Twin Anemia Polycythemia Sequence: Current Views on Pathogenesis, Diagnostic Criteria, Perinatal Management, and Outcome.Twin Res Hum Genet. 2016;19:222-233. [PMID: 27068715 DOI: 10.1017/thg.2016.18]

Twin-twin transfusion syndrome - What we have learned from clinical trials

Monochorionic twin pregnancies are at increased risk for adverse outcome compared to dichorionic twin pregnancies and singletons. Monochorionic-specific complications include twin-twin transfusion syndrome (TTTS), twin anemia-polycythemia sequence, single intrauterine fetal demise and its consequences on the co-twin, and selective intrauterine growth restriction. Whereas the natural history of monochorionic-specific complications carries a high risk of fetal death or severe neurologic disability, a framework now exists, based on well-designed clinical trials, for optimal treatment of these entities. Fetoscopic selective laser coagulation of anastomotic vessels on the chorionic plate has been clearly demonstrated to improve survival and neurologic outcomes for Quintero stage ≥2 TTTS. However, many challenges remain unsolved, the most important of which is preterm premature rupture of membranes. Further improvement in the outcomes of monochorionic pregnancies will require improvements in the rate of premature delivery, and improved diagnosis and treatment strategies for early and late onset TTTS.

Redness discordance in monochorionic twin placentas: Correlation with clinical and placental findings

INTRODUCTION/OBJECTIVES

Recent studies suggest redness (color) discordance of the placental basal plate may be a marker for twin anemia-polycythemia sequence (TAPS), a recently described complication of diamniotic-monochorionic twinning characterized by marked intertwin hemoglobin (Hb) discordance in the absence of oligohydramnios-polyhydramnios. In this study, we determined the clinicoplacental and choriovascular correlates of basal plate color discordance in monochorionic twin placentas, and assessed its value as postnatal indicator of TAPS.

METHODS

We performed a clinicoplacental analysis of 100 consecutive non-TTTS diamniotic-monochorionic twin placentas with available photographic documentation of the basal plate. Basal plate redness was quantified by computer-assisted analysis of digital images and expressed as intertwin color difference ratio (CDR).

RESULTS

The CDR ranged between 1.00 and 3.58 (median CDR: 1.14; 90^th %ile: 1.98). Compared to twins with low CDR (N = 90), twins with high CDR (≥2.0; N = 10) had significantly higher hemoglobin difference (11.25 g/dL versus 2.55 g/dL) and significantly fewer and smaller artery-to-artery (AA) and artery-to-vein (AV) anastomoses. Apgar scores and birth weights were equivalent in both groups. Among the 10 twin sets with high CDR, six (60%) qualified as TAPS, as defined by intertwin Hb difference >8 g/dL and absent or very small AA and AV anastomoses. Conversely, 6 of 8 (75%) twin sets with TAPS had a CDR ≥ 2.0.

CONCLUSION

Intertwin CDR correlates with intertwin hemoglobin difference and chorionic angioarchitecture. A CDR value ≥ 2.0 (the 90%ile value for CDR derived from the present cohort) has high specificity (96%), but relatively low positive predictive value (60%) as indicator of TAPS, as currently defined.

Can color difference on the maternal side of the placenta distinguish between acute peripartum twin-twin transfusion syndrome and twin anemia-polycythemia sequence?

OBJECTIVE

To investigate the color difference between two placental shares in monochorionic placentas with acute peripartum twin-twin transfusion syndrome (TTTS) and twin anemia-polycythemia sequence (TAPS).

METHODS

We evaluated all digital pictures of TAPS, acute peripartum TTTS and a control group of uncomplicated monochorionic placentas examined at our center. We determined the color intensity of the individual placental share on the maternal side of each monochorionic placenta using an image-processing program and calculated the color difference ratio (CDR).

RESULTS

Digital pictures of 5 acute peripartum TTTS, 25 TAPS and 54 control group placentas were included in this study. The median CDR in acute peripartum TTTS was significantly lower compared to TAPS placentas, 1.20 (inter-quartile range (IQR) 1.05-1.20) and 2.50 (IQR 1.85-3.34), respectively (p < 0.01), and was comparable to the control group (CDR 1.11, IQR 1.05-1.22).

CONCLUSION

TAPS placentas have a higher CDR compared to acute peripartum TTTS placentas. Examining color difference on the maternal side of the placenta might help distinguish between acute peripartum TTTS and TAPS.

Hematological disorders at birth in complicated monochorionic twins

INTRODUCTION

Monochorionic twins are at risk of severe complications including twin-twin transfusion syndrome (TTTS), twin anemia-polycythemia sequence (TAPS) and acute peripartum TTTS. The pathophysiology is based on inter-twin blood transfusion through placental vascular anastomoses. Areas covered: This review focuses on the incidence, management and outcome of neonatal hematological complications at birth in TTTS, TAPS and acute peripartum TTTS. Expert commentary: Hematological disorders are often present at birth in monochorionic twins and include acute or chronic anemia, polycythemia and thrombocytopenia. Routine measurement of complete blood counts in all complicated monochorionic twins is strongly recommended. Increased awareness on these disorders and correct diagnostic tests will lead to prompt and adequate management at birth.

Antenatal management of twin-twin transfusion syndrome and twin anemia-polycythemia sequence

INTRODUCTION

Twin-twin transfusion syndrome (TTTS) and twin anemia polycythemia sequence (TAPS) are severe complications in monochorionic twin pregnancies associated with high mortality and morbidity risk if left untreated. Both diseases result from imbalanced inter-twin blood transfusion through placental vascular anastomoses.

AREAS COVERED

This review focuses on the differences in antenatal management between TTTS and TAPS. Expert commentary: The optimal management for TTTS is fetoscopic laser coagulation of the vascular anastomoses, preferably using the Solomon technique in which the whole vascular equator is coagulated. The Solomon technique is associated with a reduction of residual anastomosis and a reduction in post-operative complications. The optimal management for TAPS is not clear and includes expectant management, intra-uterine transfusion with or without partial exchange transfusion and fetoscopic laser surgery.