Quintero and collaborators proposed a classification of TTTS to categorize the different degrees of severity that can occur in TTTS:
Quintero TTTS Staging System
- Stage I: The fetal bladder of the donor twin remains visible on ultrasound.
- Stage II: The bladder of the donor twin is not visible on ultrasound.
- Stage III: Doppler studies in either twin are critically abnormal fetal. These include: absent or reverse end-diastolic velocity (AREDV) in the umbilical artery, absent or reverse flow in the ductus venosus, or pulsatile flow in the umbilical vein.
- Stage IV: Fetal hydrops is noted. Stage V: Demise of one or both twins.