Thesis Statement Im Injection Site

Angela Cocoman and Carol Barron outline best practice for administering injections into the deltoid muscle

The aim of this article is to highlight to practitioners of the possibility of injury due to poor landmarking of intramuscular injections into the deltoid muscle. Approximately 12 billion injections are administered worldwide annually,1 the majority being vaccines that are licenced for administration into the anterolateral vastus lateralus muscle for babies/children2,3 or deltoid muscle for adolescents/ adults.4,5

Administering a vaccine by the recommended route is imperative; deviation might reduce vaccine efficacy, increase the risk of local reactions or even cause permanent injury. Although vaccines are considered routine procedures, there is a risk of trauma and injury if they are performed incorrectly. The case report below is intended to raise awareness of the importance of accurate landmarking and the potential risks associated with deltoid injections. It reviews the anatomy of the deltoid muscle and suggests best practice to minimize trauma and potential injury to patients.

Case report
This is a report of a 12-year-old first-year secondary school male (in the autumn of 2012), who received an intramuscular deltoid injection. The injection was the routine administration of the Tdap vaccine in his school, with parental consent. This vaccine is recommended for children between the ages of 13 and 18 and is a low dose tetanus, diphtheria and pertussis ‘booster’ vaccine, which was introduced to the Irish schools immunisation programme on a phased basis from September 2011. From September 2012 this vaccine is offered to all students in first year of second level schools and replaces the previous school-based vaccine, called Td, which was a booster vaccine topping up protection against tetanus (T) and diphtheria (d).

Figure 1 shows the 12-year-old boy’s forearm three days after he received the booster Tdap/IPV vaccination. It is evident from the picture that the boy did not receive a true deltoid injection. Observe his right arm which is badly swollen just above the elbow. Accurate landmarking of an injection site is essential in preventing such errors occurring. Neurological consequences of this error can range from minor transient sensory disturbance (dull pain) to severe sensory disturbance and paralysis which can lead to poor recovery.6 The most common causes of injection nerve palsy is faulty technique during administration.

Reported injuries associated with intramuscular injection sites used for intramuscular injections include:

  • Permanent damage to radial and axially nerves resulting in paralysis/ neuropathy
  • Persistent nodules – gramulomas, muscle contractures and/or palsy
  • Peripheral nerve and bone injury
  • Local irritation, pain local discomfort and redness at the site
  • Infection, abscess, cellulitis and tissue necrosis
  • Haematomas, bleeding, arterial punctures and, in rare cases, gangrene
  • Muscle fibrosis.7-9

Anatomy and landmarking of the deltoid muscle The deltoid muscle
was named after the Greek letter Delta (Δ) due to the similar shape they share. This muscle is constructed with three main sets of muscle fibres: anterior, middle and posterior. These fibres are connected by a very thick tendon and are anchored into a v-shaped channel housed in the shaft of the humerus bone in the arm.

Davidson et al 6 describe the deltoid as a triangular muscle that originates from the lateral one third of the clavicle, the acromion and the scapular spine, and converges into the deltoid tuberosity near the middle of the humerus. The site should be selected, below the bony landmark of the acromion process or midway between the acromion process and deltoid insertion (see Figure 2).

To accurately landmark this site, practitioners need to fully expose the shoulder area, simply rolling up a sleeve of a shirt or jumper does not allow for an accurate view of the deltoid region for landmarking and may form a tourniquet and constrict blood supply. Once the shoulder region is fully exposed the practitioner must measure one to two finger-widths below the acromion process – a bony process on the scapula (shoulder blade). Then, find the bottom border of the injection site by drawing an imaginary line across the arm from the crease of the axilla in front, to the crease of the armpit in back.

The middle point of this triangle is the mid deltoid, where you will inject the medication. The injection should never be given at or below the level of the axilla9 as has happened in the case of the 12-yearold boy which was earlier reported.

Best practice on administration
Intramuscular injections are common procedures, yet unexpected complications and errors occur due to inaccurate landmarking. Professional errors and negligence affects nearly every sector of health care, for this reason ongoing professional development and evidence-based education is essential.

