Microabscess within adenomyosis combined with sepsis: a report of a rare clinical case

This case study describes a rare presentation of an intermuscular abscess associated with uterine adenomyosis and sepsis, highlighting the diagnostic challenges and clinical management of this condition. A 34-year-old woman presented with severe lower abdominal pain, fever, and a history of recurrent dysmenorrhea, unresponsive to initial antibiotic therapy. Despite unremarkable findings on transvaginal ultrasound (TVS) and magnetic resonance imaging (MRI), blood cultures identified Escherichia coli, confirming a diagnosis of sepsis. Following the failure of conservative treatment, exploratory surgery revealed a uterine abscess related to adenomyosis, necessitating a total hysterectomy. The patient’s postopera- tive recovery was uneventful, with complete resolution of symptoms and infection. This report emphasizes that patients with adenomyosis presenting with persistent lower abdominal pain and high fever may not respond to antibiotics alone. Rare complications such as abscess formation should be considered, and timely surgical intervention should be pursued when conservative management proves ineffective.

Adenomyosis · Abscess · Sepsis · Case report 1 Background Adenomyosis is a benign gynecological disorder characterized by the presence of endometrial glands and stroma within the myometrium, leading to uterine enlargement and associated symptoms such as dysmenorrhea, menorrhagia, and pelvic pain. It most commonly affects women of reproductive age, particularly those in their 40 s. A 2015 study estimated its overall prevalence at 0.8%, rising to 1.5% in women aged 41–45 years [1 ]. Discrepancies in reported prevalence may

from non-standardized diagnostic criteria and tissue disruption during laparoscopic procedures, complicating histological assessment [2 ]. While relatively common, the exact pathogenesis of adenomyosis remains unclear. Two main theories have been proposed: one suggests that endometrial injury from cesarean sections, uterine curettage, or endometritis facilitates the invasion of the basal endometrium into the myometrium, disrupting the junctional zone [3]. The alternative theory attributes adenomyosis to metaplasia of embryonic Müllerian remnants. Adenomyosis can present in diffuse or focal forms, often leading to chronic inflammation and fibrosis, which increase susceptibility to infection [4]. Clinically, about one-third of patients are asymptomatic, while others experience heavy menstrual bleeding, pelvic pain, or infertility [5 , 6]. Treatment primarily targets symptom relief, with pharmacological therapies being first-line options. Refractory cases may require uterine artery embolization or hysterectomy [1 , 7]. Diagnosis is based on clinical symp - toms, transvaginal ultrasound, and pelvic magnetic resonance imaging (MRI); however, the variability in presentations * Zhongna Yu, [email protected] | 1Department of Obstetrics and Gynecology, The Affiliated People’s Hospital of NingBo University, 251 Baizhang East Road, Ningbo 315040, Zhejiang, People’s Republic of China. Vol:.(1234567890) Case Report Discover Medicine (2025) 2:168 | https://doi.org/10.1007/s44337-025-00370-1 often complicates preoperative diagnosis [8]. Microabscess formation and sepsis in the context of adenomyosis are rare complications, with only a few cases documented [9 , 10]. This report details a unique case of an intermuscular abscess and sepsis caused by adenomyosis, presenting with acute abdominal pain and high fever. 2 Case A 34-year-old woman presented with a 13-year history of secondary dysmenorrhea, along with acute lower abdominal pain for 3 days and fever for 2 days. Her medical history included a previous cesarean section, pelvic inflammatory disease, severe dysmenorrhea, and 2 years of infertility. Initial laboratory tests at another hospital revealed a white blood cell (WBC) count of 18.2 × 10⁹/L, hemoglobin (Hb) level of 76 g/L, and C-reactive protein (CRP) concentration of 2 mg/L. Due to recurrent chills, high fever, and persistent abdominal pain, she was admitted to our hospital via the emergency depart- ment. On admission, her vital signs were as follows: temperature 39.2  ℃, pulse rate 118/min, respiratory rate 19/min, and blood pressure 127/75 mmHg. Gynecological examination showed no vulvar abnormalities. The vaginal canal and fornices were