Acardiac twin: too many invasive treatment options--the problem and not the solution

"The Strange Case of Dr Pump and Mr Acardiac": The Twin Reversed Arterial Perfusion (TRAP) Sequence in Two Monochorionic Monoamniotic (MCMA) Twin Pregnancies-Diagnosis, Prognosis and Management: Review of Literature

The Twin Reversed Arterial Perfusion (TRAP) Sequence is an extremely rare complication of monochorionic twin pregnancies, with one severely malformed twin (the "acardiac") lacking autonomous placental blood supply and being perfused by the co-twin (the "pump"), through arterio-arterial (and sometimes also veno-venous) vascular anastomoses located on the placental surface. The prognosis is poor: mortality is 100% in the acardiac twin because of its severe malformations and about 50-55% in the pump twin, mainly due to heart failure and prematurity. So, the goal of perinatal management of the TRAP twin pregnancy is to deliver a healthy and near-term pump twin without heart failure or fetal hydrops. Intuitively, the earlier the diagnosis, the better the outcome. Herein, we report two cases of monochorionic monoamniotic (MCMA) twin pregnancies complicated by the TRAP Sequence, which are of interest since the objective of early diagnosis was achieved by means of transvaginal and 3D ultrasound, two techniques which revealed themselves as being useful to this purpose but are underused in the literature. The second aim of this study is to provide an overview of literature data about the diagnosis, prognosis establishment, and management of this rare condition, which are still debated and unclear due to negligible poor-quality evidence.

Twin reversed arterial perfusion syndrome in a monochorionic monoamniotic twin pregnancy

OBJECTIVE

Twin-Reversed Arterial Perfusion (TRAP) sequence is a rare complication of monochorionic multiple gestation. Conservative management should be considered if there is no poor prognostic factor.

CASE REPORT

This is a 35 year-old female with twin pregnancy with acardiac monster. Under the request of the patient, there was no intervention during the whole pregnancy. We keep regular and close sonography weekly follow up. There was no maternal complication and there was also no heart failure sign or polyhydramnios of the donor twin. Minimal blood flow was noted at the anastomotic vessels under the sonography at late gestational age. Due to breech presentation, cesarean section was performed at gestational age 37 + 1/7 weeks. She delivers a healthy baby smoothly.

CONCLUSION

Antenatal sonography is an important tool to evaluate the fetus status. Under special condition, term pregnancy is still possible without any treatment.

CASE REPORT

Twin reversed arterial perfusion syndrome in a monochorionic monoamniotic twin pregnancy.

Early vs late intervention in twin reversed arterial perfusion sequence

OBJECTIVE

To compare two different management approaches in prenatally diagnosed twin reversed arterial perfusion (TRAP) sequence.

METHODS

Retrospective analysis of all cases with TRAP sequence diagnosed in one center over a period of 10 years. Prior to 2010, all cases were managed expectantly until 19 weeks' gestation; thereafter, patients could choose either radiofrequency ablation (RFA) or expectant management (Group A). From 2010 onward all patients were offered interstitial laser at the time of diagnosis (12 weeks at the earliest) or expectant management (Group B).

RESULTS

Forty cases were included in the study. In Group A, 23 cases were diagnosed at a mean gestational age of 19.9 ± 6.3 weeks. Sixteen patients were managed expectantly (13 survivors, 81%), while six underwent RFA at the time of diagnosis and one later in pregnancy (six survivors, 86%). In Group B, 17 cases were diagnosed at a mean gestational age of 16.4 ± 4.7 weeks. Six patients chose expectant management (five survivors, 83%) and 11 had interstitial laser therapy at the time of diagnosis (eight survivors, 73%). The loss rate of the pump twin was not significantly different between Group A and Group B (three of 23 vs four of 17; P = 0.3). In Group B the rates of preterm premature rupture of membranes (PPROM) and delivery < 34 weeks were significantly lower, and gestational age at birth as well as birth weight were significantly higher than in Group A.

CONCLUSION

Despite the limitations resulting from its retrospective design, our study on management of TRAP sequence adds some evidence in favor of prophylactic intervention by intrafetal laser from 12 weeks onward.

[Multifoetal pregnancies complicated by reversed arterial perfusion: report of four cases]

INTRODUCTION

Twin reversed arterial perfusion syndrome (TRAP) or acardiac anomaly presents a rare and severe complication affecting monochorionic multiple pregnancies occurring in 1 per 35,000 pregnancies or 1 per 100 of monozygotic twins. We report four cases of multiple pregnancies with TRAP diagnosed over the last 2 years, which were under check-up and treatment during the entire pregnancy course finalized by delivery.

