Fetal anemia in monochorionic twins: a review on diagnosis, management, and outcome

INTRODUCTION

Monochorionic twins may develop fetal anemia when blood is unequally distributed via the placental vascular anastomoses. This review focuses on the causes of fetal anemia in complicated monochorionic twins and highlights the differences in management and outcome.

AREAS COVERED

Fetal anemia can occur in the context of twin anemia polycythemia sequence (TAPS), chronic twin-twin transfusion syndrome (TTTS) and acute peripartum TTTS, and in cotwins after single fetal demise. Diagnosis of fetal anemia is based on abnormal Doppler ultrasound measurements. Management options include fetoscopic laser surgery, intrauterine blood transfusion, or expectant management, depending on the type of complication and the severity of the disease. In all complications, fetal anemia may lead to perinatal mortality, neonatal morbidity, severe cerebral injury, and long-term neurodevelopmental impairment. In TAPS specifically, anemic donors may also show bilateral deafness.

EXPERT OPINION

Knowledge on the diagnosis and optimal treatment in TTTS is nowadays widespread, but caregivers often fail to distinguish TAPS from acute peripartum TTTS at birth. A full blood count including reticulocyte count is required, and placental dye injection is extremely helpful to reach the correct diagnosis and establish the optimal management.

Neonatal management and outcome in complicated monochorionic twins: What have we learned in the past decade and what should you know?

Monochorionic (MC) twin pregnancies are at increased risk of neonatal morbidity and mortality due to the shared placenta with vascular connections that can give rise to various complications, including twin-twin transfusion syndrome, twin anemia polycythemia sequence (TAPS), selective fetal growth restriction, and other hematological imbalances at birth. Each complication presents its own challenges and considerations in the neonatal period. Measurement of hemoglobin levels and reticulocyte count is required to establish a correct diagnosis. Placenta dye injection is needed to properly distinguish between the various conditions. Risk factors for adverse outcome in MC twins include prematurity, severe cerebral injury, and the type of MC pregnancy complication. We, therefore, recommend cerebral ultrasound examinations in all complicated MC twins at birth to rule out a severe brain injury. Lastly, we strongly encourage screening for hearing loss using automated auditory brainstem response in all spontaneous TAPS donors to prevent permanent speech development delay.

Fetoscopic laser ablation therapy in monochorionic diamniotic twin pregnancies with twin-to-twin transfusion syndrome treated at a single centre over 10 years: a retrospective study

OBJECTIVES

To review experience with fetoscopic laser ablation of placental anastomoses to treat monochorionic diamniotic (MCDA) twin pregnancies complicated by twin-to-twin transfusion syndrome (TTTS) in a single centre over a ten-year period.

METHODS

A retrospective study on 142 MCDA twin pregnancies complicates by TTTS treated with equatorial laser ablation of placental anastomoses (2008-2018). Solomon technique was also applied after 2013. Survival rates, neonatal outcome, intraoperative and post-laser complications were recorded, and prognostic factors analysed.

RESULTS

A total of 133 cases were included in the final analysis; 41 patients were at stage II (30.8%), 73 were at stage III (62.9%), while only 12 (9%) at stage I and two patients (1.7%) at stage IV. Solomon technique was applied in 39 cases (29.3%). Survival of both twins was 51.1% (68/133), of a single twin 20.3% (27/133), and of at least one 71.5% (95/133), with an overall survival of 61.3% (163/266). TAPS and recurrent TTTS occurred in 8 (6%) and 15 (11.3%) patients. Survival of both fetuses increased over time (44.6 vs. 57.3%). A posterior placenta (p<0.003) and the use of the Solomon technique (p<0.02) were more frequent in cases with survival of both fetuses, while TTTS recurrence was significantly associated to the loss of one or two fetuses (p<0.01). Such associations were confirmed at logistic regression analysis.

CONCLUSIONS

Survival of both twins can improve over time and seems to be favourably associated with a placenta in the posterior location and the use of the Solomon technique.

Neonatal Outcomes and Maternal Characteristics in Monochorionic Diamniotic Twin Pregnancies: Uncomplicated versus Twin-to-Twin Transfusion Syndrome Survivors after Fetoscopic Laser Surgery

Preterm birth remains a major complication of fetal laser surgery (FLS) due to twin-to-twin transfusion syndrome (TTTS).

