Pregnancy outcomes and influencing factors following high-intensity focused ultrasound treatment for adenomyosis: a single-center retrospective study

Objectives To evaluate pregnancy outcomes and influencing factors in adenomyosis patients undergoing high-intensity focused ultrasound (HIFU) treatment with fertility requirements.

From April 2012 to December 2022, 223 patients with adenomyosis desiring fertility underwent HIFU at the Third Xiangya Hospital. Patients were followed up at 1, 3, 6, and 12 months post-HIFU treatment in the first year, and subsequently every 6 months. Data on pregnancy and pregnancy outcomes were recorded.

All patients completed HIFU treatment in a single session. During the average follow-up period of 39.0 ± 19.3 months (range: 7–91 months), 103 patients achieved a total of 109 pregnancies, resulting in an overall pregnancy rate of 48.9% (109/223). Among these, 82 pregnancies occurred through natural conception and 27 through assisted reproductive technology. Among 45 infertile patients, 23 (51.1%) conceived after HIFU treatment. Among the 57 patients with a history of adverse pregnancy outcomes, 27 achieved successful pregnancies post-treatment, with 15 live births. The incidence of complications during pregnancy and delivery was 23.8% (15/63). Body mass index (BMI) and ablation rate significantly influenced post-HIFU pregnancy outcomes. Higher BMI values and excessive ablation rates were associated with lower pregnancy rates. Advanced age was significantly associated with a higher risk of adverse pregnancy outcomes.

HIFU treatment is associated with improved pregnancy outcomes in patients with adenomyosis complicated by infertility or a history of adverse pregnancy outcomes. Higher BMI values and excessive ablation rates may reduce postoperative pregnancy rates, while advanced age increases the risk of adverse pregnancy outcomes.

Adenomyosis is a common benign gynecological disease in reproductive age women, with a reported incidence ranging from 7% to 30%. In recent years, its prevalence has shown an increasing trend, particularly among younger women [Citation1–4]. Common symptoms in patients with adenomyosis include dysmenorrhea, menorrhagia. Additionally, adenomyosis is associated with an increased risk of infertility and spontaneous abortion due to factors such as abnormal uterine anatomy, impaired uterine contractility and peristalsis, as well as reduced endometrial receptivity [Citation5–8]. The treatment of adenomyosis remains an intense challenge. Hysterectomy is currently the only definitive treatment for adenomyosis, but it is not suitable for patients who desire fertility preservation. Uterine-sparing procedures, such as adenomyomectomy, can preserve the uterus; however, complete excision of adenomyotic lesions is often difficult, leading to a high postoperative recurrence rate. Moreover, adenomyomectomy can cause significant damage to the uterus, increasing the risk of uterine rupture during pregnancy. Previous studies have shown that the risk of uterine rupture after adenomyomectomy was 5.8% [Citation9]. Uterine artery embolization (UAE) has been used in the treatment of adenomyosis, but it may lead to severe complications such as ovarian failure, amenorrhea, and intrauterine adhesions, ultimately resulting in infertility and adverse pregnancy outcomes [Citation10]. Therefore, UAE is not recommended for patients with adenomyosis who wish to preserve fertility. Pharmacological treatments are widely used in the management of adenomyosis; however, symptoms often return after discontinuation of medication. Furthermore, the severe side effects of some drugs limit their application in the treatment of adenomyosis. Consequently, exploring a more effective and less invasive treatment for adenomyosis is of great importance. As a noninvasive therapeutic technique, high-intensity focused ultrasound (HIFU) can be used to precisely ablate adenomyotic lesion under real-time ultrasound guidance without damaging surrounding structures. Numerous studies have demonstrated the safety and efficacy of HIFU treatment for adenomyosis [Citation11,Citation12]. However, research on pregnancy outcomes and related factors affecting pregnancy outcomes in patients with adenomyosis following HIFU treatment remains limited, with most studies being single-center and involving only small number of subjects [Citation13–17]. In 2024, Chen et al. [Citation13] conducted a systematic review and identified 10 studies published in English and Chinese involving a total of 557 patients with adenomyosis who desired to conceive after HIFU treatment. They found a pooled estimate of pregnancy rate of 53.4% and of the live birth rate of 35.2%, and there was a substantial heterogeneity among these studies, without the influencing factors affecting pregnancy rates and pregnancy outcomes. In 2023, Wei et al. [Citation15] reported 129 infertile patients with adenomyosis who wished to conceive were treated with HIFU,50 (38.7%) became pregnant after HIFU, and patients with internal adenomyosis and adenomyotic lesions located in the posterior wall had a higher pregnancy rate, without the influencing factors affecting pregnancy outcomes. Therefore, this study aimed to analyze pregnancy outcomes and influencing factors affecting pregnancy rates and pregnancy outcomes in a larger cohort of patients with adenomyosis who underwent HIFU treatment and had fertility requirements.