OUTLINE OF CASES

In two cases pregnancies were trigeminal, and other two geminal, with acardia of one foetus, by anceps type in three and acephalus in one. Expectant management was initially done in all cases. The relation of acardiac and donor abdominal circumference was below 50% and negative signs of the donor's cardiac failure were detected in two cases, so that expectative management was continued until delivery. Due to obstetric indications, a cesarean section was performed on the 33rd and 34th gestational week, and healthy newborns were delivered. Another two acardiac twins had abdominal circumference ratio between the acardiac fetus and the donor of over 50%, and signs of congestive heart failure in the donor, which indicated invasive therapeutic procedure with absolute alcohol chemisclerosis; it was done by alcohol injection into the acardiac abdominal aorta which interrupted the retrograde blood-flow into the acardiac umbilicus. In the first case a successful intervention was performed at 29th gestational week, but after 12 hours distress signs were registered. The delivery was finalized by a cesarean section, and a live donor was delivered. In the second case the intervention was successfully done at the 20th gestational week, and after 96 hours from the intervention lethal ending of the donor was registered.

CONCLUSION

Bearing in mind that the occurrence of TRAP is rare, it is necessary to sum-up experiences from a larger number of centres to determine efficient therapeutic procedure.

Fetal surgery is a clinical reality

An increasing number of fetal anomalies are being diagnosed prior to birth, some of them amenable to fetal surgical intervention. We discuss the current clinical status and recent advances in endoscopic and open surgical interventions. In Europe, fetoscopic interventions are widely embraced, whereas the uptake of open fetal surgery is much less. The indications for each access modality are different, hence they cannot substitute each other. Although the stage of technical experimentation is over, most interventions remain investigational. Today there is level I evidence that fetoscopic laser surgery for twin-to-twin transfusion syndrome is the preferred therapy, but this operation actually takes place on the placenta. In terms of surgery on the fetus, an increasingly frequent indication is severe congenital diaphragmatic hernia as well as myelomeningocele. Overall maternal safety is high, but rupture of the membranes and preterm delivery remain a problem. The increasing application of fetal surgery and its mediagenicity has triggered the interest to embark on fetal surgical therapy, although the complexity as well as the overall rare indications are a limitation to sufficient experience on an individual basis. We plead for increased exchange between high volume units and collaborative studies; there may also be a case for self-regulation. Inclusion of patients into trials whenever possible should be encouraged rather than building up casuistic experience.

Placental pathology in trap sequence: clinical and pathogenetic implications

Twin reversed arterial perfusion sequence (TRAP) resulting in an acardiac twin is a rare occurrence. Acardia requires the presence of arterial-arterial anastomosis, with retrograde perfusion of poorly oxygenated blood from the normal twin to the acardiac twin, venous-venous anastomosis carrying blood back from the acardiac to the normal twin, and circulatory failure of the acardiac twin. Although vascular anastomoses in cases of TRAP have been well described, there is little published literature on the microscopic changes in the placenta in TRAP sequence. We report a case of monochorionic monozygotic twins with an acardiac twin, large arterial-arterial anastomosis, and direct continuity of the umbilical cord veins. The placenta showed villous immaturity, striking villous calcifications, and extensive fetal thrombotic vasculopathy of the umbilical vein of the donor twin and the chorionic plate vessels. Thrombi in the umbilical vessels of the acardiac twin have been reported, and trombi in donor twin organs have been seen after fetal demise in utero. But to our knowledge there is no previously reported thrombi in the donor twin umbilical vessels or the chorionic plate veins. This may have implications not only as a possible factor in the etiology of TRAP, but also and more important as a possible risk factor for thrombotic events in the donor twin. Further studies with clinico-pathological correlation are needed to explore this issue.

Selective cord coagulation in acardiac twins

The twin reverse arterial perfusion (TRAP) sequence is a serious complication of monochorionic multiple pregnancies in which the affected twin is reversely perfused from the healthy co-twin, resulting in severely abnormal or absent cardiac development, severe malformations, and massive hydrops fetalis. The acardiac twin threatens the survival of the pump twin either by increasing the risk of congestive cardiac failure or by the development of polyhydramnios, preterm premature rupture of membranes, preterm labour and premature delivery. A wide spectrum of surgical interventions has been applied in the management of TRAP; however, because of the rarity of this condition and the heterogeneity of its presentation, no single technique has been shown to be unequivocally optimal. In our experience, fetoscopic laser coagulation of the placental vascular anastomoses or the umbilical cord of the acardiac twin, with the possibility of applying bipolar forceps as an additional minimally invasive surgical technique, offers an effective treatment option in the management of the TRAP sequence; this treatment has a survival rate of 80%, and 67% of pregnancies with surviving pump twins go beyond 36 weeks of gestation without further complications.

