Dr. Chet’s NPI Technique: Creating the Ideal Feminine Appearance in Gender-Affirming Surgery

Over the past 30 years, Dr. Chettasak Tulayaphanich has refined his signature NPI (Non-Penile Inversion) technique to focus on crafting the most natural-looking vulva possible — with precision, sensitivity, and aesthetic harmony.
Trusted by patients from around the world, this approach is the foundation of every Male-to-Female (MTF) gender-affirming surgery he performs, regardless of the chosen vaginoplasty technique used to create the vaginal canal.

The Core Concept of NPI in Transgender Surgery

The NPI technique is dedicated to perfecting the external genitalia — the parts that are most visible, sensate, and essential to feminine identity:

Labia Minora (Inner Labia):

Dr. Chet uses pink mucosal tissue from the prepuce to sculpt thin, delicate inner labia. This tissue mimics the natural female genital anatomy in both texture and color, offering a realistic and feminine result.

Vaginal Opening (Introitus):

The vaginal opening is designed with a graceful V-shaped contour, considered the hallmark of feminine aesthetics. Penile skin is arranged vertically and joined at the base to recreate the posterior fourchette, a natural structure in natal females.

Female Urethral Opening Design:

To achieve a natural, feminine appearance, Dr. Chet meticulously creates the urethral opening in a position just above the vaginal opening (introitus), consistent with cisgender female anatomy. During surgery, all erectile tissue surrounding the urethra — especially the corpus spongiosum — is carefully removed. This ensures the area remains smooth, flat, and free from any bulging during arousal, resulting in a refined and aesthetically accurate urethral contour.

Clitoral Structures:

The clitoris, clitoral hood, and frenulum are sculpted using preserved, nerve-rich tissue — allowing patients to experience sexual sensation and achieve orgasm. This is a core benefit of the NPI technique in gender-affirming surgery.

the result of the WIH gender affirming surgery technique

Clarifying the Difference: NPI vs. Vaginoplasty Method

It’s essential to understand: NPI focuses on the external vulva design, while vaginoplasty refers to the method of creating the vaginal canal.

At WIH International Hospital, Dr. Chet offers a range of MTF vaginoplasty options:

  • Skin Graft Vaginoplasty
  • Colon Vaginoplasty
  • Peritoneal Vaginoplasty (PPV)
  • Zero-Depth Vaginoplasty

→ No matter which method is selected for the internal canal, the external feminine appearance is always created using the NPI technique.

So whether you choose skin graft, colon, or peritoneum for depth — your vulva appearance, sensation, and structure will be consistently natural, feminine, and beautifully crafted through Dr. Chet’s NPI technique.

STEP 1: E-mail Correspondence

Email is the preferred method of communication. It allows for detailed discussion, proper record-keeping, and clarity in requests or medical concerns.
You will receive comprehensive information tailored to your chosen procedure after we receive your inquiries.

→ You will be asked to complete a Health Information Form to declare any current or past health conditions.
→ Please be honest and accurate. Any undisclosed health issue may affect your safety or the outcome of surgery.

STEP 2: Booking the Surgery Date

Once you’re ready to move forward with your gender-affirming surgery, please inform us of your preferred month for surgery.

The exact surgery date will be selected and confirmed based on Dr. Chettasak’s operating schedule. Please note that Dr. Chettasak performs only one major surgery per day to ensure full attention and the highest quality of care.

If you have not yet decided which type of vaginoplasty you prefer—such as Skin Graft Vaginoplasty, Colon Vaginoplasty, or PPV (Peritoneal Vaginoplasty)—you may request an online consultation with Dr. Chettasak (consultation fees apply). This is highly recommended if you are unsure about the best option for you or wish to evaluate your genital skin condition in detail.

→ Once the date has been mutually agreed upon, a non-refundable deposit of 20% (based on the total surgery or treatment fee) must be paid within 10 days via international wire transfer.

→ To complete the booking process, you will be asked to:

  • Sign the Payment Conditions Form
  • Submit it together with the proof of transfer

This deposit officially secures your surgery date.

STEP 3: Referral Letters for Gender-Affirming Surgery

You must provide 2 referral letters:

  1. One from your psychiatrist or licensed mental health provider in your home country
  2. One from a Thai psychiatrist (arranged by our team)

Requirements:

  • Letters must be issued within 1 year of the surgery date.
  • The international letter must be sent directly to info@wihhospital.com, or brought in person.
  • Letters must include:
    – Legal and preferred name
    – Gender dysphoria diagnosis
    – Hormone therapy history
    – Surgical recommendation
    – Issuing clinic’s/hospital’s letterhead

→ If you do not have a letter from your country, we can arrange two Thai psychiatrist consultations for eligibility.

