Vascular endothelial growth factor in monochorionic twins with twin-twin transfusion syndrome

Increased Risk of Retinopathy of Prematurity in Donors with Twin-to-Twin Transfusion Syndrome: A Cohort Study

INTRODUCTION

The purpose of this study was to evaluate the within-pair difference in retinopathy of prematurity (ROP) between donors and recipients with twin-to-twin transfusion syndrome (TTTS) and to identify risk factors for ROP development.

METHODS

This retrospective cohort study included 147 TTTS twin pairs managed between 2002 and 2022 and eligible for ROP screening. Primary outcomes were any stage ROP and severe ROP. Secondary outcomes were hemoglobin at birth, red blood cell transfusions, mechanical ventilation days, postnatal steroids, and neonatal morbidity. Donor status was defined as having polyhydramnios pre-laser.

RESULTS

Rates of any stage ROP (23% vs. 14%) and severe ROP (8% vs. 3%) were significantly higher in donors compared to recipients. Donors received a higher number of blood transfusions (1 [±1.9] versus 0.7 [±1.5]). Five factors were univariately associated with any stage ROP: donor status (odds ratio [OR] 1.9; 95% CI 1.3-2.9), lower gestational age (GA) at birth (OR 1.7; 95% CI 1.4-2.1), small for GA (OR 2.1; 95% CI 1.3-3.5), mechanical ventilation days (OR 1.1; 95% CI 1.1-1.2), and blood transfusions in phase 1 (OR 2.3; 95% CI 1.2-4.3). Three factors were independently associated with any stage ROP: donor status (OR 1.8; 95% CI 1.1-2.9), lower GA at birth (OR 1.6; 95% CI 1.2-2.1), and mechanical ventilation days (OR 1.1, 95% CI 1.0-1.1). Donor status was univariately associated with severe ROP (OR 2.3, 95% CI 1.1-5.0).

CONCLUSION

Any stage ROP and severe ROP are detected twice as frequently in donors compared to recipients. Increased awareness for ROP is needed in donors, especially those with lower GA at birth and longer duration of mechanical ventilation.

Molecular Mechanisms Underlying Twin-to-Twin Transfusion Syndrome

Twin-to-twin transfusion syndrome is a unique disease and a serious complication occurring in 10–15% of monochorionic multiple pregnancies with various placental complications, including hypoxia, anemia, increased oxidative stress, and ischemia-reperfusion injury. Fetoscopic laser photocoagulation, a minimally invasive surgical procedure, seals the placental vascular anastomoses between twins and dramatically improves the survival rates in twin-to-twin transfusion syndrome. However, fetal demise still occurs, suggesting the presence of causes other than placental vascular anastomoses. Placental insufficiency is considered as the main cause of fetal demise in such cases; however, little is known about its underlying molecular mechanisms. Indeed, the further association of the pathogenic mechanisms involved in twin-to-twin transfusion syndrome placenta with several molecules and pathways, such as vascular endothelial growth factor and the renin–angiotensin system, makes it difficult to understand the underlying pathological conditions. Currently, there are no effective strategies focusing on these mechanisms in clinical practice. Certain types of cell death due to oxidative stress might be occurring in the placenta, and elucidation of the molecular mechanism underlying this cell death can help manage and prevent it. This review reports on the molecular mechanisms underlying the development of twin-to-twin transfusion syndrome for effective management and prevention of fetal demise after fetoscopic laser photocoagulation.

