Evolution of middle cerebral artery peak systolic velocity after a successful laser procedure for iatrogenic twin anemia-polycythemia sequence

Perinatal outcome of pregnancy complicated by twin anemia-polycythemia sequence: systematic review and meta-analysis

OBJECTIVE

To report the perinatal outcome of monochorionic diamniotic (MCDA) twin pregnancies complicated by twin anemia-polycythemia sequence (TAPS), according to the type of TAPS (spontaneous or postlaser) and the management option adopted.

METHODS

MEDLINE, EMBASE and The Cochrane Library databases were searched for studies reporting on the outcome of twin pregnancies complicated by TAPS. Inclusion criteria were non-anomalous MCDA twin pregnancies with a diagnosis of TAPS. The primary outcome was perinatal mortality; secondary outcomes were neonatal morbidity and preterm birth (PTB). The outcomes were stratified according to the type of TAPS (spontaneous or following laser treatment for twin-twin transfusion syndrome) and the management option adopted (expectant, laser surgery, intrauterine transfusion (IUT) or selective reduction (SR)). Random-effects meta-analysis of proportions was used to analyze the data.

RESULTS

Perinatal outcome was assessed according to whether TAPS occurred spontaneously or after laser treatment in 506 pregnancies (38 studies). Intrauterine death (IUD) occurred in 5.2% (95% CI, 3.6-7.1%) of twins with spontaneous TAPS and in 10.2% (95% CI, 7.4-13.3%) of those with postlaser TAPS, while the corresponding rates of neonatal death were 4.0% (95% CI, 2.6-5.7%) and 9.2% (95% CI, 6.6-12.3%), respectively. Severe neonatal morbidity occurred in 29.3% (95% CI, 25.6-33.1%) of twins after spontaneous TAPS and in 33.3% (95% CI, 17.4-51.8%) after postlaser TAPS, while the corresponding rates of severe neurological morbidity were 4.0% (95% CI, 3.5-5.7%) and 11.1% (95% CI, 6.2-17.2%), respectively. PTB complicated 86.3% (95% CI, 77.2-93.3%) of pregnancies with spontaneous TAPS and all cases with postlaser TAPS (100% (95% CI, 84.3-100%)). Iatrogenic PTB was more frequent than spontaneous PTB in both groups. Perinatal outcome was assessed according to the management option adopted in 417 pregnancies (21 studies). IUD occurred in 9.8% (95% CI, 4.3-17.1%) of twins managed expectantly and in 13.1% (95% CI, 9.2-17.6%), 12.1% (95% CI, 7.7-17.3%) and 7.6% (95% CI, 1.3-18.5%) of those treated with laser surgery, IUT and SR, respectively. Severe neonatal morbidity affected 27.3% (95% CI, 13.6-43.6%) of twins in the expectant-management group, 28.7% (95% CI, 22.7-35.1%) of those in the laser-surgery group, 38.2% (95% CI, 18.3-60.5%) of those in the IUT group and 23.3% (95% CI, 10.5-39.2%) of those in the SR group. PTB complicated 80.4% (95% CI, 59.8-94.8%), 73.4% (95% CI, 48.1-92.3%), 100% (95% CI, 76.5-100%) and 100% (95% CI, 39.8-100%) of pregnancies after expectant management, laser surgery, IUT and SR, respectively.

CONCLUSIONS

The present meta-analysis provides pooled estimates of the risks of perinatal mortality, neonatal morbidity and PTB in twin pregnancies complicated by TAPS, stratified by the type of TAPS and the management option adopted. Although a direct comparison could not be performed, the results from this systematic review suggest that spontaneous TAPS may have a better prognosis than postlaser TAPS. No differences in terms of mortality and morbidity were observed when comparing different management options for TAPS, although these findings should be interpreted with caution in view of the limitations of the included studies. Individualized prenatal management, taking into account the severity of TAPS and gestational age, is currently the recommended strategy. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Intrauterine Interventions for the Treatment of Twin Anemia-Polycythemia Sequence: A Systematic Review

BACKGROUND

Twin anemia-polycythemia sequence (TAPS) is a complication of monochorionic, multiple gestation pregnancies in which blood shunting through placental anastomoses results in chronic anemia in one fetus and chronic polycythemia in another. The outcomes of different treatment modalities for TAPS are not well known.

