Gauge and length selection for subcutaneous injection posts 31–56
This is a continuation of a long topic, addressed by post number rather than by page. Start at post 1 · go to the accepted answer.
That matches what I have seen, for whatever a single anecdote is worth.
Sharps containers are a legal requirement for disposal in several jurisdictions and a sensible precaution everywhere. A rigid sealed container is the minimum.
I have written this out at length because the short version keeps being misread.
Collapsed as off-topic by two members at trust level 3 or above
Building on post #36 rather than restating it.
Needle length: typical lengths for subcutaneous injection are 4-6 mm (short), 8 mm (standard), or 10-12 mm (longer). Longer needles are needed for deeper tissue or if you have abdominal adiposity.
Not a conclusion. A place to stand while looking for one.
Post #34 put the caveat in the right place and I want to underline it.
The reason gauge and length selection keeps being re-asked is that the answer is conditional and people quote it without the condition. It is not that the answer is unknown.
Reading rather than answering, but this is the post I would point somebody at.
Small correction to my own earlier position on gauge and length selection. I had the units the wrong way round, which changes the conclusion by an order of magnitude and therefore changes it entirely.
Coming back to post #40, because the follow-up matters more than the original answer.
Aspirating before injection: for subcutaneous injection, aspirating (pulling back on the plunger to check for blood) is not necessary and is sometimes discouraged because it is associated with more discomfort. Subcutaneous injection without aspiration is standard practice.
Post #40 is right about the mechanism and I think understates the practical bit.
Two people in this thread mean different things by gauge and length selection and are disagreeing about the definition while believing they are disagreeing about the facts. Worth pausing to define it.
Sharps containers are a legal requirement for disposal in several jurisdictions and a sensible precaution everywhere. A rigid sealed container is the minimum.
It is the kind of thing that is obvious once and never again.
I had written a reply contradicting post #44 and deleted it. Here is what survived.
Needle gauge: smaller numbers (30G) are finer and less painful. Larger numbers (25G) are courser. For subcutaneous injection, 27-30G is typical. Finer needles take longer to draw up but hurt less.
Gauge is the outside diameter and higher numbers are thinner. Thinner needles hurt less and draw more slowly, which is the entire trade.
That much is documented. The rest is how I have interpreted it.
Practical answer on gauge and length selection, since the theoretical one is upthread: do the simplest check first, write down the result, and only then decide whether the complicated explanation is needed. It usually is not.
U-100 means the barrel is graduated for a solution containing one hundred units of insulin per millilitre. For anything that is not insulin, the units are simply hundredths of a millilitre.
Nothing above should be read as advice about what anyone else should do.
This is the first time the answer has come with its own limits attached. Appreciated.
U-100 means the barrel is graduated for a solution containing one hundred units of insulin per millilitre. For anything that is not insulin, the units are simply hundredths of a millilitre.
The strength of my opinion here exceeds the strength of my evidence.
Gauge and length selection: I would want to see the raw numbers rather than the summary before agreeing. Summaries lose exactly the information that would settle this.
Confirming post #54 from a second method, which matters more than confirming it from a second person.
Needle length for subcutaneous delivery is a question about tissue depth and injection angle together. Short needles at ninety degrees and longer ones at an angle reach comparable depths.
That is a description of practice, not a recommendation of it.
Two sentences on gauge and length selection and then I will stop, because the rest is speculation and the thread is better without mine.
What is documented is narrow. What is inferred from it is broad. The gap between them is where every argument here lives.
Suggested topics
| Topic | Participants | Replies | Views | Activity |
|---|---|---|---|---|
|
0.3 mL versus 0.5 mL versus 1 mL barrels: resolution matters
0.3 mL versus 0.5 mL versus 1 mL barrels: resolution matters — setting out what I have, and where I think it stops being reliable. A follow-up question about 0.3 ml versus 0.5 ml that I did not know to ask…
|
+104 | 114 | 6k | 6d |
|
[2026 update] 0.3 mL versus 0.5 mL versus 1 mL barrels: resolution matters
On the subject in the title: 0.3 mL versus 0.5 mL versus 1 mL barrels: resolution matters Working notes rather than a conclusion. A follow-up question about 0.3 ml versus 0.5 ml that I did not know to ask the…
|
+108 | 124 | 27k | 2mo |
|
About the Syringes & needles category
Insulin syringe graduations, dead volume, gauge and length selection, and reading units correctly. This post is a community wiki: any member at trust level 3 or above can edit it, and every edit is recorded…
|
4 | 45k | 1mo | |
|
Fixed versus detachable needles: the trade-offs
Posting this under the heading it deserves: Fixed versus detachable needles: the trade-offs Everything below is what sits behind that. I was wrong about fixed versus detachable needles in a thread last spring…
|
+117 | 121 | 7.3k | 18mo |
|
Reading U-100 graduations, with a conversion table — one year on
Reading U-100 graduations, with a conversion table — one year on Writing it up because I had to work it out twice and would rather nobody else did. I would like to disagree carefully with the settled view on…
|
+3 | 7 | 662 | 4mo |
Related topics — sharing the tags syringe units, needle gauge & length, worked example
| Topic | Participants | Replies | Views | Activity |
|---|---|---|---|---|
|
Why we ask for units every single time, with three examples of what goes wrong
Why we ask for units every single time, with three examples of what goes wrong — that is the question, and I have not found it answered plainly anywhere I have looked. Counting it rather than describing it,…
|
+115 | 135 | 2.2k | 11d |
|
Second pass at: Pen dose counters: what a click does and does not guarantee
Second pass at: Pen dose counters: what a click does and does not guarantee — setting out what I have, and where I think it stops being reliable. Two things I would like separated before anyone answers on Pen…
|
+63 | 68 | 51k | 13mo |
|
Revisiting: What to include when your question involves arithmetic
Revisiting: What to include when your question involves arithmetic — setting out what I have, and where I think it stops being reliable. Counting it rather than describing it, because the count is the part…
|
+21 | 25 | 384 | 12mo |
|
Over-dilution: when your dose falls below one readable graduation
On the subject in the title: Over-dilution: when your dose falls below one readable graduation Working notes rather than a conclusion. I have read the maintained page on this and I still have a gap, so I am…
|
+15 | 19 | 248 | 15mo |
|
A pen that felt like it delivered nothing: diagnosing it afterwards
On the subject in the title: A pen that felt like it delivered nothing: diagnosing it afterwards Working notes rather than a conclusion. Question about a metering device rather than about a syringe, because…
|
+35 | 39 | 584 | 6mo |