Simpson Obstetric Forceps: Uses, Types & Sterilization Guide

Simpson obstetric forceps are the classic outlet and low-cavity delivery forceps used in assisted vaginal delivery. Designed by the Scottish obstetrician James Young Simpson in 1848, they have been the workhorse instrument for operative vaginal delivery for over 175 years. Modern obstetric trays still include them as the default forceps for routine assisted delivery.

This guide is written for obstetric residents, OR scrub nurses, and surgical procurement managers. As an ISO 13485-certified manufacturer of CE-marked surgical instruments since 1980, we cover the clinical, anatomical, and material specifications that distinguish surgical-grade Simpson forceps.

What Are Simpson Forceps?

Simpson forceps are a two-blade obstetric instrument used to grasp the fetal head during the second stage of labor and assist delivery. The instrument has two separate blades — left and right — that articulate at a central lock. Each blade has two curves: the cephalic curve (matching the contour of the fetal skull) and the pelvic curve (matching the maternal pelvic axis).

The instrument was designed by Sir James Young Simpson (1811–1870), Professor of Midwifery at Edinburgh and the physician who introduced chloroform anesthesia to obstetrics. His forceps design was the first to combine cephalic and pelvic curves elegantly, and it has carried his name in obstetric practice ever since.

Anatomy of the Instrument

Each Simpson forceps blade has four functional parts:

1. Blade (toe and heel) — fenestrated (with a window/opening) to reduce weight and improve grip on the fetal head. The toe is the distal end; the heel is the part nearest the lock.
2. Cephalic curve — the curve of the blade in the plane of the parietal bones. Allows the blade to grip the fetal head along the bi-parietal diameter without compression of the face.
3. Pelvic curve — the curve in the plane perpendicular to the cephalic. Matches the curve of the maternal birth canal so the blade follows the pelvic axis without trauma.
4. Shank — the section between blade and lock. Simpson forceps have parallel shanks (a defining feature versus other patterns).
5. English (sliding) lock — the central articulation between the two blades. A simple sliding lock that the obstetrician engages once both blades are positioned.
6. Handles — long, finger-grooved, with a posterior bar for traction.

Surgical-grade Simpson forceps are mirror-polished. Blade fenestrations have rounded, deburred edges — sharp edges trauma fetal scalp.

Clinical Uses

Outlet Assisted Delivery

The most common indication. Used when fetal head is at or below the perineum (+2 to +3 station), occiput anterior or occiput posterior, with the maternal pelvic floor visible. The Simpson facilitates delivery when maternal effort is exhausted, fetal distress requires immediate delivery, or instrumentation is otherwise indicated.

Low Forceps Delivery

Fetal head at +2 station with leading point through pelvic outlet. Same instrument, slightly higher position than outlet.

Mid-cavity Delivery (specialized indication)

Used less commonly. Requires advanced operator skill and is often substituted with vacuum or cesarean in modern practice.

Education and Training

The Simpson is the standard teaching forceps for obstetric residents — its mechanics illustrate cephalic and pelvic curve principles that apply to all obstetric forceps families.

Clinical technique for any obstetric forceps is learned under direct supervision and with simulator training. This guide is reference material, not procedural instruction.

Sizes and Variants

Material and Manufacturing

Simpson forceps are forged from AISI 420 martensitic stainless steel. Hardness 40–48 HRC — softer than cutting instruments, which is intentional. Slightly softer steel allows the blade to flex very slightly under fetal head compression rather than transmitting all force rigidly. Hardness above 50 HRC creates brittleness at the lock.

Blade alignment is critical — the two blades must articulate cleanly at the lock without binding, with their cephalic curves matching to within ±0.5 mm. Misaligned blades create asymmetric pressure on the fetal head.

Surface finish: mirror polish (Ra ≤ 0.4 µm) on all tissue-contact surfaces. Handle finish can be brushed for grip.

Sterilization and Care

Simpson forceps see limited tissue contact during routine delivery, but strict sterilization protocol is essential due to neonatal contact:

Step 1 — Pre-soak in enzymatic cleaner immediately after delivery. Amniotic fluid, vernix, and blood harden in the lock mechanism.

Step 2 — Manual cleaning. Brush blade fenestrations, lock mechanism, shanks, and handles. Pay attention to blade fenestrations — vernix collects there.

Step 3 — Ultrasonic. 8–10 minutes at 40 kHz, neutral pH detergent, blades separated.

