Debra,
That is incorrect. The endoscopy and colonscopy are two different organs and two different anatomical sites. As I mentioned earlier, a 59 modifier would be the correct modifier according to coding guidelines.
Why would you use a 51 modifier and get a reduced pricing rate when the carrier is stating that they will pay both procedures at 100% if you use the 59 instead? It may be beneficial to you to do a little research on your own about the difference between distinct and mulitple procedures, you appear to be a little confused on this issue.
ENCODER PRO: DEFINITION OF 59 MODIFIER
"Under certain circumstances, it may be necessary to indicate that a procedure or service was distinct or independent from other non-E/M services performed on the same day. Modifier 59 is used to identify procedures/services, other than E/M services, that are not normally reported together, but are appropriate under the circumstances. Documentation must support a different session, different procedure or surgery, different site or organ system, separate incision/excision, separate lesion, or separate injury (or area of injury in extensive injuries) not ordinarily encountered or performed on the same day by the same individual. However, when another already established modifier is appropriate it should be used rather than modifier 59. Only if no more descriptive modifier is available, and the use of modifier 59 best explains the circumstances, should modifier 59 be used. Note: Modifier 59 should not be appended to an E/M service. To report a separate and distinct E/M service with a non-E/M service performed on the same date, see modifier 25"