May 13, 2023
Tatnai L. Burnett, M.D., a minimally invasive gynecologic surgeon at Mayo Clinic in Minnesota, indicates that a common complaint of women with abdominal wall endometriosis (AWE) is the substantial pain experienced when they bump against the kitchen counter.
AWE is rarer than cystic, superficial or deep endometriosis. One in 10 women has endometriosis, but of women who visit Mayo Clinic for endometriosis, approximately 1 out of 30 has AWE, says Dr. Burnett. This type of endometriosis also forms uniquely from other endometrioses.
"It's unrelated to other types of endometrioses," says Dr. Burnett. "We definitely know it's a different disease process. There's a lot of room for research on abdominal wall endometriosis."
Dr. Burnett indicates AWE is usually iatrogenic, likely related to prior surgery — especially C-sections — and resulting endometrial translocation. However, in rare cases women are diagnosed with AWE with no preceding surgery.
"In a C-section, there's a lot of pulling and cleaning," says Dr. Burnett. "Any little bit of tissue could end up elsewhere."
With the growth of C-sections — now representing 32% of all deliveries — Dr. Burnett expects AWE will grow to affect greater numbers of patients.
Though AWE may start at a C-section, patients with this disease are often delayed in diagnosis, seeking help many years following their deliveries, explains Brian T. Welch, M.D., an interventional radiologist at Mayo Clinic in Minnesota.
AWE's seriousness depends on one's definition of the word "serious," says Dr. Burnett. Though it can result in significant symptoms, AWE rarely develops into cancer. He says he's seen only one case in the last eight years in which malignancy developed.
In AWE, a patient's disease becomes a palpable mass. Symptoms arise differently among patients. Some find their pain is cyclic, following their menstrual cycles. For others, the pain is noncyclic. Pain intensity can range from mild to significantly bothersome.
"Many patients have debilitating pain — at times causing them to stay home and out of work," says Dr. Welch.
Mayo Clinic gathers a team around AWE, begins cryoablation
Dr. Burnett partnered with Wendaline M. VanBuren, M.D., a diagnostic radiologist based in Rochester, Minnesota, to develop Mayo Clinic's Complex Endometriosis Clinic. This clinic focuses on AWE plus cystic, deep or superficial endometriosis.
As the team started seeing larger AWE areas, treatment needs became more complex.
"With larger disease areas, you have to move the muscle and fascia and put it all back together," says Dr. Burnett. "This becomes more challenging with more AWE."
To address the growing complexity of AWE requiring treatment, Dr. VanBuren pointed Dr. Burnett to Dr. Welch and fellow interventional radiologists, who have used ablation for benign and malignant lung, kidney, bone and soft tissue tumors for over 20 years.
"Talking with Dr. Burnett, we realized what we've been doing with cryoablation for tumors could be applied here in abdominal wall endometriosis," says Dr. Welch.
The new partners discussed the use of heat-based thermal ablation versus cryoablation, and cryoablation came out the front-runner, an easy decision according to Dr. Welch.
"With cryoablation, you use probes that form an ice ball you can see," says Dr. Burnett. "So, you can map out treatment and see the extent of treatment in real time."
The AWE cryoablation procedure
Before the procedure, the team conducts preoperative imaging with contrast MRI, which provides information on the extent of disease. The MRI is reviewed during a multidisciplinary endometriosis imaging conference with minimally invasive gynecology, interventional radiology and diagnostic radiology team members. This patient-centric, team-based approach helps guide triage and inform treatment decisions.
Cryoablation for AWE is minimally invasive and often utilizes fluid to protect and displace normal structures such as the bowel, bladder or skin, according to Dr. Welch. This avoids creating frostbite or other injuries. The interventional radiologist constantly monitors the cryoablation process for safety as the ice ball forms. During this process, treatment can be sculpted to the patient's individual needs and anatomy.
"One of the nice things about the cryoablation process is it's very tailored to the patient," says Dr. Welch. "We choose among different kinds and shapes of needles to fit each particular individual."
In this process, the endometriosis cells die due to the cold temperatures. Extraction of dead AWE cells is unnecessary, explains Dr. Welch, as the body reabsorbs the cells over time. A local inflammatory response forms on the patient's abdominal wall, which dissipates well.
Advantages of cryoablation for AWE
Dr. Burnett and colleagues now choose cryoablation over surgery for most patients with AWE. Advantages for patients include less pain, reduced abdominal wall damage, smaller incision, less invasiveness and avoidance of complex reconstruction. Minor scarring occurs at the cryoablation site.
"Cryoablation is just a cleaner and less dramatic process for the patient," says Dr. Burnett.
Most patients with AWE are cryoablation candidates, says Dr. Burnett. He sees no benefit of surgery versus ablation if a patient has no contraindications for AWE. These would include AWE involvement with skin or extensive involvement with intra-abdominal processes, such as disease causing the bowel to become stuck under the abdominal wall.
While a larger disease area may take slightly longer to heal, Dr. Welch says most patients recover within 48 hours of AWE cryoablation and can often return to work within the same week.
Next steps for AWE cryoablation
Dr. Burnett says endometriosis specialists need long-term data on AWE cryoablation to determine whether it is curative. He and colleagues studied and published a safety and feasibility study in a 2022 issue of Abdominal Radiology. This study found the cryoablation technique feasible, durable, repeatable and well tolerated by patients.
Dr. Burnett theorizes this therapy is as effective as surgery, though these results must be borne out in a larger patient population followed over multiple years. He is writing an AWE cryoablation versus surgery comparison study currently.
AWE cryoablation education and referral
Currently, few medical centers are applying cryoablation to AWE, according to Dr. Welch. It started at Mayo Clinic five years ago with only a few patients a year, but the number of patients seeking cryoablation for this disease is growing as awareness of the procedure spreads.
Dr. Welch says he and his colleagues can work with external health care professionals to share Mayo Clinic's experience with the AWE cryoablation procedure, offering helpful tips and insights to those desiring to learn. He also suggests referral to Mayo Clinic as an option, especially due to the multidisciplinary team approach in working with patients with AWE, state-of-the-art MRI and excellent anesthesiology.
Drs. Burnett and Welch indicate Mayo Clinic has treated one of the largest volumes of patients with AWE using cryoablation. This experience has strengthened their techniques, allowing them to take more challenging cases and thoughtfully push the envelope for which patients may be treatable.
"Much like in other procedures, volume matters when seeking a place to refer patients who are struggling with AWE," says Dr. Burnett.
Referring physicians may send patients to Mayo Clinic's Complex Endometriosis Clinic The clinic then sends potential candidates' imaging to interventional radiology for group discussion at a weekly multidisciplinary imaging review. The multidisciplinary team determines whether a patient with AWE might benefit from cryoablation. Then an interventional radiologist such as Dr. Welch sees the patient to make a final determination on whether to pursue the procedure.
"Cryoablation for AWE is a wonderful offering we have here at Mayo Clinic for patients," says Dr. Burnett. "I'm thrilled for them to take advantage of it."
For more information
Smith KA, et al. Feasibility and safety of percutaneous image-guided cryoablation of abdominal wall endometriosis. Abdominal Radiology. 2022;47:2669.
Refer a patient to Mayo Clinic.