{"paper_id":"a13d0350-5faa-4a36-95a3-b61a345a31e1","body_text":"Imaging in Abnormal Uterine Bleeding: Key\nInsights for Enhancing Radiologists ’ Expertise\nRupa Renganathan 1 Prema Subramaniam 1 Suganya Palanisamy 1 Divya Vishwanatha Kini 2\n1 Division of Breast and Women ’s Imaging, Department of Diagnostic\nand Interventional Radiology, Kovai Medical Center and Hospitals\nLimited, Coimbatore, Tamil Nadu, India\n2 Department of Diagnostic and Interventional Radiology, Kovai\nMedical Center and Hospitals Limited, Coimbatore, Tamil Nadu,\nIndia\nJ Gastrointestinal Abdominal Radiol ISGAR 2026;9:54 –68.\nAddress for correspondence Rupa Renganathan, DMRD, DNB, FRCR,\nEBBI, Division of Breast and Women ’s Imaging, Department of\nDiagnostic and Interventional Radiology, Kovai Medical Center and\nHospitals Limited, Coimbatore, Tamil Nadu, PIN: 641014, India\n(e-mail: drrrupa@gmail.com).\nIntroduction\nAbnormal uterine bleeding (AUB) is a comprehensive term\nthat encompasses nongestational abnormal bleeding from\nthe uterus in women of reproductive age. AUB is character-\nized by irregularities in the duration, volume, frequency,\nand/or regularity of uterine bleeding. Additionally, it\nincludes postmenopausal bleeding, de fined as any bleeding\noccurring after menopause in women who are not receiving\nhormonal therapy, as well as unscheduled or excessive\nbleeding in those undergoing hormonal therapy.\n1\nResearch indicates that approximately one-third of wom-\nen will experience symptoms associated with AUB at some\nstage in their lives. This condition is most frequently ob-\nserved in women during menarche and the perimenopausal\nphase.2 Notably, up to 50% of affected women do not pursue\nmedical evaluation.\nIn 2007, the International Federation of Gynecology and\nObstetrics (FIGO) Menstrual Disorders Working Group estab-\nlished standardized terminology and de finitions for various\ntypes of AUB (referred to as AUB system 1). The subsequent\nclassification of the causes of AUB was undertaken in 2011\nusing the PALM-COEIN classi fication system (designated as\nAUB system 2).\n1,3 This initiative replaced previously\nemployed, poorly de fined, and often confusing terms such\nas menorrhagia, metrorrhagia, and dysfunctional uterine\nKeywords\n► abnormal uterine\nbleeding\n► PALM COEIN\nclassification\n► structural and\nnonstructural causes\nof abnormal uterine\nbleeding\nAbstract Abnormal uterine bleeding (AUB) is a commo n gynecological symptom experienced by\napproximately one-third of women at some point in their lives. There are various\nterminologies used to describe the symptoms of AUB, which can lead to inconsistency\nin interpretation. To address this, the International Federation of Gynecology and\nObstetrics (FIGO) Menstrual Disorders Working Group established standardized termi-\nnology and de finitions for different types of AUB in 2007. AUB can have both structural\nand nonstructural causes, and it is possible for more than one cause to coexist in a\nsingle patient. To categorize and evaluate the causes of AUB consistently, FIGO de fined\nac l a s s ification system in 2011 known as the AUB system 2. This system is referred to by\nthe acronym PALM-COEIN. “PALM” stands for the structural causes: Polyp (P),\nAdenomyosis (A), Leiomyoma (L), and Malignancy and hyperplasia (M). “COEIN”\nrepresents the nonstructural causes: Coagulopathy (C), Ovulatory dysfunction (O),\nEndometrial causes (E), Iatrogenic factors (I), and causes that are Not yet classi fied (N).\nIn this article, we review the standardized de finitions and terminologies used to\nd e s c r i b et h es y m p t o m so fA U Ba n dd i s c u s st h er o l eo fi m a g i n ga n da p p r o a c hi n\nidentifying and classifying its causes.\narticle published online\nJanuary 15, 2026\nDOI https://doi.org/\n10.1055/s-0045-1815710.\nISSN 2581-9933.\n© 2026. The Author(s).\nThis is an open access article published by Thieme under the terms of the\nCreative Commons Attribution License, permitting unrestricted use,\ndistribution, and reproduction so long as the original work is properly cited.\n(https://creativecommons.org/licenses/by/4.0/)\nThieme Medical and Scienti fic Publishers Pvt. Ltd., A-12, 2nd Floor,\nSector 2, Noida-201301 UP , India\nReview Article\nTHIEME\n54\nArticle published online: 2026-01-15\n\nbleeding. An update to these classi fication systems was\npublished in 2018.\nMoreover, FIGO published recommended terminologies\nand de finitions concerning myometrial abnormalities in\n2015, followed by updates in 2021 through the Morphologi-\ncal Uterus Sonographic Assessment (MUSA) classi fication\nsystem.4,5 Furthermore, the FIGO ovulatory disorders classi-\nfication system was introduced in 2022. 6 This review aims to\nelucidate the causes of AUB, their associated imaging fea-\ntures, and the differential diagnoses relevant to this\ncondition.\nDefinition and Terminologies\n(AUB System 1)\nA normal menstrual cycle is characterized by a frequency\nranging from 24 to 38 days, 4.5 to 8 days, and a blood flow\nmeasuring between 5 and 80 mL. Additionally, the cycle\nlength may vary by 2 to 20 days over 12 months. Deviations\nfrom these established parameters are classi fied as AUB. 1\n►Table 1 delineates the accepted de finitions and termi-\nnology about various types of AUB, while ►Table 2 provides a\ncomprehensive overview of the acceptable abbreviations and\ntheir corresponding de finitions.\nAUB can be categorized into two types: acute and chronic.\nAcute AUB is de fined as a sudden episode of bleeding in a\nnonpregnant woman that requ ires immediate medical in-\ntervention to avert further blood loss. In contrast, chronic\nAUB is characterized by abnormal bleeding from the uterine\ncorpus that deviates from normal duration, volume, or\nfrequency for the majority of the preceding 6 months.\nAUB System 2\nThe AUB system 1 addresses the inconsistencies in terminol-\nogy utilized to describe AUB. Nevertheless, discrepancies\nremain in the investigation and categorization of the causes\nof AUB, with several of these causes potentially coexisting in\na single individual. In response to this issue, the FIGO has\nintroduced the PALM-COEIN classi fication system.