Step 4 — Rinse and inspect. Distilled water rinse. Test blade articulation — should slide together cleanly without binding. Check fenestration edges for burrs.

Step 5 — Lubricate. Surgical-grade water-soluble lubricant on the lock mechanism.

Step 6 — Pack as a paired set. Both blades together, lock disengaged.

Step 7 — Steam autoclave. 134 °C, 3-minute hold (ISO 17665 / EU MDR 2017/745). Pre-vacuum preferred.

Step 8 — Storage. Sealed sterilization wrap.

What to Look For When Sourcing

• Material: AISI 420 martensitic stainless steel. Forged, not cast.
• Hardness: 40–48 HRC. Above this — brittle; below — too soft.
• Blade alignment: ±0.5 mm tolerance on cephalic curve match between left and right blades.
• Lock mechanism: English sliding lock that engages cleanly without forcing.
• Fenestration edges: Deburred and rounded.
• Surface finish: Mirror polish, Ra ≤ 0.4 µm on tissue-contact surfaces.
• CE Mark: EU MDR 2017/745, Class IIa for obstetric instruments.
• ISO 13485 manufacturer certification.
• FDA establishment registration for US market.
• Marking: Manufacturer mark, size, and L/R blade identification.

Frequently Asked Questions

What are Simpson forceps used for?

Simpson forceps are used for assisted vaginal delivery — specifically outlet and low forceps deliveries. The instrument grips the fetal head during the second stage of labor when assisted delivery is indicated due to maternal exhaustion, fetal distress, or other clinical factors. They are the standard forceps in most obstetric trays and the default teaching forceps for residents.

Why are they called Simpson forceps?

The forceps are named after Sir James Young Simpson (1811–1870), Professor of Midwifery at Edinburgh. He designed the elegantly-curved double-curve blade in 1848 and is also notable for introducing chloroform anesthesia to obstetric practice. His forceps design has been the standard outlet/low forceps instrument for over 175 years.

What is the difference between Simpson and Elliot forceps?

Simpson forceps have parallel shanks — the two blade shanks run side-by-side without overlap. Elliot forceps have overlapping shanks that curve toward each other at the lock. The mechanical difference: Simpson’s parallel shanks distribute compression more evenly along the fetal head; Elliot’s overlap concentrates it slightly, useful for specific anterior fetal head positions.

What is the difference between Simpson and Kielland forceps?

Simpson forceps have a strong pelvic curve, matching the maternal birth canal — used for outlet and low forceps where the head is descending the pelvic axis. Kielland forceps have almost no pelvic curve and are used for mid-cavity rotation when the fetal head is in a transverse or asynclitic position. Simpson is the routine instrument; Kielland is the specialized rotation instrument.

Can Simpson forceps be sterilized in an autoclave?

Yes. AISI 420 stainless steel Simpson forceps tolerate steam sterilization at 134 °C for 3 minutes per ISO 17665. Pre-vacuum cycles are preferred. Pack as a paired set with the lock disengaged.

How long do Simpson forceps last?

With correct cleaning, sterilization, and storage, a surgical-grade Simpson forceps lasts 1,000–3,000 deliveries before significant wear. Wear points are the lock mechanism (loosens over many cycles), blade fenestrations (edges can roll), and the cephalic curve alignment (drifts very slightly with use). A pair where the blades no longer articulate cleanly should be retired.

Sourcing Simpson Obstetric Forceps from Fizza Surgical

We manufacture Simpson obstetric forceps and the Simpson-DeLee modification in standard adult sizes. Material AISI 420 martensitic stainless steel, forged and heat-treated to 40–48 HRC, mirror-polished. English sliding lock, calibrated blade alignment, deburred fenestration edges. Each pair laser-marked with manufacturer mark, L/R blade identification, and lot/batch number.

Certifications: ISO 13485:2016 (DEKRA), ISO 9001:2016, CE Mark (EU MDR 2017/745, Class IIa), FDA Establishment Registration No. 3019842214, Japan MHLW, Brazil ANVISA.

OEM private-label manufacturing from 300 units per SKU. Custom packaging and distributor branding. Lead time 6–8 weeks.

For a quote or full obstetric and gynecology instrument catalogue, contact our sales team or view the Simpson obstetric forceps product page.

Related Resources

• Simpson Obstetric Forceps — Product Details
• Complete Obstetrics & Gynecology Range
• Our Certifications and Regulatory Approvals