Supplementary Material for: Rheology of Twin Anaemia Polycythaemia Sequence – Insights from haemoglobin electrophoresis: a case report

Introduction: Twin Anaemia Polycythaemia Sequence (TAPS) is a recognised complication of monochorionic (MC) twins due to abnormal placental vasculature. Determining the rheology involved within the abnormal placental vasculature may help in identifying the optimum treatment option. Case Presentation: We describe a case of TAPS which was treated via intrauterine transfusions (IUTs) with partial exchange transfusions (PETs) in which additional haemoglobin electrophoresis (HbEp) testing was performed on cordocentesis samples taken before and after intrauterine transfusions and partial exchange transfusions for the donor and recipient twin, respectively. The aim was to assess the flow dynamics from the donor to recipient twin. No differences in hemoglobin A were found in the polycythemic twin after 30 minutes of IUT of the anemic co-twin but within 13 days of first transfusion greater than a 3-fold rise in adult Hemoglobin A was apparent. Within 5 days of second treatment a further 9% rise in Adult Hemoglobin A was encountered. Conclusion: The use of HbEp testing in this case provided preliminary insights into the fluid dynamics involved in TAPS, however, further studies are required to achieve better understanding.