OBJECTIVES

We tested the hypothesis that neonatal outcomes in fetuses born at >24 weeks are worse in TTTS survivors compared to uncomplicated monochorionic diamniotic (MCDA) twins.

METHODS

196 patients with TTTS treated with laser therapy and 91 uncomplicated MCDA gestations were compared. Neonatal outcomes included respiratory distress syndrome (RDS), transient tachypnea of the newborn (TTN), bronchopulmonary dysplasia, intraventricular hemorrhage, necrotizing enterocolitis, and neonatal death. Risk factors assessed were TTTS, maternal age, maternal body mass index, race, premature prolonged rupture of membranes, stage of TTTS, parity, and gestational age (GA) at delivery.

RESULTS

GA at delivery was lower in the TTTS group (31.0 ± 4.6 vs. 33.5 ± 2.4 weeks, p < 0.001). RDS and TTN occurred at higher rates in the TTTS than in the uncomplicated MCDA group. After multivariate logistic regression, the only factor significantly associated with the composite adverse outcome was GA at delivery (OR 0.61; 95% CI: 0.58-0.7).

CONCLUSION

TTTS twins treated with FLS are deliver 2.5 weeks earlier than uncomplicated MCDA twins. Respiratory complications were significantly higher in TTTS twins and were mainly the consequence of the early GA at delivery.

Congenital limb deficiency requiring transfemoral amputation

A healthy female infant was born from a twin pregnancy with an isolated congenital lower extremity malformation. Aside from prenatally diagnosed polyhydramnios, the infant had normal prenatal and postnatal diagnostic workup. She underwent transfemoral amputation and healed uneventfully. Congenital limb anomalies may be the result of an unidentified amniotic band, thromboembolic event or twin-twin transfusion syndrome, though in this case, prenatal screening did not indicate any evidence of a limb anomaly and postnatal workup was negative.

Long-term outcomes for monochorionic twins after laser therapy in twin-to-twin transfusion syndrome

Twin-to-twin transfusion syndrome typically occurs in the second trimester in 10-15% of monochorionic twin pregnancies. Vascular anastomoses of monochorionic placentae are the underlying cause of the development of the syndrome. If a blood flow imbalance occurs, one fetus becomes the so-called donor twin and the other the recipient. If untreated, perinatal mortality is 80-90%. Fetoscopic laser coagulation of the vascular anastomoses destroys the cause of the syndrome and leads to dual twin survival rates of around 70% and more than 90% of pregnancies with at least one survivor. However, unequal placental sharing, intrauterine death, and severe prematurity are still limiting factors for further improvement of survival rates and decreases in long-term morbidity. Prematurity and neurodevelopmental impairment affect the donor and recipient twins, whereas cardiovascular failure and obstruction of the right ventricular outflow tract are typical complications of recipients, which can lead to long-term morbidity. In this Review, we summarise the literature on follow-up data for survivors of twin-to-twin-transfusion syndrome after laser therapy, including neurodevelopmental outcomes, cardiovascular outcomes, growth, renal function, and ischaemic events, as well as the potential effects of intrauterine programming on later life.

Fetal distress and circulatory disturbance in monochorionic twins: Possible risk factors for sialadenitis?

Neonatal sialadenitis is a rare condition. The vast majority of cases are caused by Staphylococcus aureus with predominant involvement of the parotid gland and need for long-term antimicrobial therapy. We reviewed three distinct cases of submandibular sialadenitis in preterm infants from monochorionic pregnancies. The association with neonatal sialadenitis is unproven. We speculate about the role of fetal distress and circulatory compromise in monochorionic twins as a risk factor in the development of this serious condition.

Fetal surgery: an overview

In utero fetal surgery interventions are currently considered in selected cases of congenital diaphragmatic hernia, cystic pulmonary abnormalities, amniotic band sequence, selected congenital heart abnormalities, myelomeningocele, sacrococcygeal teratoma, obstructive uropathy, and complications of twin pregnancy. Randomized controlled trials have demonstrated an advantage for open fetal surgery of myelomeningocele and for fetoscopic selective laser coagulation of placental vessels in twin-to-twin transfusion syndrome. The evidence for other fetal surgery interventions, such as tracheal occlusion in congenital diaphragmatic hernia, excision of lung lesions, fetal balloon cardiac valvuloplasty, and vesicoamniotic shunting for obstructive uropathy, is more limited. Conditions amenable to intrauterine surgical treatment are rare; the mother may consider termination of pregnancy as an option for many of them; treatment can be lifesaving but in itself carries risks to both the infant (preterm premature rupture of the membranes, preterm delivery) and the mother. This makes conducting prospective or randomized trials difficult and explains the relative lack of good-quality evidence in this field. Moreover, there is scanty information on long-term outcomes. It is recommended that fetal surgery procedures be performed in centers with extensive facilities and expertise. The aims of this review were to describe the main fetal surgery procedures and their evidence-based results and to provide generalist obstetricians with an overview of current indications for fetal surgery.

