**5. Conclusion**

Difficult venous access is characterized by non-visible and non-palpable veins and is caused by the various patient- and practitioner-related factors, such as age, obesity, history of chemotherapy, and vein characteristics of the patients, and the clinical experience of the practitioners [1, 7, 8, 12]. Understanding these factors for DIVA may facilitate the management of difficult venous access and improve patient outcomes in this population. In difficult intravenous catheter intervention, determining the appropriate vein and placing the catheter with the appropriate technique is required. Evaluation of veins before catheter insertion is crucial in determining the appropriate vein. For this, vein grading scales should be used [31, 32, 47]. Techniques to increase vein fullness (e.g. fist clenching, hot application, topical vasodilator, tapping) can be used to determine the vein, or ultrasound and vein imaging devices can be used to view veins [2, 23, 30, 35, 43, 46]. In addition, difficult venous access guidelines, which are limited in the literature, need to be developed.
