Dorsogluteal Intramuscular Injection Depth Needed to Reach Muscle Tissue According to Body Mass Index and Gender: A Systematic Review

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Aims and objective(s)

The objective of this systematic review was to determine the needle length required to reach the dorsogluteal muscle based on body mass index and sex. Our aim was to provide evidence-based recommendations to current intramuscular injection guidelines from the result(s) of this review.


Studies worldwide are documenting reduced medication effectiveness due to improperly placed dorsogluteal intramuscular injections because of incorrect needle length, wrong site selection and/or obesity. Current intramuscular injection guidelines lack specific instructions according to weight or sex. While there are similar concerns with other injectable sites, this review focuses solely on adult dorsogluteal intramuscular injections.


A systematic review of relevant literature of dorsogluteal intramuscular injections based on body mass index and sex.


This systematic review was reported using the PRISMA checklist 2020. The review protocol was registered with Center for Open Science (OSF). We analysed 1,412 articles from nine databases. We compared twelve studies that utilised computerised tomography or ultrasonography using The Johns Hopkins Evidence-Based Practice Model and Guidelines.


A significant number of dorsogluteal intramuscular injections are administered into subcutaneous tissue rather than muscle because needles are too short for populations with body mass indexes over 25, especially women. Poor landmarking often results in improperly placed injections.


To prevent administering a dorsogluteal intramuscular injection into subcutaneous tissue, women with a BMI of 25 and over require needles longer than 38 mm (1.5 inches). Men have less subcutaneous tissue in the dorsogluteal area and only require longer needles if BMI is 35 and over. If skin-to-muscle depth is questionable in either sex, an ultrasound-guided intramuscular injection is warranted for accurate dorsogluteal placement. Landmarking and needle length are key to appropriately placed IM injections.

Relevance to clinical practice

Dorsogluteal injections are often injected into subcutaneous tissue rather than muscle because needles are not long enough to reach muscle, especially in women. Critical elements that determine placement of intramuscular injections into muscle versus subcutaneous tissue are sex, BMI, needle length and landmarking.

Medications delivered into subcutaneous tissue may have reduced bioavailability.


This article is currently in press, the publication date provided is the online early release date. Any information regarding this publication is subject to change at the time of official publication.