Mohs Surgery Process Explained: What to Expect on Surgery Day

Mohs surgery is a specialized, highly effective technique for the removal of skin cancer. Among treatment options, Mohs surgery uniformly produces the highest success rate and has the lower risk of tumor recurrence. However, for many prospective patients the idea of undergoing Mohs surgery can feel intimidating. It is natural to have concerns about what the procedure entails and how the day will unfold.

This blog post provides a comprehensive, step-by-step explanation of the Mohs surgery process. By understanding what to expect, patients can approach surgery day with confidence and peace of mind.

Preparing for Surgery

Arrival at the Clinic
Patients typically arrive at the clinic early in the morning, as Mohs surgery often takes several hours depending on how many stages are required. Upon arrival, they will check in with the front desk and may be asked to fill out or confirm paperwork. A comfortable waiting area is usually provided as patients prepare for their first step.

Initial Consultation
Before the procedure begins, patients will meet with their Mohs surgeon. During this consultation:

• The surgeon will review the patient’s medical history to ensure they are fully informed of any potential complications or concerns.
• The surgical site will be confirmed using biopsy photos for comparison. In some cases, patients may be asked to verify the location as part of the confirmation process.

This initial step is essential for ensuring both patient safety and the precision of the procedure.

Local Anesthesia
To ensure the patient remains comfortable throughout the surgery (and any pain is minimized), local anesthesia is administered to the surgical area.

• This involves a small injection that numbs the area.
• While patients may feel a slight pinch or mild discomfort during the injection, the local anesthetic takes effect quickly and lasts throughout the procedure.

The use of local anesthesia allows patients to remain awake, eliminating the risks associated with general anesthesia and ensuring a faster recovery time.

The Surgical Process

First Layer Removal
The Mohs procedure begins with the removal of a narrow margin of skin around the visible tumor.

• Using a scalpel, the surgeon excises only the visible portion of the cancerous tissue, along with a narrow margin of surrounding skin.
• This meticulous approach is designed to remove as little healthy tissue as possible while ensuring that all cancerous cells are targeted.

Tissue Analysis
Once the first layer is removed, the surgeon processes and examines it in an on-site laboratory.

• The tissue is processed, stained, and placed under a microscope to determine whether cancer cells are present at the margin.
• This step is crucial to ensure no cancerous cells are left behind.

The typical waiting time for analysis is about 45 minutes to an hour. During this time, patients can relax in a designated waiting area.

Additional Stages
If cancerous cells are still detected, the surgeon will remove an additional layer of tissue only where tumor is still present. This process is repeated as many times as necessary until no cancer cells remain.

• Studies show that the cure rate for Mohs surgery is as high as 99% for certain types of skin cancer. This high success rate is due to the precise, iterative nature of the procedure.
• Mohs surgery also minimizes the removal of healthy tissue, which is particularly important for cancers located on cosmetically or functionally sensitive areas, such as the face or hands.

What Happens After Tissue Removal

Wound Repair Options
Once all cancerous tissue has been removed, the surgeon will determine the best method for closing or healing the wound. Options include:

• Suturing the wound: Used when the wound edges can be brought together with a linear fashion or with a skin flap. Stiches will be placed under and on top of the skin to close the wound after more local anesthetic is administered
• Skin grafts: If the wound cannot be sutured together, the surgeon may take a skin graft from another area such as behind the ear and use the graft to repair the wound. This is employed for larger wounds, areas with limited skin elasticity, or areas that stitching side to side might distort anatomy (like the nostril).
• Natural healing (secondary intention): Sometimes, the most appropriate option is to allow the wound to heal on its own with proper wound care and follow up (sometimes used on the scalp or lower legs).

Post-Surgical Care Instructions
Patients receive detailed written and verbal instructions for wound care, including how to clean and dress the site, what to expect during the healing process, and signs of potential complications. Appropriate follow up will be scheduled at checkout for any necessary suture removal or wound check.

Cosmetic Procedures
For patients concerned about scarring, cosmetic procedures such as laser treatments or scar revision may be offered later to further minimize the appearance of the surgical site.

Patient Comfort Throughout the Day

Breaks Between Stages
While waiting for tissue analysis, patients are encouraged to relax. The clinic staff often provide a comfortable space, with access to refreshments and opportunities to read, listen to music, or simply rest.

Staff Support
The medical team plays a vital role in ensuring patient comfort. Nurses and assistants are available to answer questions, address concerns, and provide reassurance throughout the day. Many clinics prioritize creating a calm, supportive atmosphere to reduce stress.

How Long Does the Procedure Take?

The duration of Mohs surgery can vary depending on several factors:

• Number of tissue layers removed: If cancer is cleared in the first layer, the procedure is shorter. Additional layers increase the time.
• Tissue analysis: While typically completed within 60 minutes, complex cases may take longer.
• Wound repair: Larger or more complex wounds may require additional time for reconstruction.

On average, patients should expect to spend three to four hours at the clinic, though some cases may take longer. It is recommended to bring a warm jacket, any desired drinks or snacks, and a book or other entertainment to pass the wait time.

Mohs surgery is a highly effective, precise method for treating skin cancer, offering unparalleled success rates and minimal impact on healthy tissue. While the process may seem daunting at first, understanding each step can help alleviate anxiety and prepare patients for a smooth experience.

If you have further questions or concerns about Mohs surgery, please do not hesitate to reach out to our experienced team. We are here to guide you every step of the way.

Jessica “Nikki” Dietert, MD is a board-certified dermatologist ad fellowship-trained Mohs surgeon at Westlake Dermatology. She then earned her medical degree at The University of Texas Southwestern Medical School in Dallas before completing a residency at The University of Texas at Houston/M.D. Anderson Cancer Center, where she served as chief resident in her final year. She then finished training with a fellowship in Mohs micrographic surgery at Washington University in St. Louis.