DHI hair transplant (Choi pen): how it works

If you're researching hair restoration, you'll quickly meet a wall of initials — FUE, DHI, sapphire. This guide focuses on DHI and its signature tool, the Choi implanter pen: what it actually does, the control it gives a surgeon, and how it compares with FUE so you can ask better questions before you commit. For the bigger picture, start with our hair transplant hub.

It's general information to help you prepare — not medical advice.

What DHI is

DHI stands for Direct Hair Implantation. Like FUE, it begins by harvesting individual follicular units — the natural groupings of one to four hairs — from a donor area, typically the back and sides of the scalp where hair is more resistant to thinning. Hair loss itself has many causes, and the NHS overview of hair loss is a sensible place to understand yours before considering surgery.

What makes DHI distinct is the implantation step. Instead of first cutting recipient channels and then placing grafts into them, DHI uses a specialised implanter pen that does both jobs at once. The most widely used is the Choi implanter, which is why DHI is often called the "Choi pen technique".

How the Choi pen works

The Choi implanter is a pen-shaped device with a hollow needle at the tip and a plunger mechanism. The workflow looks like this:

1. Extraction. Follicular units are removed one by one from the donor area, just as in FUE.
2. Loading. A technician carefully loads each graft into the hollow tip of the pen, so the follicle sits ready inside the needle.
3. Placement. The surgeon presses the tip into the scalp at a chosen point, angle and depth, then pushes the plunger to release the graft as the needle withdraws.

Because the needle creates the incision and delivers the follicle in the same motion, there is no pre-made channel waiting to be filled. Clinics usually work with several pens and interchangeable tips of different diameters, matched to graft size, so a team can keep a steady rhythm. Since the surgeon's hand chooses each site live, the outcome leans heavily on the experience and artistry of the person holding the pen.

Control over angle, direction and density

The strongest argument for DHI is precision. Natural-looking hair doesn't grow straight out of the scalp — it emerges at specific angles and flows in directions that differ across the hairline, crown and temples. Because the Choi pen sets the angle, direction and depth at the moment of placement, a skilled surgeon can:

• Match the natural exit angle of surrounding hair, which matters most at the frontal hairline.
• Steer growth direction so hair lies the way it should as it grows out.
• Place grafts closely for density in a defined area, useful for detailed, small-zone work.

This is why DHI is frequently chosen for hairline and frontal work, where a few degrees of angle change how natural the result looks. Getting that front edge right is a design task in itself — our guide to hairline design explains how surgeons plan a hairline that suits your face and ages well. That said, the tool doesn't create the artistry; the surgeon does. The International Society of Hair Restoration Surgery (ISHRS) stresses that outcomes depend heavily on the training and judgement of the surgical team, whichever technique is used.

The pen is only as good as the hand guiding it. Ask about the surgeon's experience with DHI specifically — not just the equipment on offer.

DHI vs FUE at a glance

If you want a deeper head-to-head, see our dedicated FUE vs DHI comparison. It's also worth knowing that "FUE" itself has variations — for example the sapphire FUE technique, which uses sapphire blades to open channels.

Pros and cons of DHI

Potential advantages

• Fine angle, direction and depth control at the point of placement.
• No separate channel-opening step, which can shorten the time a graft spends outside the body.
• Well suited to hairlines and detailed, high-density small areas.
• Can support unshaven or partially shaven recipient approaches in suitable cases.

Honest trade-offs

• Often slower per graft, which can make it less practical for very large single sessions.
• Highly technique-dependent — loading and placing grafts with the pen demands a well-drilled, experienced team.
• It is a method, not a magic result; density and coverage still depend on your donor supply and biology.

Procedure & recovery

A DHI session commonly runs across several hours, sometimes a full day for larger areas, under local anaesthetic. The donor area is trimmed so follicles can be harvested; some clinics offer an unshaven approach for the recipient zone depending on the case.

Recovery generally follows a familiar pattern with modern transplants:

• First days: the scalp is tender; tiny scabs form around each graft. Most people resume everyday activities within a few days.
• One to two weeks: scabs typically shed. Careful washing and aftercare, exactly as your clinic instructs, protect the new grafts.
• Weeks to months: transplanted hairs commonly shed first — this is expected — before new growth gradually emerges. Visible change develops over many months, not weeks.

Because it's still a medical procedure, screening beforehand and follow-up afterwards matter. At SaluVista you speak with your surgeon before travelling, and booking and screening happen in the app, with a qualified human making the final decision on your plan.

Who DHI suits — and the SaluVista approach

DHI is often a strong fit for people focused on a natural frontal hairline, those wanting dense, detailed work in a defined area, or candidates exploring less-shaven options. It may be less ideal as the sole method for someone needing very high graft counts across a large area in one sitting, where efficiency matters more.

At SaluVista, hair restoration is led by Op. Dr. Caner K., a board-certified plastic surgeon with more than 10,000 surgeries performed. The technique is chosen to fit you — not sold as a one-size headline. Our pricing is transparent: a hair transplant starts from £1,500 (approximately €1,750) for a single session with an unlimited number of grafts, all-inclusive, with your final plan confirmed after assessment.

Frequently asked questions

Sources & further reading

• NHS — Hair loss (causes, when to see a doctor)
• International Society of Hair Restoration Surgery (ISHRS) (professional standards and patient information)

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