Hi it just crossed my mind that your sister might have Paralytic Ileus.When i did my surgical nurse training back in the dark ages one of the major down sides from abdomonal surgery was Paralytic Ileus which was caused by the Ileum being handled.It effectively meant that the muscles that squeeze food and waste down the digestive tract became paralysed and didnt work. Hence the reason why we were always taught to make sure a patient had had their bowels open in the days following surgery and to report it if they didnt.I am not sure if what she has is a similar thing and i realise she hasnt had surgery but it might be worth "Googling"

Liz in the UK