Limited prognostic value of a staging system for twin-to-twin transfusion syndrome

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. Conclusion: 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. Copyright (C) 2004 S. Karger AG, Basel.