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Bulky Uterus : What’S Beyond Disclosure Fibroids? the Authors Have No Disclosure of Funding Received Shweta Bhatt, MD for This Work from Any Organizations

Bulky Uterus : What’S Beyond Disclosure Fibroids? the Authors Have No Disclosure of Funding Received Shweta Bhatt, MD for This Work from Any Organizations

3/28/21

Bulky : What’s beyond Disclosure fibroids? The authors have no disclosure of funding received Shweta Bhatt, MD for this work from any organizations. Professor of Radiology Mayo Clinic, Jacksonville, Florida

Introduction/Objectives Normal Physiologic Appearance of the Uterus Woman of childbearing age: • Average length x width = 8.0 x 5.0 cm • Menstrual phase: • Endometrial thickness < 4mm Introduction: • Ill-defined myometrium with poor definition of the junctional zone • The uterus is a dynamic organ that varies in appearance throughout a woman’s life. A • Proliferative phase: • Endometrial thickness 4-8 mm thorough understanding of its response to hormonal fluctuations and is • Well defined zonal anatomy of , junctional zone, and myometrium necessary for distinguishing between normal variation and abnormal enlargement. • Secretory phase: Additionally, a multitude of neoplastic processes can cause diffuse or focal enlargement, • Endometrial thickness 8-16 mm • making the diagnostic process quite challenging. Increasing thickness of the endometrium and myometrium with well defined zonal anatomy Postmenopausal woman: Objectives: • Average length x width = 5.0 x 2.0 cm • • Endometrial thickness <5mm Review the normal physiologic variation in size and appearance of the uterus • Myometrium becomes isointense with junctional zone • Review the normal physiologic appearance of the postpartum uterus • Review the most common causes of uterine enlargement • Discuss their imaging appearance across multiple modalities with a focus on ultrasound and MRI • This educational exhibit is intended for the general radiologist or radiology resident

Menstrual Proliferative Secretory Postmenopausal

Causes of Uterine Enlargement Physiologic Enlargement: Hormonal Causes

Physiologic Peripartum Anatomic Vascular Neoplastic Abnormal physiologic enlargement of the uterus is most commonly due to excess circulating estrogen/progesterone from either exogenous or endogenous Pelvic Congestion Myometrial Hormonal Delay of Involution Syndrome Neoplasm sources • Exogenous causes (Common):

Retained Arteriovenous • Tamoxifen (See next slide) Myometrial /Products Malformation Endometrial Contraction Cervical Stenosis Neoplasm of Conception (AVM) • Oral contraceptives • Typically combination of estrogen and progesterone

Mullerian Duct Cervical • Most common imaging findings: abnormalities Neoplasm • Globular enlargement of the myometrium • Atrophy of the endometrium

Gestational Gestational Trophoblastic Trophoblastic Neoplasm Neoplasm • Endogenous causes (Rare): • Hormone producing adnexal tumor • Similar imaging findings as Tamoxifen from estrogen or gonadotropin Lymphoma producing effects

Metastases

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Physiologic Enlargement: Physiologic Enlargement: Tamoxifen related changes Myometrial Contraction • Contraction of the endometrial/subendometrial complex producing a mass-like Tamoxifen related changes: A - Pro-estrogen effects on the uterus convexity into the endometrial canal - Causes spectrum of changes including: • Does not deform the outer uterine contour - (Most common) • Transient: Resolves within 45 minutes - • Best seen with cine MRI although can be seen between multiple acquisitions - Cystic Atrophy over the course of a non-cine MRI - Endometrial Carcinoma - Adenomyosis

Most Common Ultrasound Features: Sagittal grayscale ultrasound image demonstrates - Hyperechoic endometrial thickening (≥ 8mm) with hyperechoic endometrial thickening with cystic spaces multiple irregular cystic spaces B Most Common MRI Features: - T1WI: Isointense endometrial thickening - T2WI: Heterogeneous endometrial thickening +/- endometrial/subendometrial cysts

Best Diagnostic clue: - Clinical history of a breast cancer patient on Tamoxifen Sagittal T2WI demonstrates heterogeneous signal Most common presentation: throughout a widened endometrium with multiple - Irregular endometrial thickening with cystic spaces subendometrial cysts Sagittal T2WI Sagittal T2WI fat suppressed obtained 25 minutes later