\nPALM-COEIN is an acronym that categorizes the etiologies\nof AUB into two primary groups: structural and nonstruc -\ntural. The “PALM” category encompasses structural causes\nthat can be identi fied through imaging or histopathological\nexamination: Polyp (P), Adenomyosis (A), Leiomyoma (L),\nand Malignancy and hyperplasia (M). The “COEIN” category\ncomprises nonstructural causes, which include Coagulop-\nathy (C), Ovulatory dysfunction (O), Endometrial causes (E),\nTable 1 Summary of terminologies and de fin i t i o n so fv a r i o u st y p e so fA U B\nParameters of the menstrual cycle and menstruation Descriptive terms Definitions\nFrequency of cycle (d) Frequent < 24\nNormal 24 –38\nInfrequent > 38\nRegularity of cycles - Variation over 12 months Absent/amenorrhea No bleeding in 90 days\nRegular Variation: /C62 to 20 days\nIrregular Variation > 20 days\nDuration of flow (d) Prolonged > 8\nNormal 4.5 –8\nShortened < 4.5\nVolume of blood loss (mL) Heavy > 80\nNormal 5 –80\nLight < 5\nAbbreviation: AUB, abnormal uterine bleeding.\nTable 2 Acceptable abbreviations describing menstrual symptoms\nAbbreviation Expansion Definition\nAUB Abnormal uterine bleeding Any deviation in menstrual flow/cycle\nHMB Heavy menstrual bleeding Excessive menstrual blood loss that interferes with the physical,\nemotional, social, and material quality of life\nHPMB Heavy, prolonged menstrual\nbleeding\nE x c e s s i v eb l o o dl o s sa l o n gw i t hp r o l o n g e db l e e d i n gf o r> 8 days\nIMP Intermenstrual bleeding Irregular episodes of bleeding occurring between otherwise normal\nmenstrual cycles\nPMB Postmenopausal bleeding Bleeding occurring > 1 year after the acknowledged menopause\nJournal of Gastrointestinal and Abdominal Radi ology ISGAR Vol. 9 No. 1/2026 © 2026. The Author(s).\nImaging in Abnormal Uterine Bleeding Renganathan et al. 55\n\n\nIatrogenic factors (I), and causes that are Not yet classi fied\n(N).\nThis classi fication system has been developed with con-\ntributions from clinicians and researchers across 6 conti-\nnents and over 17 countries. It facilitates a systematic\napproach to diagnosis, thereby enhancing clinical communi-\ncation, research methodologies, and treatment strategies for\nAUB.\nEndometrial Polyp: AUB-P\nEndometrial polyps form when endometrial glands and\nstroma excessively grow within the endometrium. Endome-\ntrial polyps are primarily composed of epithelial tissue on\nthe surface and have a predominantly vascular core. These\npolyps can be classified into three categories: sessile, pedun-\nculated, or prolapsing. A prolapsed polyp may exhibit areas\nof squamous metaplasia, infection, or ulceration.\n7\nThese polyps can range from a few millimeters to several\ncentimeters in diameter and may appear as single or multiple\ngrowths. Endometrial polyps can occur at any age but are\nmost found between the ages of 40 and 49. Patients with\nendometrial polyps may either be asymptomatic or present\nwith AUB, which is the most common symptom. The preva-\nlence of endometrial polyps in reproductive-aged women\nexperiencing AUB is estimated to be between 20 and 40%.\n8\nThe most common patterns include menorrhagia and inter-\nmenstrual bleeding (IMB). The other symptoms are abdomi-\nnal or pelvic pain and infertility. The location of the polyp,\nnumber, and diameter do not correlate with the reported\nsymptoms.\n9\nChronic use of tamoxifen has been linked to the develop-\nment of endometrial polyps, with an incidence rate ranging\nfrom 20 to 35%.\n10 Additionally, hormone replacement thera-\npy for menopausal symptoms may also contribute to the\nformation of endometrial polyps. Symptoms can include\nirregular bleeding and a thickened endometrium on ultra-\nsound (US). 11\nWhile most polyps are typically benign, there is a small\nrisk of them becoming malignant. 12 Malignant changes in\nendometrial polyps are associated with the patient ’s age,\nparticularly in those over 60, and their menopausal status,\nespecially in postmenopausal women. The other risk factors\nfor malignant endometrial polyps include the size of the\npolyps, the presence of symptomatic bleeding, and polycys-\ntic ovary syndrome (PCOS).\n13 The prevalence of malignant\nendometrial polyps is 4.47% in symptomatic postmenopaus-\nal females, compared to 1.51% in asymptomatic postmeno-\npausal females.\n14\nImaging\nTransvaginal US (TVS) represents the most utilized and\neffective technique for imaging pelvic structures. The find-\nings from US examinations may occasionally be nonspeci fic,\nrevealing either diffuse or localized echogenic thickening of\nthe endometrium. 15 In patients presenting with postmeno-\npausal bleeding, an endometrial thickness exceeding 4 mm is\nassociated with the potential for endometrial pathology,\nincluding the presence of polyps. 11\nSaline infusion sonography (SIS) is a better method for\nevaluating the lesions within the endometrial cavity. It\ninvolves instilling about 5 to 30 mL of warmed saline into\nthe cavity using a thin catheter during the proliferative phase\nof the menstrual cycle.\nEndometrial polyps are more effectively visualized utiliz-\ning SIS, as the introduced fluid delineates the polyps dis-\ntinctly. Moreover, SIS enhances the differentiation between\nsubmucosal fibroids and endometrial polyps by distinctly\nillustrating their respective positions within the endometrial\nlayer. Specifically, endometrial polyps are observed to arise\nfrom the endometrial layer, whereas submucosal fibroids are\npositioned beneath this layer.\n16\nThe contraindications for SIS include the presence of\nactive uterine or cervical infections, as well as pregnancy.\nFurthermore, SIS provides a superior evaluation of the\nadnexa and cornua in comparison to TVS.\nDuring the TVS/SIS procedure, the following details are\nnoted when the polyp is detected: the number and type of\nthe polyp, its site of attachment within the endometrial\ncavity, and the presence and pattern of internal vascularity.\nSubmucosal polypoidal adenomyoma can resemble an\nendometrial polyp; however, it often contains cysts of vary-\ning sizes. These cysts, along with the stroma, may exhibit\nareas of focal hemorrhage, resulting in dark brown material\nfilling the cystic spaces. On imaging, submucosal polypoidal\nadenomyoma typically shows cysts accompanied by myo-\nmetrial invasion.