Patients Between April 2012 and December 2022, 2957 patients with adenomyosis were treated with ultrasound-guided HIFU (USgHIFU). The protocol was approved by the ethics committee and institutional review board of the institution (No.Quick21001). Written informed consent was waived. Inclusion criteria for this study were: (1) Patients with adenomyosis aged between 20 and 45 years; (2) The diagnosis of adenomyosis was primarily based on medical history, confirmed by ultrasound and magnetic resonance imaging (MRI), showing an enlarged uterus with at least one side of the myometrium ≥3 cm in thickness, with or without symptoms such as menorrhagia or dysmenorrhea; (3) A confirmed diagnosis of adenomyosis with indications for treatment and a desire for fertility; (4) No contraindications to sedation or analgesia. Exclusion criteria were as follows: (1) Patients who had no sexual intercourse or used contraception after HIFU, patients whose male partner was infertile, abandoning fertility intentions; (2) Patients who underwent hysterectomy, or adenomyomectomy after HIFU treatment and subsequently abandoned their fertility plans; (3) Patients lost to follow-up. Among all adenomyosis patients who underwent HIFU treatment, 328 patients had a desire for future fertility at the time of HIFU treatment. During follow-up, 38 patients were lost to follow-up, 57 changed their fertility plans by adopting measures such as levonorgestrel intrauterine system (LNG-IUS) placement or oral contraceptive use, 3 remained unmarried throughout the follow-up period, 7 underwent hysterectomy or adenomyomectomy after HIFU treatment. Ultimately, 223 patients were included in this study.As shown in . Pre-HIFU MRI evaluation All patients underwent MRI (1.5 T AVANTO, Siemens, Germany) examination prior to HIFU treatment. The lesion lacks a clear boundary with the outer myometrium and may sometimes show linear high-signal-intensity streaks (). Based on Kishi’s classification of adenomyosis [Citation18], we categorized adenomyosis into the following subtypes: Intrinsic type (Kishi type I), Extrinsic type (Kishi type II), Intramural type (Kishi type III), Indeterminate type (Kishi type IV). Ultrasound-guided HIFU ablation The HIFU procedure was performed as described in our previous papers [Citation19]. Briefly, after 2–3 days bowel preparations, the patient was positioned prone on the HIFU JC-200D focused ultrasound tumor therapeutic system (Chongqing Haifu Tech Co., Ltd., Chongqing, China). The procedure was performed under conscious sedation (fentanyl at 1 µg/kg, midazolam hydrochloride at 0.02 mg/kg, repeating administration of each on 40 min intervals if needed). A point scan of energy delivery with the power of 200–400 W was used. Follow the principle of point-by-point treatment, with each point receiving a dose of 6–15 s. In order to avoid local injury of the endometrium and the serosa of the uterus, it is recommended to start with 6–10 s per point, spaced 1 cm apart and keep at least 1.5 cm away from the endometrium and the uterine serosa. After completing the point-by-point treatment, perform an contrast-enhanced ultrasound examination to determine whether additional treatment dosage is required. All patient successfully received one session of HIFU ablation. Evaluation of HIFU treatment The ablation volume and ablation rate of adenomyotic lesions were calculated based on contrast-enhanced ultrasound images before and after HIFU treatment (). The ablation volume of the AM lesion is calculated as: Ablation volume = 0.523 × a × b × c, where a, b, and c represent the longitudinal, transverse, and anteroposterior diameters of the non-perfused area in the contrast-enhanced ultrasound, respectively [Citation20]. The ablation rate is determined by: Ablation rate = (Volume of non-perfused area/Total volume of adenomyosis lesion) × 100%. Follow-up Patients were followed up at 1, 3, 6, and 12 months after HIFU treatment, and then every 6 months after the first year. Postoperative management and fertility-related information were recorded. Follow-up content included: the time interval from HIFU treatment to conception, method of conception (natural or assisted reproductive