intact, and the cervix appeared normal. Notably, there was marked cervical motion tenderness. The uterus was anteverted and enlarged, measuring approximately equivalent to a 10-week gestation, with significant tenderness on palpation. No adnexal masses were detected, and there were no signs of peritoneal irritation. Laboratory findings at our hospital showed a WBC count of 12.5 × 10⁹/L, CRP level of 90.38 mg/L, Hb concentration of 82 g/L, and procalcitonin (PCT) level of 0.43 ng/mL. Chest computed tomography (CT) findings were unremarkable. A three-dimensional trans- vaginal ultrasonography (TVUS) revealed a uterus measuring approximately 100 × 97 × 105 mm with irregular myometrial echotexture and endometrial thickening, but no apparent abnormalities in the bilateral adnexal regions. To provide a clear overview of the patient’s clinical course, Table  1 outlines the timing of key symptoms, diagnostic investigations, and therapeutic interventions from symptom onset through postoperative follow-up. Based on the clinical presentation, laboratory findings, and gynecological history, the preliminary diagnoses included pelvic inflammatory disease (PID), adenomyosis, and moderate anemia. Upon admission, the patient was initiated on a combination of piperacillin sodium-tazobactam and metronidazole (4.5 g + 0.5 g every 8 h) for antimicrobial treatment. Supportive care included the intravenous administration of potassium chloride (3.0 g) and vitamin C (2 g) for rehydration, along with indomethacin (100 mg) for antipyresis and analgesia. However, within 24 h, the patient’s body temperature escalated to 40.9 °C, accompanied by persistent chills and unrelieved abdominal pain. Blood cultures (aerobic and anaerobic) revealed the presence of Escherichia coli, while laboratory tests showed WBC 12.8 × 10⁹/L, CRP 81.31 mg/L, Hb 70 g/L, and PCT 0.43 ng/mL. In light of the uncontrolled infection, consultation with the infectious disease depart - ment led to an escalation of antibiotic treatment through the administration of meropenem (1 g every 8 h). Concurrent transvaginal 3D ultrasound revealed uterine enlargement and adenomyosis, with pelvic MRI confirming adenomyosis of the uterus. After 3 days of intensive antimicrobial therapy, the patient’s fever persisted, with daily spikes exceeding 40 ℃, and abdominal pain remained unresolved. To further assess the source of infection, contrast-enhanced ultrasound (CEUS) was performed on hospital day 4. The CEUS revealed a hyperechoic area in the posterior uterine wall with irregular internal perfusion, suggestive of a localized abscess within adenomyotic tissue (Fig. 1). Based on these findings, surgical intervention was strongly recommended; however, the patient initially declined. Consequently, the infectious diseases team recommended continuing meropenem therapy along with supportive care, including rehydration, analgesics, and antipyretics. After 10 days of antimicrobial therapy, the patient’s body temperature normalized, and her abdominal pain had subsided. However, follow-up blood tests revealed a WBC count of 15.5 × 10⁹/L, a CRP level of 20.51 mg/L, an Hb level of 79 g/L, and a PCT level of 0.24 ng/mL. Repeated transvaginal ultrasound imaging suggested adenomyosis with abscess formation (Fig. 2). Eventually, the patient consented to surgery. A laparoscopic total hysterectomy was performed under general anesthesia. Intraoperative findings included a focal abscess and necrosis measuring 1.5 × 1.0 × 0.3 cm between the uterine muscle walls (Fig. 3). Cultures of the necrotic tissue confirmed the presence of E. coli. Histopathological analysis of the excised uterus revealed extensive neutrophilic infiltration within the myometrium, formation of microabscesses, focal necrosis, and ectopic endometrial glands and stroma consistent with adenomyosis (Fig.  4A, B). These findings confirmed the diagnosis of adenomyosis complicated by localized abscess formation and sepsis. Postoperatively, the patient received intravenous cefmetazole (2.0 g every 12 h) for infection prophylaxis and recovery support. She reported no significant abdominal pain, and her temperature stabilized. The surgical incision healed without complication. On the first postoperative day, her WBC was 10.1 × 10⁹/L and CRP was 35 mg/L. By postoperative day 3, inflammatory markers continued to decline (WBC 7.1 × 10⁹/L, CRP 29 mg/L, Hb 113 g/L). At the 2-week follow-up