For fairly obvious reasons flat front dresses are my nemesis, there's little place to hide a colostomy bag behind a dress that has no disruption to the fabric like the ruffled, twisted or ruched varieties, but if I'm feeling bold and brave I will give it a go. I have to be honest though, on both the occasions in the photos below my car was parked near by and my plan should I have needed to was to pop back to my car and change the bag there (Even after all these years I've never gotten used to the thought of changing my bag in a public toilet, which is crazy, its solely what they're for!!) Therefore I take comfort in my car being close by. (a bottle of water, removal spray, nappy sacks and dry wipes can always be found in the glove box.)
The trick I have learnt with a flat front dress is fairly simple, if not a little old fashioned. I use a slip or petticoat to smooth the edges of the bag and the bumps within. It works an absolute treat. I do remember one dress I fell in love with and desperately wanted to wear it but the bag showed even with a slip underneath it, I bought it anyway and came home to have a think, I found that wearing TWO slips underneath it made it wearable.
The key is to find slips that work with the dress or skirt, they're not a massively popular item these days so it can take a while to find just the right one both in length and thickness. Marks and Spencer do some really nice mini half slips which helped resolve one of the problems I had that my slip was longer than the dress I was wearing. If you don't fancy forking out for a collection of slips that your'e not going to want to wear that often, I'd go for a flesh toned one, which will go under any colour.
LEFT Dress from Hobbs, shoes and handbag from Chanel. RIGHT dress from White Stuff, shoes from Jimmy Choo.