Normal Postpartum Appearance Peripartum Enlargement: Imaging Findings: • Endometrium: A Delay of Involution • Heterogeneous in appearance • Ultrasound: Endometrial canal filled with hypoechoic material Definition: A (fluid) and echogenic material (hemorrhage) - Delay in the expected decrease in size of the postpartum uterus • MRI: Endometrial canal filled with high T2 signal (fluid) and low T2 signal (hemorrhage) • Myometrium: Clinical Presentation: • Enlarged and typically of lower echogenicity (US)/higher T2 - Most commonly presents with abnormal postpartum bleeding signal (MRI) consistent with edematous changes. • Junctional zone: Imaging Findings: • Ill defined up to 6 weeks postpartum - Uterus larger than expected given time passed since delivery B - Persistence of fluid/hemorrhage in the endometrial canal Size: - Persistence of myometrial engorgement/edema B • The postpartum uterus gradually decreases in size over several weeks with the greatest decrease occurring during the 1st week Potential causes including: Mean Uterine Length Postpartum (cm) - Endometrial hematoma - Endometritis 15 13.8 - Retained products of conception 10.2 - Gestational trophoblastic neoplasm 10 8.6 6.1 - Leiomyomas - Uterine anomalies 5 Axial (A) and Sagittal (B) T2 fat suppressed MRI images in a patient 3 days post vaginal delivery. The Axial T1WI (A) and T2 fat suppressed (B) MRI 0 myometrium is diffusely enlarged with heterogeneous images in a patient 3 weeks postpartum. The signal and cystic changes. The junctional zone is poorly uterus demonstrates persistent enlargement as 30 hrs 1 we ek 2 we eks 6 we eks defined. There is also low signal in the endometrial well as high T2 signal throughout the myometrium. canal consistent with hemorrhage (red arrow). D+C revealed endometrial hematoma

Peripartum Enlargement: Endometritis Peripartum Enlargement: Retained Products of Conception Clinical Presentation: A - Fever and pelvic tenderness in a postpartum patient A - More common in complicated (Premature rupture of membranes, prolonged labor, retained products, etc.) Clinical Presentation: - Pain and bleeding after a recent miscarriage, abortion, or delivery Imaging Findings: - Elevated hCG - Endometritis is a clinical diagnosis and imaging findings are frequently normal Imaging Findings: - CT is the most common modality ordered to assess for alternative - Ultrasound: Endometrial mass of heterogeneous echotexture with explanation of postpartum fever positive vascularity - Most common finding includes endometrial thickening with - CT/MRI: Heterogeneous endometrial mass with variable fluid/gas in the endometrial cavity enhancement B - Caveats: B - Thinning of the myometrium on any modality suggests mal- - Uncomplicated endometritis may have normal imaging implantation of the placenta (ie: placenta accreta, increta, percreta) findings - Gas in the endometrial cavity can be a normal finding Key differential diagnoses in a postpartum patient: within the first 3 weeks postpartum - Endometrial hematoma: No appreciable vascularity/enhancement - Serial exams may be helpful for distinguishing endometritis from - Gestational trophoblastic neoplasm: Markedly elevated hCG normal postpartum fluid/gas

Best Diagnostic Clue: - Clinical history of fever and pelvic tenderness in a postpartum Sagittal (A) and axial (B) CECT in a patient 5 days post C-section demonstrates Sagittal T2WI (A) and T1+C (B) MRI images in a patient patient post abortion with a hCG 51 - Fluid and gas in the endometrial cavity thickened endometrium with fluid and gas demonstrates a heterogeneous endometrial in the endometrial cavity mass with avid contrast enhancement.

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Peripartum Enlargement: Peripartum Enlargement: Gestational Trophoblastic Neoplasm Gestational Trophoblastic Neoplasm Background: A B • Comprises a spectrum of premalignant and malignant placental lesions • Premalignant lesions: Complete hydatidiform mole (CHM), Partial hydatidiform mole(PHM) • CHM: 46XX diploid, usually no fetal tissue present unless dizygotic twin pregnancy • PHM: Triploid, fetus/embryo present • Malignant lesions: Invasive mole, choriocarcinoma, placental site trophoblastic tumor (PSTT) • Invasive mole: A CHM or PHM that has invaded the myometrium • Choriocarcinoma: Abnormal proliferation of trophoblastic tissue that has often invaded myometrium and metastasized at time of diagnosis • PSTT: Focal neoplastic proliferation of trophoblasts in the myometrium at the site of placental insertion C D Imaging Findings: • GTN typically discovered as an absent/abnormal intrauterine pregnancy on prenatal ultrasound • CT/MRI can be used as follow up studies to assess for myometrial invasion or metastatic disease • CHM: Cystic endometrial mass with no associated embryo/fetus • PHM: Enlarged cystic placenta associated with an abnormal fetus • Invasive mole: Heterogeneous cystic endometrial mass invading into the myometrium • Choriocarcinoma: Heterogeneous echogenic mass with marked vascularity, often metastatic at time of diagnosis • PSTT: Heterogeneous echogenic mass with little vascularity. Can have cystic spaces like CHM/PHM.