technology), pregnancy-related complications, pregnancy outcomes, mode of delivery (vaginal or cesarean section, including reasons for cesarean), delivery-related complications (uterine rupture, postpartum hemorrhage, placenta accreta, etc.), neonatal outcomes (term/preterm birth, fetal weight). Statistical analysis Statistical analysis was performed using SPSS 20.0 software (SPSS, Inc.), with a two-sided p < 0.05 considered statistically significant. Continuous variables: Normality was assessed using the Shapiro-Wilk test. Normally distributed data were expressed as mean ± standard deviation (χ ± SD). Non-normally distributed data were expressed as median and interquartile range (IQR). Categorical variables: Expressed as number (percentage). Univariate analysis: Normally distributed continuous variables: Student’s t-test. Non-normally distributed continuous variables: Wilcoxon rank-sum test. Categorical variables: Chi-square test or Fisher’s exact test. Multivariate analysis: Factors with p < 0.10 in univariate analysis were included in a binary logistic regression model.

Baseline characteristics The mean age of the 223 patients was 35.5 ± 4.3 (range: 22–44) years, with an average BMI of 22.54 ± 3.26 (range:15.6–36.3). The median disease duration of adenomyosis before HIFU treatment was 48 (range:1–240) months. Among them, 45 patients had infertility (26 with primary infertility and 19 with secondary infertility), and 37 patients had concurrent endometriotic cysts. The median number of previous pregnancies was 3.0 (IQR:1.0–4.0), including 123 patients with 1 prior delivery, 13 patients with 2 deliveries, and 87 patients without any delivery before HIFU. A total of 57 patients had histories of adverse pregnancy outcomes (11 missed abortions, 25 spontaneous abortions, 10 induced abortions, and 11 ectopic pregnancies). The median preoperative CA125 level was 95.32 (IQR:55.34–149.05) U/mL, with 28 patients having normal CA125 levels, 175 patients showing elevated CA125, and 23 patients lacking CA125 data. According to MRI classification, there were 65 cases of type I adenomyosis, 64 cases of type II adenomyosis, 12 cases of type III adenomyosis, and 82 cases of type IV adenomyosis. The median MRI uterine volume was 176.25 cm³ (IQR: 128.11–247.46), and the median adenomyotic lesion volume was 48.98 cm³ (IQR: 25.22–83.32) (). HIFU treatment parameters The median HIFU treatment time for the 223 patients was 60.00 (IQR: 43.50–82.00) min, with a median sonication time of 400.00 (IQR: 263.00–603.00) s and an average treatment power of 383 (range: 200–400) watts. The median treatment energy delivered was 157.5 (range: 10.8–867.6) kJ, with an average treatment intensity of 410.87 (IQR: 350.04–475.87) s/h. The immediate post-treatment non-perfused volume (NPV) was 21.7 (range: 0-226.5) cm³, showing a mean NPV ratio of 63.0 ± 23.1% (range: 0–117.9%). Notably, 16 patients exhibited only reduced perfusion without definitive NPV on contrast-enhanced ultrasound, while 3 cases (all intrinsic type I) demonstrated over-ablation (NPV > 100%). Postoperatively, patients were routinely recommended 3–6 courses of GnRH-a therapy. In practice, 105 patients did not receive the advised treatment, 116 patients underwent 1–6 courses, and 2 exceptional cases received extended regimens of 7 and 8 courses, respectively (). Among the 223 patients, adverse effects during and after the procedure included: 28 patients experienced radiating leg pain, all of which resolved within 24–72 h postoperatively without sequelae. No cases of skin burns or intestinal damage occurred post-HIFU. Additionally, 4 patients experienced postoperative vaginal bleeding and discharge, all of whom improved after hemostatic management (). Pregnancy and delivery outcomes Among the 223 patients followed for an average of 39.0 ± 19.3 months (range: 7–91) post-HIFU, 103 patients achieved 109 pregnancies (6 with two pregnancies), yielding an overall pregnancy rate of 48.9% (109/223). Of these, 82 conceived naturally and 27 through assisted reproduction. The median time from HIFU to conception was 12 (range: 3–47) months, with pregnancies occurring within 3 months (n = 3), 4–6 months (n = 21), 