Large statistical scatter and effective pressure boundary conditions are two critical problems in the computation of microchannel flows with the direct simulation Monte Carlo (DSMC) method. To address these issues, an extension of the DSMC-IP (information preservation) coupled method is developed from the one-dimensional case to the two-dimensional case for microchannel flow. Simulation results in a microchannel flow from DSMC, IP, and numerical and analytical solutions to the Navier-Stokes equations are compared. The DSMC-IP coupled method successfully reduces the large statistical scatter usually obtained with DSMC in such low-speed flow systems. It also provides a suitable implementation of pressure boundary conditions.