The deltoid site should be used only for the administration of small volume non-irritating medication such as vaccines, analgesics, antiemetics, antibiotics and antipsychotics.9 Various authors2-4 describe the administration of deltoid injections. While several vaccines may come pre-packed with syringes and needles attached, it is important to note that when injecting males and females weighing less than 60kg a 25 gauge 5/8, one inch (25mm) needle is sufficient to ensure intramuscular injection.

For females weighing 60-90kg and males weighing 60-118kg, a 25 gauge or 23 gauge 1-1½-inch (25-40mm) needle is needed. For females weighing more than 90 kg or males weighing more than 118kg, a 23 gauge 1½-inch (40mm) needle is required.10

To avoid injecting into subcutaneous tissue in adolescent and adults, it is necessary to spread the skin of the selected vaccine site taut between the thumb and forefinger in order to isolate the muscle.11 For children and/or emaciated elderly patients, it may be necessary to grasp the tissue and ‘bunch up’ the muscle.3

The needle should be inserted fully into the muscle at a 90° angle and the vaccine injected into the muscle tissue (at a rate of 1ml per 10 seconds). When the needle is withdrawn, light pressure should be applied to the injection site for several seconds with a dry cotton ball or gauze.

When administering multiple vaccinations, practitioners are advised to never mix vaccines in the same syringe unless approved by the vaccine manufacturer. When more than one vaccine needs to be administered the injection sites should be separated by one to two inches so that any local reactions can be differentiated.

When administering two vaccines into the same muscle one should not exceed suggested volume ranges for the deltoid muscle in any age group and the location of each injection should be documented in the patient’s medical record.1

The purpose of this brief report is to make practitioners aware of the potential for injury with vaccine administration into the deltoid muscle, due to poor landmarking. Sufficient anatomical knowledge and the user of evidence based techniques to accurately landmark the injection site, in combination with the selection of appropriate needles may help to minimise trauma and injury and thereby reduce patient discomfort, improve vaccination tolerability and acceptance, maximise patient safety and ensure injection efficacy.

Angela Cocoman and Carol Barron are lecturers at Dublin City University

We wish to thank the parents of the 12-year-old boy documented in this case study who has made a full medical recovery and granted permission for this case to be reported. Their son’s anonymity and confidentiality will be protected.


  1. World Health Organization. Immunization in Practice. Geneva: WHO 2004.
  2. Diggle L, Richards S. Best practice when immunising children. Primary Health Care 2007; 17(7): 41-36
  3. Barron C, Cocoman A. Administering intramuscular injections to children: what does the evidence say? Journal Of Children’s and Young Peoples Nursing 2008; 2(3): 138-145
  4. Mallet J, Dougherty L. The Royal Marsden Manual of Clinical Nursing Procedures. 5th ed. London: Blackwell Science 2000
  5. Cocoman A, Murray J. Intramuscular injections: A review of best practice for mental health nurses. Journal Of Psychiatric & Mental Health Nursing 2008;15(5): 424-434
  6. Davidson LT, Carter GT, Kilmer DD, Han JJ. Iatrogenic Axillary Neuropathy after Intramuscular Injection of the Deltoid Muscle. American Journal of Medicine and Rehabilitation 2007; 86: 507-511
  7. Rodger MA, King L. Drawing up and administering intramuscular injections: a review of the literature. Journal of Advanced Nursing 2000;31: 574-582
  8. Small SP. Preventing sciatic nerve injury from intramuscular injections: literature review. Journal of Advanced Nursing 2004; 47: 287-296
  9. McGarvey MA, Hooper ACB. The deltoid intramuscular site in the adult. Current practice among general practitioners and practice nurses. Irish Medical Journal 2005; 89: 105-107
  10. Ostendorf W. Parenteral medications. In: Perry AG, Potter AP, editors. Clinical nursing skills & techniques. 7th ed. | St Louis, US: Mosby Elsevier 2010: 598-603
  11. Altman GB. Medication administration. Fundamental & advanced nursing skills. 3rd ed. Clifton Park, New York: Delmar Cengage Learning 2010

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An intramuscular injection is a technique used to deliver a medication deep into the muscles. This allows the medication to be absorbed into the bloodstream quickly. You may have received an intramuscular injection at a doctor’s office the last time you got a vaccine, like the flu shot.