OBJECTIVE

To determine the outcomes of the intrauterine interventions used to treat TAPS.

STUDY DESIGN

A systematic literature search of MEDLINE, EMBASE, and CENTRAL was performed in June 2016. Primary outcomes were mortality, morbidity, and adverse perinatal outcomes. Data were summarized in the form of weighted means, and statistical difference was determined.

RESULTS

Twenty-one articles were identified for inclusion in this review and were composed of 105 cases of TAPS. In the cases presented in the literature, there was no statistically significant difference in mortality, morbidity, or emergent Caesarean section rates between expectant management, intrauterine transfusion (IUT), and laser ablation therapy. Laser ablation therapy and IUT were found to have a significantly lower rate of adverse perinatal outcomes when compared to expectantly managed cases.

CONCLUSIONS

The literature looking into the treatment of TAPS is very limited, with no randomized controlled trials and only one includable comparative study. Based on the data in the case report and case study literature, there is no mortality difference between any of the treatment modalities. Expectant management may be associated with an increase in adverse perinatal outcomes when compared to laser therapy and IUT. More comparative studies are needed to assist clinicians in adopting an evidence-based approach to the treatment of TAPS.

Prenatal diagnosis of spontaneous twin anemia-polycythemia sequence and postnatal examination of placental vascular anastomoses

Twin anemia-polycythemia sequence (TAPS) is characterized by a wide discrepancy of hemoglobin between two monochorionic fetuses without sign of twin oligo-polyhydramnios sequence. A primiparous woman with monochorionic diamniotic twin transferred for preterm labor. Ultrasonographic evaluation at 32+3 weeks of gestation revealed increased middle cerebral artery-peak systolic velocity (77.4 cm/sec, 1.69 multiples of median) in donor and decreased in recipient twin (36.4 cm/sec, 0.79 multiples of median), the twin was diagnosed with TAPS. Repeated cesarean section was performed at 32+5 weeks of gestation following preeclampsia and preterm labor. After delivery, TAPS was confirmed through neonatal hematologic examination. There were no signs of acute hemorrhagic shock or brain injury. Placental evaluation via dye infusion and barium angiogram revealed one arterioarterial anastomoses with six arteriovenous anastomoses of placenta. We report a prenatally diagnosed case of spontaneous TAPS with arterioarterial and arteriovenous anastomoses and suggest careful monitoring of monochorionic twin and opinion on placenta vascular architecture.

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.

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.

Review of the correlation between blood flow velocity and polycythemia in the fetus, neonate and adult: appropriate diagnostic levels need to be determined for twin anemia-polycythemia sequence

Twin anemia-polycythemia sequence (TAPS) is recognized increasingly antenatally by the demonstration of an anemic twin and a polycythemic cotwin using the middle cerebral artery peak systolic velocity (MCA-PSV). While the MCA-PSV has been shown to correlate well with anemia in singleton fetuses, the evidence to support its use to diagnose fetal polycythemia appears to be less clear-cut. We aimed to evaluate fetal, neonatal and adult literature used to support the use of MCA-PSV for the diagnosis of polycythemia. Comprehensive literature searches were performed for ultrasound evidence of polycythemia in the human fetus, neonate and adult using key search terms. Only manuscripts in the English language with an abstract were considered for the review, performed in June 2014. Fifteen manuscripts were found for the human fetus, including 38 cases of TAPS. Nine of these defined fetal polycythemia as MCA-PSV < 0.8 multiples of the median (MoM), five used < 1.0 MoM and one used 0.8-1.0 MoM. Only two studies, involving a total of 15 cases, proposed a diagnostic level, acknowledging false-positive and -negative cases, though neither reported sensitivities or specificities. Six neonatal studies (96 neonates) demonstrated evidence of decreased cerebral velocities in polycythemia and a consequent increase with hemodilution. In the adult, five studies (57 polycythemic adults) demonstrated increased flow or velocity with hemodilution. Neither neonatal nor adult studies conclusively defined levels for screening for polycythemia. Despite widespread adoption of a cut-off of < 0.8 MoM in the published literature for the polycythemic fetus in TAPS, this is based upon minimal evidence, with unknown sensitivity and specificity. We recommend caution in excluding TAPS based purely upon the absence of a reduced MCA-PSV.

