title: Limited prognostic value of a staging system for twin-to-twin transfusion syndrome.
abstract: OBJECTIVE
  Severe twin-to-twin transfusion syndrome (TTTS) is usually classified according to a staging system (I-V) based on ultrasonographic findings of polyhydramnios in the recipient, oligohydramnios in the donor, the presence or absence of the donor's bladder, Doppler waveform changes and (impending) hydrops. Stage correlates with the severity of disease, and it is assumed that, without intervention, severe TTTS will evolve in succession from stage I to stage V (fetal demise). However, this progression has not been validated in longitudinal studies. Herein, we report on the natural progression of severe TTTS in a cohort of patients from a regional Fetal Treatment Program.
  
  
  METHODS
  Eighteen patients with severe TTTS, diagnosed between 15 and 25 weeks of gestation, were managed over a 28-month period. Data were collected until delivery, endoscopic surgical intervention or dual fetal demise. Patients were evaluated at least once a week. Stage, estimated fetal weight, percent recipient/donor body weight discordance and survival were recorded.
  
  
  RESULTS
  The present study represents a total follow-up of 108 patient-weeks. Of 90 week-to-week evaluations, 65 showed no change in stage; 11 showed downstaging (by more than 1 stage in 3, or 27%), and 13 showed upstaging (by more than 1 stage in 8, or 62%). Nine patients (all stage II or above) underwent endoscopic laser ablation. Overall survival was 67%, and survival of at least 1 twin occurred in 78% of pregnancies. Weight discordance between the donor and recipient did not predict outcome.
  
  
  CONCLUSIONS
  The current staging system for severe TTTS may not be helpful in predicting the direction, degree or speed of progression of the condition. Indications for intervention should remain stage-related, and not based on projected progression.
authors.affiliation: Fetal Treatment Program, Women and Infants' Hospital and Hasbro Children's Hospital, Providence, RI, USA. Francois_Luks@brown.edu
authors.forename: François I
authors.initials: FI
authors.lastname: Luks
authors.forename: Stephen R
authors.initials: SR
authors.lastname: Carr
authors.forename: Michael
authors.initials: M
authors.lastname: Plevyak
authors.forename: Sabrina D
authors.initials: SD
authors.lastname: Craigo
authors.forename: Achilles
authors.initials: A
authors.lastname: Athanassiou
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Ralston
authors.forename: Thomas F
authors.initials: TF
authors.lastname: Tracy
mesh_terms: D015331:Cohort Studies; D018450:Disease Progression; D005260:Female; D005330:Fetofetal Transfusion / Q000000981:diagnostic imaging* / Q000601:surgery; D005332:Fetoscopy; D005500:Follow-Up Studies; D006801:Humans; D053685:Laser Therapy; D016104:Oligohydramnios / Q000000981:diagnostic imaging; D006831:Polyhydramnios / Q000000981:diagnostic imaging; D011247:Pregnancy; D011379:Prognosis; D012189:Retrospective Studies; D012720:Severity of Illness Index; D016019:Survival Analysis; D014430:Twins, Monozygotic; D014463:Ultrasonography