visit, Vol.:(0123456789) Discover Medicine (2025) 2:168 | https://doi.org/10.1007/s44337-025-00370-1 Case Report Table 1 Timeline of clinical events, diagnostic evaluations, and interventions Time point Clinical features and findings Diagnostic evaluations Interventions 3 days before admission Onset of acute lower abdominal pain – – 2 days before admission Onset of high fever (up to 39 °C) with chills WBC 18.2 × 10⁹/L, CRP 2 mg/L Symptomatic analgesic therapy (external hospital) Day of admission Persistent fever (39.2 °C), worsening abdominal pain Repeat labs: WBC 12.5 × 10⁹/L, CRP 90.38 mg/L, PCT 0.43 ng/mL; TVUS: uterine enlargement Admitted via emergency department; initiated piperacillin-tazobactam Hospital days 1–3 Fever peaked at 40.9 °C; persistent pain; clinical suspicion of sepsis Blood cultures (aerobic and anaerobic): E. coli posi- tive; MRI and TVUS inconclusive Escalated to meropenem; supportive care Hospital day 4 No clinical improvement; ongoing fever and pain CEUS: hyperechoic lesion in posterior uterine wall with reduced perfusion, suggestive of abscess Surgical intervention recommended; initially declined Hospital day 10 Partial symptom relief; inflammatory markers remained elevated Repeat TVUS confirmed intrauterine abscess Patient consented to surgery Hospital day 11 (operation) Partial symptom relief; inflammatory markers remained elevated Laparoscopy confirmed intrauterine abscess; histo- pathology and cultures confirmed E. coli Total laparoscopic hysterectomy Postoperative days 1–3 Afebrile; symptoms resolved WBC and CRP gradually normalized Prophylactic antibiotics (cefmetazole) 2 weeks post-op Full recovery; no recurrence of symptoms Gynecological follow-up confirmed satisfactory healing – Vol:.(1234567890) Case Report Discover Medicine (2025) 2:168 | https://doi.org/10.1007/s44337-025-00370-1 the patient remained asymptomatic, and gynecological examination confirmed proper healing of the vaginal stump, indicating a favorable postoperative course. 3 Discussion Adenomyosis manifests with diverse clinical symptoms, and its diagnosis can be challenging, especially in the pres - ence of concurrent pelvic conditions such as leiomyomas, endometrial polyps, endometrial hyperplasia, or endometrial carcinoma [11]. For example, Rezzan Erguvan described a case involving a 54-year-old postmenopausal woman who presented with groin pain, night sweats, and hot flashes. Imaging revealed a 95 × 85 mm leiomyomatous lesion, com- prising a 53 × 43 mm cystic mass and a 9 × 6 mm intrauterine papillary formation, initially suspected to be malignant. Fig. 1 Abscess formation in the posterior uterine wall. Contrast ultrasound of the uterus showing an uneven 85 × 80 × 82 mm area in the posterior uterine wall, with unclear boundaries and uneven internal echoes. Multiple small dark areas were observed, the largest of which was irregularly shaped and measured approximately 19 × 20 × 19 mm. The white arrow indicates an abscess and the red arrow indicates adenomyosis Fig. 2 Uterine enlargement with abscesses (Transvaginal 3D ultrasound). Transvagi- nal 3D ultrasound images showing that the size of the uterine body was about 102 × 91 × 97 mm, the echo distribution of the posterior wall muscle of the uterus was uneven, the boundary was unclear, and two irregular dark areas were visible inside, the larger of which was irregularly shaped and measured approx- imately 14 × 11 × 16 mm Vol.:(0123456789) Discover Medicine (2025) 2:168 | https://doi.org/10.1007/s44337-025-00370-1 Case Report However, intraoperative frozen section analysis confirmed adenomyosis with abscess formation [3 ]. Advances in diag- nostic techniques have increased the detection of adenomyosis, with transvaginal ultrasound (TVUS) and magnetic resonance imaging (MRI) being the primary imaging modalities [4]. MRI has demonstrated a sensitivity of 70–93% and a specificity of 86–93% for the diagnosis of adenomyosis [12], making it instrumental in confirming diagnoses, assessing disease extent, and identifying concurrent uterine lesions [12, 13]. The diagnosis of adenomyosis on MRI primarily relies on the presence of junctional zone thickening (≥ 12 mm) on T2-weighted images, along with high-signal lesions in the myometrium. Additional indicators include poorly defined junctional zone borders, high-signal lesions on T1-weighted images, and high-signal linear stripes [14, 15]. However, MRI’s