Evaluation of the Utility of in utero Treatment of Twin Anemia-Polycythemia Sequence

OBJECTIVE

The aim of this study is to evaluate the interest in the in utero treatment of twin anemia-polycythemia sequence (TAPS).

METHODS

The obstetrical and neonatal data on all cases of TAPS followed up in our institution between 2006 and 2013 were reviewed. Statistical analyses were conducted using Bayesian methods.

RESULTS

Twenty cases of TAPS were included. Laser therapy or intrauterine transfusion (IUT) was performed on the donor twin in 9 cases. Eleven cases were included in the 'nontreated' group (managed expectantly or diagnosed at birth). The gestational age at diagnosis was lower in the group with treated TAPS [difference (diff) = -22.20 days (-57.13, 14.28), probability (Pr) (diff >0) = 10.6%]. The rate of preterm premature rupture of membranes was higher in the group with treated TAPS [diff = 22.5% (-14, 57), Pr (diff >0) = 89%], but overall mortality was similar. The interval between diagnosis and delivery was longer [diff = 44.37 days (9.41, 77.90), Pr (diff >0) = 99.2%], the TAPS resolution rate was higher [diff = 49.9% (12, 81), Pr (diff >0) = 99.4%], and the neonatal transfusion rate was lower [diff = -30.5% (-60, 0), Pr (diff >0) = 2.6%] in the treated group.

CONCLUSION

In utero treatment for TAPS is associated with a higher resolution rate of TAPS and a longer time between diagnosis and birth, but overall mortality is the same as with expectant management.

Laser surgery as a management option for twin anemia-polycythemia sequence

OBJECTIVE

To evaluate the effectiveness of laser treatment for antenatally detected twin anemia-polycythemia sequence (TAPS) compared with intrauterine transfusion or expectant management.

METHODS

All monochorionic twin pregnancies with TAPS managed between 2005 and 2013 in two European fetal therapy centers were evaluated. The outcomes of TAPS cases treated primarily with laser surgery were compared with the outcomes of cases managed expectantly or treated with intrauterine transfusion.

RESULTS

In this retrospective study 52 cases of TAPS were detected antenatally and were managed with either laser surgery (n=8; 15%) or intrauterine blood transfusion (n=17; 33%) or expectantly (n=27; 52%). Perinatal survival in the laser group was 94% (15/16) vs 85% (29/34) in the intrauterine-transfusion group and 83% (45/54) in the expectant-management group (P=0.30). The rates of severe neonatal morbidity in liveborn neonates in the laser, intrauterine-transfusion and expectant-management groups were 7% (1/15), 38% (12/32) and 24% (12/50), respectively (P=0.17). There was a significant reduction in respiratory distress syndrome in cases treated by laser. No severe postnatal hematological complications were detected in the laser group compared with 72% (23/32) in the intrauterine-transfusion group and 52% (26/50) in the expectant-management group (P<0.01). Median time between diagnosis and birth was 11 weeks in the laser group compared to 5 weeks after intrauterine transfusion and 8 weeks after expectant management (P<0.01). After injection of colored dye no residual anastomoses were found in the laser group.

CONCLUSIONS

Laser surgery for TAPS appears to improve perinatal outcome by prolonging pregnancy and reducing respiratory distress syndrome. Larger, adequately controlled studies are needed to reach firm conclusions on the optimal management of TAPS.

Treatment of Complicated Spontaneous Twin Anemia-Polycythemia Sequence via Fetoscopic Laser Ablation of the Vascular Communications

Monochorionic diamniotic twins share a single placenta and have intertwin vascular communications that link the circulatory systems of the twins together. Twin anemia-polycythemia sequence (TAPS) is an atypical form of twin-twin transfusion syndrome (TTTS) caused by net transfer of blood from one fetus to the other and is characterized by large intertwin hemoglobin differences in the absence of oligohydramnios and polyhydramnios. This condition may develop spontaneously (sTAPS) or as a result of residual vascular communications after prior laser surgery. Because of the relatively low prevalence and lack of clinical awareness, the natural history of sTAPS is unclear and the antenatal treatment remains controversial. Case series of sTAPS have described expectant management with timed delivery, intrauterine blood transfusion, and fetoscopic laser treatment. Favorable outcomes have been described in cases of uncomplicated sTAPS that underwent conservative measures. However, we believe that there may be a subgroup of high-risk or complicated sTAPS patients that may benefit from definitive treatment afforded by fetoscopic laser therapy. We describe 3 complicated cases of sTAPS successfully treated with selective laser photocoagulation of communicating vessels. In 2 of the cases, placental pathology identified thrombosed fetal vessels of the polycythemic twin.