Key point: Sagittal grayscale (A) and color doppler (B) images in a patient 10 weeks from her last menstrual period - No reliable way to distinguish CHM, PHM, or miscarriage on imaging. Role of imaging is to identify abnormal with hCG 287,395. There is a heterogeneous, primarily isoechoic mass arising from the uterus that pregnancy and assess for myometrial invasion/metastatic disease. All require uterine evacuation and demonstrates intense peripheral vascularity. Follow up axial (C) and coronal (D) CECT images ultimately pathologic diagnosis. demonstrate a hypoattenuating mass arising from the right uterine wall (red arrow). There is intense peripheral enhancement, similar to the ultrasound. Surgical pathology revealed a choriocarcinoma. - Gestational trophoblastic neoplasm clinically suspected when hCG continues to rise after uterine evacuation

Anatomic Enlargement: Adenomyosis Anatomic Enlargement: Cervical Stenosis Definition: Definition: • Heterotopic endometrial glands and stroma within the myometrium - Narrowing of the to <2.5 mm Ultrasound Findings: • Heterogeneous myometrium with poor definition of the junctional zone Clinical Presentation: • +/- Myometrial cysts - and inability to pass catheter during sonohysterogram or D+C • “Venetian Blind”/”Rain Shower” appearance due to alternating subendometrial echogenic linear striations and acoustic - Most commonly iatrogenic from prior endometrial/cervical biopsies shadowing MRI Findings: • Ill-defined enlargement of the junctional zone (> 12mm) Imaging Findings: • Junctional zone < 8mm essentially excludes adenomyosis - Typically evaluated with ultrasound which reveals: • Subendometrial/Myometrial foci of high T2 signal representing cystically dilated endometrial glands - Normal appearing • High T2 linear striations (finger-like projections) radiating from endometrium into myometrium - Enlargement/filling of the endometrial canal with: Diagnostic Keys: - Anechoic/hypoechoic fluid (Hydrometra) • Globular uterus with enlarged, poorly defined junctional zone C - Echogenic fluid ( or ) • Lack of mass effect is key in distinguishing adenomyosis from myometrial neoplasm - Role of imaging is to evaluate for an alternative diagnosis (ie: obstructing cervical mass) A B A B

(A,B) Sagittal grayscale ultrasound images of a demonstrates ill definition of the junctional zone. The myometrium is (A) Sagittal grayscale ultrasound in a patient with known cervical stenosis demonstrates hydrometra and an heterogeneous and has multiple myometrial cysts (red arrows). There are also areas of alternating echogenic linear striations and shadowing echogenic mass in the endometrial cavity. This was proven to be a blood clot on . (B) Sagittal consistent with a “rain shower appearance.” (C) Sagittal T2WI again demonstrates an enlarged ill defined junctional zone with multiple grayscale ultrasound in a multigravida patient with history of demonstrates a dilated fluid filled subendometrial and myometrial cysts. endometrial cavity (hydrometra). Patient was found to have cervical stenosis on subsequent attempted D+C.

Anatomic Enlargement: Anatomic Enlargement: Mullerian Duct Anomalies Mullerian Duct Anomalies A B C Clinical Presentation: • Usually asymptomatic • Recurrent abortions • /bleeding with hydrometra, hematometra, or pyometra from partial obstruction

Imaging Findings: • Ultrasound usually first line to investigate clinical symptoms • MRI is the modality of choice to differentiate the various anomalies • Unicornuate: Single uterine horn +/- contralateral rudimentary horn • Didelphys: Complete duplication of and cervix with no communication between them D E • Bicornuate: Partial duplication of the uterine horns down to the cervical os with a fundal cleft • Septate: Septum separating uterine horns with no fundal cleft • Arcuate: Small indentation of fundal endometrial canal with no separation of uterine horns (Considered a normal variant)

