Outcome of pregnancy after adenomyomectomy: a review

Adenomyosis is a benign uterine condition characterized by ectopic endometrial glands and stroma infiltrating at least 2.5 mm into the myometrium, which is frequently surrounded by hypertrophic muscle tissue [ 1 ]. Histologically, adenomyosis is defined as the presence of non-neoplastic endometrial tissue embedded within the myometrium and it is often associated with lymphatic and vascular invasion [ 2 ]. Prevalence estimates for adenomyosis vary widely, ranging from 5% to 70%, primarily because of differing diagnostic criteria and variations in study populations [ 1 ]. A national population-based study in South Korea reported an overall prevalence of 3.86 per 1,000 women, with a significant increase from 1.42 per 1,000 women in 2002 to 7.50 per 1,000 in 2016 [ 3 ]. Although traditionally viewed as a condition affecting women in their 40s and 50s, adenomyosis is now increasingly diagnosed in younger and infertile women, with rates of 7.5–25.0% among infertile women under 40 years and up to 24.4% in those over 40 years [ 4 ]. The posterior uterine wall is more commonly involved than the anterior wall and the disorder frequently coexists with other gynecological conditions such as myoma (35–55%) and endometriosis (65–70%) [ 1 ]. Beyond its association with gynecologic comorbidities, adenomyosis itself has been increasingly recognized as a condition linked to adverse pregnancy outcomes. Large population-based studies have shown that women with adenomyosis have significantly higher risks of hypertensive disorders of pregnancy, gestational diabetes mellitus, postpartum hemorrhage, placental abruption, preterm birth, and delivery of small-for-gestational-age infants, even after adjustment for confounding variables. These findings underscore the broader reproductive and obstetric impact of adenomyosis and highlight the importance of evaluating pregnancy outcomes in women undergoing fertility-sparing treatments such as adenomyomectomy [ 5 ].

Pregnancies after adenomyomectomy require intensive prenatal monitoring because of the increased risk of uterine rupture and PAS. Evaluation should begin with a comprehensive surgical history, including the surgical technique used, extent and location of myometrial excision, method of uterine reconstruction, and intra-or postoperative complications [ 21 , 22 ]. This information is essential for individualized risk assessment and delivery planning. Effective risk stratification after adenomyomectomy requires systematic evaluation of both surgical and clinical parameters that may influence perinatal outcomes. A thorough review of operative records should include the specific surgical techniques employed (such as triple-flap, wedge resection, or laparoscopic approach), the extent and location of adenomyotic tissue removal, and whether the endometrial cavity was entered during the procedure. Uterine wall reconstruction should also be considered. Intraoperative findings, such as endometrial perforation or excessive thinning of the myometrium, must be documented, as these directly affect uterine integrity and the safety of future pregnancies. The extent of adenomyosis is a critical determinant of perinatal risk [ 18 ]. In advanced cases, complete removal of the adenomyotic tissue while preserving an adequately healthy myometrium has become increasingly difficult. Clinical data and surgical experience suggest that a nodule weight >100 g may indicate a relatively high-risk profile, whereas small, well-localized lesions confined to the inner or outer myometrium with an intact junctional zone are considered safer candidates for surgical intervention [ 18 ]. Diffuse adenomyosis with extensive junctional zone involvement presents significant challenges with higher rates of incomplete resection and a greater risk of subsequent pregnancy complications, including abnormal placentation and hemorrhage. The surgical approach profoundly affects subsequent pregnancy-related risks. Entry into the uterine cavity during surgery is associated with a substantially increased risk of rupture, as demonstrated by all reported rupture cases in a large series of cavity-opening procedures [ 14 ]. Furthermore, the method of myometrial reconstruction and adequacy of tissue approximation directly influence uterine wall strength and future obstetric outcomes. Early pregnancy ultrasound measurement of the RMT is fundamental to risk assessment. Clinical evidence shows that women with a uterine wall thickness ≤7 mm experience abnormal gestational courses in 60% of cases compared to 40% in those with normal outcomes [ 21 ]. Women who proceeded successfully to delivery had a mean minimum uterine wall thickness of 10.8 mm (95% CI, 8.8–12.7 mm), suggesting this range as a potential safety threshold for risk assessment and delivery planning [ 21 ]. The thinnest portion of the myometrial wall was identified and documented as a primary risk parameter. Postoperative hysteroscopic evaluations provide crucial prognostic information. Endometrial defects are detected in 60% of post-adenomyomectomy cases; however, restoration typically