• Welcome to Crohn's Forum, a support group for people with all forms of IBD. While this community is not a substitute for doctor's advice and we cannot treat or diagnose, we find being able to communicate with others who have IBD is invaluable as we navigate our struggles and celebrate our successes. We invite you to join us.

What if I miss a day on a 3-day stool test?

After 10 days of diarrhea, my GI doc ordered a stool test where I'm supposed to take samples over three consecutive days. Day 1 was fine, but I didn't have a BM today. What do I do? Just give in two samples or add another day? I will try to call the lab tomorrow, but am not sure how easy it will be to get info on a Saturday. Any advice?


Super Moderator
Being a three day test I assume it is for FOB (faecal occult blood)?

This is the protocol I work off but I can’t guarantee that your lab doesn't differ…

- it doesn’t matter if you miss day, the main thing is that the last sample is collected no later than 10 days after the first sample. I have never seen a FOBx3 stretch out to the 10 day limit but it certainly isn’t unusual for people to miss a day or two.

I would carry on and get the next two samples when you can and contact the lab when they are next open.

Dusty. :)