Obstetric Forceps: Wrigley vs Simpson vs Neville-Barnes

The Chamberlen family kept their forceps design secret for roughly 150 years, arriving at deliveries with the instrument in a locked box and clearing the room before using it. When the design finally became public in the eighteenth century, the basic architecture it established — two separated blades that articulate around the fetal head — has not fundamentally changed since.

What has changed is specialisation. The instrument split into distinct obstetric forceps types, each solving a different geometric problem, and the differences between them are dimensional and mechanical rather than cosmetic. A Wrigley and a Neville-Barnes are not two brands of the same thing.

This guide compares the three patterns that dominate obstetric trays — Wrigley, Simpson and Neville-Barnes — from a manufacturing and instrument-selection standpoint.

Quick Comparison

Anatomy of the Instrument

Every pattern shares four components, and the design decisions live in how each is proportioned.

Blades

Fenestrated (windowed) or solid, the blade carries two curves at once. The cephalic curve is the concavity that matches the biparietal contour of the fetal head — its radius determines how the load spreads across the skull rather than concentrating on a point. The pelvic curve is the upward sweep in the plane at right angles, matching the curve of the birth canal.

Those two curves are the reason a forceps blade cannot be a simple spoon. Get the cephalic curve too flat and pressure concentrates on the malar region; too deep and the blades will not seat. Published biometric work has questioned whether classical blade dimensions still match contemporary newborn head measurements, which is an active discussion in the obstetric literature rather than a settled matter.

Shanks

The section between blade and lock. Parallel shanks (Simpson, Neville-Barnes) give length and allow application at a higher station. Short shanks (Wrigley) put the operator’s hands close to the perineum and make it mechanically awkward to generate large traction — which was the entire point.

Lock

Three lock designs exist and they are not interchangeable:

• English lock — a fixed socket on each shank; the blades articulate at one point and stay there. Used on all three patterns discussed here. Secure, simple, and it prevents the blades sliding relative to each other.
• French lock — a screw or pivot arrangement, tightened after articulation.
• Sliding (German) lock — permits the shanks to slide longitudinally relative to each other, accommodating asynclitism where the head is tilted. This is the Kielland arrangement and it is what makes that instrument rotational.

Handles

Plain or with finger guards. Finger guards (Neville-Barnes, some Simpson patterns) give a defined hand position and a purchase point for two-handed traction. Wrigley handles are short and plain, consistent with the instrument’s design intent.

Wrigley’s Forceps: Deliberately Limited

Arthur Wrigley (1902–1983) opposed the use of forceps on a high fetal head, and he designed an instrument whose proportions make a heavy pull physically awkward. It is short, it is light, and the short shank means the operator cannot get into a stance that generates significant force. The design constraint is the safety feature.

Practical characteristics:

• Applied when the head is on the perineum — outlet application only.
• Shallow pelvic curve, because at the outlet there is little canal curvature left to negotiate.
• Frequently sufficient under perineal infiltration alone rather than regional block, because traction requirement is low.
• Widely used to deliver the fetal head at caesarean section, where the short shanks are an advantage working through a uterine incision. This is arguably now its commonest application.

If a Wrigley will not deliver the head with modest traction, the correct response is to reassess rather than to pull harder. The instrument is not built to be pulled harder, and a forceps that is being forced beyond its design envelope will flex at the shank.

Simpson Forceps: The American Standard

Derived from James Young Simpson’s 1848 design, this is the pattern most obstetricians trained in the United States will reach for first. Long parallel separated shanks, English lock, pronounced pelvic curve, fenestrated blades.

The separated shanks are the distinguishing visual feature against a Tucker-McLane (solid blades, overlapping shanks). Separated shanks accommodate a moulded, elongated head — the shape typical after a long first stage — which is why Simpson-pattern instruments are associated with the moulded head and solid-blade patterns with the unmoulded one.

It is a non-rotational instrument. It grips the head in the position it finds and permits traction along the pelvic axis. That restricts correct application to an occipito-anterior position, with the sagittal suture in the anteroposterior plane. Applying a non-rotational pattern to a transverse or posterior position is a misapplication, not a technique variant.

Neville-Barnes: Axis Traction Built In

The UK and Commonwealth counterpart to Simpson, and closely similar in overall architecture — long parallel shanks, English lock, fenestrated blades, pronounced pelvic curve. The meaningful difference is the provision for axis traction.