occurs within 7 months to 21 months in most instances [ 20 , 22 ]. This healing interval is a critical period during which myometrial remodeling and endometrial regeneration occur, ultimately determining the safety profile for subsequent pregnancies. The duration of healing appears to depend on the extent of initial myometrial disruption and individual patient factors, including age and hormonal status. The relationship between endometrial integrity and PAS development is a key clinical observation in postadenomyomectomy pregnancies. Current evidence reveals a marked correlation between preconceptional endometrial status and PAS incidence: pregnancies conceived with persistent endometrial defects have a 100% incidence of PAS, compared to 20% in cases with documented endometrial restoration and 0% in pregnancies without detectable endometrial defects [ 20 ]. This temporal relationship underscores the importance of an adequate healing interval before conception, with current evidence suggesting a minimum waiting period of 12–24 months for complete endometrial recovery. Patients with persistent endometrial defects beyond this period require individualized counseling regarding the substantially increased risk of life-threatening placental complications, and may benefit from alternative reproductive strategies. Based on the above parameters, patients can be stratified into distinct risk categories for obstetric counseling and management. 1) High-risk patients include those with RMT ≤7 mm at any time [ 21 ], a history of endometrial cavity entry during surgery [ 14 ], large adenomyotic nodules (>100 g) [ 18 ], persistent endometrial defects without documented restoration [ 22 ], or multiple surgical complications involving extensive myometrial excision. These patients require careful counseling regarding reduced pregnancy success rates (30–50%) and significantly increased risks of uterine rupture, severe placental complications, and preterm delivery. 2) Moderate-risk patients were characterized by RMT measurements between 7 mm and 10 mm, localized adenomyosis excision without cavity involvement (50–100 g), or minor endometrial disruption with confirmed restoration. These patients have pregnancy rates ranging from 50–70%, and require enhanced surveillance for placental abnormalities and preterm labor. 3) Lower-risk patients demonstrate an RMT of >10 mm throughout pregnancy [ 21 ], have limited myometrial excision with preservation of the junctional zone (<50 g) [ 18 ], and show no endometrial defects or confirmed healing. These patients had optimal pregnancy rates (70–85%) and minimal obstetric complications. This stratification framework facilitates individualized prenatal monitoring and delivery planning, enabling clinicians to tailor surveillance strategies according to each patient’s surgical and anatomical profile. Serial ultrasound examinations are recommended throughout pregnancy to monitor fetal growth and assess placental location, with special attention paid to avoiding implantation in the lower uterine segment. Second-trimester Doppler ultrasonography should be performed to screen for PAS, focusing on characteristic findings such as placental lacunae and bridging vessels. Ultrasound remains the first-line imaging modality; however, MRI is indicated when visualization is limited or when a precise assessment of PAS is needed. The overall sensitivity of MRI for predicting PAS is 94.4% (95% CI, 86.0–97.9), and specificity is 84.0% (95% CI, 76.0–89.9), making it a valuable adjunct when ultrasound findings are inconclusive or when a detailed evaluation of placental invasion is required for surgical planning. Given the risk of uterine rupture, thorough patient counseling is essential, including education on warning signs, such as severe abdominal pain without contractions, uterine tenderness, fetal heart rate abnormalities, abnormal bleeding, hematuria, loss of fetal station, and maternal hypotension. After adenomyomectomy, emphasis should be placed on recognizing severe abdominal pain without contractions. Clinical management should involve prompt assessment and continuous fetal and uterine monitoring in symptomatic patients. Although long-term tocolytics have not been proven to prevent preterm birth, their short-term use may provide symptomatic relief in cases of uterine irritability or persistent contractions after adenomyomectomy [ 22 ]. Therefore, tocolytics should be used cautiously in this population. As uterine rupture can occur as early as 16 weeks after birth, patients must remain vigilant throughout pregnancy and have clear emergency contact instructions, seeking immediate care for any concerning symptoms at any gestational age. Patients should be counseled that while uterine rupture can occur at any gestational age as early as 16 weeks, clinical series demonstrate an increased risk in the third trimester and during labor. Therefore, heightened vigilance is particularly important during late pregnancy, although patients must remain alert throughout pregnancy and have clear emergency contact instructions for any concerning symptoms at any gestational age. For