Twin anemia-polycythemia sequence: the importance of an accurate diagnosis

Twin anemia-polycythemia sequence (TAPS), which was first described in 2007, is an atypical chronic form of twin-twin transfusion syndrome (TTTS). It presents as a large intertwin hemoglobin difference, with one twin developing anemia and the other polycythemia, without the traditional “polyhydramnios-oligohydramnios sequence” that is usually seen in TTTS. So far, ideal management of TAPS is not clear. We report here the case of a monochorionic biamniotic gestation, complicated by TAPS, detected at 30 weeks’ gestation that led to an emergent cesarean section. The recipient twin had an uneventful evolution. The donor twin was severely anemic, with a hemoglobin level of 2.5 g/dL that required immediate blood transfusion and intensive care management measures. Clinical evolution was favorable with good outcome in both twins. This case report intends to emphasize the association between hydrops fetalis and severe anemia, as well as the relevance of antenatal Doppler ultrasound investigations and the importance of an accurate management decision.

Early detection by diffusion-weighted sequence magnetic resonance imaging of severe brain lesions after fetoscopic laser coagulation for twin-twin transfusion syndrome

OBJECTIVE

Monochorionic twins treated by fetoscopic laser coagulation (FLC) for twin-twin transfusion syndrome (TTTS) are at increased risk of neurodevelopmental impairment. Our aim was to evaluate the additional value of diffusion-weighted imaging (DWI) over fetal sonography and T2 magnetic resonance imaging (MRI) in the detection of acute ischemic cerebral lesions shortly following FLC.

METHODS

This was a prospective cohort study of fetuses with TTTS treated by FLC. All fetuses underwent brain DWI and T2-MRI within 24-96 h after the procedure and a follow-up MRI at 30-32 weeks' gestation. All fetuses also had frequent ultrasound evaluation until delivery.

RESULTS

Thirty pregnancies with TTTS were included in the study. Eight resulted in survival of only one twin after the procedure (Group A), while the other 22 pregnancies resulted in the survival of both twins (Group B), as assessed at the time of initial MRI. Two fetuses in Group A and four in Group B had evidence of transient bleeding in the germinal matrix. Three fetuses in Group B and none in Group A had diffuse ischemic changes in the white matter. One fetus died in utero 24 h after MRI. The other two fetuses in Group B demonstrated an acute infarct 24-48 h after the procedure. Subsequent scans at 28-29 and 32 weeks showed brain atrophy compatible with an old infarct.

CONCLUSIONS

DWI can demonstrate cerebral damage immediately after FLC. Larger cohorts are needed to determine the role of fetal MRI in the prenatal assessment and follow-up of patients with TTTS.

Severe cerebral injury in a recipient with twin anemia-polycythemia sequence

Twin anemia-polycythemia sequence (TAPS) results from slow intertwin blood transfusion through minuscule placental vascular anastomoses and is characterized by large intertwin hemoglobin differences in the absence of amniotic fluid discordance. The optimal management of TAPS is not clear. We report a case of TAPS detected antenatally by Doppler ultrasound examination at 15 + 6 weeks' gestation. After counseling, the parents opted for expectant management. Regular Doppler measurements were performed and these remained fairly stable. An emergency Cesarean section was performed at 34 + 5 weeks following signs of fetal distress. The donor twin was severely anemic while the recipient twin had severe polycythemia-hyperviscosity syndrome. On day 1, the recipient developed respiratory insufficiency and subclinical status epilepticus. Magnetic resonance imaging showed a total loss of gray-white matter differentiation as a sign of severe diffuse cerebral ischemia and bilateral intra- and extra-axial hemorrhages. There was almost complete lack of arterial and venous cerebral blood flow. On day 3 intensive care treatment was withdrawn in view of the severity of the brain injury. This case report demonstrates that TAPS may lead to severe cerebral injury and fatal outcome in the recipient twin, and highlights the importance of antenatal Doppler ultrasound monitoring and choice of management.