Safety and Efficacy of Radiofrequency Ablation for Abdominal Wall Endometriosis: A Single-center Experience

This retrospective study aims to evaluate the safety and efficacy of ultrasound (US)-guided RFA for patients with AWE at the Security Forces Hospital in Riyadh, Saudi Arabia, between January 2020 and January 2024.

Forty-two female patients with pathologically confirmed AWE who underwent US-guided RFA were included in the study. Lesions were assessed radiologically before the procedure using abdominal US, contrast-enhanced computed tomography (CT), and magnetic resonance imaging (MRI). All patients were followed for a minimum of 6 months after the intervention, with MRI used to evaluate lesion response. Treatment efficacy was assessed based on symptom relief, lesion volume reduction, and complication rates during the follow-up period.

Patient ages ranged from 28 to 52 years, with a median age of 42 years. All patients had a history of cesarean section and presented with cyclic pain. Preprocedure imaging revealed irregular hypoechoic lesions on US, solid soft-tissue masses on CT, and low signal intensity with heterogeneous enhancement on MRI. Histopathology confirmed the presence of endometrial cells in all cases, with most patients (40.48%) having lesions located below the scar. The majority of patients (95.2%) required only a single session of RFA. The complications included a minor scar wound, occurring in one case (2.4%). Complete radiological resolution was achieved in all patients (100%).

This study demonstrates that RFA is a safe and effective treatment for AWE, offering significant symptom relief with minimal complications. Further research is warranted to validate these findings and optimize the treatment protocol.

Endometriosis is an estrogen-mediated inflammatory disorder that often causes significant pain and debilitation. It is characterized by the presence of endometrial glands and stroma outside the uterus, commonly found in the ovary, cul-de-sacs, broad ligament, uterus, and fallopian tubes.[1,2] In the United States, at least 10% of reproductive-age women are diagnosed with endometriosis, a condition associated with chronic pain and infertility.[3] Extraperitoneal endometriosis refers to functional ectopic endometrial tissue located outside the peritoneal cavity and is exceedingly rare. Abdominal wall endometriosis (AWE) is a rare type of extrapelvic endometriosis, affecting 0.3%–3.5% of women.[4] Delayed diagnosis often occurs due to its overlap with more common conditions, such as hernias.[5] While most cases of AWE occur following a cesarean section, up to 20% of cases may arise spontaneously.[6] Most effective diagnostic tools for AWE include magnetic resonance imaging (MRI) and ultrasound (US). Computed tomography (CT) is considered suboptimal due to its radiation exposure and lower resolution. US-guided core-needle biopsy offers a valuable, noninvasive option for confirming the diagnosis and differentiating AWE from other conditions.[6-8] Medical management of AWE often provides only temporary relief, with symptoms frequently returning after discontinuation of treatment. Surgical resection has traditionally been the first-line treatment. However, minimally invasive techniques in interventional radiology are gaining importance for selected patients. Case reports and small series have demonstrated the successful use of thermal ablation, particularly radiofrequency ablation (RFA), for achieving long-term symptom relief in AWE.[7-9] This study aims to assess the safety and efficacy of using RFA as a treatment technique for patients with AWE through assessing postprocedural complications, symptoms, and volume reduction.

Study design and patients This retrospective, observational, and descriptive study included all patients with symptomatic, pathologically confirmed AWE who underwent RFA at the Security Forces Hospital (SFH), Riyadh, Saudi Arabia, between January 2020 and January 2024. The study was approved by the Institutional Review Board at SFH with a waiver for informed consent as the study is retrospective in its nature. The included patients were aged 25 years or above and had undergone RFA for symptomatic AWE and had a minimum follow-up period of 6 months. Patients under the age of 25 years or who had incomplete medical records were excluded. The diagnostic criteria for AWE included: Women of reproductive age with a history of cesarean section Masses or nodules located near the cesarean section scar, accompanied by cyclic pain that worsened during menstruation The presence of nodules near the cesarean section scar as an US finding US-guided biopsy with H and E staining confirming the presence of endometrial glands or stroma. Patient demographics and medical history were extracted from the medical records of the SFH. The collected patients’ characteristics included the patient age, symptoms, parity, and number of cesarean deliveries. Preprocedure preparation All the patients underwent preprocedure imaging to record lesion characteristics using US, CT, and MRI. All patients underwent US-guided core needle biopsy for histopathological confirmation. The area to be operated on was sterilized with iodine alcohol, and the US probe was used to guide the operation. To obtain sufficient tissue for a representative histopathological evaluation, we carried out at least three biopsies with sonographic guidance. After aspiration, each patient was monitored for 10–30 min while the biopsy site was compressed firmly on the local level. All US-guided core-needle biopsy procedures were performed by experienced staff with 15 years of clinical experience in performing US examinations. The morphological characteristics of the AWE specimens were examined using H and E staining. The following endometrial characteristics were included in the histopathological criteria for the diagnosis of endometriosis in our study: hemosiderin pigment, endometrial-like glands, and stroma, which were analyzed to establish the histological diagnosis of AWE. We described the type of biopsies performed, the location of lesions, as well as the pathological findings in this study. The procedure A RFA device (created by RF Medical, South Korea) was utilized. The RFA was performed with US guidance being adjusted after each portion was ablated. All patients underwent RFA using local anesthetic with 1% lidocaine, without sedation. An 18G needle (5 cm × 7 cm) was used with RFA power ranging from 20 to 50 Watts. After the procedure, patients were monitored for 6 h and allowed to go back home on the same day if no complications occurred. Cephalexin 500 mg was prescribed every 6 h for 3 days, and the bandages were removed on the next day. Individual procedure details, including the number of RFA sessions, RFA power output, and procedure duration, were collected for each case. Follow-up and postprocedure outcomes All patients were followed for a minimum duration of 6 months to assess symptomatic relief, complications, and MRI findings after the procedure. All initial presenting symptoms were reassessed on follow-up and were recorded. Complications were classified according to the Common Terminology Criteria for Adverse Events and the Society of Interventional Radiology classification system. MRI was used to assess the volume reduction as the MRI is considered a sensitive tool to detect thermal lesions and may provide more accurate data about the penetration, extension, and type of content of the nodule. An MRI pelvis was used at 1.5 Tesla (Magnetom Symphony, Siemens) using an 18-channel pelvic phased-array coil with the capability of parallel imaging. MRI images were interpreted by two board-certified abdominal imaging radiologists with at least 7 years of experience in MRI images, and any discrepancy was resolved by the consensus.