7–12 months (n = 36), 13–24 months (n = 35), and >24 months (n = 14). Among 109 pregnancies, 60 patients delivered successfully 63 times (live birth rate: 57.8%, 63/109). Pregnancy rates: 53.8% (35/65) for type I, 56.3% (36/64) for type II (highest), 25.0% (3/12) for type III (lowest), and 34.1% (28/82) for type IV. Delivery modes included vaginal births (25.4%, 16/63) and cesarean sections (74.6%, 47/63), with indications including maternal request (n = 14), scarred uterus (n = 11), oligohydramnios (n = 2), polyhydramnios (n = 1), placenta previa (n = 3), premature rupture of membranes (n = 2), cephalopelvic disproportion (n = 2), gestational diabetes (n = 5), gestational hypertension (n = 2), fetal distress (n = 2), twin pregnancy (n = 2), and preterm labor (n = 1). The 63 deliveries resulted in 65 live neonates (2 twins), with 10 weighing <2500 g and 55 at normal weight; all survived (). Among the 109 pregnancies in 103 patients, there were 46 pregnancy losses including 19 spontaneous abortions, 15 missed abortions, 2 induced abortions (1 for fetal anomalies at 22 weeks and 1 for intrauterine fetal death at 22 weeks), 1 ectopic pregnancy, and 7 elective terminations (1 due to teratogenic medication exposure, 1 due to radiation exposure, 2 due to advanced maternal age, and 3 for personal reasons), with 1 patient experiencing both an ectopic pregnancy and live birth and another having both spontaneous abortion and live birth. Obstetric complications occurred in 23.8% (15/63) of deliveries, including 9 preterm births (1 from placenta previa bleeding, 1 from gestational hypertension, 3 from premature rupture of membranes, 1 twin pregnancy, and 3 with unknown causes), 2 cases of placenta previa, 3 postpartum hemorrhages, and 1 case of placenta accreta, while notably no uterine ruptures occurred during any pregnancy or delivery. Among the 223 patients, 45 (20.2%) had infertility before HIFU treatment (26 with primary infertility and 19 with secondary infertility). After HIFU, 23 pregnancies (51.1%) were achieved, including 12 natural conceptions and 11 through assisted reproductive technology. By the end of follow-up, there were 19 live births, 3 spontaneous abortions, and 1 missed abortion. Of the 57 patients (25.6%, 57/223) with a history of adverse pregnancy outcomes (including spontaneous abortion, missed abortion, ectopic pregnancy, or induced abortion) before HIFU treatment, 27 (47.4%, 27/57) achieved pregnancy after HIFU (20 natural conceptions and 7 through assisted reproduction), resulting in 15 live births and 12 pregnancy losses. Factors affecting pregnancy after HIFU treatment This study compared 103 patients who achieved pregnancy after HIFU treatment with 120 non-pregnant patients, identifying several influencing factors through univariate analysis (p < 0.10) including BMI category, lesion location, treatment duration, treatment intensity, ablation rate, prior pregnancy history, parity, and adenomyosis classification (). Multivariate binary logistic regression analysis revealed that higher BMI (overweight/obese group, OR < 1, p < 0.05), greater ablation rates (OR < 1, p < 0.05), were independent risk factors for reduced pregnancy rates, demonstrating that elevated BMI correlated with lower pregnancy success, higher ablation rates were associated with decreased fertility outcomes(). Factors influencing pregnancy outcomes after HIFU treatment Among 109 pregnancies following HIFU treatment, 63 resulted in live births, while the remaining cases included 19 spontaneous abortions, 15 missed abortions, 2 induced abortions, and 1 ectopic pregnancy, yielding an adverse pregnancy outcome rate of 33.9% (37/109). An additional 7 cases underwent elective termination. Comparative analysis between the normal delivery group and adverse outcome group identified potential influencing factors (p < 0.10), including maternal age, post-ablation volume, preexisting infertility, number of prior pregnancies, and adenomyosis classification. Multivariate binary logistic regression (stepwise method) revealed that younger age significantly increased the likelihood of successful delivery (p < 0.05, ), with no other independent risk factors identified.