Pseudoamniotic Band Syndrome after In Utero Intervention for Twin-to-Twin Transfusion Syndrome: Case Reports and Literature Review

Pseudoamniotic band syndrome (PABS) is a rare iatrogenic complication that arises after invasive procedures in monochorionic twins. We report 3 cases of PABS, 2 after fetoscopic laser photocoagulation and 1 after bipolar cord coagulation. Two cases were detected antenatally by ultrasound; out of the two, one underwent successful fetoscopic release of amniotic band, which is the first report in twin pregnancy to our knowledge. In our centre, the incidence of PABS was found to be 2%. There were 25 cases of PABS reported previously, of which 12 cases with clinical details were reviewed together with our 3 cases. The fetal limbs were involved in all 15 cases, leading to constriction or amputation. The umbilical cord was involved in 2 cases, resulting in fetal death in one and pregnancy termination in the other. Antenatal detection of PABS is rare (27%; 4/15) as this requires a high index of suspicion. Serial postoperative targeted ultrasound surveillance of the fetal limbs and umbilical cord is necessary, particularly when features of septostomy or chorioamniotic membrane separation are found. Colour Doppler examination for the perfusion of the affected limb should be performed when PABS is detected. Fetoscopic release of amniotic band could salvage the fetal limb from amputation when impaired blood flow is detected.

Upper limb vascular occlusion in the recipient of a monochorionic twin pair

Monochorionicity is responsible for an increased rate of severe complications because of unequal splitting of the placental mass and/or an imbalance in the blood flow across placental vascular anastomoses. Vascular limb occlusion is one of the rare complications of monochorionic twins, usually occurring in the lower extremities after intra-uterine death of one twin, antenatal intervention (amnio-reduction or laser therapy) or in the presence of twin anemia-polycythemia syndrome. We report a case of vascular occlusion of the upper extremity in the recipient twin of a monochorionic pair in the absence of those predisposing factors.

Fetal Limb Ischaemia in Twin-to-Twin Transfusion Syndrome

Objective. To describe the rare association between prenatal vascular limb occlusion and twin-to-twin transfusion syndrome. The Case. A woman with severe twin-to-twin transfusion syndrome was treated with fetoscopic laser ablation at 19-week gestation. At 27 weeks, the twins were delivered by an emergency caesarean section. The right arm of twin 1, the recipient twin, was noted to be “ischaemic” and was later amputated. Conclusion. This case is unusual in that it affected the upper limb and there was no evidence of polycythaemia, which is a suggested pathological mechanism. It was initially thought that the limb damage was due to the laser ablation, but after discussion with the fetal medicine team vascular limb occlusion in association with twin-to-twin transfusion syndrome was considered. Limb ischaemia is a serious complication of twin-to-twin transfusion syndrome and is unrelated to any form of fetal therapy. Implications. Neonatologists and paediatricians need to be aware of this association as it has medicolegal implications and parents should be counselled as to the possible, albeit rare, occurrence, especially when twin-to-twin transfusion syndrome is of advanced stage at presentation.

Twin-to-twin transfusion syndrome and limb ischemia: a case report

Twin-to-twin transfusion syndrome (TTTS) is a severe complication of monochorionic twin pregnancies. This condition is associated with high mortality if untreated. Treatment consists of either serial reduction of amniotic fluid or selective laser photocoagulation (SLP). In utero limb ischemia is a known complication of TTTS. An interaction between this condition and SLP has never been established. Here, we describe the first of twins born at 34 weeks’ gestational age, delivered by emergency cesarean section for fetal distress after a pregnancy complicated by severe TTTS. The first twin, the recipient in the TTTS, showed a necrotic right limb, which was amputated above the knee joint on the 23rd day of life. Anatomic-pathological investigation revealed vascular thrombosis. The foot-length was compatible with a gestational age of 16–18 weeks, the time of limb ischemia, which is well before 26 weeks, when SLP was performed. Therefore, we refute that the fetal limb ischemia was a complication of SLP.

