Diagnostic modalities for the evaluation of small bowel pathology include video capsule endoscopy (VCE), antegrade and retrograde device-assisted enteroscopy, CT and MR enterography (1). Despite VCE being the first-line evaluation modality, it lacks interventional capability. Deep enteroscopy (DE) allows tissue sampling and other therapeutic interventions with real-time endoscopic assessment. DE is usually performed with specific endoscopes (balloon-assisted device or spiral overtube) making it time consuming and there is limited availability since special instruments and accessories are required.(1,2) The through-the-scope (TTS) balloon system consists of a balloon catheter designed for anchoring in the small bowel, inserted through the instrument channel of a standard colonoscope.(3) The catheter is advanced, the balloon is inflated and anchored in the small intestine and the endoscope slides over the guiding catheter to the inflated balloon. The most common indications for DE are obscure GI bleeding, iron deficiency anemia, abnormal capsule endoscopy and chronic diarrhea. As compared to spiral, single-or double-balloon enteroscopy, TTS (NaviAid, SMART Medical Systems Ltd, Ra'anana, Israel) is a simpler technique, which requires less investment in infrastructure. The balloon catheter is advanced blindly in front of a standard adult colonoscope as it bends around the curves of the small bowel. To prevent perforation/trauma the catheter is fitted with a soft silicone tip which easily bends under pressure. Insertion depth can be calculated during the withdrawal of the enteroscope. The Aim of the study: To compare the depth of maximal ileal insertion between through-the-scope balloon enteroscopy (NaviAid) with enteroscopy using the adult colonoscope (Olympus CF-190) alone, in the same patient, in a prospective cohort at University Medical Center of El Paso, Texas.