Vascular access is an important, sometimes critical, step in the care of sick infants and children. Peripheral vascular catheterization provides a direct route for administration of fluids and medications. Many anatomic sites are available for intravenous (IV) catheterization, with peripheral sites being the most common and most readily available. For more information, see Axillary Vein Catheterization.
Placing an IV line into a peripheral vein in a small child or infant can be a difficult task, for many reasons. Small children and infants have smaller peripheral veins, they may have more subcutaneous fat, they are prone to vasoconstriction, and they are much less likely to remain motionless and cooperative during a painful procedure than adults. The scalp veins provide a secondary option for peripheral intravascular access in small children and infants because of minimal subcutaneous fat and less movement and the lack of a flexible joint; this reduces the likelihood of dislodging the catheter, which is common with IV catheters placed in the arms or legs.
Indications and Contraindications
Scalp vein catheterization is indicated in any patient who requires intravascular access for the administration of fluids or medications.
The decision to attempt access via one of the scalp veins should be based on inspection or palpation of various sites. Although the scalp veins provide certain advantages, the best site at which to attempt access is whichever vein the clinician feels offers the greatest chance for successful catheterization on the basis of his or her ability to visualize or palpate the vessel. Using scalp veins can also help preserve the vessels of the arms and legs for peripherally inserted central catheters. 
Scalp vein catheterization is often considered only after attempts to insert a catheter at other peripheral sites have failed.
Attempting IV access near sites of superficial skin injury or infection should be avoided.