\n17\nIn contrast, endometrial polyps usually have a smooth,\nbosselated surface and tend to appear fibrous when viewed\nin cross-section. They often possess small cystic spaces that\nreflect the dilation of glandular elements, but they do not\nexhibit myometrial invasion ( ►Figs. 1 and 2).18\nWhile endometrial carcinoma can also show myometrial\ninvasion, it rarely contains cysts. Therefore, when both cysts\nand myometrial invasion are observed, submucosal poly-\npoidal adenomyoma should be considered. Magnetic reso-\nnance imaging (MRI) can help differentiate between these\nthree entities.\n18,19\nImaging thus plays a vital role in predicting the malignant\npotential of a polyp thereby guiding further management.\nAdenomyosis (AUB-A)\nAdenomyosis is a benign gynecological condition that pri-\nmarily affects multiparous women between the ages of 30\nand 50. While many individuals with this condition remain\nasymptomatic, it may present with symptoms such as AUB,\ndysmenorrhea, chronic pelvic pain, and dyspareunia.\n10\nThe prevalence of adenomyosis exhibits considerable\nvariation, ranging from 5 to 70%, depending on the diagnostic\nmethods employed, with an average prevalence estimated at\n20 to 30%. 20 The precise etiology of adenomyosis remains\nunclear; however, potential risk factors include hyperestro-\ngenism and a history of surgeries, such as cesarean sections\nand dilatation and curettage. The hallmark of adenomyosis is\nthe presence of ectopic endometrial glands and stroma\nwithin the myometrium, accompanied by hypertrophy and\nhyperplasia of the smooth muscle.\n21\nJournal of Gastrointestinal and Abdominal Radio logy ISGAR Vol. 9 No. 1/2026 © 2026. The Author(s).\nImaging in Abnormal Uterine Bleeding Renganathan et al.56\n\n\nImaging\nDiagnosis of adenomyosis typically involves various imaging\nmodalities, including TVS and MRI. TVS is generally the initial\nimaging technique utilized for evaluating patients present-\ning with AUB. The MUSA group has established a consensus\non the terminology to be used when documenting US find-\nings related to myometrial lesions. The US report should\nencompass the following features: the presence or absence of\nadenomyosis, its anatomical location, classi fication as focal\nor diffuse, cystic versus noncystic nature, involvement of\nuterine layers, and the extent and dimensions of the lesion.\nThe findings of adenomyosis can be categorized into\ndirect and indirect features.\n5 Direct features, observable\nthrough US imaging, are characteristic of adenomyosis,\nwhereas indirect features result from the presence of ectopic\nendometrium within the myometrium ( ►Fig. 3 ).\nThe direct US features indicative of adenomyosis include:\n Myometrial cysts\n Hyperechoic islands\n Echogenic subendometrial lines and buds\nThe indirect features may present as:\n A globular uterine shape\n Asymmetric thickening of the myometrium\n Fan-shaped shadowing\n Translesional vascularity\n An irregular and interrupted junctional zone (JZ)\nIt is crucial to note that in the absence of direct features,\nthe presence of indirect features alone does not provide\nconclusive evidence for the diagnosis of adenomyosis. Fur-\nthermore, a regular and uninterrupted JZ is a reliable indica-\ntor of the absence of this condition.\n22 ►Table 3 shows the\nclassification and reporting guidelines for adenomyosis.\nMRI, due to its superior soft tissue resolution, facilitates\nthe differentiation between adenomyosis and leiomyomas,\nas well as other uterine pathologies. The sequences most\ncommonly employed include T2-weighted imaging in axial,\ncoronal, and sagittal planes, along with T1-weighted imaging\nin axial and sagittal planes. It is pertinent to note that the use\nof contrast MRI does not yield any additional diagnostic\ninformation for adenomyosis.\nRecently, a classification system for MRI findings has been\nproposed by Kobayashi and Matsubara,\n23 which encom-\npasses five distinct parameters:\n1. Affected area: This parameter differentiates between\ninternal myometrium (internal adenomyosis, which\ninvolves the inner one-third of the uterine wall) and\nexternal myometrium (external adenomyosis).\n2. Pattern: Adenomyosis is categorized as either diffuse or\nfocal.\nFig. 1 Transvaginal ultrasound ( A) and sonohysterosalpingography ( B) images demonstrate a solitary, homogeneously hyperechoic intra-\ncavitary lesion with smooth outline arising from the posterior wall with preserved endom yometrial junction(marked by white arrows in A and B).\nSonohysterosalpingography image of another patient ( C) shows similar lesion demonstrating single vessel with no branching (marked by black\narrow in C). These findings are consistent with endometrial polyp (abnormal uterine bleeding [AUB]-P).\nFig. 2 Transvaginal ultrasound ( A) and Doppler ( B) images demonstrate a solitary hyperechoic intracavitary lesion with regular cysts, color score of 2\nand preserved endomyometrial junction (marked by black arrow in A). T2 axial ( C) and postcontrast sagittal T1 fat-saturated ( D) magnetic resonance\nimaging (MRI) images show a well-de fined polypoidal lesion limited to the endometrial cavity with regular nonenhancing cystic areas within with\nmaintained subendometrial enhancement (marked by white arrow in C and black arrow in D) (abnormal uterine bleeding [AUB]-P).\nJournal of Gastrointestinal and Abdominal Radi ology ISGAR Vol. 9 No. 1/2026 © 2026. The Author(s).\nImaging in Abnormal Uterine Bleeding Renganathan et al. 57\n\n\n3. Size: This is classi fied into three volumetric categories:\nless than one-third, less than two-thirds, or more than\ntwo-thirds of the uterine wall.\n4. Location: The location is speci fied as anterior, posterior,\nleft-lateral, right-lateral, or fundal.\n5. Presence of concomitant pathologies: This includes the\nabsence of additional conditions, peritoneal endo-\nmetriosis, ovarian endometrioma, deep in filtrating\nendometriosis (DIE), uterine fibroids, or other relevant\npathologies.