Adenoid Curettes: St Clair Thomson vs Beckmann vs Barnhill

Three patterns dominate every adenoidectomy tray, and the differences between them come down to one question: what happens to the tissue after it is cut.

The Cage Is the Whole Argument

The St Clair Thomson pattern carries a wire or sheet-metal guard behind the cutting edge. When the blade sweeps down the posterior nasopharyngeal wall, the resected adenoid mass is trapped in that cage and comes out of the mouth attached to the instrument.

The reason this design exists is not tidiness. It is that a detached adenoid mass in an anaesthetised, head-extended patient has one obvious place to go, and it is not out through the mouth. Retaining the specimen on the instrument removes that risk entirely and hands the histology a clean, intact sample rather than fragments fished out of a pack.

The trade-off is bulk. The cage adds width and profile to an instrument that is being passed behind the soft palate into a space measured in centimetres. In a small child with a narrow nasopharynx, the guarded pattern can be the one that will not sit correctly against the vomer, and forcing it is how the palate and the eustachian tube cushions get damaged.

Beckmann — the Fenestrated Workhorse

The Beckmann traces directly back to Gottstein’s ring knife of 1886, which Beckmann modified into a curette form in 1897. The lineage shows: it is essentially a sharpened window on a handle.

The tip is squared and fenestrated, with the cutting edge on the leading inner margin. Tissue is engaged and shaved off in one firm sweep, passing through the fenestration rather than accumulating in front of the blade. That is what makes it fast and what makes it the usual first instrument for a bulky adenoid pad.

Widths run from roughly 13 mm to 23 mm. The wide end of that range is genuinely wide — a 23 mm blade in a paediatric nasopharynx is not a size choice, it is a mistake — and the practical working sizes for most lists sit between 14 and 18 mm.

Because the Beckmann does not retain what it cuts, it is always used with the airway secured and a pack in place, and the specimen is retrieved separately with a Luc’s or Tilley forceps before the pack comes out.

Barnhill — the Narrow-Field Alternative

The Barnhill is close enough to the Beckmann that catalogues sometimes shelve them together, and different enough that surgeons who use both will not accept a substitution.

Its working end is longer front-to-back and narrower across, giving a more rectangular window than the Beckmann’s square one. Overall length is slightly greater. In use, the narrower blade tracks the midline more predictably in a tight nasopharynx and is easier to angle into the lateral recesses and around the choanae, where a wide square blade tends to skate.

Most surgeons who keep a Barnhill set keep three — 10, 14 and 16 mm — and use them as a graduated sequence: the widest that will sit comfortably for the bulk of the pad, then a narrower one for the lateral gutters and the posterior choanal margin.

Choosing a Blade Width

The blade should span most of the adenoid pad without touching the lateral walls. Too narrow and the resection takes multiple overlapping passes, each one bleeding into the field and obscuring the next. Too wide and the instrument engages the eustachian tube cushions — a scarred cushion means eustachian dysfunction and glue ear, and it is the complication that follows oversized curettes rather than bad technique.

As a working starting point: 10–12 mm for children under about four, 14–16 mm for most school-age children, 16–20 mm for adolescents and adults. Then adjust on what the mirror or endoscope actually shows, because the range of nasopharyngeal width at any given age is wide.

What Else Is on the Trolley

The curette is never used alone. A self-retaining gag holds the mouth open and the tongue down — the choices and their blade sizes are covered in our guide to Doyen, Jennings and Boyle-Davis gags. A soft palate retractor or catheters retract the palate. A post-nasal mirror or an endoscope confirms the pad and, more importantly, confirms the clearance afterwards.

Then packs, a suction — a Zoellner or fine Yankauer — and bipolar or a post-nasal pack for haemostasis. Where the adenoidectomy is combined with tonsillectomy, the same setup carries straight through to the tonsillectomy instruments.

Edge Maintenance and Inspection

An adenoid curette is a cutting instrument that gets treated like a blunt one, and that is the source of most complaints about them.

The edge is a shallow bevel on a thin section. It dulls, and a dull curette does not cut cleanly — it tears, which increases raw surface area, bleeding, and post-operative pain. Test it at inspection the way you would test scissors: it should shave cleanly through a single layer of thin latex or a rolled gauze edge, not drag it.

Check the fenestration margins for burring, since that is where tissue drags. On guarded patterns, check the cage is not sprung — a bent guard changes the relationship between cage and cutting edge and the specimen stops being retained. Compare against a new instrument if there is any doubt.

These are AISI 420 martensitic stainless, hardened for edge retention per ISO 7153-1, and they should be re-sharpened by a service that understands the bevel geometry rather than ground flat on a bench. Steam at 134 °C is standard; there are no lumens or joints.

Fizza Surgical manufactures all three patterns across the full width range, guarded and unguarded. Every adenoid curette is made under ISO 13485 and CE marked under MDR 2017/745.