Meconium peritonitis in both fetuses with early twin-to-twin transfusion syndrome

Twin-to-twin transfusion syndrome (TTTS) is due to unbalanced inter-twin bloodflow through placental vascular anastomoses. We present a TTTS case treated with fetoscopic laser photocoagulation (FLP) that was complicated by perinatal meconium peritonitis in both twins. Ten weeks following laser treatment, the two fetuses showed intra-abdominal hyperechogenicity and ascites. After birth, the two newborns were surgically managed for peritonitis. We discuss the pathogenesis of this double insult. The present case highlights the role of end-circulation bowel thrombi as the potential cause of subsequent intestinal perforation.

Vascular limb occlusion in twin-twin transfusion syndrome (TTTS): case series and literature review

OBJECTIVE

The purpose of this study was to evaluate the phenomenon of vascular ischemic limb necrosis in twin-twin transfusion syndrome (TTTS).

STUDY DESIGN

This was a multicenter retrospective review of ischemic limb necrosis in patients with TTTS.

RESULTS

Twenty cases of fetal ischemic limb necrosis in association with TTTS were identified from 10 fetal medicine centers. The recipient was affected in 19 cases, and the lower limb was affected in 17 cases. The extent of the damage correlated with TTTS severity. Eighty percent of limb defects (16/20) clearly were unrelated to laser treatment (3 cases untreated, 7 cases after amnioreduction, 6 cases present at time of laser). The recipient was relatively polycythemic in 5 of 7 cases in which neonatal or fetal hemoglobin/hematocrit levels were available.

CONCLUSION

Ischemic limb necrosis is a rare complication of TTTS. The lesion is unrelated to therapy and may be the result of polycythemia, hypertension, and vasoconstriction.

[Spontaneous neonatal arterial thrombosis: a report of 4 neonates]

Arterial thromboses are rare in newborns, mostly caused by arterial catheters. Neonatal arterial thrombosis occurring in other contexts is much rare. We report arterial thrombosis, not caused by catheterisation in 4 neonates hospitalised in the neonatology department of the Farhat Hached de Sousse hospital in Tunisia. The diagnosis of arterial thrombosis was made based on signs of ischemia in 2 patients affected by thrombosis of the iliac arteries. The symptoms were less clear: anuria associated with arterial high blood pressure in 1 patient affected by thrombosis of the abdominal aorta and by anuria with melena in a newborn with aortic and mesenteric thrombosis. Diagnosis was confirmed by Doppler sonography in 3 patients and based on autopsy data in 1 patient. A delay to consultation was noted in 3 patients, whose outcome was fatal. The progression was favourable after thrombolysis and anticoagulation using heparin in 1 patient with major aortic thrombosis. A review of the literature on the epidemiological, clinical, therapeutic and outcome data of the arterial thrombosis in the newborn child is provided.

Neonatal morbidity in twin-twin transfusion syndrome

Twin-twin transfusion syndrome (TTTS) is a severe complication of monochorionic twin pregnancies associated with high perinatal mortality and morbidity rates. Management in TTTS is a major challenge for obstetricians and neonatologists. Twins which are often born prematurely and may suffer from typical conditions associated with prematurity. In addition, surviving twins with TTTS are at increased risk for other complications including neurological, cardiovascular, renal and hematologic morbidity. Rare complications such as hypoxic-ischemic lesions to limbs or intestines and amniotic band syndrome have also been reported in TTTS survivors. This review focuses on the neonatal and pediatric mortality and morbidity in TTTS survivors, with special emphasis on the long-term neurodevelopmental outcome.

Laser therapy for twin-to-twin transfusion syndrome (TTTS)

Monochorionic twins are subjected to specific complications which originate in either imbalance or abnormality of the single placenta serving two twins including twin-to-twin transfusion syndrome. The diagnosis is well established in overt clinical forms with the association of polyuric polyhydramnios and oliguric oligohydramnios. The best treatment of cases presenting before 26 weeks of gestion is fetoscopic laser ablation of the intertwin anastomoses on the chorionic plate. Although subjected to subtle variations, the core technique follows robust guidelines which could help understanding and acquiring the required skills and experience to perform this procedure. However appropriate and tailored hands-on training and appropriate perinatal set-up are critical not only for surgical management but also for the follow-up and management of related complications.