limitations include its high cost, longer examination times, and sensitivity to the patient’s menstrual cycle [16]. Furthermore, false-positive or false-negative results can occur, neces- sitating the interpretation of imaging by trained professionals. Transvaginal ultrasound (TVS) offers several advantages in diagnosing adenomyosis, including ease of use, rapid execution, lack of radiation exposure, and suitability for outpatient or bedside assessments. TVS effectively visualizes uterine structures, aiding in the initial screening for lesions. Diagnostic criteria for adenomyosis on TVS include a spherical uterine shape, myometrial asymmetry, uneven myometrial echo patterns, poorly defined boundaries, and the presence of endometrial cysts [9 , 17, 18]. However, TVS is less effective in detecting mild or early-stage adenomyosis and as a means of identifying deep or localized lesions, potentially leading to false negatives or missed diagnoses [15, 19]. Although transvaginal ultrasound and pelvic MRI are the main imaging modalities for diagnosing adenomyosis and its complications, chest CT was used in this case as an adjunct investiga- tion. Given the patient’s systemic symptoms including persistent high fever and chills chest CT was necessary to rule out alternative infectious foci such as pneumonia or septic emboli. The absence of pulmonary findings helped confirm a localized uterine source of infection. In this case, both TVS and MRI failed to provide a definitive diagnosis, which could be attributed to several factors. First, focal uterine adenomyosis and abscesses can be difficult to differentiate and are often confused. Second, small adenomyotic lesions, particularly those deep within the myometrium or obscured by surrounding tissues, may escape detection. Third, technical factors such as operator expertise and equipment quality can affect ultrasound results, while MRI outcomes may depend on scanning parameters and image quality. Finally, understanding of uterine adenomyosis complicated by abscesses and sepsis remains limited. Additional diagnostic modalities can aid in identifying adenomyosis with abscesses. En-Tzu Wu reported a case of a 49-year-old woman with a long-standing history of adenomyosis who developed an unexplained fever lasting 3 weeks. 67 Ga SPECT/CT demonstrated increased tracer uptake in the myome - trium, and hysterectomy confirmed adenomyosis with abscess formation [20]. Similarly, Ka Wang Cheung described a 49-year-old nulliparous woman with adenomyosis and type 2 diabetes who presented with fever and lower abdominal pain. CT imaging revealed multiple marginally enhanced low-density collections in the uterus, consistent with uterine Fig. 3 Postoperative purulent secretions in the uterine wall (Intraoperative Image). Purulent secretions (red arrow) were observed in the posterior wall muscle layer of the uterus (white arrow) after the operation Vol:.(1234567890) Case Report Discover Medicine (2025) 2:168 | https://doi.org/10.1007/s44337-025-00370-1 abscesses. Intraoperative findings confirmed pyoadenomyosis, with histological examination verifying uterine adeno - myosis complicated by abscess formation [21]. Contrast-enhanced ultrasound (CEUS) is a diagnostic imaging technique that uses intravenous microbubble contrast agents to enhance ultrasound images. This technique improves contrast resolution by amplifying the acoustic impedance difference between blood flow and surrounding tissues, enabling differentiation between diseased and normal tissue. CEUS has been widely studied for evaluating blood perfusion in parenchymal organs such as the liver and kidneys, and its use in gynecology has focused on diagnosing uterine lesions. CEUS can reveal endometrial microcirculation charac - teristics and assess lesion infiltration depth into the myometrium [22]. Studies have shown that contrast enhancement patterns in adenomyomas often progress from the periphery toward the center, without surrounding blood flow [23]. Abulafia et al. [24] demonstrated that patients with myometrial infiltration exhibited higher microvascular densities in their tumors compared to those without myometrial involvement, providing a pathological foundation for evaluating lesion depth via CEUS. Despite these advancements, the diagnosis of uterine adenomyosis with intermuscular abscesses remains rare. In this case, CEUS facilitated a definitive