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Twin Anemia-Polycythemia Sequence (TAPS) is a novel form of chronic Twin-Twin transfusion, characterized by large inter-twin differences in red blood cell count and Hemoglobin level, without signs of ''twin oligo-polyhydramnios sequence'', which is also known as ''classic TTTS''. (TOPS).〔Lopriore E, Middeldorp JM, Oepkes D, Kanhai HH, Walther FJ, Vandenbussche FP. Twin anemia-polycythemia sequence in two monochorionic twin pairs without oligo-polyhydramnios sequence. Placenta 2007; 28(1):47-51.〕 The pathogenesis of TAPS is based on the presence of a few, tiny arterio-venous (AV) placental ''shared connections'' (anastomoses) of a diameter <1mm, allowing a slow ''transfusion'' of blood from the donor to the recipient, with a very small amount of fluid transfused due to small size of the shared connections. This leads gradually to highly ''discordant''(unequal) red blood cell counts and Hemoglobin levels.〔Lopriore E, Deprest J, Slaghekke F, Oepkes D, Middeldorp JM, Vandenbussche FP et al. Placental characteristics in monochorionic twins with and without twin anemia-polycythemia sequence. Obstet Gynecol 2008; 112(4):753-758.〕 TAPS may occur spontaneously or after laser surgery for TTTS (post-laser form). The spontaneous form complicates approximately 3 to 5% of monochorionic twin pregnancies,〔Lewi L, Jani J, Blickstein I, Huber A, Gucciardo L, Van Mieghem T et al. The outcome of monochorionic diamniotic twin gestations in the era of invasive fetal therapy: a prospective cohort study. Am J Obstet Gynecol 2008; 199(5):514-518.〕〔Slaghekke F, Kist WJ, Oepkes D, Pasman SA, Middeldorp JM, Klumper FJ et al. Twin anemia-polycythemia sequence: diagnostic criteria, classification, perinatal management and outcome. Fetal Diagn Ther 2010; 27(4):181-190.〕 whereas the post-laser form occurs in 2 to 13% of TTTS cases.〔Robyr R, Lewi L, Salomon LJ, Yamamoto M, Bernard JP, Deprest J et al. Prevalence and management of late fetal complications following successful selective laser coagulation of chorionic plate anastomoses in twin-to-twin transfusion syndrome. Am J Obstet Gynecol 2006; 194(3):796-803.〕〔Habli M, Bombrys A, Lewis D, Lim FY, Polzin W, Maxwell R et al. Incidence of complications in twin-twin transfusion syndrome after selective fetoscopic laser photocoagulation: a single-center experience. Am J Obstet Gynecol 2009; 201(4):417.〕 The optimal management in TAPS is not clear, and includes expectant management,〔Lopriore E, Hecher K, Vandenbussche FP, van den Wijngaard JP, Klumper FJ, Oepkes D. Fetoscopic laser treatment of twin-to-twin transfusion syndrome followed by severe twin anemia-polycythemia sequence with spontaneous resolution. Am J Obstet Gynecol 2008; 198(2):e4-e7.〕 induction of labor, intrauterine blood transfusion (intravenous and/or intraperitoneal, with or without partial exchange transfusion),〔Herway C, Johnson A, Moise K, Moise KJ, Jr. Fetal intraperitoneal transfusion for iatrogenic twin anemia-polycythemia sequence after laser therapy. Ultrasound Obstet Gynecol 2009; 33(5):592-594.〕〔Lopriore E, van den Wijngaard JP, Middeldorp JM, Oepkes D, Walther FJ, van Gemert MJ et al. Assessment of feto-fetal transfusion flow through placental arterio-venous anastomoses in a unique case of twin-to-twin transfusion syndrome. Placenta 2007; 28(2-3):209-211.〕 selective feticide or fetoscopic laser surgery.〔Slaghekke F, Kist WJ, Oepkes D, Pasman SA, Middeldorp JM, Klumper FJ et al. Twin anemia-polycythemia sequence: diagnostic criteria, classification, perinatal management and outcome. Fetal Diagn Ther 2010; 27(4):181-190.