FNA Syringe Stylet Ejection Mechanism for Continuous Ultrasound Guidance
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Solution Overview
Problem
Conventional fine needle aspiration (FNA) procedures require operators to hold the needle with one hand and an ultrasound probe with the other, leading to inefficiencies and potential displacement of the needle tip from the lesion during stylet removal and syringe attachment, especially for small lesions, resulting in suboptimal specimen collection.
Innovation Solution
A syringe assembly with an integrated extraction mechanism, including a spring-loaded device and trigger, allows for the automatic retraction of the stylet into the syringe, enabling continuous ultrasound guidance and aspiration with one hand, maintaining needle visibility and improving sample yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the stylet is removed manually during FNA procedure, then the syringe can be attached to the needle, but the needle tip may be displaced from the lesion leading to suboptimal specimen
Solution Approach 1:
The syringe is pre-attached to the needle assembly before the procedure begins. The stylet is designed to be removable while the syringe remains securely coupled to the needle hub, eliminating the need for manual attachment after stylet removal and preventing needle displacement.
Solution Approach 2:
The needle assembly is segmented into distinct components: a hub portion with threaded engagement features, a needle portion with lumen, and a stylet. The hub serves as a permanent connection point for the syringe, while the stylet can be independently removed through the hub opening without affecting the syringe-needle connection.
2Ease of operation
If the operator uses one hand for needle insertion and the other for ultrasound probe, then initial needle placement is achieved, but the operator must put down the probe to remove stylet and attach syringe causing time loss
Solution Approach 1:
The syringe is designed with a plunger that can be actuated to automatically eject the stylet from the needle assembly. This self-ejecting mechanism allows the operator to maintain grip on both the ultrasound probe and the syringe/needle assembly simultaneously, eliminating the need to release the probe for stylet removal.
Solution Approach 2:
The stylet ejection mechanism incorporates a movable plunger that transitions from a loaded state (stylet retained) to an actuated state (stylet ejected). This dynamic mechanism enables rapid stylet removal without requiring manual manipulation, allowing continuous ultrasound guidance throughout the procedure.
3Device complexity
If manual stylet removal is performed, then the syringe can be attached, but the procedure requires multiple steps increasing complexity
Solution Approach 1:
The stylet ejection function and syringe operation are merged into a single integrated device. The plunger mechanism serves dual purposes: it maintains negative pressure for aspiration and simultaneously ejects the stylet when actuated, combining multiple functions into one operational component.
Solution Approach 2:
The syringe assembly is designed as a multi-functional unit that performs needle insertion, maintains aspiration negative pressure, and automatically ejects the stylet. The hub portion provides both structural support and syringe attachment, while the plunger provides both aspiration control and stylet ejection capabilities.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution reduces procedure time, enhances sample quality, and increases patient safety by allowing for uninterrupted ultrasound guidance and efficient specimen collection.
Implementation Method 1
The extraction mechanism may be a spring-loaded device and may further include a spring located within the extraction chamber and coupled to the proximal portion of the stylet, where the spring is configured to extract the stylet from the hollow needle into the extraction chamber when the trigger is activated. The spring may be helical and extend coaxially within the extraction chamber, where the trigger when activated releases a stored potential energy of the spring to draw the stylet into the syringe.
Data Source
AI summary
A syringe assembly includes a syringe casing defining an aspiration cavity therein and including a barrel having opposite first and second ends, and a plunger movable within the barrel to define a volume of the aspiration cavity. The syringe assembly also includes a hollow needle having a distal end configured for piercing tissue, and a proximal end detachably fixed to the first end of the syringe casing, the hollow needle in fluid communication with the aspiration cavity. The syringe assembly further includes a stylet having a distal portion extending within the needle and a proximal portion extending within the syringe casing, an extraction mechanism coupled to the proximal portion of the stylet, and a trigger at least partially exposed externally of the aspiration cavity of the syringe casing. The trigger when activated causes the extraction mechanism to extract the stylet from the needle.