Hi Clara
I just posted this morning about my experiences with my rectal stump; what you are describing sounds very much like what I have, it is called a Hartmann's procedure. My rectal stump is approximately 4 cm in length. And I too, in the beginning (I have had my ileostomy for somewhere between 25 and 27 years now).
It is nothing to worry about.
Your rectal stump is the remaining portion of the rectum after a bowel operation. The rectal stump still needs emptying because even though the stool now exits through the ileostomy, the rectal tissue remains and continues to produce mucus, which needs to be periodically expelled from the body through the anus, often causing a feeling of needing to go to the toilet, even though no solid stool is present; this is a normal occurrence and can be managed by sitting on the toilet to gently evacuate the mucus buildup.
My mucus usually comes out as diarrhea, not firm, and is white/creamy in color. Sometimes there is a smell. But my surgical specialist has reassured me that this is completely normal. Also, sometimes I get a little bleeding as well.
I pray that this will make you feel a bit less scared. But if you need further reassurance, you could always talk to your surgeon or your stoma nurse.
All the best from New Zealand,
Gracie