Intestinal flow after anastomotic operations in neonates.

Stagnation of contents at the anastomotic site for intestinal flows after anastomotic operation is a critical issue in neonates. Although various anastomosis methods have been developed, in the clinical field, poor passage at the anastomotic site in cases of jejunal atresia is still observed. A CFD study was carried out to clarify the reasons for the stagnation and to find favorable anastomosis methods from a fluid dynamical point of view. Direct numerical simulations were performed using OpenFOAM. The boundaries of the computational domain were peristaltically moved to reproduce flow. The results reveal that the peristaltic motion on the distal side dominates the flow and that on the proximal side has a negligible influence. In particular, the contents do not pass the anastomotic site when the peristaltic motion on the distal side is not active. The flow rate as a measure of the driving force of the flow on the proximal side is large when the amplitude of the peristaltic motion is large and the diameter is small. It was also found that anastomosis methods do not affect flow resistance.