Cannula

A cannula is a slim tube inserted into tissue to deliver or withdraw fluid, distinguished from a hypodermic needle by its tip: many cannulas are blunt or rounded rather than sharp, so they push tissue planes apart and slide alongside vessels instead of cutting straight through them. A cannula is specified by three numbers that must appear together on any order — outer gauge, working length, and tip type (blunt, rounded, or sharp) — plus the hub fitting that connects it to a syringe.

In hair restoration work, cannulas carry tumescent anesthetic and saline into the donor and recipient scalp, and blunt micro-cannulas are chosen precisely because a rounded tip disperses fluid over a plane with less trauma than a cutting needle. Gauge is the sizing convention, where a higher number means a thinner tube, so a 22G cannula is finer than an 18G one. That inverse scale is the classic spec-sheet trap: a buyer who reasons "bigger number, bigger tube" orders the opposite of what the procedure needs. Always confirm gauge against the millimeter outer diameter stated in the instructions for use, and record both in the purchase specification so quotes are comparable.

Buyers should treat the hub connection as part of the specification, not an afterthought. Most cannulas terminate in a female luer that mates to a male luer lock syringe; if the fitting type is left unstated, a delivered lot may not seat on the syringes already in stock. At goods receipt, verify gauge marking, length, tip geometry and hub type against the label, and dry-fit a sample to a mating syringe. Inspect tips under light for burrs or bends, because a deformed blunt tip stops behaving like a blunt tip.

Almost all clinic cannulas are single-use, supplied inside a sterile barrier system and governed by a printed shelf life. That makes stock rotation the standing task: receive against a lot number, shelve so the earliest expiry sits at the front, and pull the oldest sealed pack first. Store flat and protected so fine tubes are not crushed or kinked in a crowded drawer, and keep packs dry and out of direct heat. A kinked or dented cannula is a receipt-or-storage failure that should never reach a tray. For how packaged consumables move through inspection, storage and use across the clinic, see the instrument sterility and packaging guide and the broader clinic equipment picture.