Treatment of twin reversed arterial perfusion sequence by septostomy and amniodrainage: a case report

INTRODUCTION

An acardiac fetus is the most severe malformation seen in humans. It is an extremely rare complication, occurring in approximately 1% of all monozygotic twin gestations, with an incidence of about 1 in 35,000 births. This malformation happens as a result of the syndrome of reversed arterial perfusion of the acardiac twin from the other normal fetus (pump twin), due to the presence of arterio-arterial anastomoses in a monochorionic placenta. Several obstetric and perinatal complications have been associated to this anomaly and several treatments have been proposed to reduce the morbimortality of the pump twin. There's no report in MEDLINE about the treatment of twin gestations with acardiac fetus through septostomy.

CASE REPORT

The present article reports a case of reversed arterial perfusion sequence complicated by polyhydramnios diagnosed at 19th week of pregnancy, treated with septostomy and serial amniodrainage.

DISCUSSION

This case presented it demonstrate favorable development of the gestation, with labor happening at 35 weeks gestation and pump twin presenting good vitality conditions. In cases with no major factors of bad prognosis, septostomy combined with amniodrainage could be an interesting therapeutic option for a safe and efficacious management of selected cases of TRAP sequence.

Twin reversed arterial perfusion: fetoscopic laser coagulation of placental anastomoses or the umbilical cord

OBJECTIVE

To assess the feasibility and outcome of fetoscopic laser coagulation in pregnancies with twin reversed arterial perfusion (TRAP) sequence.

METHODS

In a prospective multicenter study, percutaneous fetoscopic laser coagulation of placental anastomoses (n = 18) or the umbilical cord of the acardiac twin (n = 42) was performed in 60 consecutive pregnancies at a median gestational age of 18.3 (range, 14.3-24.7) weeks under local or locoregional anesthesia.

RESULTS

Vascular coagulation with arrest of blood flow was achieved in 82% (49/60) of cases by laser alone and in a further 15% (9/60) by laser coagulation in combination with bipolar forceps. The overall survival rate of the pump twin was 80% (48/60). Median gestational age at delivery was 37.4 (range, 23.7-41.4) weeks and the median interval between the procedure and delivery was 18.2 (range, 1.1-25.7) weeks. Median birth weight was 2720 (range, 540-3840) g. Preterm premature rupture of membranes before 34 weeks' gestation occurred in 18% (11/60) at a median of 62 (range, 1-102) days after the procedure. However, only two (3%) women delivered within 28 days of the procedure.

CONCLUSIONS

Fetoscopic laser coagulation of placental vascular anastomoses or the umbilical cord of the acardiac twin is an effective treatment of TRAP sequence, with a survival rate of 80%, and 67% of pregnancies with surviving pump twins going beyond 36 weeks' gestation without further complications.

MR findings of complicated multifetal gestations

This paper presents a review of various complications of multifetal gestations identified on MR imaging and highlights findings of those complications unique to monochorionic twinning. The goal is to illustrate the potential of MR as a useful application in these clinical circumstances. A total of 32 women with multifetal gestations and suspected complication detected initially by US underwent T2-weighted MR imaging. Additional T1-weighted images were obtained when intracranial hemorrhage was suspected. MR and US findings were compared in all cases. Of 32 cases, six demonstrated fetal complications specific to monochorionic twinning; the findings consisted of conjoined twins (n=2), twin-twin transfusion syndrome (n=1), co-twin demise with embolic disease (n=2), and twin-reversed arterial perfusion. (TRAP) syndrome (n=1). MR imaging confirmed US findings in all cases and was particularly helpful in delineating the extent of intracranial complications of monochorionic twins. The technique also showed improved anatomical detail in cases of conjoined twins. MR imaging provided additional information in cases of complicated monochorionic twinning, making it a useful complementary technique when combined with initial sonographic assessment.

Acardiac anomaly: current issues in prenatal assessment and treatment

Acardiac anomaly is a rare condition affecting monochorionic multiple pregnancies. We review this condition with emphasis on its prenatal diagnostic features and treatment options. Due to the parasitic hemodynamic dependence of the acardiac twin on the pump twin, it is important to monitor the pump twin for signs of decompensation and, if indicated, intervene by interrupting vascular supply to the acardiac twin. The goal of treatment is to maximize the pump-twin's chance of survival. To assist with the decision of when to treat, we suggest a new classification system based on prognostic factors, specifically the size and growth of the acardiac twin and the cardiovascular condition of the pump twin. When the acardiac twin is small and no signs of cardiovascular impairment in the pump twin are present, we suggest serial ultrasound surveillance to detect any worsening of the condition. In cases with a large acardiac twin or rapid growth of the acardiac mass, we recommend prompt intervention. Once treatment is indicated, the intrafetal approach to interrupt the vascular supply to the acardiac twin appears to be superior to cord occlusion techniques as it is simpler, safer and more effective. The first line of treatment, if available, should be ultrasound-guided laser coagulation or radiofrequency ablation of the intrafetal vessels.