Influence of maternal obesity and metabolic and vascular mediators in twin-twin transfusion syndrome

Obesity is a risk factor for complications in singleton and twin pregnancies; however, there are limited data regarding maternal body mass index (BMI) in the setting of twin-twin transfusion syndrome (TTTS). We hypothesized that increased BMI in TTTS is associated with adverse perinatal outcomes and vascular pathology. A retrospective study of twin reversed arterial perfusion (n = 4), selective intrauterine growth restriction (n = 10) and TTTS (n = 33) was conducted. Treatment included fetoscopic laser photocoagulation (FLP) (n = 35) or Solomon technique (n = 12). Ex vivo placental intravascular injections, immunohistochemistry, and perinatal outcomes were compared by maternal BMI. In pregnancy complicated by TTTS, 16/33 women were obese (BMI > 30 kg/m²) and 11/33 were overweight (BMI 25-29.9 kg/m²). Women who were overweight or obese had an increased rate of premature rupture of membranes (PPROM), cesarean delivery, and/or concomitant co-morbidities when compared to the normal weight group. Duration of neonatal intensive care unit (NICU) admission was longer in neonates of overweight/obese women versus normal weight. Placental examination of FLP sites in the obese group showed larger infarcts, increased adipose triglyceride lipase, and a proangiogenic phenotype. Increased BMI is common in our TTTS cohort and it is associated with higher rate of co-morbidity, PPROM, prolonged NICU stay, and an imbalance of placental metabolic and vascular mediators.

Twin-twin transfusion syndrome as a possible risk factor for the development of retinopathy of prematurity

PURPOSE

The objective of this study was to evaluate the correlation between twin-twin transfusion syndrome (TTTS) and the development of retinopathy of prematurity (ROP) in premature infants.

METHODS

Fifty-one infants who were less than 32 postmenstrual gestational weeks at birth or with a birth weight less than 1,501grams were included in this longitudinal observational study. The infants were matched by gestational age and birth weight, and divided into three groups: multiples with TTTS, multiples without TTTS, and singletons. The primary outcome variable was the incidence of ROP in infants affected by TTTS versus infants not affected by TTTS. Secondary outcome variables were multiple pregnancy, gestational age, and birth weight.

RESULTS

Infants affected by TTTS showed a significantly higher incidence of ROP than infants not affected by TTTS (p < 0.01). TTTS donors and TTTS recipients were both at greater risk of developing ROP. ROP occurred in infants with TTTS whose gestational age at birth was significantly higher than that of infants with ROP who were not affected by TTTS (p = 0.01). Multiple pregnancy itself was not a risk factor for ROP disease.

CONCLUSIONS

Infants affected by TTTS during pregnancy are at high risk of developing ROP, even if they were born at an older gestational age. Special awareness in ROP screening is necessary for these infants.

The effects of fetal surgery on retinopathy of prematurity development

Background

Fetal surgery is selectively offered for severe or life-threatening fetal malformations. These infants are often born prematurely and are thus at risk for retinopathy of prematurity (ROP). It is not known whether fetal surgery confers an increased risk of developing severe ROP relative to published rates in standard premature populations ≤37 weeks of age grouped by birth weight (<1500 grams or ≥1500 grams).

Design

This is a retrospective chart review.

Methods

We reviewed the charts of 137 patients who underwent open fetal/fetoscopic surgery from 1996–2004. Surgical indications included twin-twin transfusion syndrome (TTTS), myelomeningocele (MMC), congenital diaphragmatic hernia (CDH), sacrococcygeal teratoma (SCT), cystic adenomatoid malformation of the lung (CCAM), and twin reversed arterial perfusion sequence (TRAP). Of these, 17 patients had local ROP examination data. Binomial tests were performed to assess whether rates of ROP in our fetal/fetoscopic surgery cohort were significantly different from published rates.

Results

There were 5 patients each with an underlying diagnosis of TTTS and MMC, 2 patients each with CDH and TRAP, and 1 patient each with SCT, CCAM, and mediastinal teratoma. The mean gestational age at surgery was 23⁴/₇ ± 2³/₇ weeks, mean gestational age at birth was 30 ± 2⁵/₇ weeks, and mean birth weight was 1449 ± 510 grams (610–2485). Compared to published rates of ROP and threshold ROP, our fetal surgery patients had significantly higher rates of ROP and threshold ROP in both the <1500 grams and the ≥1500 grams group (all p-values < 0.05).

Conclusions

Fetal/fetoscopic surgery appears to significantly increase the rate of ROP and threshold ROP development. Greater numbers are needed to confirm these observations.