Risk factors for postoperative recurrence of cesarean scar endometriosis

Qiyu Zhong: Writing – review & editing, Writing – original draft, Methodology, Formal analysis, Data curation, Conceptualization. Shuhang Qin: Writing – original draft, Methodology, Formal analysis, Data curation, Conceptualization. Huiling Lai: Investigation, Formal analysis. Shuzhong Yao: Writing – review & editing, Supervision, Project administration. Shuqin Chen: Writing – review & editing, Supervision, Project administration, Funding acquisition.

In this study, the cumulative recurrence rates at 12 and 36 months after open lesion resection of CSE were 5.6% (15/268) and 11.17% (21/188), respectively. Univariate analysis of risk factors for recurrent CSE revealed statistically significant factors; age at surgery, VAS for abdominal pain, type of surgery, and incision length were risk factors for CSE recurrence. Multivariate analysis further showed that VAS for abdominal pain ≥4 was a risk factor for the recurrence of CSE, whereas the method of integrated excision was a protective factor. In patients with local excision of mass, depth of involvement was found to be a meaningful factor in postoperative recurrence. Symptoms of CSE are mostly experienced approximately 2–3 years after CS. 10 In this study, the median latency period was 3 years, which was consistent with previous literature reports. The typical symptoms of CSE include a palpable mass under or away from the scar, with cyclic pain and swelling during menstruation. In this study, CSE was mainly characterized by cyclic abdominal pain (86.03%) and abdominal mass (100%). The mechanism for this is the implantation of ectopic endometrium in the abdominal incision, which causes cyclic bleeding and abdominal pain with changes in sex hormones during the menstrual cycle. A minority of the patients had noncyclic (7.35%) or no abdominal pain (3.68%). Therefore, attention should be given to avoid the delayed diagnosis and misdiagnosis of patients with these atypical symptoms. The main treatment for CSE is surgical excision. Although drugs, lasers, physical therapy, and other methods have been used to treat CSE, the above methods are not effective because of the wrapping of fibrous tissue. Here, we observed that neither preoperative nor postoperative drug therapy had a significant effect on the incidence of postoperative recurrence disease. The local microenvironment of CSE lesions may lead to some changes in hormones, enzymes, and various factors, resulting in poor drug response; therefore, routine drug use after surgery does not guarantee benefits to clinical outcomes. Pelvic explorations in 51 CSE patients revealed that 45.1% (23/51) of the patients had concurrent pelvic endometriosis and/or adenomyosis. Different incidences of concurrent pelvic endometriosis have been reported in patients with AWE, 7 , 16 , 20 , 21 , 22 ranging from 0% to 25%. This rate of our result is higher than that reported for pelvic endometriosis and adenomyosis in the general population 23 , 24 and may be correlated. However, our studies did not analyze these rates in terms of different patterns and with stratification of severity. Therefore, further subgroup analysis is needed to confirm the association between pelvic endometriosis/adenomyosis and CSE. Our study indicated that younger patients (aged <35 years) had higher recurrence disease rates, possibly because of CS secondary to postoperative pregnancy and higher estrogen levels. Iatrogenic implantation is the most common cause of AWE. 25 During CS and other surgical operations, endometrial debris or cells escape from the uterine cavity and are implanted into the abdominal wound. However, this theory does not explain all cases of AWE. There are a small number of cases with spontaneous AWE. 26 Estrogen is considered to be a key factor in endometriosis. Its effect on the endometrium is complicated by the local distribution and expression of several estrogen receptors. 27 , 28 In addition, because AWE responds to hormonal stimuli, 29 it is necessary to further explore the expression patterns and functions of estrogen receptors in AWE in basic studies. Ten articles published after the year 2000 showed that the recurrence rates were 0.0% to 22.2%, which was similar to our study (9.85%). 