Methods of colon cleansing and/or inspection are described which safely maintain the colon in an uncollapsed state. Balanced replacement of the volume of fluid, gas and/or solids evacuated during cleansing of a colon is described. Replacement volume comprises, for example, cleansing fluid, jetting gas, and/or inflation gas. In some embodiments, the balancing of evacuated and replacement volume is achieved under automatic control, based on monitored volume of material exchange, and/or measurement of resulting pressures.