diagnosis, providing clinically valuable insight. CEUS should be considered when MRI and TVS yield inconclusive results. Microabscess formation in uterine adenomyosis complicated by sepsis often involves mixed infections of anaerobic bacteria, aerobic bacteria, and Chlamydia. Studies reporting bacterial cultures from uterine abscesses detect Staphy- lococcus epidermidis and E. coli in 20–30% of cases, with Chlamydia detected in 4.1–25.3% of cases. This condition is extremely rare and may result from cesarean sections, endometritis, or compromised immunity leading to uterine abscess Fig. 4 A Histopathological features: neutrophilic infiltra- tion and abscess formation. A Red arrow: Extensive neutro- phil infiltration; Green arrow: Abscess; Blue arrow: Necrotic lesion; Yellow arrow: Necrotic Myometrium; B Histopatho- logical features: endometrial glands and myometrium. Orange arrow: Myometrium; Black arrow: Endometrial glands and interstitium Vol.:(0123456789) Discover Medicine (2025) 2:168 | https://doi.org/10.1007/s44337-025-00370-1 Case Report formation. Additional contributing factors include inadequate drainage of uterine inflammatory secretions, untreated chronic pyosis, and adenomyosis invading the uterine muscle wall. Abscess rupture can result in peritonitis or sepsis, posing significant risks to the patient. 4 Conclusion This case illustrates that microabscess within adenomyosis combined with sepsis, although rare, can occur as severe complications of uterine adenomyosis. Persistent fever and abdominal pain unresponsive to antibiotic therapy should prompt reconsideration of the diagnosis, even when initial imaging findings are inconclusive. The integration of CEUS with conventional imaging modalities can improve detection of occult intrauterine infection. When conservative treat - ment fails, timely surgical intervention is essential to achieve definitive diagnosis and prevent progression to systemic infection.

We would like to thank MogoEdit (https:// www. mogoe dit. com) for its English editing during the preparation of this manuscript. Author contributions Zhongna Yu: Conceptualization, Data curation, Formal analysis, Writing—original draft, Visualization. Mengyu Zheng: Writing—review & editing, Supervision, Project administration. Funding No funding was received for this work from any governmental, private, or non-profit entities. Data availability Declaration Availability of Data and Materials The data supporting the findings of this study are available from the corre - sponding author upon reasonable request. However, due to patient confidentiality and institutional policies, access requires prior approval from the Ethics Committee of The Affiliated People’s Hospital of Ningbo University. Ethical Approval and Consent to Participate The study was approved by Institutional Review Member of the board of directors of The Affiliated People’s Hospital of NingBo University Implemented in accordance with the Declaration of Helsinki. The reference number for ethical approval is 2025-N-004. Written informed consent for publica- tion of the case details and any accompanying images was obtained from the patient prior to manuscript submission. Declarations Ethics approval and consent to participate The study was approved by Institutional Review Member of the board of directors of The Affiliated People’s Hospital of NingBo University Implemented in accordance with the Declaration of Helsinki. The reference number for ethical approval is 2025-N-004. Written informed consent for publication of the case details and any accompanying images was obtained from the patient prior to manuscript submission. Consent for publication Written informed consent for publication of this case report and any accompanying images was obtained from the patient. The patient has reviewed the manuscript and understands that all identifying details have been anonymized to ensure confidentiality. Competing interests The authors declare no competing interests. Open Access This article is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License, which permits any non-commercial use, sharing, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if you modified the licensed material. You do not have permission under this licence to share adapted material derived from this article or parts of it. The images or other third party

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