17 , 21 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 A retrospective study by Zhao et al 21 revealed that the risk factors for recurrence after surgical treatment were the size of the lesion and mass involving the muscle or peritoneum. Interestingly, mass size was not a risk factor for postoperative recurrence in the retrospective study by Kim et al. 17 In our study, both the diameter of mass and infiltrating depth had no significant differences between patients with or without recurrence disease. However, in the local excision of the mass group, the cumulative postoperative recurrence rate of the Skin or subcutaneous or adipose group was significantly lower than that of the fascia or muscle group and peritoneum group. Given that the main method of CSE treatment was local resection with a negative margin, the possibility of a deeper mass might be difficult to remove completely with small local incisions. This might have affected the recurrence. Large-scale prospective studies are expected to validate these potential risk factors. Ultrasound is currently the main diagnostic method for endometriosis because of its noninvasiveness, simplicity, and high patient acceptance. 38 In most cases of CSE, ultrasound examination findings reveal abdominal masses that are hypoechoic masses with irregular size and depth. Compared with ultrasound, magnetic resonance imaging can better judge the depth and scope of lesion infiltration and easily detect smaller lesions. 39 By combining the above imaging and physical examinations, the depth of lesion invasion can be initially assessed, thereby providing a basis for decision-making on subsequent surgical methods. Our study obtained insight into the clinical risk factors for postoperative recurrence of CSE after open lesion resection with a relatively large sample size. The limitations of our study are those inherent to a retrospective review. Retrospective reviews are subject to information bias in terms of missing or errors in data acquisition. Because this study is retrospective, a clear criterion for the selection of the 2 surgical methods was not initially determined. Moreover, in our research design, we cannot reveal the incidence of CSE. Although various approaches were employed to avoid confounding, residual confounding may exist. At present, the margin of the lesion is not evaluated in the pathologic examination via a pathologist, and the division between recurrence and residual is still flawed, which may lead to a high recurrence rate in the evaluation. Local excision of mass and VAS for abdominal pain ≥4 may have a higher rate of postoperative recurrence, whereas the surgical method of integrated excision is a protective factor. In patients with local excision of mass, depth of involvement was found to be a meaningful factor in postoperative recurrence. Given that, when the depth of lesion invasion is deep, the use of integrated excision may reduce the recurrence rate to a certain extent.

Patients (n=85) with substantial missing clinical data, missed visits, or who did not fulfill the inclusion criteria were excluded. Three patients who underwent laparoscopic resection of CSE were also excluded. Ultimately, 272 patients who underwent the open excision of pathologically confirmed CSE were reviewed systematically, of whom 26 had recurrent symptoms, and 246 did not (nonrecurrent) ( Figure 2 ). Figure 2 Flow diagram for patient enrollment and analysis AWE , abdominal wall endometriosis. Figure 2 Zhong. Two-center study of cesarean scar endometriosis. Am J Obstet Gynecol Glob Rep 2024. Flow diagram for patient enrollment and analysis AWE , abdominal wall endometriosis. The baseline characteristics are summarized in Table 1 . The recurrence group had a significantly higher rate of moderate/severe abdominal pain (VAS ≥4) than the nonrecurrence group ( P =.008). There were no significant differences between the 2 groups in terms of age at surgery, BMI, parity, number of CD, history of dysmenorrhea, preoperative medication, previous surgery for CSE, characteristics of abdominal wall pain, the maximum diameter of the mass during physical examination, original CD incision type, latency period, preoperative cancer antigen (CA) 125, and CA199 ( P >.05) ( Table 1 ). Table 1 Baseline characteristics of patients with CSE Table 1 Factors Overall (n=272) Recurrence group (n=26) Nonrecurrence group (n=246) P value Age (y) 33.53±4.8 32.04±4.49 33.68±4.81 .097 BMI (kg/m 2 ) 21.78±3.38 21.79±2.94 21.78±3.43 .997 Parity ≥2 105 (38.6) 12 (46.15) 93 (37.8) .406 Number of CD >1 68 (25) 9 (34.62) 59 (23.98) .234 History of dysmenorrhea 128 (47.06) 11 (42.31) 117 (47.56) .610 Preoperative medication 27 (9.93) 3 (11.54) 24 (9.76) 1.000 Previous surgery for CSE 21 (7.72) 2 (7.69) 19 (7.72) 1.000 Moderate/severe abdominal pain (VAS ≥4) 84 (30.88) 14 (53.85) 70 (28.46) .008 a Characteristics of abdominal wall pain b .452  Cyclic abdominal pain 234 (86.03) 22 (84.62) 212 (86.18)  Noncyclic abdominal pain 20 (7.35) 3 (11.54) 17 (6.91)  Persistent abdominal pain 8 (2.94) 1 (3.85) 7 (2.85) Maximum diameter of the mass during physical examination (cm) 3 (2–4) 2.5 (1.65–4.00) 3 (2–4) .195 Original CS incision type 1.000  Pfannenstiel 253 (93.01) 24 (92.31) 229 (93.09)  Vertical midline 19 (6.99) 2 (7.69) 17 (6.91) Latency period (y) 3 (2–5) 2 (2–5) 3 (2–5) .966 Preoperative CA125 >35 U/mL 68 (25) 7 (26.92) 61 (24.8) .817 Preoperative CA199 >35 U/mL 24 (8.82) 3 (11.54) 21 (8.54) .957 Values are presented as mean±standard deviation, median (interquartile range), and n (%). BMI , body mass index; CD , cesarean delivery; CSE , cesarean scar endometriosis; VAS , visual analog scale. a P <.05 b Ten patients had no pain. Zhong. Two-center study of cesarean scar endometriosis. Am J Obstet Gynecol Glob Rep 2024. Baseline characteristics of patients with CSE Values are presented as mean±standard deviation, median (interquartile range), and n (%). BMI , body mass index; CD , cesarean delivery; CSE , cesarean scar endometriosis; VAS , visual analog scale. P <.05 Ten patients had no pain. The operative findings between the 2 groups are shown in Table 2 . Patients with local excision of mass ( P <.001) had higher recurrence rates. The incision length in the recurrence group (median, 5 cm; IQR, 4–8) was shorter than that in the nonrecurrence group (median, 10 cm; IQR, 5–12; P =.002). However, the number of lesions, infiltrating depth, concomitant pelvic endometriosis and/or adenomyosis, stitching approach, size of pathology specimen, intraoperative bleeding, duration of surgery, catheterization and antibiotic use, probability of abdominal compression, abdominal wall drainage, and postoperative medication showed no significant differences between patients with or without recurrent disease. Table 2 Operation findings in the 2 groups Table 2 Factors Overall (n=272) Recurrence group (n=26) Nonrecurrence group (n=246) P value Perform other disease-related surgeries meanwhile 63 (23.16) 8 (30.77) 55 (22.36) .334 Method of surgery a <.001 b  Integrated excision 128 (47.06) 3 (11.54) 125 (50.81)  Local excision of mass 142 (52.21) 21 (80.77) 121 (49.19) Multiple lesions 43 (15.81) 6 (23.08) 37 (15.04) .432 Infiltrating depth .312  Skin or subcutaneous or adipose 37 (13.6) 1 (3.85) 36 (14.63)  Fascia or muscle 161 (59.19) 17 (65.38) 144 (58.54)  Peritoneum 74 (27.21) 8 (30.77) 66 (26.83) Intraperitoneal invasion (excluding peritoneal) 23 (8.46) 2 (7.69) 21 (8.54) 1.000 Intraoperative pelvic exploration 51 (18.75) 6 (23.08) 45 (18.29) .741  Simplex style 28 (54.9) 3 (50) 25 (55.56) 1.000  Complex style 23 (45.1) 3 (50) 20 (44.44) Stitching approach .101  Traditional suture 241 (88.6) 21 (80.77) 220 (89.43)  Mesh placement 29 (10.66) 4 (15.38) 25 (10.16)  Skin flap repair 2 (0.74) 1 (3.85) 1 (0.41) Incision length (cm) 8 (5–12) 5 (4–8) 10 (5–12) .002 b Size of pathology specimen (cm) 4 (3–5) 3.75 (2.5–5) 4 (3–5) .245 Intraoperative bleeding (mL) 20 (10–50) 20 (10–50) 20 (10–50) .607 Operation time (min) 65 (40–110) 70 (40–107) 63 (37–110) .753 Retention catheterization 1 (0–2) 1 (0–2.25) 1 (0–2) .896 Abdominal drainage 72 (26.47) 3 (11.54) 69 (28.05) .070 Abdominal compression 20 (7.35) 2 (7.69) 18 (7.32) 1.000 Antibiotic use (d) 3 (1–4) 2 (0–3) 3 (1–5) .133 Postoperative medication 23 (8.46) 4 (15.38) 19 (7.72) .335 Values are presented as median (interquartile range) and n (%). BMI , body mass index; CD , cesarean delivery; CSE , cesarean scar endometriosis; VAS , visual analog scale. a Two patients underwent simultaneous open lesion resection during CD and, therefore, were not classified into these 2 incision types b P <.05. Zhong. Two-center study of cesarean scar endometriosis. Am J Obstet Gynecol Glob Rep 2024. Operation findings in the 2 groups Values are presented as median (interquartile range) and n (%). BMI , body mass index; CD , cesarean delivery; CSE , cesarean scar endometriosis; VAS , visual analog scale. Two patients underwent simultaneous open lesion resection during CD and, therefore, were not classified into these 2 incision types P <.05. The