Maternal pulmonary oedema during foetoscopic surgery

We report a case of maternal pulmonary oedema necessitating intubation and ventilation with associated hyperchloraemic metabolic acidosis during foetoscopic laser surgery for twin-twin transfusion syndrome (TTTS), believed to be secondary to absorption of normal saline irrigation fluid. TTTS complicates 10% to 20% of monochorionic twin pregnancies and develops due to imbalanced vascular anastomoses and consequent unidirectional transfusion between the twins. The recipient is at risk of cardiac failure due to circulatory overload and the donor twin becomes hypoperfused. The recipient is polyhydramniotic and the donor is oligohydramniotic. Untreated severe TTTS has a mortality rate of up to 90%. Treatment options include delivery if viable, serial amnioreduction or foetoscopic laser ablation of the communicating vessels. Since the Eurofoetus study, laser ablation has been the mainstay of treatment for pre-viable TTTS, involving insertion of endoscopes transabdominally into the polyhydramniotic sac to allow visualisation and ablation of the anastosmotic vessels. Amnioreduction does not correct the underlying pathology and offers very little in advanced disease. Foetoscopic laser ablation leads to an improved survival past 28 days and a lower incidence of neurological complications compared to serial amnioreduction.