Femke Slaghekke

Twin Anemia-Polycythemia Sequence: Diagnostic Criteria, Classification, Perinatal Management and Outcome

Monochorionic twins share a single placenta with intertwin vascular anastomoses, allowing the transfer of blood from one fetus to the other and vice versa. These anastomoses are the essential anatomical substrate for the development of several complications, including twin-twin transfusion syndrome (TTTS) and twin anemia-polycythemia sequence (TAPS). TTTS and TAPS are both chronic forms of fetofetal transfusion. TTTS is characterized by the twin oligopolyhydramnios sequence, whereas TAPS is characterized by large intertwin hemoglobin differences in the absence of amniotic fluid discordances. TAPS may occur spontaneously in up to 5% of monochorionic twins and may also develop after incomplete laser treatment in TTTS cases. This review focuses on the pathogenesis, incidence, diagnostic criteria, management options and outcome in TAPS. In addition, we propose a classification system for antenatal and postnatal TAPS.

Fetoscopic laser coagulation of the vascular equator versus selective coagulation for twin-to-twin transfusion syndrome: an open-label randomised controlled trial

BACKGROUNDnMonochorionic twin pregnancies complicated by twin-to-twin transfusion syndrome are typically treated with fetoscopic laser coagulation. Postoperative complications can occur due to residual vascular anastomoses on the placenta. We aimed to assess the efficacy and safety of a novel surgery technique that uses laser coagulation of the entire vascular equator (Solomon technique).nnnMETHODSnWe undertook an open-label, international, multicentre, randomised controlled trial at five European tertiary referral centres. Women with twin-to-twin transfusion syndrome were randomly assigned by online randomisation (1:1) with permuted blocks to the Solomon technique or standard laser coagulation. The primary outcome was a composite of incidence of twin anaemia polycythaemia sequence, recurrence of twin-to-twin transfusion syndrome, perinatal mortality, or severe neonatal morbidity. Analyses were by intention to treat, with results expressed as odds ratios (ORs) and 95% CIs. This trial is registered with the Dutch Trial Registry, number NTR1245.nnnFINDINGSnBetween March 11, 2008, and July 12, 2012, 274 women were randomly assigned to either the Solomon group (n=139) or the standard treatment group (n=135). The primary outcome occurred in 94 (34%) of 274 fetuses in the Solomon group versus 133 (49%) of 270 in the standard treatment group (OR 0·54; 95% CI 0·35-0·82). The Solomon technique was associated with a reduction in twin anaemia polycythaemia sequence (3% vs 16% for the standard treatment; OR 0·16, 95% CI 0·05-0·49) and recurrence of twin-to-twin transfusion syndrome (1% vs 7%; 0·21, 0·04-0·98). Perinatal mortality and severe neonatal morbidity did not differ significantly between the two groups. Outside of the common and well-known complications of twin-to-twin transfusion syndrome and its treatment, no serious adverse events occurred.nnnINTERPRETATIONnFetoscopic laser coagulation of the entire vascular equator reduces postoperative fetal morbidity in severe twin-to-twin transfusion syndrome. We recommend that fetoscopic surgeons consider adopting this strategy for treatment of women with twin-to-twin transfusion syndrome.nnnFUNDINGnNetherlands Organization for the Health Research and Development (ZonMw 92003545).

Residual anastomoses in twin-to-twin transfusion syndrome treated with selective fetoscopic laser surgery: localization, size, and consequences

OBJECTIVEnTo study the localization and size of residual anastomoses in twin-to-twin transfusion syndrome treated with fetoscopic laser surgery and correlate the findings with outcome.nnnSTUDY DESIGNnPlacental injection in twin-to-twin transfusion syndrome placentas treated with laser was performed by using colored dye.nnnRESULTSnA total of 77 twin-to-twin transfusion syndrome placentas were included in the study. Residual anastomoses (n = 48) were found in 32% (25/77) of lasered placentas. Most residual anastomoses were localized near the margin of the placenta. The majority of residual anastomoses (67%; 32/48) were very small (diameter, < 1 mm). Eleven of the 25 cases (44%) in the residual anastomoses group developed twin anemia-polycythemia sequence.nnnCONCLUSIONnMost residual anastomoses in twin-to-twin transfusion syndrome placentas treated with laser are very small and localized near the placental margin. Almost half of cases with residual anastomoses developed twin anemia-polycythemia sequence after laser surgery.