(A) Unicornuate, (B) Didelphys, (C) Bicornuate, (D) Septate, (E) Arcuate

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Vascular Enlargement: Vascular Enlargement: Uterine AVM Ultrasound Findings: Pelvic Congestion Syndrome • Grayscale: • Multiple, tubular anechoic spaces within the myometrium Clinical Presentation: • Normal appearing endometrium - Vague chronic pelvic pain secondary to dilated, congested ovarian and pelvic veins • Doppler: • Color doppler demonstrates intense vascularity of the anechoic spaces with color aliasing CT/MRI Findings: • Spectral doppler demonstrates high flow (PSV > 100 cm/s), low resistance waveforms (RI: < 0.6) - Enlarged uterus +/- engorged arcuate vessels in the myometrium C MRI Findings: - Multiple parauterine varices with at least one measuring > 4 mm in diameter • T1/T2 • Bulky, ill-defined myometrial mass - Enlarged ovarian vein > 8 mm diameter • Multiple, serpiginous flow voids within the myometrium • High T1 signal focus if hemorrhage is present Angiography Findings: • T1 + C - Retrograde ovarian venogram demonstrating ovarian vein > 8 mm in diameter • Serpiginous, myometrial mass that enhances intensely similar to surrounding vessels - Retrograde opacification of a dilated ovarian venous plexus Angiography Findings: • Hypertrophied uterine arteries with a complex tangle of vessels in the region of the uterus • Early venous filling secondary to rapid shunting of arterial blood to venous plexus A B A B C D

Transverse CECT (A) demonstrates multiple left para-uterine varices measuring up to 10 mm (yellow arrow). Axial T2WI (B) demonstrates Transverse grayscale (A) and color doppler (B) ultrasound images demonstrate an enlarged uterus with multiple tubular anechoic spaces in a dilated left ovarian vein measuring up to 16 mm (red arrow). Digital subtraction angiogram (C) demonstrates retrograde filling of a the myometrium. There is intense vascularity with color aliasing (red arrow). Axial T1 MRI (C) demonstrates an enlarged uterus with dilated left ovarian vein and pelvic venous plexus. multiple serpiginous flow voids in the myometrium. No areas of high T1 signal are seen to suggest hemorrhage. Digital subtraction angiogram (D) image demonstrates a complex tangle of vessels in the region of the uterus. Early venous filling is identified (blue arrow).

Neoplastic Enlargement: Myometrium Neoplastic Enlargement: Myometrium Leiomyoma Leiomyoma

Imaging Findings: • Described by location: submucosal, Intramural, subserosal • Ultrasound Findings: • Hypoechoic mass in the myometrium • Hyperechoic components seen with calcification • Anechoic components seen with cystic degeneration • CT Findings: • Homogenous attenuation similar to myometrium • Calcification is common • Low attenuation components seen with cystic degeneration • MRI Findings: • T1: Isointense to myometrium • T2: Hypointense to surrounding myometrium with surrounding pseudocapsule of normal myometrium • GRE: Foci of susceptibility if calcified

Best Diagnostic Clue: - MRI is the best imaging modality to distinguish fibroid from surrounding myometrium and characterize their location Submucosal Intramural (Multiple) Subserosal (Pedunculated)

Neoplastic Enlargement: Myometrium Neoplastic Enlargement: Myometrium Leiomyolipoma Leiomyosarcoma

Background: A • Rare benign tumor composed of fat, , and connective tissue • Discovered incidentally or presents with pelvic pain/bleeding (Similar to leiomyoma)

Imaging findings: • Ultrasound • Myometrial based mass that is very echogenic secondary to large fat component • Typically no/minimal internal vascularity • CT B • Fat density mass arising from the myometrium • MRI • High T1 signal due to fat • Loss of signal on fat suppression techniques

Key to diagnosis: • Identification of internal fat on any modality • Identifying clear separation from the is key…Otherwise ovarian teratoma may look similar Acc: 10407649 (A) Sagittal grayscale/color doppler ultrasound demonstrates a large hyperechoic mass replacing the uterine body/fundus of a retroverted uterus. No appreciable internal vascularity. (B) Axial CECT demonstrates a large fat density myometrial mass in the uterine body.