relationship among the size of the pathology specimen, infiltrating depth, and postoperative recurrence was further studied using different surgical methods. As shown in Table 3 and Supplementary Table , there was no significant difference in the size of the pathology specimen between the recurrence group and the nonrecurrence group in the local excision of the mass group, and both the size of the pathology specimen and infiltrating depth showed no significant differences between the 2 groups in the group of integrated excision. However, in the local excision of the mass group, the postoperative recurrence rate in the fascia or muscle group and peritoneum group was higher than that in the Skin or subcutaneous or adipose group ( P =.036), suggesting that local excision of mass may not completely remove deep lesions, resulting in partial residual lesions, or some deeper lesions may be missed. Table 3 The relationship between the size of the pathology specimen, infiltrating depth, and postoperative recurrence in the local excision of the mass group Table 3 Local excision of the mass Overall (n=142) Recurrence group (n=21) Nonrecurrence group (n=121) P value Size of pathology specimen (cm) .466  <4 78 (54.93) 10 (47.62) 68 (56.2)  ≥4 64 (45.07) 11 (52.38) 53 (43.8) Infiltrating depth .036 a  Skin or subcutaneous or adipose 22 (15.49) 1 (4.76) 21 (17.36)  Fascia or muscle 102 (71.83) 14 (66.67) 88 (72.73)  Peritoneum 18 (12.68) 6 (28.57) 12 (9.92) Values are presented n (%). a P <.05. Zhong. Two-center study of cesarean scar endometriosis. Am J Obstet Gynecol Glob Rep 2024. The relationship between the size of the pathology specimen, infiltrating depth, and postoperative recurrence in the local excision of the mass group Values are presented n (%). P <.05. HRs for postoperative recurrence of CSE were analyzed using Cox proportional hazard regression analyses in univariate and stepwise multivariate models ( Table 4 ). After adjusting for incision length, infiltrating depth, size of pathology specimen, and probability of abdominal wall drainage, the results indicated that VAS for abdominal pain ≥4 was a significant risk factor for postoperative recurrence (HR, 3.72 [95% CI, 1.65–8.43]; P =.002). Patients who received integrated excision had a lower risk of recurrence than those who received local excision of mass (HR, 0.14 [95% CI, 0.04–0.48]; P =.002). In addition, older patients (aged ≥35 years) had a lower risk of postoperative recurrence than those aged <35 years (HR, 0.35 [95% CI, 0.12–1.04]; P =.058). Table 4 Univariate and multivariate Cox regression analyses: women with recurrence compared with or without recurrence Table 4 Variables Univariate Cox regression P value Multivariate Cox regression P value Age (≥35 vs <35 y) 0.337 (0.127–0.894) .029 a 0.353 (0.12–1.035) .058 a Abdominal wall mass pain (VAS ≥4 vs <4) 2.836 (1.311–6.134) .008 a 3.723 (1.645–8.425) .002 a Type of surgery (integrated vs local excision of mass) 0.159 (0.047–0.534) .003 a 0.143 (0.042–0.482) .002 a Incision length (cm) 0.851 (0.758–0.955) .006 a Infiltrating depth  Skin or subcutaneous or adipose 1 .359  Fascia or muscle 4.039 (0.538–30.356) .175  Peritoneum 4.536 (0.567–36.294) .154 Size of pathology specimen 0.842 (0.636–1.114) .228 Abdominal drainage (yes vs no) 0.441 (0.131–1.481) .185 Values are presented as hazard ratio (95% confidence interval). VAS , visual analog scale. a P <.05. Zhong. Two-center study of cesarean scar endometriosis. Am J Obstet Gynecol Glob Rep 2024 Univariate and multivariate Cox regression analyses: women with recurrence compared with or without recurrence Values are presented as hazard ratio (95% confidence interval). VAS , visual analog scale. P <.05. Furthermore, Kaplan-Meier analysis and log-rank tests were applied to analyze the potential risk factors for CSE. The results showed that 3 conditions lead to a higher cumulative recurrence rate: aged <35 years ( P =.021), VAS for abdominal pain ≥4 ( P =.005), and patients in the local excision of the mass group ( P <.001) ( Figure 3 , A-C). In addition, in the local excision of the mass group, the cumulative postoperative recurrence rate of the Skin or subcutaneous or adipose group was significantly lower than that of the fascia or muscle group and peritoneum group ( P =.018), whereas in the group of integrated excision, there was no significant difference in the cumulative postoperative recurrence rate among the 3 groups ( Figure 4 , A and B). Figure 