Hematological characteristics in neonates with twin anemia-polycythemia sequence (TAPS).

To evaluate the neonatal hematological features of monochorionic twins with twin anemia–polycythemia sequence (TAPS) and to determine the additional diagnostic value of reticulocyte count measurement.

Accurate and simple evaluation of vascular anastomoses in monochorionic placenta using colored dye.

The presence of placental vascular anastomoses is a conditio sine qua non for the development of twin-to-twin transfusion syndrome (TTTS) and twin anemia polycythemia sequence (TAPS)(1,2). Injection studies of twin placentas have shown that such anastomoses are almost invariably present in monochorionic twins and extremely rare in dichorionic twins(1). Three types of anastomoses have been documented: from artery to artery, from vein to vein and from artery to vein. Arterio-venous (AV) anastomoses are unidirectional and are referred to as deep anastomoses since they proceed through a shared placental cotyledon, whereas arterio-arterial (AA) and veno-venous (VV) anastomoses are bi-directional and are referred to as superficial since they lie on the chorionic plate. Both TTTS and TAPS are caused by net imbalance of blood flow between the twins due to AV anastomoses. Blood from one twin (the donor) is pumped through an artery into the shared placental cotyledon and then drained through a vein into the circulation of the other twin (the recipient). Unless blood is pumped back from the recipient to the donor through oppositely directed deep AV anastomoses or through superficial anastomoses, an imbalance of blood volumes occurs, gradually leading to the development of TTTS or TAPS. The presence of an AA anastomosis has been shown to protect against the development of TTTS and TAPS by compensating for the circulatory imbalance caused by the uni-directional AV anastomoses(1,2). Injection of monochorionic placentas soon after birth is a useful mean to understand the etiology of various (hematological) complications in monochorionic twins and is a required test to reach the diagnosis of TAPS(2). In addition, injection of TTTS placentas treated with fetoscopic laser surgery allows identification of possible residual anastomoses(3-5). This additional information is of paramount importance for all perinatologists involved in the management and care of monochorionic twins with TTTS or TAPS. Several placental injection techniques are currently being used. We provide a simple protocol to accurately evaluate the presence of (residual) vascular anastomoses using colored dye injection.

Clinical outcome in neonates with twin anemia-polycythemia sequence

OBJECTIVEnThe purpose of this study was to evaluate neonatal outcome of monochorionic twin pregnancies complicated by twin anemia-polycythemia sequence (TAPS).nnnSTUDY DESIGNnA cohort of consecutive monochorionic twins with TAPS with double survivors was included in the study. Each twin pair with TAPS was compared with 2 monochorionic twin pairs who were unaffected by TAPS or twin-to-twin transfusion syndrome and who were matched for gestational age at birth. Neonatal death, severe morbidity, and cerebral injury were studied.nnnRESULTSnWe included 19 twin pairs in the TAPS group and 38 control twin pairs. The incidence of neonatal death and severe neonatal morbidity was similar in the TAPS group and control group (3% [1/38] vs 1% [1/76] and 24% [9/38] vs 28% [21/76], respectively). Severe cerebral injury was detected in 1 infant (5%) in the TAPS group and 1 infant (2%) in the control group.nnnCONCLUSIONnNeonatal mortality and morbidity rates in a select population of TAPS neonates are similar to control neonatal rates.