Infertility improvement after HIFU treatment Adenomyosis primarily impacts fertility in reproductive age women by causing infertility and increasing risks of miscarriage, preterm birth, and other adverse pregnancy outcomes [Citation5,Citation21,Citation22]. In this study, the incidence of infertility among patients with adenomyosis was approximately 20.2%, consistent with the rate of 19.5% in previous studies [Citation1]. Of the 45 infertile patients, 51.1% (23/45) achieved successful pregnancy following HIFU treatment, with 19 successful deliveries. These results demonstrated that HIFU treatment can significantly improve pregnancy outcomes in adenomyosis patients with concurrent infertility. This result aligns with the findings from Huang, Wei, and Xiong, who reported post-HIFU pregnancy rates of 52%, 38.7%, and 40.7%, respectively in previously infertile adenomyosis patients [Citation15,Citation16,Citation23], they were significantly higher than the pregnancy rates of 27.8-30.2% following traditional adenomyomectomy. More importantly, most pregnancies occurred naturally, with natural conception rates reaching 76.9% (20/26) in Huang’s study and 72.7% (8/11) in Xiong’s research [Citation15,Citation23], compared to 52.2% (12/23) in our study. These findings suggested that HIFU ablation of adenomyotic lesions can effectively improve the uterine environment for conception and enhance pregnancy outcomes in infertile adenomyosis patients. Improvement of adverse pregnancy after HIFU treatment Previous studies indicated that adenomyosis patients have higher risk of miscarriage and preterm delivery [Citation5]. In our study, 25.6% (57/223) of patients had a history of adverse pregnancy outcomes. After HIFU treatment, 47.4% (27/57) of these patients with poor obstetric histories achieved subsequent pregnancies, with 15 eventually delivering healthy infants. Therefore, HIFU treatment may improve pregnancy outcomes in adenomyosis patients with previous adverse obstetric histories. The potential reasons for improved adverse pregnancy outcomes after HIFU treatment may include: reduction in lesion volume, decreased local inflammation, normalization of uterine contractions, endometrial microenvironment improvement, hormonal modulation [Citation23]. Pregnancy rates and outcomes across different types of adenomyosis after HIFU treatment Our study investigated the relationship between the types of adenomyosis and pregnancy rates. Type I patients achieved a pregnancy rate of 53.8% (35/65), type II patients showed the highest rate at 56.3% (36/64), while type III had the lowest rate at 25.0% (3/12), and type IV patients demonstrated a pregnancy rate of 34.1% (28/82). Interestingly, these results contrast with Ma et al. [Citation17] who reported Type III patients had the highest pregnancy rate (87.5%), but align with Wei’s [Citation15] findings showing a similarly low pregnancy rate (17.6%) for Type III. This discrepancy may be attributed to the small sample size of Type III cases in our study. For type IV patients, our results (34.6%) were consistent with Ma and Wei (37.8% and 32.0% respectively) [Citation15,Citation17]. Univariate analysis revealed significantly higher pregnancy rates in Type I and II patients compared to Type IV (p = 0.013, ). Wei’s study [Citation15] similarly found Type I patients had the highest postoperative pregnancy rate (59.6%). Collectively, these results suggest that Types I and II AM generally have better postoperative pregnancy outcomes than Type IV, while the pregnancy rate for Type III requires further investigation with larger samples. Focal (intrinsic and extrinsic) adenomyosis patients showed better pregnancy outcomes than indeterminate-type patients, consistent with Wei et al. [Citation15] who found diffuse AM was associated with worse pregnancy outcomes. While univariate analysis indicated adenomyosis types affected pregnancy and live birth rates, multivariate logistic analysis showed no significant difference, possibly due to the small number of sample size. Huang et al. [Citation23] similarly reported poor pregnancy outcomes in patients with diffuse adenomyosis after HIFU treatment, likely because extensive lesions are more prone to recurrence, creating a less favorable uterine environment for embryo implantation. Further molecular-level research is needed to identify targeted therapies for improving fertility in diffuse adenomyosis patients.