3 Kaplan-Meier estimates of cumulative postoperative recurrence rate Estimates are shown for (A) age at surgery, (B) abdominal wall mass pain (VAS), and (C) surgical approach. VAS , visual analog scale. Figure 3 Zhong. Two-center study of cesarean scar endometriosis. Am J Obstet Gynecol Glob Rep 2024. Figure 4 Kaplan-Meier estimates of cumulative postoperative recurrence rate Estimates are shown by infiltration depth for each surgical approach: A, Local excision of mass; B, Integrated excision. Figure 4 Zhong. Two-center study of cesarean scar endometriosis. Am J Obstet Gynecol Glob Rep 2024. Kaplan-Meier estimates of cumulative postoperative recurrence rate Estimates are shown for (A) age at surgery, (B) abdominal wall mass pain (VAS), and (C) surgical approach. VAS , visual analog scale. Kaplan-Meier estimates of cumulative postoperative recurrence rate Estimates are shown by infiltration depth for each surgical approach: A, Local excision of mass; B, Integrated excision.

This retrospective study was reviewed and approved by the Ethics Committee of the First ([2022]186) and Sixth (2021ZSLYEC‒510) Affiliated Hospital, Sun Yat-sen University (n=253 and 19, respectively). A cohort of 272 women who underwent open lesion resection at these 2 institutions from January 1, 2011 through October 31, 2021, and had a confirmed diagnosis of CSE on histopathology were included. The medical records and follow-up information of the patients were retrospectively reviewed. All patients have signed consent for disclosure of the medical information for publication. Patients were enrolled if they were (1) aged 20–45 years, (2) presenting with abdominal pain and/or masses, (3) undergoing open lesion resection of CSE as the main treatment method, (4) without contraindications, and (5) postoperative histopathologic confirmation of CSE. The exclusion criteria were as follows: (1) subject lost to follow-up, (2) evidence of coexistent precancerous or malignant disease, (3) organ dysfunction, (4) refusal to participate or incomplete clinical data, (5) psychiatric and/or neurologic disorders, or (6) autoimmune disease. Two surgical methods were used: (1) removal of scar, excision of the mass, and exploration underneath the scar (ie, integrated excision), and (2) local excision of the mass. The integrated excision was referred to using the complete original cesarean scar as the surgical incision, whereas the local excision of mass referred to an incision made at the location of the partial original surgical scar within 1 cm longer than the mass ( Figure 1 ). The CSE excisions were performed via open incision. A cold knife was used to sharply separate the lesion and surrounding normal tissues along the 0.5–1.0 cm edge of the lesion, and the CSE mass was completely removed. Pelvic and abdominal cavities were explored when the lesions invaded the peritoneum or when the preoperative auxiliary examination was complicated by a pelvic mass. Mesh placement or flap repair may have been performed when the tissue defect was large, resulting in high tissue tension and unsatisfactory abdominal wall remodeling. Figure 1 Schematic diagram of integrated excision and local excision of mass CSE , cesarean scar endometriosis. Figure 1 Zhong. Two-center study of cesarean scar endometriosis. Am J Obstet Gynecol Glob Rep 2024. Schematic diagram of integrated excision and local excision of mass CSE , cesarean scar endometriosis. The following data were extracted from the medical records: age at the time of excision, gravity, parity, body mass index (BMI), prior medical and surgical history, visual analog scale (VAS) for the pain of dysmenorrhea and abdominal pain, preoperative treatment, symptoms, time to presentation/excision, preoperative examination, surgical approach, stitching approach, pelvic exploration, operative time and blood loss, and postoperative treatment. The latency period was defined as the time from the onset of clinical symptoms to the latest relevant surgery. BMI was applied to evaluate the degree of obesity (<18.5, underweight; 18.5–24.9, normality; 25.0–29.9, overweight; ≥30, obese), 18 and VAS was used to assess the degree of abdominal wall mass pain (0, no pain; 1–3, mild pain; 4–7, moderate pain; 8–10, severe pain). 