Management of Twin Anemia-Polycythemia Sequence Using Intrauterine Blood Transfusion for the Donor and Partial Exchange Transfusion for the Recipient

Twin anemia-polycythemia sequence (TAPS) is a rare condition which may occur either spontaneously in uncomplicated monochorionic twin pregnancies or may develop after laser treatment in twin-twin transfusion syndrome. TAPS is characterized by a large intertwin discordance in hemoglobin levels without discordance in amniotic fluid levels, and may lead to severe complications including fetal hydrops, hematological morbidity and perinatal mortality. Several treatments have been proposed including intrauterine transfusion, laser surgery, elective delivery and expectant management. The optimal treatment remains unclear. In this case series we report 3 TAPS cases managed recently at our center with a combination of intrauterine blood transfusion for the anemic twin and intrauterine partial exchange transfusion for the polycythemic twin. In 1 case, the donor was found to have severe cerebral injury on neuroimaging examination. We propose etiologic mechanisms for cerebral injury in TAPS, discuss the rationale behind this treatment alternative, and evaluate the pros and cons of the various management options.

Cerebral injury in monochorionic twins with selective intrauterine growth restriction and/or birthweight discordance

OBJECTIVEnThe objective of the study was to study the incidence of severe cerebral injury in monochorionic (MC) twins with selective intrauterine growth restriction (sIUGR) and/or birthweight discordance.nnnSTUDY DESIGNnAll MC twin pregnancies with 2 liveborn twins were included in the study. We excluded all cases with twin-to-twin transfusion syndrome (TTTS). Sequential cranial ultrasound scans were performed in all MC twin infants.nnnRESULTSnA total of 117 MC twin pairs were included in the study. The sIUGR of at least 1 fetus was found in 50 twin pregnancies (43%), and birthweight discordance of 25% or greater occurred in 26 twin pregnancies (22%). The overall incidence of severe cerebral injury was 3% (6/218). The incidence of severe cerebral injury in infants from twin pregnancies with and without sIUGR was 2% (2/94) and 3% (4/124), respectively (P = .62). The incidence of severe cerebral injury in infants with and without birthweight discordance was 0% (0/48) and 4% (6/170), respectively (P = .19).nnnCONCLUSIONnThe incidence of severe cerebral injury in MC twin pregnancies not complicated by TTTS with 2 liveborn twins is low. No association could be demonstrated with sIUGR or intertwin birthweight discordance of 25% or greater.

Twin Anemia Polycythemia Sequence: Current Views on Pathogenesis, Diagnostic Criteria, Perinatal Management, and Outcome.

Monochorionic twins share a single placenta and are connected with each other through vascular anastomoses. Unbalanced inter-twin blood transfusion may lead to various complications, including twin-to-twin transfusion syndrome (TTTS) and twin anemia polycythemia sequence (TAPS). TAPS was first described less than a decade ago, and the pathogenesis of TAPS results from slow blood transfusion from donor to recipient through a few minuscule vascular anastomoses. This gradually leads to anemia in the donor and polycythemia in the recipient, in the absence of twin oligo-polyhydramnios sequence (TOPS). TAPS may occur spontaneously in 3-5% of monochorionic twins or after laser surgery for TTTS. The prevalence of post-laser TAPS varies from 2% to 16% of TTTS cases, depending on the rate of residual anastomoses. Pre-natal diagnosis of TAPS is currently based on discordant measurements of the middle cerebral artery peak systolic velocity (MCA-PSV; >1.5 multiples of the median [MoM] in donors and 8 g/dL), and at least one of the following: reticulocyte count ratio >1.7 or minuscule placental anastomoses. Management includes expectant management, and intra-uterine blood transfusion (IUT) with or without partial exchange transfusion (PET) or fetoscopic laser surgery. Post-laser TAPS can be prevented by using the Solomon laser surgery technique. Short-term neonatal outcome ranges from isolated inter-twin Hb differences to severe neonatal morbidity and neonatal death. Long-term neonatal outcome in post-laser TAPS is comparable with long-term outcome after treated TTTS. This review summarizes the current knowledge after 10 years of research on the pathogenesis, diagnosis, management, and outcome in TAPS.

Middle cerebral artery peak systolic velocity to predict fetal hemoglobin levels in twin anemia–polycythemia sequence

To evaluate the diagnostic accuracy of middle cerebral artery peak systolic velocity (MCA‐PSV) Doppler measurements in prediction of hemoglobin levels in twin anemia–polycythemia sequence (TAPS).