I've had that during a flare, when I'd get only a nanosecond warning that I needed to go and couldn't even make it 30 feet to the bathroom in time. I always assumed it was because of the severe rectal inflammation. Your rectal meds should help with this.
Moderate to severe left-sided UC (21 cm) diagnosed 2001.
Intolerant to Asacol and rectal mesalamine preparations.
On Prednisone then Entocort 2001-2006 with only short periods off.
Current meds are Colazal,
Azathioprine Remicade, Nature's Way Primadophilus Reuteri.
In remission since April, 2006. Remicade has been my wonder drug.