twin; (2) oligohydramnios, MVP ≤ 2 cm in the donor twin; (3) single placenta, thin dividing membrane, and similar external genitalia.
In a study of 178 twin pairs [9], only four pairs had a hemoglobin difference > 5 g/dL and a weight difference >20%, and none of those pregnan- cies showed evidence of polyhydramnios or oligo- hydramnios. Similarly, percutaneous umbilical blood sampling in six TTTS patients failed to show hemoglobin differences >5g/dL, except in one pregnancy [10]. Consequently, the previous pedi- atric criteria of a hemoglobin difference >5g/dL and a weight difference > 20% are no longer appli- cable [6].
The severity of TTTS depends on several prog- nostic factors, the most important of which is the Doppler flow of the two involved fetuses; the most widely used criteria for TTTS staging is that of Quintero et al [11], which is as follows:
• Stage I — the bladder of the donor twin is still visible, and Doppler studies are still normal;
• Stage II — the bladder of the donor twin is not visible (during the length of the examination, usually 1 hour), but Doppler studies are not crit- ically abnormal;
• Stage III — Doppler studies are critically abnormal in either twin and are characterized as absent or reverse end-diastolic velocity in the umbilical artery, reverse flow in the ductus venosus, or pulsatile umbilical venous flow;
• Stage IV — presence of ascites, pericardial or pleural effusion, scalp edema, or overt hydrops;
• Stage V — demise of one or both fetuses.
There were about 80 cases of TTTS predicted to occur each year in Taiwan [12]; half of them would be the severe form (diagnosed before gestational age of 26 weeks). So familiarity with the diagnostic criteria of TTTS would be necessary for medics who would possibly manage the high-risk multiple
pregnancy.
twin; (2) oligohydramnios, MVP ≤ 2 cm in the donor twin; (3) single placenta, thin dividing membrane, and similar external genitalia.In a study of 178 twin pairs [9], only four pairs had a hemoglobin difference > 5 g/dL and a weight difference >20%, and none of those pregnan- cies showed evidence of polyhydramnios or oligo- hydramnios. Similarly, percutaneous umbilical blood sampling in six TTTS patients failed to show hemoglobin differences >5g/dL, except in one pregnancy [10]. Consequently, the previous pedi- atric criteria of a hemoglobin difference >5g/dL and a weight difference > 20% are no longer appli- cable [6].The severity of TTTS depends on several prog- nostic factors, the most important of which is the Doppler flow of the two involved fetuses; the most widely used criteria for TTTS staging is that of Quintero et al [11], which is as follows:• Stage I — the bladder of the donor twin is still visible, and Doppler studies are still normal;• Stage II — the bladder of the donor twin is not visible (during the length of the examination, usually 1 hour), but Doppler studies are not crit- ically abnormal;• Stage III — Doppler studies are critically abnormal in either twin and are characterized as absent or reverse end-diastolic velocity in the umbilical artery, reverse flow in the ductus venosus, or pulsatile umbilical venous flow;• Stage IV — presence of ascites, pericardial or pleural effusion, scalp edema, or overt hydrops;• Stage V — demise of one or both fetuses.There were about 80 cases of TTTS predicted to occur each year in Taiwan [12]; half of them would be the severe form (diagnosed before gestational age of 26 weeks). So familiarity with the diagnostic criteria of TTTS would be necessary for medics who would possibly manage the high-risk multiplepregnancy.
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