19 Based on intraoperative exploration, patients with pelvic endometriosis and/or adenomyosis were considered to have the complex type; otherwise, patients were considered to have the simplex type. The medical records were reviewed by 1 researcher, and 2 other researchers validated the information to confirm accuracy. All patients were followed up for 2–11 years postoperatively in person at an outpatient clinic visit or by telephone interview. Follow-up visits continued until November 2022 or menopause. Postoperative recurrence was defined as a postoperative painful mass found on physical and ultrasound examination. Continuous data with a normal distribution are given as the mean and standard deviation and were compared using the Student t test and analysis of variance. Nonnormally distributed, continuous data are described as the median and interquartile range (IQR) and were analyzed with Mann-Whitney U tests. The categorical data were expressed as counts and percentages and analyzed with χ 2 and Fisher exact test. Potential risk factors ( P <.1), infiltrating depth, and size of pathology specimens were identified using Cox's univariate and multivariate proportional hazard analyses. The hazard ratio (HR) and 95% confidence interval (CI) were calculated as a measure of the risk of recurrence. Kaplan-Meier survival method and log-rank test were further performed for time to the incidence of recurrence. All statistical analyses were 2-sided, and a value of P <.05 was considered statistically significant. Statistical analyses were conducted using SPSS software (version 21.0; IBM Armonk, NY) and GraphPad Prism (version 9; GraphPad Software, San Diego, CA).

Endometriosis is defined as the presence of endometrial-like tissue outside the uterus, which may lead to pelvic pain and infertility. 1 , 2 Extrapelvic implants are rare but can be found in the gastrointestinal and urinary tract, diaphragm, and abdominal scars. 3 , 4 Abdominal wall endometriosis (AWE) is a rare condition defined by the presence of endometrial-like tissue in the subcutaneous fat and muscles of the abdominal wall, 5 resulting from pelvic surgeries such as cesarean delivery (CD), hysterectomy, and appendectomy. 6 , 7 The incidence of AWE in women following obstetric or gynecologic surgeries has been reported to range from 0.03% to 3.5%, 8 , 9 with the rate increasing because of the rising application of CD and laparotomies. 3 The most common type of AWE is cesarean scar endometriosis (CSE). 10 , 11 The most accepted theory for CSE is iatrogenic implantation. Furthermore, the pathogenic mechanisms involve the local environment at the implantation site, including local metalloproteinase activation and chronic inflammation caused by growth factors, altered immunity, potential epigenetic changes, and estrogen stimulation of estrogen receptors. 3 , 5 , 12 Cyclic changes in estrogen and progesterone can cause congestion, edema, and bleeding, resulting in fibrosis and adhesion of surrounding tissues, eventually forming local nodules. 12 Therefore, patients with CSE will experience periodic pain accompanying the menstrual cycle, and in severe cases, they may have persistent pain that is not related to menses, which will have a serious impact on women's health and quality of life. 13 Wide surgical resection is the standard treatment for CSE, 3 , 14 and pathologic diagnosis is the basic criteria for confirmation. Surgical resection with a margin of at least 1 cm should be performed during surgical treatment to prevent recurrence. 15 In addition, some parts of adjacent tissues, such as fascia or muscles, need to be excised. 15 Currently, using a location slightly larger than the local area where the mass is located as a surgical incision is the most commonly used surgical method. In this study, we tried an alternative surgical approach, which involved excision of the original cesarean scar, detailed exploration beneath the scar, and complete resection of all suspicious masses. Here, the impact of both modalities on postoperative recurrence rates will be further elucidated in our study. A retrospective review in Shanghai 16 reported that the disease recurrence rate of AWE was 1.5%; however, if those patients who had ever experienced surgical removal for AWE at other institutions were considered, the recurrence rate became 7.5%. A recent study revealed that the recurrence rate was 22.2% in AWE. 17 However, the risk factors affecting the recurrence of CSE after surgical resection are rarely elucidated. Therefore, this study aimed to explore the risk factors for postoperative recurrence after open lesion resection with a follow-up period of 2–11 years.