patients with a history of adenomyomectomy, particularly those with high-risk features such as residual myometrial thickness <7 mm, endometrial cavity entry, complex multilayer uterine repair, suspicious symptoms (e.g., abdominal pain, uterine irritability), history of uterine rupture, or prior surgical complications, close monitoring during the late second and early third trimesters is warranted. Although formal guidelines on the optimal timing for inpatient monitoring are lacking, clinical series have shown that uterine rupture may occur at any gestational age, as early as the second trimester (12–35 weeks) [ 23 ]. Several reports have described elective hospital admission between 24 weeks and 26 weeks of gestation, even in the absence of overt symptoms, as part of a proactive surveillance strategy [ 23 ]. When patients present with regular uterine contractions or persistent abdominal discomfort, empirical tocolytic therapy with agents such as ritodrine or magnesium sulfate is often administered to provide symptom relief [ 22 , 23 ]. This practice persists despite limited evidence supporting the maintenance of tocolysis for neonatal benefits in the general obstetric population [ 22 ]. MRI evaluation between 30 weeks and 34 weeks has been utilized in select cohorts to assess placental location, presence of PAS, and myometrial thickness [ 23 ]. Based on these findings, inpatient monitoring may be considered starting at 32–34 weeks in patients at the highest risk, especially those with uterine irritability, imaging findings suggestive of PAS, or a thinned myometrium. Upon admission, continuous monitoring of fetal heart rate and uterine activity is strongly recommended if symptoms are present [ 22 , 23 ]. Owing to the cumulative risk of uterine rupture and abnormal placentation following adenomyomectomy, elective cesarean delivery is universally recommended. Clinical studies have consistently reported 100% cesarean delivery rates in this population, reflecting a consensus on the safest mode of delivery. The optimal timing of delivery should be tailored to each patient’s risk profile. However, most studies recommend early delivery (between 35 weeks and 36 weeks), particularly in cases with thinned residual myometrium or suspected PAS [ 23 ]. This timing was aimed at balancing the risk of spontaneous uterine rupture with the need for neonatal maturity. Antenatal corticosteroids are recommended between 32 0/7 weeks and 33 6/7 weeks for patients at risk of delivery within 7 days, in accordance with current guidelines [ 24 ]. In a clinical series, the mean gestational age at delivery was 36.2 weeks, with 31.8% of the cases requiring preterm delivery and neonatal intensive care unit admission [ 22 ], underscoring the need to balance maternal safety with neonatal outcomes [ 25 ]. Given the risk of early uterine rupture and high PAS prevalence, delivery should be planned at a tertiary center with comprehensive maternal and neonatal support, including blood banks, interventional radiology, and pelvic surgery expertise. A multidisciplinary teamcomprising maternal-fetal medicine specialists, gynecologic surgeons, anesthesiologists, and neonatologists should coordinate care. Preoperative planning should involve a detailed review of imaging findings, myometrial thickness, and preparation for possible cesarean hysterectomy if placenta accreta is present. Owing to the increased risk of PAS after adenomyomectomy, careful preparation for postpartum hemorrhage is essential, including ready access to blood products and multidisciplinary surgical support. The hemorrhage response team should include interventional radiologists, gynecological surgeons experienced in complex pelvic surgeries, and anesthesiologists trained in massive transfusion protocols. For PAS, surgical options include leaving the placenta in situ or performing a cesarean hysterectomy in cases of extensive placental invasion [ 7 ]. Conservative placental retention may be considered to preserve fertility but carries risks of delayed hemorrhage, infection, and subsequent hysterectomy. Prophylactic uterine artery balloon catheters can be considered in high-risk patients. Cell salvage and massive transfusion protocols should be prepared for a rapid bleeding response.

This review highlights the need for evidence-based guidance for the management of pregnancies after adenomyomectomy. Improved outcomes depend on individualized patient selection considering disease severity, surgical history, residual myometrial thickness, and reproductive goals. Standardized myometrial-preserving surgical techniques and structured prenatal surveillance, including early imaging and planned delivery to tertiary centers, are critical for reducing these risks. Despite growing evidence, significant evidence gaps persist. Future prospective multicenter studies should establish standardized criteria for determining the surgical complexity, myometrial thickness, delivery timing, and surveillance protocols. Integrating these clinical strategies with further research will support individualized care and improve outcomes in this high-risk population.