\nInternal adenomyosis is further subdivided into three\ntypes: focal, diffuse, and super ficial. The focal and diffuse\ntypes are associated with JZ hypertrophy, whereas the\nsuperficial type is not associated with JZ hypertrophy. Exter-\nnal adenomyosis involves the outer myometrium, extending\nFig. 3 (A and E) Transvaginal ultrasound image of a patient with pain during menstruation showing globular enlargement of the uterus with\nheterogeneous myometrial echoes, indistinct endomyometrial junction (black dotted line in A) with tiny myometrial cysts (black arrows in\nA and E), and hyperechogenic islands (white arrows in A and E), consistent with diffuse adenomyosis. Volume contrast image (VCI) in E better\ndepicts the findings. ( B) Transabdominal ultrasound image shows asymmetrical thickening of anterior myometrium (marked by white dotted\nlines in B) with heterogeneous myometrial echoes and hyperechogenic islands consistent with anterior wall adenomyosis. ( C and D) Transvaginal\nultrasound and Doppler images show an ill-de fined heterogeneous focal lesion with thin lines of posterior shadowing (marked by white stars in\n(C)a n d( D) and diffuse vascularity consistent with adenomyoma (abnormal uterine bleeding [AUB]-A).\nTable 3 Classification and reporting guideline for ultrasound features of adenomyosis\nCriteria Ultrasound features\nPresence or absence of adenomyosis Look for the direct and indirect features using the MUSA criteria\nLocation Anterior, posterior, right lateral, left lateral, and fundal\nDifferentiation Focal if > 25% of the circumference of the lesion is surrounded by normal\nmyometrium\nDiffuse if < 25% of the lesion is surrounded by normal myometrium\nMixed type if both focal and diffuse adenomyosis coexist\nPresence or absence of cysts Cystic - presence of cysts, which are anechoic or low-level echoes and surrounded by\nan echogenic rim\nNoncystic adenomyosis - absence of cysts\nUterine layer involvement Involvement of junctional zone (inner myometrium, Type 1), middle myometrium\n(Type 2), or outer myometrium (Type 3)\nExtent Mild ( < 25% affected), moderate (25 –50%), or severe ( > 50% affected).\nSize of lesion Measured and documented in the plane of the largest diameter of the largest lesion.\nIf more than 1 adenomyotic lesion is present in different locations, the sum of\nvolumes of different lesions should be taken into account to assess the total extent\nAbbreviation: MUSA, Morphological Uterus Sonographic Assessment.\nJournal of Gastrointestinal and Abdominal Radio logy ISGAR Vol. 9 No. 1/2026 © 2026. The Author(s).\nImaging in Abnormal Uterine Bleeding Renganathan et al.58\n\n\nto the serosa, while sparing the JZ. This form of adenomyosis\nis frequently observed in young nulliparous women and is\noften associated with deep pelvic endometriosis (DIE), mak-\ning it distinguishable from endometriotic deposits when DIE\ncoexists.\nOn MRI, the characteristic features of both internal and\nexternal adenomyosis manifest as ill-de fined areas of T2-\nweighted hypointensity, attributed to smooth muscle prolif-\neration, alongside multiple T2-weighted hyperintense foci.\nSmall cystic regions may also be present. In T1-weighted\nimaging, small areas of T1 hyperintensity may be observed\nwithin the adenomyotic regions, indicating the presence of\nhemorrhage.\n►Fig. 4 shows the MRI features of adenomyosis.\nAdenomyomas typically present as well-de fined, heteroge-\nneous lesions con fined within the myometrium, without\ninvolving the JZ or the serosa. 24\nLeiomyoma\nBenign fibromuscular tumors of the myometrium are often\nreferred to by various terms, including “fibroid,”“ leio-\nmyoma,” and “myoma.” According to the FIGO, the term\n“leiomyoma” is regarded as the most precise designation.\nLeiomyomas represent the most common benign tumors of\nthe uterus and are frequently asymptomatic. However, they\nmay contribute to AUB, particularly when located in a\nsubmucosal position.\n25\nImaging\nDiagnosis of leiomyomas typically occurs through the iden-\ntification of an enlarged uterus or pelvic mass during clinical\nexamination. The initial and preferred method of investiga-\ntion for diagnosing leiomyomas is US, which may be con-\nducted via transabdominal and/or transvaginal approaches.\nTVS is recognized for its increased sensitivity in detecting\nsmall leiomyomas or submucosal leiomyomas, especially in\npatients with obesity.\n26 Literature suggests that the sensi-\ntivity and speci ficity of US in the identi fication of fibroids\nexhibit considerable variability, ranging from 24 to 96% for\nsensitivity and from 29 to 93% for speci ficity. SIS has been\nshown to provide signi ficantly higher sensitivity (85 –91%)\nand specificity (83–100%) in detecting abnormalities such as\npolyps, submucosal fibroids, and adhesions. 26\nMRI is noted for its superior sensitivity (88 –93%) and\nspecificity (66–91%) in detecting fibroids and differentiating\nthem from focal adenomyosis. 26 Furthermore, MRI findings\nare reproducible and capable of accurately de fining the\nextent of fibroid degeneration.\nUS\nOn US, leiomyomas present as well-de fined solid masses\ncharacterized by a whorled appearance, posterior shadow-\ning, and circumferential vascularity. The MUSA consensus\nopinion describes the classical imaging features of fibroids\nand points to differentiate them from adenomyosis. 4\nThe US report should encompass the total uterine volume,\nthe number of leiomyomas, the volumes of up to four\nleiomyomas, and their speci fic locations as per the FIGO\nclassification. This classi fication delineates the relationships\nof the fibroids with the endometrium and serosa, as well as\nthe uterine wall (anterior, posterior, right or left lateral wall,\nor fundal region) and their vertical positioning (upper or\nlower uterine segment). The anatomical location of fibroids\nis a critical parameter in predicting bleeding symptoms, with\nsubmucosal fibroids demonstrating a greater association\nwith an increased risk of bleeding than their size.