A neonate, born at 38 weeks gestation, presents with bilious vomiting starting 12 hours after birth. Antenatal ultrasound revealed polyhydramnios. On examination, the baby is active and has a distended upper abdomen but a scaphoid lower abdomen. An abdominal X-ray shows a 'double bubble' sign. Which of the following is the most appropriate next step in the management of this neonate, considering potential associated complications?