Patient characteristics The patients’ ages ranged from 28 to 52 years, with a median age of 42 years. Parity ranged from two to eight, with an average of five. All patients had a history of at least one cesarean section. Multiple cesarean sections were reported in 30 patients (71.43%), with 15 (35.71%) having two, 10 (23.81%) having three, 4 (9.52%) having four, and 1 (2.38%) having five cesarean sections. Cyclic pain was the presenting symptom reported in all patients – 42 (100%). Detailed data are presented in Table 1. Summary of patient demographics, clinical characteristics, and biopsy findings Preprocedure imaging All patients showed similar lesion findings on per-procedural imaging, including the US, CT, and MRI. The predominant finding on US was an ill-defined, irregular heterogeneous, hypoechoic lesion associated with minimal vascularity, as shown in Figure 1. On CT scan, a speculated solid soft-tissue mass with mild-to-moderate enhancement after intravenous (IV) contrast was observed, as shown in Figure 2. MRI findings included low signal intensity lesion on T1 and T2-weighted images, increased signal intensity in T2 fat saturation sequences, an ill-defined margin, diffuse fibrous speculation, and significant enhancement in the post-IV contrast injection, as shown in Figure 3. Sonographic images of the abdominal wall demonstrate an ill-defined, irregularly shaped hypoechoic lesion within the subcutaneous tissue with minimal vascularity Contrast-enhanced computed tomography scan of the abdomen and pelvis demonstrates a well-circumscribed, homogeneously enhancing lesion inseparable from the left rectus muscle Multisequential magnetic resonance imaging of the pelvis, showing an ill-defined soft-tissue mass with speculated borders occupying the subcutaneous fat and abutting the anterior surface of the left rectus sheath (yellow arrows). The mass demonstrates predominantly low-signal intensity on T1- and T2-weighted images, heterogeneous increased signal intensity on T2 fat saturation sequences, and significant enhancement in the postcontrast phase Core-needle biopsy and histopathology US-guided biopsy was used in all patients as the type of biopsy – 42 (100%). All hematoxylin and eosin staining in the histological specimen of US-guided biopsies confirmed the presence of endometrial cells in all patients (100%), as shown in Figure 4. Most patients (40.48%) had lesions below the scar, where 13 patients (30.95%) and 12 patients (28.57%) had lesions on the scar and above the scar, respectively, as shown in Table 1. Representative images of hematoxylin–eosin staining in the histological specimen of abdominal wall endometriosis show scarce endometrial glands and stroma Radiofrequency ablation procedure and postprocedure outcomes The duration of the treatment varied from 1.4 to 4.6 min (median of 1.4) with a median RFA power output of 32.3 Watt. There were forty patients (95.2%) who underwent a single RFA session, while only 2 patients (4.8%) had double RFA sessions, as presented in Table 2. No immediate complications were observed in all cases, as shown in Figure 5. Under ultrasound guidance, the left anterior abdominal wall endometrioma was targeted with local anesthesia, this was followed by insertion of 18G radiofrequency probe and ablation was done. The whole lesion was covered with ablation. No immediate complication Table 2 also shows the clinical and radiological postprocedure findings for a minimal 6-month follow-up period. All patients, 42 (100%), reported complete symptomatic relief on follow-up, while only one patient (2.4%) had complications in the form of a minor wound scar. Complete radiological lesion resolution on follow-up MRI images was observed in all patients 42 (100%) with no evidence of residual lesions, as shown in Figures 6 and 7. Preprocedure magnetic resonance imaging of the pelvis demonstrating an ill-defined mass lesion on the right rectus muscle with diffuse fibrous speculated margins showing heterogeneous signal intensity in T2 fat saturation sequences with enhancement in the postintravenous contrast injection (yellow arrow) Postprocedure follow-up magnetic resonance imaging of the same patient showing complete resolution of the mass lesion without residual, compared to the previous study

