Pregnancy testing is not routinely performed in women below 50 who are attending for colonoscopy but should be performed when fluroscopy may be performed. Please see the below guidance from the American Society for Gastrointestinal Endoscopy:
There should be availability of test kits should there be a query regarding pregnancy to give the patient choice of going ahead or declining the procedure. It is safe to do colonoscopy in pregnancy but there would be risks associated with the drugs.