\nThe FIGO PALM-COIEN classi fication system for\nleiomyomas comprises primary, secondary, and tertiary\ncategorizations. The primary classi fication addresses the\npresence or absence of leiomyomas, irrespective of their\nnumber, size, or location. The secondary classi fication differ-\nentiates fibroids based on the presence or absence of sub-\nmucosal components, categorizing them as submucosal (SM)\nor other (O) leiomyomas. Furthermore, the tertiary classi fi-\ncation introduces additional categorizations for submucosal,\nFig. 4 T2 sagittal magnetic resonance imaging (MRI) image ( A) globular enlargement of the uterus with diffuse thickening of junctional zone\nwith multiple myometrial cysts (marked by white arrows in A) consistent with diffuse adenomyosis. T2 oblique axial MRI image ( B) of the uterus\nshows an ill-de fined T2 hypointense area with multiple tiny T2 hyperintense cysts within the posterior myometrium extending from the\njunctional zone (marked by white star in B) consistent with focal adenomyosis. T2 sagittal MRI image ( C) shows diffuse thickening of the\njunctional zone with subendometrial T2 hyperintense lines (marked by black arrow in C) involving the anterior wall consistent with adenomyosis\n(abnormal uterine bleeding [AUB]-A).\nJournal of Gastrointestinal and Abdominal Radi ology ISGAR Vol. 9 No. 1/2026 © 2026. The Author(s).\nImaging in Abnormal Uterine Bleeding Renganathan et al. 59\n\n\nintramural, subserosal, and transmural locations. 27 ►Fig. 5\nshows the US features of intramural, subserosal, and submu-\ncosal fibroids.\nApplying the FIGO classi fication in the imaging assess-\nment of leiomyomas enhances the correlation between\nclinical symptoms and imaging features, thereby improving\nconfidence in identifying the underlying etiology. The\nFIGO classi fication further helps in determining the appro-\npriate management for each subtype, guiding the choice\nbetween minimally invasive and surgical techniques.\n►Table 4 presents the FIGO classi fication of fibroids\naccording to their location. ►Fig. 6 shows the various FIGO\nclasses of fibroids.\nMRI\nMRI is indicated in cases where US findings are indetermi-\nnate or before the planning of uterus-sparing interventions\nsuch as myomectomy or uterine artery embolization, as it\nprovides accurate information regarding vascularity and the\nextent of degeneration. Furthermore, MRI is the imaging\nmodality of choice for follow-up assessments following\nuterus-sparing treatments.\n28\nTable 4 FIGO secondary and tertiary system of classi fication of leiomyomas\nSecondary system Tertiary system:\nFIGO class\nDefinition\nSM - Submucous 0 Pedunculated intracavitary with stalk diameter /C2010% of the mean diameter\nof leiomyoma\n1 Submucosal with < 50% intramural component\n2 Submucosal with /C2150% intramural component\n3 Contacts endometrium, 100% intramural\n0-O t h e r 4 I n t r a m u r a l\n5S u b s e r o s a l w i t h /C2150% intramural\n6S u b s e r o s a l w i t h < 50% intramural\n7 Pedunculated subserosal with stalk diameter /C2010% of the mean diameter of\nthe leiomyoma\n8 Other (e.g., cervical/ parasitic, etc.)\nHybrid - Contacts both\nthe endometrium\nand serosa\nTwo numbers\nseparated by\nah y p h e n\nE.g., 2 –5\nFirst number - relationship with the endometrium\nSecond number - relationship with serosa\n2–5: Submucosal and subserosal, each with < 50% submucosal and\nsubserosal components, respectively\nAbbreviation: FIGO, International Federation of Gynecology and Obstetrics.\nFig. 5 Transvaginal ultrasound image ( A) shows a well-circumscribed hypoechoic lesion within the myometrium —intramural International\nFederation of Gynecology and Obstetrics (FIGO) class 4 fibroid (white arrow) and similar lesion adjacent to serosa with < 50% myometrial\ncomponent —FIGO class 6 subserosal fibroid(black arrow) (abnormal uterine bleeding [AUB]-L O). Transvaginal ultrasound image ( B)s h o w saw e l l -\ndefined hypoechoic lesion in the anterior wall extending to the endometrial cavity with < 50% intramural component and disruption of\nendomyometrial junction (marked by white arrow) —FIGO class 1 submucosal fibroid (AUB-L SM).\nJournal of Gastrointestinal and Abdominal Radio logy ISGAR Vol. 9 No. 1/2026 © 2026. The Author(s).\nImaging in Abnormal Uterine Bleeding Renganathan et al.60\n\n\nIn MRI examinations, typical leiomyomas exhibit hypo-\nintensity on T2-weighted images, isointensity on T1-weight-\ned images, and demonstrate no diffusion restriction along\nwith heterogeneous postcontrast enhancement. In instances\nof degeneration, fibroids may present with heterogeneous\nsignals or increased signal intensity on T2-weighted images,\naccompanied by minimal or absent enhancement. Cellular\nleiomyomas are characterized by intermediate signal\nintensity on T2-weighted images, evidence of diffusion\nrestriction, and pronounced enhancement after contrast\nadministration.\nIn older women, the identi fication of recent or rapidly\nenlarging lesions, heterogeneous signal intensity with hem-\norrhagic or necrotic areas, diffusion restriction within the\nlesion, and signs of invasion into adjacent tissues should raise\nclinical suspicion for leiomyosarcoma.\n29\nEndometrial Malignancy/Hyperplasia (AUB-M)\nEndometrial hyperplasia is the abnormal proliferation of\nendometrial stroma and glands, which is representative\nof an entire spectrum of endometrial variation, ranging\nfrom mild atypical glandular proliferation to obvious\nneoplasia.\n30\nHyperplasia and neoplasms form an important compo-\nnent of the long list of etiologies of AUB, especially in women\nin the reproductive age group.\n30 The primary purpose of the\nPALM-COEIN system is to categorize the etiologies of AUB,\nand on further identi fication of speci fic etiologies, such as\nendometrial hyperplasia, classi fication according to the\nWorld Health Organization (WHO) classi fication systems\nmust be performed. 3\nThe classi fication of endometrial hyperplasia according\nto the revised WHO classi fication system, 2014, 3 is as\nfollows:\n(1) Hyperplasia without atypia\n(2) Atypical hyperplasia/endometrioid intraepithelial neop-\nlasia\nHyperplasia without atypia is a form of benign prolifera-\ntion that spontaneously regresses once the internal hormon-\nal stimulus is corrected. Only about 1 to 3% of the times do\nthese progress to invasive disease when there is uncontrolled\nprolonged exposure to the hormonal stimulus. On the other\nhand, atypical endometrial hyperplasias exhibit mutations\nwithin them that are characteristic of invasive malignancies.