Criteria of Khalil et al for the Twin Anemia-Polycythemia Sequence (TAPS)

Patient selection: twin gestation

Monitoring frequency:

(1) initially every 2 weeks

(2) if TAPS identified, then every week

Antenatal measurement: middle cerebral artery peak systolic velocity (MCA PSV), as multiple of mean (MoM)

Criteria 1 (antenatal):

Criteria 2 (antenatal):

MCA PCV discordance [(anemic MoM) - (polycythemic MoM)] >= 1.0

Criteria 3 (postnatal):

Hemoglobin difference between the neonates >= 8.0 g/dL

Criteria 4 (postnatal):

ratio of reticulocyte count in anemic topolycythemic neonates >= 1.7