In some cases, a person may also self-administer an intramuscular injection. For example, certain drugs that treat multiple sclerosis or rheumatoid arthritis may require self-injection.


What are intramuscular injections used for?

Intramuscular injections are a common practice in modern medicine. They’re used to deliver drugs and vaccines. Several drugs and almost all injectable vaccines are delivered this way.

Intramuscular injections are used when other types of delivery methods aren’t recommended. These include:

  • oral (swallowed into the stomach)
  • intravenous (injected into the vein)
  • subcutaneous (injected into the fatty tissue just under the layer of skin)

Intramuscular injections may be used instead of intravenous injections because some drugs are irritating to veins, or because a suitable vein can’t be located. It may be used instead of oral delivery because some drugs are destroyed by the digestive system when a drug is swallowed.

Intramuscular injections are absorbed faster than subcutaneous injections. This is because muscle tissue has a greater blood supply than the tissue just under the skin. Muscle tissue can also hold a larger volume of medication than subcutaneous tissue.

Injection sites

Intramuscular injection sites

Intramuscular injections are often given in the following areas:

Deltoid muscle of the arm

The deltoid muscle is the site most typically used for vaccines. However, this site is not common for self-injection, because its small muscle mass limits the volume of medication that can be injected — typically no more than 1 milliliter.

It’s also difficult to use this site for self-injection. A caregiver, friend, or family member can assist with injections into this muscle.

To locate this site, feel for the bone (acromion process) that’s located at the top of the upper arm. The correct area to give the injection is two finger widths below the acromion process. At the bottom of the two fingers, will be an upside-down triangle. Give the injection in the center of the triangle.

Vastus lateralis muscle of the thigh

The thigh may be used when the other sites aren’t available or if you need to administer the medication on your own.

Divide the upper thigh into three equal parts. Locate the middle of these three sections. The injection should go into the outer top portion of this section.

Ventrogluteal muscle of the hip

The ventrogluteal muscle is the safest site for adults and children older than 7 months. It’s deep and not close to any major blood vessels and nerves. This site is difficult for self-injection, and may require the help of a friend, family member, or caregiver.

Place the heel of your hand on the hip of the person receiving the injection, with the fingers pointing towards their head. Position the fingers so the thumb points toward the groin and you feel the pelvis under your pinky finger. Spread your index and middle fingers in a slight V shape, and inject the needle into the middle of that V.

Dorsogluteal muscles of the buttocks

The dorsogluteal muscle of the buttocks was the site most commonly selected by healthcare providers for many years. However, due to the potential for injury to the sciatic nerve, the ventrogluteal is most often used now. This site is difficult to use this site for self-injection and not recommended.

You shouldn’t use an injection site that has evidence of infection or injury. If you’ll be giving the injection more than once, make sure to rotate injection sites to avoid injury or discomfort to the muscles.


How to administer an intramuscular injection

Any person who administers intramuscular injections should receive training and education on proper injection technique.

The needle size and injection site will depend on many factors. These include the age and size of the person receiving the medication, and the volume and type of medication. Your doctor or pharmacist will give you specific guidelines about which needle and syringe are appropriate to administer your medication.

The needle should be long enough to reach the muscle without penetrating the nerves and blood vessels underneath. Generally, needles should be 1 inch to 1.5 inches for an adult, and will be smaller for a child. They’ll be 22-gauge to 25-gauge thick, noted as 22g on the packaging.

Follow these steps for a safe intramuscular injection:

1) Wash your hands

Wash your hands with soap and warm water to prevent potential infection. Be sure to thoroughly scrub between fingers, on the backs of hands, and under fingernails.