\nUnderstandably, close to 60% of these harbor concurrent\nFig. 6 (A) T2 axial magnetic resonance (MR) image shows multiple well-de fined predominantly T2 hypointense lesions (marked by white stars in\nA) in submucosal location with > 50% intramural component —International Federation of Gynecology and Obstetrics (FIGO) class 2 submucosal\nfibroids. ( B) T2 sagittal MR image shows a well-encapsulated T2 hypointense lesion within the posterior myometrium (marked by white star in B)\n—FIGO class 4 intramural fibroid. ( C) T2 sagittal MR image shows a similar posterior to the uterus with pedicle attached to the posterior wall of\nthe uterus (marked by white star in C)—FIGO class 7 pedunculated subserosal fibroid. ( D) T2 sagittal MR image shows a well-encapsulated\nheterogeneous lesion arising from the fundus of the uteru s with hyperintense areas within (marked by white star in D)—FIGO class 7\npedunculated subserosal fibroid with degeneration. ( E) T2 axial magnetic resonance imaging (MRI) image shows a well-de fined pedunculated\nintracavitary lesion with pedicle attached to left lateral wall (marked by white star in E)—FIGO class 0 submucosal fibroid (abnormal uterine\nbleeding [AUB]-L SM,O ).\nJournal of Gastrointestinal and Abdominal Radi ology ISGAR Vol. 9 No. 1/2026 © 2026. The Author(s).\nImaging in Abnormal Uterine Bleeding Renganathan et al. 61\n\n\nmalignancies or are at extremely high risk of developing\ninvasive cancers. 31\nThe fundamental etiology of these hyperplasias is a\nhormonal imbalance with unopposed estrogen stimulation\nand simultaneously inadequate progesterone levels. Some\nof the conditions which result in this underlying imbalance\nare polycystic ovarian syndrome, metabolic syndrome,\nnulliparity, tamoxifen therapy, corpus luteum insuf ficiency,\nLynch syndrome, or improper hormonal supplementa-\ntion in postmenopausal patients.\n32 Also, about one-\nthird of endometrial carcinomas are known to begin as\nhyperplasias.\n30\nAccordingly, management of hyperplasia without atypia\nis based on conservative measures with lifestyle modi fica-\ntions and oral contraceptives spearheading the management\nprotocol, with rare cases requiring preventive hysterectomy.\nContrarily, patients with atypical hyperplasia and endome-\ntrioid intraepithelial neoplasia are candidates for upfront\ntotal hysterectomy, with very rare indications for conserva-\ntive management.\n32\nCertain other nonendometrial etiologies are also known\nto present as AUB. One such is carcinoma of the cervix, which\nis usually seen in middle-aged women, usually with certain\nhigh-risk factors and known to commonly present as IMB or\npost-coital bleeding. There are also other malignancies, such\nas leiomyosarcoma (secondary malignant transformation of\nuterine fibroids), which are also known to present with AUB\nwith associated sudden interval increase in size of the\nfibroid.\n25\nImaging\nUltrasound\nUtilization of US has become an indispensable component of\nroutine gynecological assessment. 33 More so, when it comes\nto detailed evaluation of the uterus, especially the endome-\ntrium, higher resolution and a more dynamic and focused\nimaging is necessary with use of transvaginal sonography.\nThe endometrial thickness is the primary feature that\npoints to endometrial hyperplasia in the absence of an\nobvious lesion. The limit beyond which the endometrial\nthickness is considered pathological differs according to\nthe menstrual status and phase of the menstrual cycle as\ndetailed in\n►Fig. 7 .33–35\nA more streamlined US evaluation and interpretation\nalgorithm of the endometrium has been put forth with the\nuse of the consensus opinion from the International Endo-\nmetrial Tumor Analysis (IETA) group aiding in predicting the\nrisk of different endometrial pathologies.\n36 In addition to the\nquantification of the endometrial thickness, the following\nother aspects are also to be assessed:\n(1) Endometrial thickness\n(2) Echogenicity/uniformity\n(3) Midline\n(4) Outline\n(5) Color score\n(6) Vascular pattern\n(7) Endomyometrial junction\nMRI\nMRI is an extremely sensitive modality with excellent\nsoft tissue resolution that helps to better delineate the\nendometrium and the adjacent JZ. This is most bene ficial in\nthe assessment of malignancies and gauging the extent of\ndeeper uterine in filtration. The regular protocol consists of\nT2-weighted, T1-weighted, diffusion-weighted imaging,\nand dynamic postcontrast images with axial, coronal, and\nsagittal planes planned in line with the endometrial\nalignment.\n37\nThe uterine anatomy is best appreciated on a T2-weighted\nimage and is homogeneously T2 hyperintense, surrounded\nby a low-signal intensity JZ and intermediate-signal intensity\nmyometrium.\n37\nContrast enhancement is usually a relative assessment of\nthe myometrium, and myometrial enhancement usually\nvaries with the phase of the menstrual cycle. The postmeno-\npausal endometrium and myometrium are usually atrophic\nwith an indistinct JZ.\n37 A thickness of 4 mm with no focal\nchanges is usually considered normal for a postmenopausal\nwoman with a < 1% risk of development of cancer.\nFig. 7 Endometrial thickness in various age grou ps and various phases of menstrual cycle.\nJournal of Gastrointestinal and Abdominal Radio logy ISGAR Vol. 9 No. 1/2026 © 2026. The Author(s).\nImaging in Abnormal Uterine Bleeding Renganathan et al.62\n\n\nPreoperative pelvic MRI is known to have a moderate sensi-\ntivity and speci ficity in identifying invasion to the myome-\ntrium in endometrial cancer and a rather weak predictive\nvalue when used to assess the absence of myometrial inva-\nsion, thus guiding in triaging and managing endometrial\nneoplasia.\n38 ►Figs. 8 and 9 show the US and MRI of simple\nendometrial hyperplasia without atypia and endometrial\ncarcinoma, respectively. ►Table 5 summarizes the reporting\nchecklist for structural causes of AUB.\nCoagulopathy (AUB-C)\nThe term “coagulopathy” denotes a systemic disorder that\nimpairs hemostasis. It is estimated that approximately 13% of\nwomen who suffer from bleeding disorders exhibit\nFig. 8 Transvaginal ultrasound ( A) and magnetic resonance imaging (MRI) images ( B) show diffuse thickening of endometrium with preserved\nendomyometrial junction (marked by black arrows in A) and regular midline (marked by white arrow in B). Histopathology was simple\nendometrial hyperplasia without atypia (abnormal uterine bleeding [AUB]-M).