Plug, Reflux, Repeat

A real-world take on forming the perfect plug — with timing, layering, and control. If you’re injecting Onyx, this is the rhythm you’ll want to master.

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Script:

Welcome back. In this segment, I want to talk about a technique I personally use a lot — the classic push and plug technique — and exactly how I do it.

Once my microcatheter is in position and I’m happy with the placement, I start the Onyx injection.

At the very beginning, a little bit of Onyx penetrates into the nidus. That small initial penetration increases the resistance to further flow, and that’s when the reflux starts to happen. The Onyx starts pushing back and begins to layer around the catheter tip.

Now, I let that reflux happen just a little bit — a short segment. I don’t wait too long. Just a couple of seconds.

Then I reset my blank roadmap and re-inject.

This time, I usually find that the Onyx starts layering inside that same refluxed segment — building the plug a little deeper.

I stop again, just for a few seconds. Reset the roadmap. Re-inject. And I repeat this cycle.

Again, I don’t wait too long between steps — just a few seconds at a time. And with each cycle, I watch for the Onyx to layer inside the already formed segment.

Eventually, I’ll reach a point where I stop seeing layering. Instead, I see the reflux getting longer. That’s when I stop.

At that point, I set a timer on the angio machine for two minutes.

And in most cases — not all, but most — when I re-inject after the two-minute pause, the Onyx flows forward beautifully into the nidus. The plug has matured, the resistance behind it is stable, and now the embolic moves exactly where I want it.

That’s the rhythm of how I personally do the push and plug technique — short, controlled cycles, with visual feedback every step of the way.

Now let’s talk about microcatheter entrapment.

This is something we really don’t want. Because if you let the reflux go too far and the Onyx hardens around the catheter — you might have to cut it or leave it behind. And that’s never ideal.

So, whenever possible, I use a detachable tip microcatheter.

With a detachable tip, you can control your Onyx reflux precisely. The goal is to keep the reflux between the two markers on the catheter. You don’t have to reach both markers — it just needs to stay somewhere in between.

And as long as the reflux stays within that zone, you can inject as long as you want. There’s nothing trapping me. I know that if I need to, I can simply detach and walk away clean.

That’s why I use detachable tips whenever I can. They give you control, safety, and confidence throughout the injection.

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