This paper describes a magnetic, nonoperative device and control system designed to treat long-gap esophageal atresia (LEA). This congenital disorder occurs in approximately 100 newborn infants every year and is characterized by a discontinuity in the esophagus between the mouth and stomach. Our device builds upon previous work investigating the use of internal permanent magnets to stretch the proximal and distal esophageal pouches together until anastomosis occurs. We implement a hydraulic standoff device for the proximal magnet assembly to control the distance between the two magnets independent of the esophageal gap size. The standoff allows for controllable, intermittent force between the two pouches and provides a layer of safety from runaway magnetic forces that could potentially damage delicate esophageal tissue. The proximal device comes in two variations: a convex tip for stretching the esophagus and a concave mating tip for meeting the distal end during anastomosis. A light emitting diode (LED) and phototransistor pair estimates the esophageal gap size for the duration of the procedure, and a fluid pressure sensor enables the force on the esophageal tissue to be calculated. The external control circuitry, physician interface, and pump are described that demonstrate the core functionality of the system.