Table 5.

New proposed classification for sFGR in monochorionic pregnancies.

Stage	Ultrasound Findings
Stage I	Normal umbilical artery Doppler in the small twin (positive end-diastolic flow)
Stage IIa	Persistent absent or reversed end-diastolic flow in umbilical artery Doppler in the small twin
Stage IIb	Intermittent absent or reversed end-diastolic flow in umbilical artery Doppler in the small twin
Stage III	Abnormal ductus venosus in the small twin
Stage IV	Superimposed TTTS
Stage V	Intrauterine demise of the small twin