology, and Reproductive Science, Division of Maternal-Fetal Medicine, Mount Sinai Medical Center, New York, New York 10029, USA. meredith.rochon@mssm.edu
authors.forename: Meredith
authors.initials: M
authors.lastname: Rochon
authors.forename: Joanne
authors.initials: J
authors.lastname: Stone
mesh_terms: D000025:Abortion, Eugenic; D000649:Amniocentesis; D015193:Chorionic Villi Sampling; D005260:Female; D005865:Gestational Age; D006801:Humans; D013513:Obstetric Surgical Procedures / Q000009:adverse effects; D011247:Pregnancy; D018607:Pregnancy Reduction, Multifetal; D011272:Pregnancy, Multiple; D011296:Prenatal Diagnosis / Q000379:methods*