〕〔Weingertner AS, Kohler A, Kohler M, Bouffet N, Hunsinger MC, Mager C et al. Clinical and placental characteristics in four new cases of twin anemia-polycythemia sequence. Ultrasound Obstet Gynecol 2010; 35(4):490-494.〕 The outcome in TAPS is not well known. International cooperation between fetal centers using a web-based TAPS registry is needed to improve our knowledge on the short- and long-term outcome in TAPS cases and determine the optimal management.〔http://www.tapsregistry.org〕 == Monochorionic twin pregnancy complication == Monochorionic (MC) twin pregnancies are at increased risk of serious complications. The higher rate of perinatal mortality and morbidity is related directly to the unique angio-architecture of the MC placenta. All MC placentas have vascular anastomoses connecting the circulations of both fetuses. Imbalanced inter-twin blood flow is the accepted etiology in twin-twin transfusion syndrome (TTTS), of one of the most severe disorders in MC pregnancies. Recently (2007), a new complication in MC twins has been discovered, termed twin anemia-polycythemia sequence (TAPS). TAPS is a form of chronic feto-fetal transfusion, characterized by large inter-twin hemoglobin (Hb) differences, without signs of twin oligo-polyhydramnios sequence (TOPS).〔Lopriore E, Middeldorp JM, Oepkes D, Kanhai HH, Walther FJ, Vandenbussche FP. Twin anemia-polycythemia sequence in two monochorionic twin pairs without oligo-polyhydramnios sequence. Placenta 2007; 28(1):47-51.〕 TAPS may occur spontaneously or after laser surgery for TTTS (post-laser form). The spontaneous form complicates approximately 3% to 5% of monochorionic twin pregnancies,〔Lewi L, Jani J, Blickstein I, Huber A, Gucciardo L, Van Mieghem T et al. The outcome of monochorionic diamniotic twin gestations in the era of invasive fetal therapy: a prospective cohort study. Am J Obstet Gynecol 2008; 199(5):514-518.〕〔Slaghekke F, Kist WJ, Oepkes D, Pasman SA, Middeldorp JM, Klumper FJ et al. Twin anemia-polycythemia sequence: diagnostic criteria, classification, perinatal management and outcome. Fetal Diagn Ther 2010; 27(4):181-190.〕 whereas the post-laser form occurs in 2% to 13% of TTTS cases.〔Robyr R, Lewi L, Salomon LJ, Yamamoto M, Bernard JP, Deprest J et al. Prevalence and management of late fetal complications following successful selective laser coagulation of chorionic plate anastomoses in twin-to-twin transfusion syndrome. Am J Obstet Gynecol 2006; 194(3):796-803.〕〔Habli M, Bombrys A, Lewis D, Lim FY, Polzin W, Maxwell R et al. Incidence of complications in twin-twin transfusion syndrome after selective fetoscopic laser photocoagulation: a single-center experience. Am J Obstet Gynecol 2009; 201(4):417.〕 The pathogenesis of TAPS is based on the presence of few, minuscule arterio-venous (AV) placental anastomoses (diameter <1mm)〔Lopriore E, Deprest J, Slaghekke F, Oepkes D, Middeldorp JM, Vandenbussche FP et al. Placental characteristics in monochorionic twins with and without twin anemia-polycythemia sequence. Obstet Gynecol 2008; 112(4):753-758.〕 allowing a slow transfusion of blood from the donor to the recipient and leading gradually to highly discordant Hb levels.〔Slaghekke F, Kist WJ, Oepkes D, Pasman SA, Middeldorp JM, Klumper FJ et al. Twin anemia-polycythemia sequence: diagnostic criteria, classification, perinatal management and outcome. Fetal Diagn Ther 2010; 27(4):181-190.〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Twin Anemia-Polycythemia Sequence (TAPS)」の詳細全文を読む スポンサード リンク
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