\nFig. 9 Transvaginal ultrasound ( A and B) and Doppler images of a patient with postmenopausal bleeding showing an irregular isoechoic mass\nwithin the endometrial cavity (marked by white star in A and B) with indistinct endomyometrial juncti on in the posterior aspect (marked with\nblack arrows) with multifocal vascularity and a color score of 4 (marked by white arrows in C). Note the preserved endomy ometrial junction in the\nanterior aspect (marked by white arrows in B). T2 sagittal ( D) and postcontrast T1 fat-saturated magnetic resonance imaging (MRI) images ( E and\nF) show a heterogeneously enhancing mass within the endometrial cavity with myometrial invasion (marked by white arrows in D)a n d\ninterruption of subendometrial enhancement in the posterior aspect (marked by black arrows in E and F)—consistent with myometrial invasion\n(abnormal uterine bleeding [AUB]-M).\nJournal of Gastrointestinal and Abdominal Radi ology ISGAR Vol. 9 No. 1/2026 © 2026. The Author(s).\nImaging in Abnormal Uterine Bleeding Renganathan et al. 63\n\n\nmenorrhagia, with von Willebrand disease identi fied as the\nmost prevalent condition contributing to this phenome-\nnon.39 Furthermore, patients who are undergoing anticoag-\nulant therapy often present with AUB, particularly in the\nform of heavy menstrual bleeding (HMB). The frequency\nwith which these coagulopathies contribute to AUB in\nsymptomatic women remains uncertain. Nevertheless, it is\nimperative to take these conditions into account when\nassessing patients with AUB, particularly in the absence of\nunderlying pelvic pathologies.\n3\nOvulatory Disorders (AUB-O)\nOvulatory disorders represent a common etiology of AUB\nand arise from episodic or chronic dysfunction of the hypo-\nthalamic -pituitary-ovarian axis.40 These disorders are char-\nacterized by unpredictable menstrual bleeding patterns and\nvarying degrees of flow. The clinical manifestations can differ\nsignificantly, ranging from amenorrhea to infrequent or light\nbleeding, as well as episodes of unpredictable and excessive-\nly HMB that may necessitate medical intervention. In certain\ninstances, AUB associated with ovulatory disorders is attrib-\nuted to the absence of regular cyclic production of proges-\nterone from the corpus luteum due to anovulation, or\nirregular ovulations resulting from luteal out-of-phase follic -\nular events occurring in the later stages of reproductive\nyears.\n41\nDiagnosis of ovulatory disorders is often achievable\nthrough a comprehensive assessment of menstrual history\nand clinical presentation. Presenting symptoms may include\ndelayed menarche, infrequent or irregular menstruation,\nprimary or secondary infertility, and hirsutism. Additional\ndiagnostic methods for ovulatory disorders include the\nmeasurement of basal body temperature, the use of ovula-\ntion predictor kits to assess urine luteinizing hormone levels,\nand the evaluation of progesterone levels.\nUpon con firming the presence of an ovulatory disorder,\nthe subsequent step involves categorizing the disorder into\none of the four primary classi fications as delineated by\nthe FIGO classi fication system for ovulatory disorders.\nThe secondary classi fication re fines the identi fication of\nthe speci fic type of abnormality within a designated ana-\ntomical category, while the tertiary classi fication elucidates\nTable 5 Reporting checklist for structural causes of AUB\nPolyp (AUB-P) Dimension\nLocation\nNumber\nMorphology\nAdenomyosis (AUB-A) MUSA features - Direct and indirect features\nLocation (anterior/poster ior/lateral wall/fundal)\nDifferentiation - Focal/Diffuse/Mixed ( > 25% myometrium/ < 25%)\nCystic/noncystic\nUterine layer involvement (JZ/middle/outer myometrium)\nDisease extent (mild/moderate/severe)\nMeasurement of lesion size - The Largest dimension of the largest lesion\nLeiomyoma (AUB-L) Classi fication\nTotal uterine volume\nNo of leiomyoma (1/2/3/4/ > 4)\nVolume of up to 4 leiomyoma\nLocation – Ant/post/lat/central, vertical plane – upper/lower half/both\nEndometrial contact\nEndometrial malignancy/hyperplasia\n(AUB-M) - Based on International\nEndometrial Tumor Analysis (IETA)\nEndometrium:\nThickness\nEchogenicity/Uniformity\nMidline\nOutline\nColor score\nVascular pattern\nEMJ\nIntracavitary fluid:\nThickness and echogenicity\nIntracavitary lesion:\nTotal endometrial thickness and three dimensions\nExtent\nEchogenicity\nOutline\nColor score\nVascular pattern\nBright edge\nSynechiae\nAbbreviations: AUB, abnormal uterine bleeding; JZ, junctional zone; MUSA, Morphological Uterus Sonographic Assessment; EMJ, endo myometrial\njunction.\nJournal of Gastrointestinal and Abdominal Radio logy ISGAR Vol. 9 No. 1/2026 © 2026. The Author(s).\nImaging in Abnormal Uterine Bleeding Renganathan et al.64\n\n\nthe speci fic causative factors contributing to the ovulatory\ndisorder.6 ►Table 6 shows the FIGO ovulatory disorders\nclassification.\nUtilizing the modified Rotterdam criteria, the diagnosis of\nPCOS may be established if at least two of the following\ncriteria are met: (1) evidence of clinical or biochemical\nhyperandrogenism, (2) indications of oligoanovulation, and\n(3) observation of polycystic ovarian morphology via US,\nafter ruling out other relevant conditions. The US criteria for\ndiagnosing polycystic ovarian morphology include the pres-\nence of a minimum of 20 follicles per ovary and an ovarian\nvolume of at least 10 cm\n3. ►Fig. 10 shows polycystic ovarian\nmorphology in US. This diagnosis is typically made through\ntransvaginal ultrasonography employing a transducer fre-\nquency of 8 MHz or greater. 40 Usage of simple, easily avail-\nable, and cost-effective modality such as US in evaluation of\novulatory dysfunction helps in identifying the ovarian etiol-\nogy and thereby improves the clinical acumen.\nEndometrial (AUB-E)\nIn instances where identi fiable causes for AUB are not\napparent, local endometrial pathologies may be in fluencing\nendometrial hemostasis. The etiology typically involves hor-\nmonal imbalances within the uterus. A local de ficiency of\nvasoconstrictors, such as endothelin-1 and prostaglandin\nF2α, may result in excessive bleeding by promoting the\nproduction of plasminogen activators, which facilitate the\nlysis of blood clots.\n42 Concurrently, there tends to be an\nincreased synthesis of prostaglandin E2 and prostacyclin (I2),\nboth of which serve as potent vasodilators and possess\nantiplatelet aggregation properties.