Subcutaneous Injection
A subcutaneous injections, sometimes abbreviated as SC or SQ (although SQ is falling out of favor as there is no actual "Q" in the word) is a method of medication administration where drugs are administered into the adipose tissue layer just below the epidermis and dermis. This tissue has few blood vessels, so drugs administered here have a slow, sustained rate of absorption into the capillaries.
Unlike with IM injections, there is no need to aspirate the syringe prior to injecting the medicine. The likelyhood of hiting a blood vessel is slim.
With heparin in particular it is important not to aspirate, as this can cause the formation of a hematoma.
Injection Sites
There are many sites that can be used to administer subcutaneous injections. Absorption rates differ at different sites.
Injections in the...
- abdomen are absorbed most rapidly
- arms are absorbed somewhat more slowly
- thighs, even more slowly
- upper ventral or dorsolateral areas have the slowest absorption
It is necessary to rotate sites or areas for injection if the patient is to receive frequent injections. This helps to prevent buildup of fibrous tissue and permits complete absorption of the medication.
Sizes & Amounts
- 25-30 gage
- 3⁄8 to 1 inch needle
- most common sizes are 3⁄8 and 5⁄8)
- you choose the needle length based on the amount of subcutaneous tissue present, which is based on the patient’s body weight and build
- 45-90 degree angle
- generally speaking the longer the needle the more acute the angle.
- no more than 1 mL in all locations
- giving larger amounts adds to the patient’s discomfort and may predispose to poor absorption