A DHI procedure involves three core phases: extracting individual follicular units from the donor area, loading each graft into a Choi Implanter Pen, and implanting them directly into the recipient zone without pre-made channels. The entire process takes 6 to 10 hours depending on graft count and is performed under local anesthesia.
This article is for informational purposes only and does not constitute medical advice.
Before the Procedure Begins
Day-of Arrival and Preparation
You arrive at the clinic in the morning, typically between 7:00 and 9:00 AM. The preparation phase takes approximately 30 to 60 minutes before any surgical work begins.
What happens during preparation:
- Blood pressure and basic vitals are checked
- The surgeon reviews the transplant plan, confirms graft count, and marks the hairline design on your scalp with a surgical marker
- You review and approve the hairline design in a mirror
- The donor area is trimmed or shaved (full or partial, depending on clinic protocol and whether you opted for unshaved DHI)
- Local anesthesia is administered to both the donor and recipient areas
Anesthesia
Local anesthesia is injected into the donor area first, then the recipient area. The injections use a fine needle and cause a stinging sensation for approximately 30 to 60 seconds. After the anesthesia takes effect (1-2 minutes), you feel pressure but no pain for the remainder of the procedure.
Some clinics offer comfort-enhancing options:
- Needle-free jet anesthesia: Uses pressurized air to deliver anesthetic without a needle
- Oral sedation: A mild sedative to reduce anxiety (you remain awake)
- Scalp nerve blocks: Targeted anesthesia that numbs larger areas with fewer injection points
Phase 1: Graft Extraction
Extraction in DHI is identical to the extraction phase in traditional FUE. The surgeon uses a micro-punch tool (0.6-1.0mm diameter) to isolate individual follicular units in the donor area.
How Extraction Works
- The surgeon positions the micro-punch over a follicular unit in the donor zone
- The punch rotates and cuts a tiny circle around the follicular unit, separating it from surrounding tissue
- The graft (containing 1-4 hair follicles) is lifted out with fine forceps
- The tiny circular wound left behind heals on its own within 5-7 days, leaving a minimal dot scar
Extraction Details
| Aspect | Detail |
|---|---|
| Punch size | 0.6-1.0mm diameter |
| Grafts per hour | 500-800 (varies by surgeon) |
| Scarring | Tiny dot scars, virtually invisible at 3mm hair length |
| Area used | Back and sides of head (occipital and parietal regions) |
| Anesthesia | Local, already administered |
The extraction phase for a 2,000-graft session takes approximately 2 to 3 hours. Extracted grafts are placed in a chilled holding solution (typically Hypothermosol or normal saline) to maintain viability until implantation.
Sorting and Quality Control
After extraction, technicians sort the grafts under magnification:
- Single-hair grafts: Reserved for the hairline where natural-looking single hairs create a soft, irregular edge
- 2-hair grafts: Used behind the hairline for the transition zone
- 3-4 hair grafts: Placed in the mid-scalp and crown where density is the priority
This sorting ensures the right graft type goes to the right area during implantation.
Phase 2: Loading the Choi Implanter Pen
This is the step that distinguishes DHI from every other hair transplant technique. Each extracted graft is individually loaded into the hollow needle of a Choi Implanter Pen.
How Loading Works
- A technician picks up a single follicular unit using fine-tipped forceps
- The graft is gently inserted into the hollow needle of the Choi pen, hair-first (follicle end pointing outward)
- The graft sits inside the needle, ready to be deployed when the surgeon presses the plunger
- The loaded pen is handed to the surgeon or placed in a rack for immediate use
The Relay System
A single surgeon cannot load pens and implant simultaneously. DHI clinics use a relay system with a team of 3 to 6 trained technicians:
- While the surgeon implants a graft from one pen, technicians load the next pens
- A typical relay uses 6 to 8 Choi pens in rotation
- The surgeon finishes implanting from one pen, hands it back, picks up the next loaded pen, and continues
- This cycle keeps the surgeon working continuously without downtime
The relay system is critical for two reasons: it minimizes the time each graft spends outside the body (improving survival), and it keeps the procedure moving at a reasonable pace despite the one-graft-at-a-time implantation method.
