The Art of Operation: Optimizing Menghini Needle EUS-FNB Techniques to Maximize Tissue Acquisition and Diagnostic Yield

A fine sword must be wielded with exquisite skill to unleash its full power. In endoscopic ultrasound (EUS)-guided biopsy, the Menghini needle-an impeccably designed "weapon"-derives its ultimate clinical efficacy not only from its inherent inner-bevel cutting and negative-pressure coring design but also critically from the operator's ability to master and optimize the tailored "technique" for it. From pre-puncture strategic planning, to delicate tactile feedback during insertion, to precise control of negative pressure, every step determines whether the ideal diagnostic tissue core can be obtained. Mastering optimized techniques specific to the Menghini needle is the key to translating its theoretical advantages into consistently high diagnostic yields.

I. Pre-Puncture Planning: Laying the Foundation for Success

Three-Dimensional Lesion and Pathway Mapping: Unlike some other needle types that may rely on "blanket coverage," the Menghini needle demands precision targeting. Under EUS, the operator must scan the lesion in multiple planes and angles to accurately assess its size, borders, internal echotexture (notably necrotic areas), blood supply, and relationship to adjacent large vessels (e.g., splenic artery/vein, superior mesenteric vessels). Select a target area with relatively rich blood supply and homogeneous solid components, avoiding large necrotic regions. Plan a safe puncture trajectory that reaches the target with the needle as perpendicular to the bowel wall as possible-this enables the Menghini needle to cut at the most "orthogonal" angle.

Informed Selection of Needle Type and Gauge: While reviews note no definitive consensus on the merits of 22G vs. 25G needles, the following considerations apply to the Menghini needle:

22G Needle: Thicker with greater rigidity. It resists bending and deflection when traversing the gastric/duodenal wall and tough pancreatic capsule, reliably transmitting puncture force to the tip. It is a more stable choice for firm lesions, yielding theoretically larger tissue strips.

25G Needle: Thinner and more flexible. It excels at navigating curved endoscope channels and adjusting angles, with a theoretically lower risk of complications (e.g., bleeding). It may be preferred for small, anatomically challenging lesions or patients with a bleeding diathesis.

Decision: For most solid pancreatic lesions, especially suspected carcinoma or highly fibrotic lesions, a 22G Menghini needle is first-line to maximize tissue acquisition potential. For lesions in difficult locations (e.g., uncinate process) or requiring transduodenal bulb puncture, the 25G needle's flexibility offers advantages.

II. Puncture and Sampling: Essence of the Core Technique

This is the critical phase to leverage the Menghini needle's design, summarized as speed, precision, stability, gentleness.

Speed and Precision: Decisive Puncture: Once the needle trajectory and target are clearly visualized on EUS, insert the needle into the target with a firm, swift motion. The Menghini needle's inner-bevel design facilitates low-resistance puncture; rapid insertion minimizes tissue displacement, avoids target migration, and harnesses kinetic energy to aid cutting. Hesitant, slow insertion increases tissue deformation and needle tract deviation.

Stability: The Art of Negative Pressure Control: This distinguishes Menghini needle technique from other needle types. Conventional continuous high negative pressure (e.g., full aspiration with a 20mL/10mL syringe and locked suction) for FNA may cause excessive cellular fragmentation. For Menghini needle FNB, negative pressure requires nuanced regulation:

Synchronization: Ideally, initiate negative pressure exactly as the needle tip enters the target lesion to maximize the "coring effect."

Pressure Magnitude: Maximum negative pressure is unnecessary. Moderate, stable suction (e.g., withdrawing a 10mL syringe to the 5–7mL mark and holding) optimally "draws" tissue into the needle groove without prematurely tearing delicate tissue or over-aspirating it deep into the lumen (hindering retrieval). Some operators advocate "no suction" or "pulsed suction," but the Menghini needle's classic design relies on negative pressure-abandoning it entirely may impair efficacy. Start with moderate suction and adjust based on tactile feedback.

Syringe Selection: A dedicated biopsy syringe with precise volume graduations is superior to a standard syringe, enabling standardized operation.

Gentleness: Micro-Needle Movement: After the tip enters the lesion, it should remain mobile, not static. To enhance cutting and tissue yield, perform small (3–5mm), rhythmic piston-like back-and-forth movements while maintaining moderate negative pressure. The motion must be extremely gentle: the goal is repeated, limited cutting within the lesion via the needle's cutting surface, not gross tearing. Maintain a frequency of 1–2 cycles per second for 10–20 seconds.

III. Post-Sampling Handling: Ensuring Specimen Integrity

Upon completing sampling, release negative pressure, then rapidly withdraw the needle entirely from the puncture tract into the endoscope's biopsy channel.

Tissue Retrieval Technique: After fully removing the needle from the endoscope, slowly and steadily expel the tissue strip from the needle groove onto filter paper or fixative using air insufflation. Never forcefully flush with saline-this risks fragmenting precious tissue or damaging cellular architecture. Air delivers controlled, consistent pressure for atraumatic retrieval.

Specimen Processing: Transfer intact tissue strips to formalin fixative for paraffin embedding. Residual micro-fragments or fluid within the needle lumen can be used for cytology smears or liquid-based cytology, complementing histology. One needle, two uses maximizes diagnostic information.

IV. Complication Prevention and the Menghini Needle's Advantages

The Menghini needle's inner-bevel design enables low-resistance puncture, theoretically reducing trauma to tissues along the trajectory. Its relatively "gentle" tissue acquisition method may also lower the risk of needle tract bleeding. However, standard precautions remain critical: always avoid vessels under direct EUS visualization; refrain from repeated punctures in cystic components of cystic-solid lesions; monitor patients closely post-procedure for abdominal pain or bleeding signs.

Conclusion: Achieving Synergy Between Operator and Needle

The use of the Menghini needle in EUS-FNB represents a clinical art merging advanced instrumentation with refined technique. Its superior design is fully unlocked only by the operator's speed, precision, stability, gentleness and mastery of nuanced negative pressure control. It demands the operator be not merely a "puncturer" but a "controller of micro-maneuvers." When endoscopists deeply understand the Menghini needle's design philosophy and develop a tailored operational rhythm through deliberate practice, they transcend technical proficiency to achieve synergy between operator and needle. In this state, the Menghini needle becomes not just a tissue-acquisition tool, but an extension of the clinician's senses-capable of precisely, completely extracting the truth of disease from the pancreas, a deep and complex organ, securing patients the clearest diagnosis and optimal treatment timing.