The aim of this study was to describe the neonatal management and outcome in monochorionic twins with twin-to-twin transfusion syndrome (TTTS) not treated with fetoscopic laser surgery. All consecutive live-born neonates with TTTS managed at our center between 2002 and 2021 were included in this retrospective study. Neonatal outcome was assessed in 44 twin pairs with TTTS not treated with laser (nonlaser group) compared to a control group of 88 twin pairs with TTTS successfully treated with laser (laser group), matched for gestational age at birth. Primary outcome was adverse neonatal outcome, a composite outcome including neonatal mortality or severe neonatal morbidity. The incidence of adverse neonatal outcome in the nonlaser group and laser group was 30% (26/88) and 11% (19/176), respectively (relative risk = 3.46, 95% CI [1.79, 6.71]). In the nonlaser group, 11% had necrotizing enterocolitis (vs. 2% in the laser group) and 24% had hypotension (vs. 10% in the laser group). Recipients in the nonlaser group had, compared to recipients in the laser group, significantly more severe cerebral injury (18% vs. 5%) and more polycythemia at birth (21% vs. 1%). Donors in the nonlaser group had, compared to donors in the laser group, more severe growth restriction (71% vs 42%), renal failure (11% vs 1%), and anemia at birth (25% vs. 7%). Thus, the risk for neonatal mortality and/or severe morbidity is three-fold higher in TTTS not treated with laser than in TTTS treated with laser, which highlights the fact that these neonates with TTTS are very sick at birth, requiring accurate and prompt intensive treatment.

Historical suggestions of twin-to-twin transfusion syndrome (TTTS) date back to the early 17th century. Placental anastomoses were first reported in 1687; however, it was Schatz who first identified their importance in 1875. He recognized ‘the area of transfusion’ within the ‘villous district’ of the placenta, which he named the ‘third circulation’. This article describes how the management of TTTS has evolved as we have gained a more sophisticated understanding and appreciation of the complex vascular anastomoses that exist in monochorionic twin placentae. Currently, fetosopic laser occlusion is the preferred treatment option for TTTS.

Twin–twin transfusion syndrome (TTTS) is a severe complication of monochorionic (MC) twin pregnancies associated with high perinatal mortality and morbidity rates. Management in TTTS is a major challenge for obstetricians and neonatologists. Twins with TTTS are often born prematurely after an extremely distressing and highly hazardous fetal period. Follow-up studies report varying rates of cerebral palsy (CP) and long-term neurodevelopmental impairment (NDI). This review discusses the latest findings on the long-term outcome of TTTS survivors, possible risk factors for long-term impairment, and provides recommendations for future research.