Our study demonstrated that all patients remained asymptomatic following US-guided RFA throughout the outpatient follow-up. We monitored the patients for a minimum duration of 6 months. Clinical and radiographic findings indicate full clearance of AWE after RFA.[10] US-guided RFA is a nonsurgical radiological intervention and minimally invasive technique. It is considered a promising treatment modality for AWE. The RFA uses high-frequency electrical currents to generate heat, which induces thermal coagulation and necrosis of the targeted endometrial tissue. This method enables accurate targeting of lesions while reducing harm to adjacent healthy tissue. Utilizing US guidance enhances the precision of needle placement, ensuring effective ablation of endometrial lesions.[8,11-14] Our results align with previous case reports and small series documenting successful thermal ablation of AWE.[15] However, the larger sample size in our study provides more robust evidence supporting the use of RFA as a potential first-line treatment for AWE. RFA offers an alternative management option for chronic symptoms, refractory cases, patients with contraindications to medical management, and those with treatment preferences. The goal of treating AWE, including symptom resolution, reduction, and obliteration of lesion volume, and the benefits of a minimally invasive procedure with fewer complications and a shorter recovery time are critical factors for both physicians and patients during treatment. The therapeutic approaches for AWE include medical management, surgical excision, and minimally invasive techniques.[15] While medical therapy, such as oral contraceptives, progestogens, danazol, progesterone, and aromatase inhibitors, can provide temporary symptom relief, its overall success rate is low, with symptoms frequently recurring after discontinuation of medication. Studies have shown that recurrence rates after stopping medical treatment can be high, with some estimates suggesting that up to 50% of women may experience recurrence within 5 years. This significant recurrence rate underscores the chronic nature of the disease and the limitations of relying on medical treatment alone.[16] Kim et al. conducted a study in which the cumulative recurrence rates at 24 and 60 months after surgical treatment of AWE were 23.8% and 39.1%, respectively. These rates were found to correlate with the length of follow-up, regardless of the surgical intervention. The mean time to recurrence was 17.5 ± 9.7 months.[17] This recurrence rate is lower compared to medical management, although it is still present. The lack of data on long-term outcomes following minimally invasive procedures, combined with the current study results suggesting favorable outcomes and a low complication rate, indicates promising potential for these techniques.

We demonstrated that US-guided RFA significantly reduces AWE volume and alleviates clinical symptoms, with minimal complications. This treatment technique is feasible and effective for treating patients with AWE who are refractory to other forms of management. However, more data and research are needed in the medical literature regarding the long-term follow-up outcomes and the potential cumulative recurrence rates following minimally invasive procedures. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.

1. Gabriel A, Shores JT, Poblete M, Victorio A, Gupta S. Abdominal wall endometrioma:Case report and review. Ann Plast Surg 2007;58:691–3. 3. Grigore M, Socolov D, Pavaleanu I, Scripcariu I, Grigore AM, Micu R. Abdominal wall endometriosis:An update in clinical, imagistic features, and management options. Med Ultrason 2017;19:430–7. 4. Dai Y, Luo HJ, Peng Y, Liu BG, Jin P. High intensity focused ultrasound for large abdominal wall endometriosis:A case report. Int J Hyperthermia 2022;39:1276–82. 5. Mori T, Ito F, Koshiba A, Kataoka H, Takaoka O, Okimura H, et al. Local estrogen formation and its regulation in endometriosis. Reprod Med Biol 2019;18:305–11. 7. Lee JS, Kim YJ, Hong GY, Nam SK, Kim TE. Abdominal wall endometriosis treatment by ultrasound-guided high-intensity focused ultrasound ablation:A case report. Gynecol Endocrinol 2019;35:109–11. 8. Liu Y, Wen W, Qian L, Xu R. Safety and efficacy of microwave ablation for abdominal wall endometriosis:A retrospective study. Front Surg 2023;10:1100381. 14. Zhu X, Chen L, Deng X, Xiao S, Ye M, Xue M. A comparison between high-intensity focused ultrasound and surgical treatment for the management of abdominal wall endometriosis. BJOG 2017;124:53–8. 17. Kim SJ, Choi SH, Won S, Shim S, Lee N, Kim M, et al. Cumulative recurrence rate and risk factors for recurrent abdominal wall endometriosis after surgical treatment in a single institution. Yonsei Med J 2022;63:446–51. Thought you might appreciate this item(s) I saw in The Arab Journal of Interventional Radiology. Your message has been successfully sent to your colleague. Some error has occurred while processing your request. Please try after some time. Export to End Note Procite Reference Manager Save my selection Article Level Metrics Article Keywords

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