Phase 3: Direct Implantation
This is the defining phase of DHI. The surgeon implants each graft directly into the recipient zone using the loaded Choi pen, creating the channel and placing the graft in a single motion.
How Implantation Works
- The surgeon holds the loaded Choi pen at the desired angle (typically 10-45 degrees, matching natural hair growth direction)
- The needle tip is positioned precisely on the recipient scalp at the planned location
- The surgeon presses the needle into the scalp, creating a tiny channel
- Simultaneously, the plunger is depressed, pushing the graft out of the needle and into the freshly created channel
- The surgeon withdraws the pen, and the graft sits securely in its new position
- The surgeon takes the next loaded pen and repeats
Implantation Precision
The surgeon controls three variables with each implantation:
| Variable | What It Means | Why It Matters |
|---|---|---|
| Angle | The tilt of the graft relative to the scalp surface | Determines how naturally the hair lays flat or stands up |
| Depth | How deep the graft is inserted | Too shallow risks poor anchoring; too deep can damage the follicle |
| Direction | Which way the hair shaft points | Must match surrounding natural hair growth patterns |
At the hairline, single-hair grafts are placed at acute angles (10-20 degrees) pointing forward, mimicking natural hairline growth. Behind the hairline, angles increase gradually and multi-hair grafts are used for density.
Implantation Speed
| Graft Count | Approximate Implantation Time | Total Procedure Time |
|---|---|---|
| 1,000 | 2-3 hours | 4-5 hours total |
| 2,000 | 3-5 hours | 6-7 hours total |
| 3,000 | 5-7 hours | 8-9 hours total |
| 3,500 | 6-8 hours | 9-10 hours total |
After the Procedure
Once all grafts are implanted, the surgical team inspects the recipient area under magnification to confirm graft placement. The donor area is cleaned and may have a light dressing applied.
Immediate Post-Procedure
- The recipient area is left open (no bandages over the grafts)
- A loose bandage may be wrapped around the donor area
- You receive aftercare instructions, prescribed medications (typically antibiotics and anti-inflammatory drugs), and a special pillow or neck support for sleeping
- You can leave the clinic the same day, though most patients arrange nearby accommodation
What the Scalp Looks Like Immediately After
The recipient area has hundreds or thousands of tiny implantation sites, each with a hair graft sitting just below the surface. The area appears red with small dots of blood at each site. The donor area has tiny circular marks where grafts were extracted. Both areas look most dramatic on day 1 and improve rapidly through the first week.
For a full breakdown of what to expect in the days and weeks following DHI, see the DHI recovery timeline. For a broader understanding of the technique, visit the DHI overview.
FAQ
How long does a DHI procedure take?
A DHI procedure takes 6-10 hours depending on the number of grafts. A session of 1,500-2,000 grafts typically takes 6-7 hours. Larger sessions of 3,000-3,500 grafts may take 8-10 hours or be split across two consecutive days. The procedure is longer per graft than traditional FUE because each graft is individually loaded into the Choi pen and implanted one at a time.
Is DHI painful during the procedure?
DHI is performed under local anesthesia, so you feel no pain during extraction or implantation. The initial anesthesia injections cause a brief stinging sensation that lasts about 30-60 seconds. Some clinics use needle-free anesthesia devices to reduce this discomfort. You remain awake and alert throughout, and most patients describe the experience as boring rather than painful.
Do they shave your head for DHI?
DHI can be performed without shaving the recipient area, which is one of its advantages over traditional FUE. The donor area typically requires at least partial shaving or trimming for clean extraction. Some clinics offer fully unshaved DHI where the donor hairs are trimmed individually before extraction, though this is more time-consuming and may limit the number of grafts harvested.
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