\n43\nIn addition to local hormonal disturbances, various con-\nditions may contribute to AUB, presenting as IMB or pro-\nlonged menstrual bleeding. These conditions may include\ninfections and in flammatory processes in the endometrium,\nsuch as chronic endometritis; however, the precise mecha-\nnisms underlying these conditions remain poorly under-\nstood.44 For women with normal ovulatory function, the\ndiagnosis of local endometrial pathology as a causative factor\nfor AUB is generally established through a process of exclu-\nsion, occurring only when no structural causes have been\nidentified.\nIatrogenic (AUB-I)\nIatrogenic factors contributing to AUB include intrauterine\ndevices (IUDs) and various medications. Breakthrough\nbleeding (BTB) refers to unscheduled bleeding during treat-\nment with gonadal steroids, such as estrogens and proges-\ntins, which are primarily used as contraceptives in oral,\ntransdermal, vaginal, or injectable forms. BTB often occurs\ndue to decreased levels of these steroids resulting from poor\nadherence to the medication regimen.\nAdditionally, certain medications, including tricyclic anti-\ndepressants and phenothiazines, can alter dopamine metab-\nolism by decreasing serotonin uptake, leading to reduced\ninhibition of prolactin release. This may result in anovulation\nand irregular vaginal bleeding.\n3\nCertain IUDs, particularly the levonorgestrel intrauterine\nsystem, may also induce unscheduled vaginal bleeding with-\nin the initial 3 to 6 months of use, potentially leading to\npremature removal of the device. 45\nNot Yet Classi fied (AUB-N)\nThe conditions categorized within this group include chronic\nendometritis, arteriovenous malformations, isthmocele\n(►Fig. 11 ), and myometrial hypertrophy. The role of these\nconditions in AUB remains inadequately de fined, necessitat-\ning their classification in this category. It is essential to gather\nFig. 10 Transvaginal ultrasound images of a patient with irregular cycles show enlarged right ( A)a n dl e f t(B) ovaries (marked by white stars in A\nand B,r e s p e c t i v e l y )w i t hv o l u m e> 10 mL, thickened stroma, and multiple small < 9 mm peripherally arranged follicles (abnormal uterine\nbleeding [AUB]-O, TYPE IV, polycystic ovary syndrome [PCOS]).\nTable 6 FIGO ovulatory disorders classi fication system\nPrimary classification Secondary classification\nType I:\nHypothalamic\nGenetic\nAutoimmune\nIatrogenic\nNeoplasm\nFunctional\nInfectious/In flammatory\nTrauma/Vascular\nPhysiological\nIdiopathic\nEndocrine\nType II:\nPituitary\nType III:\nOvarian\nType IV:\nPCOS\nDiagnosed and classi fied\nas recommended by the\nsinternational PCOS network\nAbbreviations: FIGO, International Federation of Gynecology and Ob-\nstetrics; PCOS, polycystic ovary syndrome.\nJournal of Gastrointestinal and Abdominal Radi ology ISGAR Vol. 9 No. 1/2026 © 2026. The Author(s).\nImaging in Abnormal Uterine Bleeding Renganathan et al. 65\n\n\nfurther evidence in the future to appropriately assign these\nconditions to a more accurate classi fication.3\n►Fig. 12 summarizes the clinical and imaging approach to\nAUB.\nConclusion\nStandard terminologies, de finitions, and structured imaging\nmethodologies are essential for the accurate identi fication of\nthe causes of AUB, facilitating effective management, enhancing\npatient outcomes, and supporting clinical research efforts. US\nrepresents the initial diagnostic modality of choice for patients\npresenting with AUB, owing to its widespread availability and\ncapability to assess the endometrium, myometrium, and ad-\nnexal structures. Additionally, sonohysterosalpingography can\nprovide further evaluation of the endometrial cavity and lining.\nMRI offers superior contrast for soft tissues, serving as a\nvaluable tool for complex problem-solving.\nThe role of imaging evaluation is pivotal in differentiating\nbetween structural and nonstructural etiologies of AUB.\nStructured reporting using PALM-COEIN with imaging\nchecklists ensures consistent communication with gynecol-\nogists and improves patient outcomes.\nFunding\nNone.\nConflict of Interest\nNone declared.\nReferences\n1 Fraser IS, Critchley HOD, Broder M, Munro MG. The FIGO recom-\nmendations on terminologies and de finitions for normal and\nabnormal uterine bleeding. Semin Reprod Med 2011;29(05):\n383–390\nFig. 12 Clinical and imaging approach to ab normal uterine bleeding (AUB).\nFig. 11 (A) Transvaginal ultrasound image of the uterus shows a myometrial d efect in the anterior wall of the lower uterine segment at the site\nof cesarean scar with clots within communicating with the endometrial cavity(black arrow) —consistent with isthmocele. T2 sagittal ( B)a n dT 1\nfat-saturated sagittal ( C) magnetic resonance (MR) images demonstrate the isthmocele with T1 and T2 hyperintense contents suggestive of clots\nwithin (black arrows in B and C) (abnormal uterine bleeding [AUB]-N).\nJournal of Gastrointestinal and Abdominal Radio logy ISGAR Vol. 9 No. 1/2026 © 2026. The Author(s).\nImaging in Abnormal Uterine Bleeding Renganathan et al.66\n\n\n2 Davis E, Sparzak PB. Abnormal Uterine Bleeding. January 21, 2025.\nIn: StatPearls [Internet]. Treasure Island, FL: StatPearls Publishing\nJanuary 2025. 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Cyclic changes in endometrial tissue plasminogen\nactivator and plasminogen activator inhibitor type 1 in women\nwith normal menstruation and essential menorrhagia. Am J\nObstet Gynecol 1994;171(01):178 –183\n43 Smith SK, Abel MH, Kelly RW, Baird DT. A role for prostacyclin\n(PGi2) in excessive menstrual bleeding. Lancet 1981;1\n(8219):522–524\n44 Pitsos M, Skurnick J, Heller D. Association of pathologic diagnoses\nwith clinical findings in chronic endometritis. J Reprod Med 2009;\n54(06):373–377\n45 Backman T, Huhtala S, Blom T, Luoto R, Rauramo I, Koskenvuo M.\nLength of use and symptoms associated with premature removal\nof the levonorgestrel intrauterine system: a nation-wide study of\n17,360 users. BJOG 2000;107(03):335 –339\nJournal of Gastrointestinal and Abdominal Radio logy ISGAR Vol. 9 No. 1/2026 © 2026. The Author(s).\nImaging in Abnormal Uterine Bleeding Renganathan et al.68","source_license":"CC0","license_restricted":false}