Choosing the correct embolization coil size is one of the most important technical decisions in a successful peripheral embolization procedure. INVAMED's Spider coil platform offers a diameter range of approximately 2–30 mm, giving interventional radiologists flexibility to match coil selection to target vessel or aneurysm anatomy. This guide walks through the sizing and configuration considerations relevant to Spider coil planning.
Why Does Coil Sizing Matter?
An appropriately sized coil is intended to conform closely to the vessel or aneurysm wall, supporting stable positioning and reducing the likelihood of coil migration into unintended locations. A coil that is undersized relative to the target space may fail to anchor securely, while an oversized coil may be difficult to deploy accurately or could distort the surrounding anatomy. Because of this, coil diameter selection is typically based directly on pre-procedural imaging measurements of the target vessel or aneurysm neck and sac dimensions.
How Are Spider Coils Categorized by Size?
Spider coils spanning 2–30 mm in diameter allow physicians to address a broad spectrum of clinical scenarios, generally grouped into functional categories:
- Smaller-diameter coils — used for narrow peripheral branch vessels or fine-tuning occlusion at the margins of a treatment zone
- Mid-range coils — commonly used for standard peripheral aneurysms, arteriovenous fistula tracts, or moderate-caliber vessel occlusion
- Larger-diameter coils — used for bigger aneurysm sacs or larger-caliber vessels requiring substantial volume filling
Within each size category, coils may also vary in stiffness (sometimes categorized as framing, filling, or finishing coils), which supports a layered packing strategy: stiffer coils to establish a stable initial framework, followed by softer coils to fill remaining space and increase packing density.
How Does Configuration Affect Deployment?
Coil configuration refers to the secondary shape the coil assumes once released from the delivery catheter—commonly a helical or complex three-dimensional pattern designed to conform to irregular vessel or aneurysm geometry. Spider's platinum-tungsten construction is engineered to help the coil reliably achieve its designed configuration upon deployment, which supports predictable, controlled packing as multiple coils are placed in sequence.
What Does the Planning Process Typically Involve?
Before coil selection, physicians typically review cross-sectional imaging (CT angiography or MR angiography) or catheter-based angiography to characterize:
- Target vessel or aneurysm diameter and length
- Neck size, in the case of aneurysm treatment
- Flow rate and any collateral vessels that may affect coil stability
- Anticipated number of coils needed to achieve adequate packing density
Final coil size and configuration selection remain the responsibility of the treating physician, informed by intraprocedural imaging and real-time assessment during deployment.
Frequently Asked Questions
What is the full diameter range available for Spider coils?
Spider coils are available in diameters of approximately 2–30 mm, supporting a wide range of peripheral vessel and aneurysm sizes.
Why might a physician use coils of different stiffness in the same procedure?
Different stiffness levels support a layered packing strategy—stiffer coils establish an initial stable framework, while softer coils fill remaining space to help achieve adequate packing density.
How is coil size determined before a procedure?
Coil size is typically determined from pre-procedural imaging measurements of the target vessel or aneurysm, then confirmed and adjusted as needed during the procedure itself.
Related INVAMED Resources
- Embolization Products — INVAMED's full embolization device portfolio
- Spider Peripheral Coil System Overview — system design and application concepts
- Contact INVAMED — request the IFU or technical specifications
Medical Disclaimer: This article is provided for general informational and educational purposes only and does not constitute medical advice, diagnosis, or treatment recommendation. It is not a substitute for consultation with a qualified healthcare professional. Product indications, availability, and regulatory status vary by country. Always refer to the official Instructions for Use (IFU) and consult a licensed physician for guidance specific to your situation. INVAMED devices are intended for use by trained healthcare professionals.