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Filling the aneurysm through a catheter

Coiling is an endovascular procedure: a specialist navigates a catheter through blood vessels to the aneurysm and places coils inside its sac. The aim is to keep blood from continuing to enter the aneurysm while preserving the parent artery. It avoids the surgical exposure used for clipping, but still carries risks, including stroke, bleeding and vessel or procedural injury. The appropriate comparison is between options that fit the actual lesion.12

The technique matters

Regular coiling uses coils without additional assisting implants. In some lesions a temporary balloon may assist placement; in others a stent may support coils at a broad neck. A permanent parent-artery implant changes medication and follow-up considerations. These methods should not be collapsed into one category with an assumed identical safety profile.3

Intrasaccular devices sit within the sac and disrupt flow. They are distinct from conventional coils and from flow-diverting stents positioned in the parent artery. Device selection concerns anatomy, rupture status, available evidence and the specific product.3

What the trials do and do not show

The 2026 European aSAH guideline recommends regular coiling over clipping for adults in good clinical condition when both are equally suitable. It explicitly limits transfer of that result to more complex anatomy or other techniques. A newer endovascular device does not acquire the randomized evidence for regular coiling merely because it is placed through a catheter.3

ISAT's original cohort consisted of selected ruptured aneurysms suitable for either treatment. The long-term UK report follows that same trial population. Coiling's clinical benefit in that setting must be considered alongside later rebleeding and retreatment, rather than dismissed because another approach can close the sac more completely on an image. It also cannot become proof that coiling is best for every unruptured lesion.42

Reopening and another procedure

A coiled aneurysm may retain some filling or later reopen. Imaging can identify changes, and the team may consider further treatment. Retreatment is an important outcome but does not by itself describe the person's neurological function, quality of life or whether a new bleed occurred. Some residual findings are observed rather than immediately treated; decisions depend on their significance and the risks of another intervention.34

Questions before and after treatment

Ask which exact technique is proposed, why it fits the neck and branches, and whether a permanent implant will be used. Ask how the team plans to assess closure, neurological harms and later retreatment. Obtain an individualized medication and imaging plan from the treating team; don't change prescribed medicines without them.2

A less invasive route does not guarantee a short hospital stay or full recovery. Recovery after emergency coiling reflects the hemorrhage as well as the procedure. Planned preventive treatment follows a different course. The recovery article explains why these situations need separate expectations.

References

  1. National Institute for Health and Care Excellence. NG228. Subarachnoid haemorrhage caused by a ruptured aneurysm: diagnosis and management. 2022. Source ↩
  2. Etminan N et al. European Stroke Journal. 2022;7: LXXXI–CVI. doi:10.1177/23969873221099736. Source ↩
  3. Vergouwen MDI et al. European Stroke Journal. 2026;11(5):aakag043. doi:10.1093/esj/aakag043. Source ↩
  4. Molyneux AJ et al. The durability of endovascular coiling versus neurosurgical clipping of ruptured cerebral aneurysms: 18 year follow-up of the UK cohort of ISAT. Lancet. 2015;385:691–697. doi:10.1016/S0140-6736(14)60975-2. Source ↩