The problem axis traction solves is geometric. The birth canal is curved, but the operator pulling on handles outside the perineum can only pull in a straight line. The resulting force vector is not aligned with the curve of the pelvic axis, so part of the applied force presses the head against the pelvic wall rather than advancing it.

An axis traction attachment — the Milne Murray rods being the classical arrangement — provides a separate handle that applies traction closer to the true pelvic axis, redirecting the vector downward before it curves anteriorly. Neville-Barnes blades are usually manufactured with the fitting for these rods; Haig-Ferguson forceps belong to the same axis-traction family.

In routine current practice the axis traction rods are often not used, and the instrument functions as a straightforward long non-rotational forceps. But the fitting is part of the pattern and it affects manufacture: the blade must carry the mounting point, which changes the forging and finishing.

The Two Patterns Worth Knowing as Contrast

Any discussion of obstetric forceps types is incomplete without the two instruments that solve problems the three above cannot.

Kielland forceps — sliding lock, minimal or absent pelvic curve, and consequently rotational. The sliding lock accommodates asynclitism; the near-absent pelvic curve permits rotation of the head within the pelvis without the blade tips sweeping through a wide arc against the vaginal wall. It is a substantially more demanding instrument, and its use has declined in many units in favour of rotational ventouse.

Piper forceps — long, with a reversed pelvic curve and a distinctive downward-sweeping shank, designed specifically for the aftercoming head in breech delivery. The operator applies them from below and behind the fetal body, which the reversed curve accommodates.

Application Classification

The station at which a forceps is applied defines which pattern is appropriate. The standard classification:

High forceps is of historical interest only and is not part of contemporary practice. Clinical decisions on operative vaginal delivery sit with the attending obstetrician and their unit protocol — the table above describes which instrument the classification implies, not when to intervene.

Manufacturing Requirements

Obstetric forceps place unusual demands on manufacture, because the instrument is long, is loaded in bending, and contacts a neonatal skull.

Steel and Forging

Forceps are drop-forged rather than machined from bar stock. The forging process aligns the grain of the steel along the blade and shank, which is what gives a 40 cm instrument the stiffness to transmit traction without flexing. A machined forceps of identical dimensions will flex measurably more under the same load.

Material is typically AISI 420 martensitic stainless for the body, or AISI 304/316 austenitic where maximum corrosion resistance is prioritised over hardness. Forceps are not cutting instruments, so extreme hardness is unnecessary; springiness and dimensional stability matter more.

Finish

The blade surface — particularly the fenestration edges and the inner cephalic surface — must be fully deburred and polished. A burr on a fenestration edge is a laceration risk against neonatal scalp. This is the single most important finishing operation on the instrument and the one most often skimped in low-cost manufacture.

Pair Matching

All obstetric forceps types are supplied and used as matched pairs. The left and right blades of a pair are finished together so the lock articulates cleanly and the blades sit symmetrically when closed. Mixing blades between pairs of nominally the same pattern produces an instrument that will not lock squarely — the commonest reason a set is condemned in CSSD.

Every pair should carry a matching serial or pair mark. Checking that the numbers agree takes two seconds at the inspection point and prevents an instrument being assembled wrong on the sterile field.

Inspection Points

• Lock articulation — blades should articulate and separate smoothly, with no play at the lock when closed.
• Blade symmetry — hold the articulated pair against a flat surface. The blade tips should sit level.
• Shank alignment — sight along the shanks. Any bend means the instrument has been over-stressed and should be withdrawn.
• Fenestration edges — run a gloved finger around each window. Any catch means a burr.
• Pair marks — matching numbers on both blades.

All obstetric instruments in our range are manufactured to ISO 7153-1 material specification under an ISO 13485:2016 quality system with CE marking under EU MDR. Details are on our certifications page.

Building the Tray

Forceps rarely stand alone. A delivery or operative delivery set pairs them with episiotomy scissors, cord clamps, sponge holders and repair instruments. Our guides to Braun-Stadler episiotomy scissors and the caesarean section instrument set cover the surrounding tray — the latter being directly relevant given how frequently Wrigley forceps are used at section.

For haemostasis instruments used alongside, see our note on Green-Armytage forceps. The complete range is available under surgical instruments.

For pricing on individual patterns, matched pairs or complete obstetric sets — including OEM manufacture to hospital specification — contact our technical team.