Are you using prepackaged enemas or anal douches? Prepackaged enemas (e.g. Fleet) contain a laxative (such as sodium biphosphate) that is absorbed through the rectal wall, so in addition to the physical "flushing out" from the enema, the rest of your intestines will contract, causing the fecal matter from your entire colon to head out. In general, enemas should only be used if they are ordered by a doctor or if you are severely constipated. Anal douches clean out your rectum but try to involve the rest of your intestine as little as possible.

Use an anal douche, as Dwtim wisely suggested. You can buy a rectal syringe at any drugstore (or buy the COLT anal douche from EF). Fill a clean cup with warm water (not cold, or that will feel "icky" inside you, but obviously not too hot as you do not want to burn your rectum). Suck the water up into the bulb, taking care not to get any bubbles (you want flushing, not gas). Attach the tip, lubricate it, get into your position of choice, and insert it. Fill your rectum slowly with the water and retain for a few minutes, just as you would with an enema, and then expel. Repeat if necessary, then wait for about an hour as I find that not all the fluid comes out right away.

Good luck! I hope I helped!