of factors influencing post-HIFU pregnancy outcomes Among 109 pregnancies, 60 patients successfully delivered 63 infants (including twins), yielding a live birth rate of 57.8% (63/109). The remaining 42.2% experienced various adverse outcomes. Univariate analysis identified age, immediate post-operative contrast volume, pretreatment infertility status, pregnancy history, and adenomyosis types as significant factors affecting outcomes. However, multivariate analysis only confirmed age as statistically significant, with the adverse outcome group being older on average - consistent with Ma’s findings [Citation17], suggesting advanced maternal age increases risks of poor pregnancy outcomes and emphasizing the need for comprehensive post-treatment care. Schwartz et al. [Citation24] demonstrated declining fertility with age, with pregnancy rates of 68.8% for women younger than 35 years versus 53.6% for equal or older than 35 years. In our study population, only 100 patients were equal or younger than 35 years old, while 87 were between 36 and 39 years and 36 patients were older than 40 years. The ACOG recommends immediate fertility evaluation and treatment for women younger than 35 years after pregnancy failure or when attempting conception. Therefore, adenomyosis patients younger than 35 years should receive multidisciplinary evaluation and individualized treatment plans to optimize conception timing and method. Time to conception, mode of conception, and delivery methods post-HIFU Our study showed that 55.0% (60/109) conceived within 12 months and 87.2% within 24 months post-HIFU. The main reasons for early conception may include: HIFU treatment has a shorter recovery time, rapid tissue healing (typically 3–6 months) allows earlier attempts at conception compared to surgical interventions. Unlike surgery, HIFU’s noninvasive nature avoids postoperative pelvic adhesions that could impair fertility. Natural conception accounted for 75.93% (82/109) of pregnancies. However, conception methods should be carefully considered based on comprehensive evaluation. We recommend attempting pregnancy within 12 months post-HIFU, with natural conception advised for patients younger than 35 years with good ovarian reserve and no adverse obstetric history. For patients older than 35 years or with infertility/poor obstetric history, ART should be pursued promptly, as AM recurrence may reduce pregnancy likelihood over time. The vaginal delivery rate was 25.4% (16/63), while cesarean section rate was 74.6% (47/63) - comparable to the literature-reported average CS rate of 79.4%. Notably, 25.4% of patients successfully delivered vaginally without complications (except one case of postpartum hemorrhage). Further analysis revealed that 14 of these 47 C-sections were performed not due to medical indications, but based on the patients’ personal preference. Therefore, the actual rate of medically indicated cesarean sections was 33/63(52.38%). In 2017, Zou et al. [Citation25] reported that vaginal delivery is feasible after HIFU for fibroids, with no increase in major obstetric complications. These results also demonstrated vaginal delivery is feasible post-HIFU for adenomyosis, though currently no evidence suggests CS reduces perinatal complications. Pregnancy complications The incidence of pregnancy/delivery complications was 23.8% (15/63), including: preterm delivery (9 cases − 1 placenta previa, 1 hypertensive disorder, 3 PROM, 1 twins, 3 idiopathic), postpartum hemorrhage (3), placenta previa (2), and placenta accreta (1). The complication rate in this study was higher than another study of 16.9% [Citation17]. All 65 neonates (including twins) survived, with 10 preterm infants weighing <2500 g. These findings highlighted the importance of vigilant monitoring for preterm labor in post-HIFU pregnancies, possibly related to adenomyosis induced uterine abnormalities. The three postpartum hemorrhage cases may reflect impaired uterine contractility from adenomyosis, necessitating careful postpartum management. In this study, no uterine ruptures occurred in our patients, attributable to real-time ultrasound guidance and strict safety protocols during HIFU. However, literature reports three cases [Citation26–28] of spontaneous uterine rupture at 34–38 weeks gestation post-HIFU (incidence 0.9% [3/333]), but it was -significantly lower than the rupture rate of 5.8% after traditional