A DHI (Direct Hair Implantation) hair transplant is a technique where individual hair follicles are extracted from the back of your scalp and implanted directly into thinning or balding areas using a specialized pen-like tool called a Choi implanter. The key difference from other transplant methods is that the Choi pen creates the recipient site and places the follicle in a single motion, eliminating the need for pre-made incisions.
How the Choi Implanter Pen Works
The Choi implanter pen is a small device with a hollow needle (0.6 to 1.5 mm in diameter) and a spring-loaded plunger. A technician loads a single hair follicle into the needle using forceps. The surgeon then presses the needle tip into the scalp at a 40 to 45 degree angle, and as the needle penetrates the skin, the plunger pushes the follicle into the newly created channel simultaneously.
In a standard FUE (Follicular Unit Extraction) transplant, the surgeon first creates hundreds or thousands of tiny slits across the recipient area, then goes back and places each graft into those pre-made channels. DHI collapses those two steps into one. This means the follicles spend less time outside the body, which can reduce the risk of graft desiccation, one of the factors that leads to poor outcomes in hair restoration.
What Happens During the Procedure
A DHI session follows three main stages. First, the surgeon numbs your donor area (typically the back of your head) with local anesthesia and extracts individual follicles using a micro-punch tool. Next, technicians sort those grafts into single, double, and triple hair units and load each one into a Choi implanter pen. Finally, the surgeon implants the follicles directly into the thinning area, controlling the angle, depth, and direction of each graft as it goes in.
The procedure typically maxes out at around 3,000 to 3,500 grafts per session. Beyond that number, the surgical team needs to stop, which means patients with extensive hair loss may need more than one session to achieve full coverage. Each graft contains one to four hairs, so 3,000 grafts can represent significantly more individual hairs than the number suggests.
DHI vs. FUE: What’s Actually Different
Both DHI and FUE extract follicles the same way, one at a time from the donor area. The difference is entirely in how they’re placed. FUE uses a blade or needle to create recipient channels first, then inserts grafts afterward. DHI does both at once with the Choi pen. This makes DHI particularly useful for adding density between existing hairs, since the pen allows more precise placement without disturbing surrounding follicles.
In terms of graft survival, the two techniques perform similarly. A study of 29 patients found a 93% survival rate with DHI, while research on 273 patients showed FUE survival rates between 93.5% and 96.6%. A separate Korean study recorded 92% graft survival at six months with DHI. The differences are small enough that surgeon skill and post-operative care likely matter more than the technique itself.
DHI does cost more. The Choi implanter pens are specialized instruments, multiple pens are used during a single session, and the technique requires additional trained staff to continuously load grafts. The premium varies by clinic and country, but expect to pay more than you would for a standard FUE procedure with the same number of grafts.
Who Is a Good Candidate
The ideal candidate has a stable, well-defined pattern of hair loss with at least 50% thinning in one or more areas. Your donor area matters just as much as the balding zone. The safe donor region at the back of the scalp typically contains 65 to 85 follicular units per square centimeter. Densities above 80 units per square centimeter are considered excellent for transplantation, while densities below 40 are less suitable because there simply aren’t enough follicles to harvest without creating visible thinning.
If your hair loss hasn’t stabilized or is below 50% thinning, medication to slow further loss is generally recommended before committing to a transplant. People with Afro-textured hair can undergo DHI, but the naturally curved, C-shaped follicles are more prone to damage during both extraction and implantation, so finding a surgeon experienced with this hair type is especially important.
Recovery: Week by Week
The first three days bring mild swelling and redness around both the donor and transplanted areas. Tiny scabs form around each implanted follicle. By days four through seven, swelling starts to fade and the scabs become more noticeable. Leave them alone. Picking at scabs can dislodge grafts.
Around week two, something counterintuitive happens: the transplanted hairs fall out. This is called shock loss, and it’s completely normal. The follicles are still alive beneath the skin. They shed the initial hair shaft before entering a resting phase and eventually producing new growth. By this point, scabs should fall off naturally.
Weeks three and four mark the return to a normal-looking scalp. Most visible signs of surgery disappear, sensitivity drops, and only minor redness may linger depending on your skin type. You can generally return to work within a week, though strenuous exercise is usually off-limits for a few weeks to avoid increased swelling or bleeding at the graft sites.
When You’ll See Results
Hair transplant results take patience. At three months, you may notice the first fine, wispy strands of new growth, representing roughly 15 to 25% of the final result. This early hair is often thinner and lighter than your natural hair.
The six-month mark is when things get noticeably better. Density increases significantly, with most patients seeing 50 to 60% of their final result. The new hairs thicken and start blending more naturally with existing hair.
Full results take about 12 months. By that point, 90 to 100% of the transplanted follicles have produced mature hair, and you can see the complete transformation. Some patients continue to see minor improvements in texture and thickness for a few months beyond the one-year mark.
Risks and Limitations
The most common risk with any hair transplant, DHI included, is damage to grafts during handling. Follicles are delicate, and trauma during extraction, loading into the pen, or implantation can reduce how many survive. Desiccation (drying out) and prolonged time outside the body also lower survival rates, though DHI’s single-step implantation is designed to minimize that window.
Infection is uncommon but does occur, particularly in patients with diabetes. Minor necrotic patches (small areas of skin that don’t heal normally) have been observed in smokers, though these tend to resolve on their own. Deeper-than-intended punctures during extraction can occasionally irritate underlying nerves, causing temporary burning sensations or neuralgia in the donor area.
The 3,000 to 3,500 graft ceiling per session is a practical limitation. If you need extensive coverage, you’re looking at multiple sessions spaced months apart, which adds both time and cost. For very large areas, some clinics recommend a hybrid approach that uses standard FUE for bulk coverage and DHI for detailed work along the hairline where precise angle control matters most.