When planning a coil embolization procedure, interventional radiologists choose between two general delivery approaches: pushable and detachable coils. Understanding pushable vs detachable coils helps clinicians select the delivery mechanism best suited to a given vessel, flow condition, and procedural goal. This comparison outlines the mechanical differences, procedural implications, and typical use considerations for each approach—without suggesting one is universally superior to the other.
What Are Pushable Coils?
Pushable coils are advanced through a microcatheter using a pusher wire and are released simply by continuing to advance the coil until it exits the catheter tip and assumes its designed shape within the vessel. Once the coil has left the catheter, it cannot be retrieved or repositioned using the pusher.
Key characteristics of pushable coils:
- Simpler delivery mechanism with fewer procedural steps
- No separate detachment step required
- Deployment is generally faster once the catheter is in position
- Final placement cannot be adjusted after the coil exits the catheter tip
What Are Detachable Coils?
Detachable coils, such as INVAMED's Spider platform described as "pushable yet detachable," are advanced similarly to pushable coils but include a mechanical (or in some systems, electrolytic) detachment mechanism. This allows the physician to observe the coil's position within the vessel before committing to final release, and to withdraw and reposition the coil if the initial placement is not satisfactory.
Key characteristics of detachable coils:
- Additional control step before permanent release
- Ability to reposition or fully withdraw the coil if placement is suboptimal
- May reduce the risk of coil migration in complex or high-flow anatomy
- Involves an additional mechanical or electrolytic detachment step during the procedure
How Do the Two Approaches Compare in Practice?
| Factor | Pushable Coils | Detachable Coils |
|---|---|---|
| Repositioning before release | Not possible | Possible before detachment |
| Procedural steps | Fewer | Includes detachment step |
| Typical use case | Straightforward, lower-risk anatomy | Complex anatomy, higher precision needs |
| Risk of migration during placement | Present if placement is imprecise | Generally reduced due to confirmation step |
Neither approach is universally preferred; the appropriate choice depends on vessel anatomy, flow characteristics, the criticality of precise placement, and physician preference and experience.
When Might Each Approach Be Considered?
Physicians may lean toward pushable coils for straightforward vessel occlusion where anatomy is favorable and precise repositioning is less critical, often valuing procedural simplicity and speed. Detachable systems may be favored in anatomically complex cases, near critical branch vessels, or in higher-flow segments where confirming placement before final release adds a meaningful safety margin. Ultimately, coil delivery mechanism selection is determined by the treating physician based on the specific clinical scenario.
Frequently Asked Questions
Is one coil delivery mechanism safer than the other?
Neither mechanism is inherently "safer" in all situations; safety and appropriateness depend on the specific vessel, anatomy, and clinical context. The treating physician selects the mechanism best suited to each case.
Can detachable coils be repositioned multiple times?
Detachable systems are generally designed to allow repositioning before final mechanical detachment, though the number of adjustments possible depends on the specific device and clinical circumstances.
Do pushable and detachable coils use the same materials?
Both delivery types can be manufactured from similar materials, such as platinum-tungsten alloys; the primary difference lies in the delivery and release mechanism rather than the coil material itself.
Related INVAMED Resources
- Embolization Products — INVAMED's full embolization device portfolio
- Spider Peripheral Coil System Overview — detachable coil system design
- Contact INVAMED — request further product information
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.