surgery [Citation9]. Analysis revealed two rupture cases involved diffuse adenomyosis with full-thickness myometrial damage on post-op MRI, despite modest ablation rates (63.76% and 52.59%). This underscores the importance of preserving myometrial integrity during HIFU, especially for fertility preservation. For all adenomyosis patients undergoing HIFU, regardless of current fertility desires, we recommend: (1) careful protection of endometrium and serosa during ablation; (2) long-term management (e.g. LNG-IUS) for non-reproductive patients; (3) for fertility-seeking patients: uniform energy distribution, point-by-point ablation (6–15s per point, 1 cm spacing), real-time gray-scale monitoring, and contrast-enhanced ultrasound evaluation; 4) HIFU should be performed by experienced operators for patients who have fertility requirement. Analysis of factors influencing post-HIFU pregnancy In the multivariate analysis of factors influencing pregnancy following HIFU treatment, BMI and the NPV ratio were identified as significant independent predictors of pregnancy outcomes. Higher BMI (OR < 1, p < 0.05) was negatively correlated with the likelihood of pregnancy, which may be attributed to their metabolic inflammatory status. Furthermore, the analysis revealed that the mean NPV ratio was significantly higher in the non-pregnant group (71%) compared to the pregnant group (63%), suggesting that excessive ablation volume may impair endometrial receptivity through thermal damage or secondary inflammatory responses, thereby compromising embryo implantation. Based on these findings, we specifically recommend that the NPV ratio should be controlled below 50% in adenomyosis patients undergoing HIFU treatment who wish to preserve fertility. This threshold is supported not only by the statistically significant difference in NPV ratios between the pregnant and non-pregnant groups observed in this study but also by previous research. Ma et al. [Citation15] reported that the NPV ratio for adenomyosis in patients who conceived after HIFU was 42.0 ± 23.2%. Their results suggested that an ablation rate no more than 50% may lead to relatively satisfactory pregnancy outcomes. This recommendation aims to balance the clinical goal of symptom relief with the preservation of reproductive potential. In addition, we emphasize the necessity of postoperative weight management for overweight patients to improve post-HIFU pregnancy success rates. Simultaneously, precise control of ablation energy and extent is critical for maintaining reproductive function. Future large-scale prospective studies are warranted to further optimize treatment parameters. Study limitations This study has several limitations: firstly, as a retrospective study spanning 10 years we encountered limitations in data completeness, potential bias may be existed due to patient loss to follow-up; secondly, the uneven distribution of different adenomyosis subtypes may have affected statistical analysis results; thirdly, the study primarily focused on postoperative pregnancy and pregnancy outcomes without analyzing or discussing adenomyosis-related symptoms such as dysmenorrhea and menorrhagia; fourthly, being a single-arm retrospective clinical study of HIFU treatment alone, it lacked comparative data with other treatment modalities including surgical and medical therapies. Therefore, future large-scale multicenter prospective randomized controlled trials are needed to further elucidate HIFU’s therapeutic effects on pregnancy outcomes in adenomyosis patients.

HIFU treatment positively impacts fertility in adenomyosis patients, improving both infertility and adverse pregnancy outcomes. Higher BMI, excessive ablation may reduce pregnancy rates, and advanced maternal age may reduce live birth rate. While serious complications remain rare but require to pay close attention. Ethical approval This study was approved by the ethics Committee of third Xiangya Hospital of Central south University in China (approval No.Quick21001). Acknowledgments We are grateful to the participating patients for their involvement. Disclosure statement No potential conflict of interest was reported by the authors. Data availability statement The data supporting the findings of this study are restricted available in Science Data Bank (DOI:10.57760/sciencedb.28250). Additional information Funding

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