title: Multiple implantation after oocyte donation: a frequent but inefficient event.
abstract: OBJECTIVE
  To evaluate the natural history of multiple implantation in a donor oocyte program.
  
  
  METHODS
  Retrospective review of clinical pregnancies resulting from donor oocytes with analysis of serial vaginal ultrasound examinations beginning 21 days after embryo transfer.
  
  
  METHODS
  University of Southern California IVF program (USC-IVF).
  
  
  METHODS
  Number of implantation sites lost during gestation, furthest development of the gestation, and clinical symptoms of those experiencing loss.
  
  
  RESULTS
  Sixty-two of 101 patients (61%) who became pregnant had multiple implantations, 41 (41%) with two sacs, 12 (12%) with three sacs, 6 (6%) with four sacs, and 3 (3%) with five sacs. Overall 28% of implantations sites were lost spontaneously. Rates of loss were similar for multiple implantations. The majority (62%) of these nonviable sacs did not develop beyond a gestational sac. All patients with three or more implantation sites had ongoing pregnancies through the first trimester. The probability of pregnancy loss after visualization of fetal heart motion was 5.7%. Few patients who underwent a natural self reduction of sacs were symptomatic.
  
  
  CONCLUSIONS
  There is a significant self-reduction in multiple implantation sites in a donor oocyte program. This may obviate the need for a selective reduction procedure. Patients should be followed for up to 10 weeks after ET before committing to a selective reductive procedure.
authors.affiliation: Department of Obstetrics and Gynecology, University of Southern California School of Medicine, Los Angeles.
authors.forename: R S
authors.initials: RS
authors.lastname: Legro
authors.forename: I L
authors.initials: IL
authors.lastname: Wong
authors.forename: R J
authors.initials: RJ
authors.lastname: Paulson
authors.forename: R A
authors.initials: RA
authors.lastname: Lobo
authors.forename: M V
authors.initials: MV
authors.lastname: Sauer
mesh_terms: D000022:Abortion, Spontaneous / Q000453:epidemiology; D010064:Embryo Implantation; D005260:Female; D006801:Humans; D015994:Incidence; D018587:Oocyte Donation; D011247:Pregnancy; D011272:Pregnancy, Multiple; D012189:Retrospective Studies; D014463:Ultrasonography; D014599:Uterus / Q000000981:diagnostic imaging