Kim is right that it CAN be a sign of spina bifida occulta. But generally only combined with other symptoms such as a tuft of hair at the sight or not being able to see the base of dimple. Most drs/MCHNs should definitely know what to look out for don't stress. Even if it did happen to be SBO chances of there being any significant problems from it are very slim (google it). FWIW my younger two have a dimple thier ds really deep but no problems here