STEP 4: Complete Preoperative Lab Tests

Lab tests must be done 4–6 weeks before your surgery date. Reports older than 6 weeks will not be accepted.

Please email the following documents in JPEG or PDF format as early as possible:

  • Lab test results
  • Digital chest X-ray (with radiologist’s report)
  • Referral letter(s) and medical clearance if required

→ All reports must be submitted at least 3 weeks before surgery for review.

Lab Test Requirements by Age Group:

Under 42 years:
CBC, Anti-HIV, Creatinine, PT/PTT, FBS, Chest X-ray

Age 42–60:
All of the above, plus EKG

Over 60:
All of the above, plus HbA1C, Lipid Profile, LFTs, and Exercise Stress Test (with cardiologist report)

STEP 5: Plan Your Travel and Recovery Stay

To ensure a smooth and safe recovery, we recommend planning to stay in Bangkok for approximately one month.

→ Arrival: Please arrive 3–4 days before surgery to allow time for your preoperative consultation, psychiatric evaluation (if needed), and final lab review.

→ Postoperative Stay: After surgery, you will remain under our care for approximately 25 days. This includes:

  • Recovery in the inpatient ward during the early healing phase
  • Continued recovery in the Recovery Ward, where you will receive daily nursing care and personalized training on vaginal dilation techniques by our specialist nurses

→ Note: Accommodation in the Recovery Ward is not included in the surgical package. You can select from three room types, depending on your preference and budget:

  • Deluxe Room: 2,900 THB per night
  • Grand Deluxe Room: 3,500 THB per night
  • VIP Room: 12,500 THB per night

STEP 6: Finalize the Remaining Fee

To ensure a smooth arrival and pre-surgery process, we kindly recommend completing all remaining payments—including the surgical fee and Recovery Ward accommodationat least 2 weeks before your travel date.

→ Payment Options:

  • International Wire Transfer – Recommended for security and ease. This method allows sufficient time for processing and confirmation before your arrival.
    Online Payment Link (2C2P) – A secure and convenient online payment gateway. If you prefer this method, please inform our team, and we will issue a personalized payment link for you.

If you plan to pay by credit card (Visa or MasterCard), whether through 2C2P or at the hospital, we suggest notifying your bank in advance to avoid any transaction issues during your stay in Thailand.

You will receive a full summary of your fees once your surgery type, accommodation, and any required services have been finalized.

FAQ (Frequently Asked Questions)

A: NPI stands for Non Penile Inversion — a specialized method developed by Dr. Chetthasak.

A: No, NPI focuses only on the external appearance. The vaginal canal is not created.

A: Yes, many patients begin with NPI and later choose to undergo vaginoplasty if desired.

Book Your Transformation Today – Consult with Our Specialists

Reviewing before and after surgery photos

The decorated works of the surgical team at WIH Hospital.

23 years old SRS patient from Poland

Example result of Dr. Chettawut’s Non-penile inversion for gender affirming surgery

This case shows a typical result of Dr. Chettawut’s non-penile inversion technique for those with average penile length (without a circumcision).

The labia minora was constructed using the whole penile and prepuce skin to form the lip-like fold starting from the clitoral frenulum down to the sides of the vaginal opening.

In the second picture, where the labia were spread apart, the vaginal opening (made using the non-penile inversion technique) is vertically elongated or has an oval shape as it usually appears in a biological woman (not too broad or big like a hole).

The urethral opening appears anatomically correct in location and size.

The labia majora looks proportionate and beautiful without any noticeable scarring. The shape, size, and proportion of the labia majora matched the patient’s body.

Overall, this 2-month post-op photo depicts a positive result with normal to rapid external genital healing. The patient reported no difficulty doing her vaginal dilation routine and maintained her 6.5 inches vaginal depth.

Sex reassignement surgery by Dr. Chettawut Thailand-labia
Sex reassignement surgery by Dr. Chettawut Thailand-labia 04

Dr. Chettawut’s gender affirming surgery

Dr. Chettawut’s gender affirming surgery

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Dr. Chettawut’s gender affirming surgery