The Centers for Disease Control and Prevention (CDC) recommends lathering for 20 seconds — the time it takes to sing the “Happy Birthday” song twice.

2) Gather all needed supplies

Assemble the following supplies:

  • needle and syringe with medication
  • alcohol pads
  • gauze
  • puncture-resistant container to discard the used needles and syringe — typically a red, plastic sharps container
  • bandages

3) Locate injection site

To isolate the muscle and target where you’ll place the injection, spread the skin at the injection site between two fingers. The person receiving the injection should get into a position that’s comfortable, provides easy access to the location, and keeps the muscles relaxed.

4) Clean injection site

Clean the site selected for injection with an alcohol swab and allow the skin to air dry.

5) Prepare syringe with medication

Remove the cap. If the vial or pen is multi-dose, take a note about when the vial was first opened. The rubber stopper should be cleaned with an alcohol swab.

Draw air into the syringe. Draw back the plunger to fill the syringe with air up to the dose that you’ll be injecting. This is done because the vial is a vacuum and you need to add an equal amount of air to regulate the pressure. This also makes it easier to draw the medication into the syringe. Don’t worry — if you forget this step, you can still get the medication out of the vial.

Insert air into the vial. Remove the cap from the needle and push the needle through the rubber stopper at the top of the vial. Inject all of the air into the vial. Be careful to not touch the needle to keep it clean.

Withdraw the medication. Turn the vial and syringe upside down so the needle points upward and pull back on the plunger to withdraw the correct amount of medication.

Remove air bubbles. Tap the syringe to push any bubbles to the top and gently depress the plunger to push the air bubbles out.

6) Self-injection with a syringe

Insert the needle. Hold the needle like a dart and insert it into the muscle at a 90-degree angle. You should insert the needle in a quick, but controlled manner. Do not push the plunger in.

Check for blood. Using the hand that’s holding the skin at the injection site, pick up your index finger and thumb to stabilize the needle. Use your dominant hand — the one that did the injection — to pull back on the plunger slightly, looking for blood in the syringe. Ask your doctor if this is needed for the type of medicine you will be injecting, as it’s not required for all injections.

  • If you see blood going into the syringe, it means the tip of the needle is in a blood vessel. If this happens, withdraw the needle and begin again with a new needle, syringe with medication, and injection site. It’s rare to have this happen.
  • If you don’t see blood going into the syringe, the needle is in the correct place and you can inject the medicine.

7) Inject the medication

Push the plunger slowly to inject the medication into the muscle.

8) Remove the needle

Withdraw the needle quickly and discard it into a puncture-resistant sharps container. Don’t recap the needle.

A sharps container is a red container that you can purchase at any pharmacy. It’s used to collect medical waste, like needles and syringes. You shouldn’t put any of these materials into the regular garbage, as needles can be hazardous to anyone who handles the trash.

9) Apply pressure to the injection site

Use a piece of gauze to apply light pressure to the injection site. You can even massage the area to help the medicine be absorbed into the muscle. It’s normal to see slight bleeding. Use a bandage if necessary.

Helpful tips

Tips for an easier injection

To minimize possible discomfort before your injection:

  • Apply ice or an over-the-counter topical numbing cream to the injection site before cleaning it with the alcohol pad.
  • Allow the alcohol to dry completely before the injection. Otherwise, it might cause stinging.
  • Warm the vial of medication by rubbing it between your hands prior to drawing the medication into the syringe.
  • Have someone you trust give you the injection. Some people find it difficult to inject themselves.


What are the complications of intramuscular injections?

It’s normal to experience some discomfort after an intramuscular injection. But certain symptoms may be a sign of a more serious complication. Call your doctor or healthcare provider right away if you experience:

It’s also normal to have some anxiety about performing or receiving an injection, especially an intramuscular injection due to the long needle. Read through the steps several times until you feel comfortable with the procedure, and take your time.

Don’t hesitate to ask your provider or pharmacist to go through the procedure with you beforehand. They’re more than willing to help you understand how to perform a safe, proper injection.

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