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Neoplastic Enlargement: Endometrium Neoplastic Enlargement: Cervix Endometrial Carcinoma Cervical Carcinoma Imaging Findings: • Expansion of endometrial canal on all modalities Clinical Presentation: • Ultrasound Findings: • and pelvic pain • Hyperechoic polypoid mass or endometrial thickening • Postmenopausal woman: Endometrial thickening > 5mm should prompt biopsy Imaging Findings: • Premenopausal woman (Proliferative phase): Endometrial thickening >8mm should prompt biopsy • Main role of imaging is staging • Premenopausal woman (Secretory phase): Endometrial thickening > 16mm should prompt biopsy • • MRI Findings: Diagnosis usually made by Pap smear/biopsy • • T1: Isointense to myometrium Ultrasound Findings: • T2: Intermediate signal (Best sequence to evaluate for invasion through junctional zone) • Hypoechoic mass at the cervix with some degree of internal vascularity • T1 + C: Avid enhancement compared to adjacent myometrium • CT Findings: • NECT: Isoattenuating mass at the cervix Best Diagnostic Clue: • CECT: Isoattenuating or slightly hypoattenuating enhancement in relation to spared cervical stroma - Expansion of the endometrial canal suggests endometrial origin • MRI Findings: - Small endometrial mass may be impossible to differentiate from polyp without biopsy • T1: Isointense mass • T2: • Slightly hyperintense mass surrounded by low signal intensity stroma • Loss of surrounding low signal intensity suggests extension of tumor beyond cervix • T1 + C: Heterogeneous enhancement

Best Diagnostic Clue: - Location…Mass lesion centered at the cervix

Important Finding: - On T2WI MRI, identifying surrounding intact/disrupted low signal intensity stroma is key (A) Sagittal grayscale ultrasound demonstrates a hyperechoic mass filling and expanding the endometrial canal. Sagittal T2 (B) and axial T2 fat suppressed (C) images in a different patient demonstrate a large intermediate signal mass expanding the endometrial canal. In certain areas, the junctional zone has become indistinct (red arrow) suggesting myometrial invasion.

Neoplastic Enlargement: Cervix Neoplastic Enlargement: Uterine Lymphoma

Cervical Carcinoma Definitions: • Primary Uterine Lymphoma: Extranodal lymphoma confined to the uterus/cervix without systemic involvement A C E elsewhere in the body • Secondary Uterine Lymphoma: Uterine involvement as part of a systemic lymphoma

Clinical Presentation: • Vaginal bleeding and pelvic pain

Imaging Findings: • Ultrasound Findings: D • Grayscale: B • Enlarged lobulated uterus with a ill-defined hypoechoic mass typically centered in the myometrium • Doppler: • Color doppler demonstrates moderate internal vascularity • CT Findings: • Enlarged uterus with or without a visible mass • If mass is visible, it typically demonstrates moderate homogenous enhancement • MRI Findings: • T1: Homogenous mass isointense to muscle • T2: Homogenous mass slightly hyperintense to muscle • T1 + C: Moderate homogenous enhancement Transverse grayscale (A) and color doppler (B) ultrasound images demonstrate an enlarged primarily isoechoic mass replacing the normal cervix. There is mild peripheral vascularity within the mass. Axial noncontrast CT (C), and axial PET (D) images demonstrate an enlarged hypoattenuating mass arising from the expected region of the cervix (blue arrow). The mass is intensely hypermetabolic (SUV Best Diagnostic Clue: max 14). Sagittal T2WI (E) in a different patient demonstrates a large mildly hyperintense mass involving the cervix and lower uterine - Homogenous appearing mass that demonstrates moderate enhancement/vascularity on all modalities. segment (red arrow). There appears to be an intact thin surrounding low signal intensity stroma (purple arrow). The uterine fundus is dilated and fluid filled (green arrow) suggesting obstruction of the endometrial canal.

Neoplastic Enlargement: Uterine Lymphoma A Neoplastic Enlargement: Metastases B C A Background: • Uterine metastasis is rare with the primary most commonly arising in the pelvis (Ovarian, Colon) • Extra-pelvic primaries are extremely rare and most commonly arise from breast, stomach, bowel, melanoma, and lung. • Myometrium involved in the majority of cases (96.2%)

Imaging findings variable: B D E • Typically a large heterogeneously enhancing mass within the myometrium • Concomitant ovarian involvement can be seen 50% of the time • Other sites of extrauterine involvement are common

Key to diagnosis: • Clinical history of known primary • If no known extrauterine primary, primary leiomyosarcoma must be considered

Axial (A) and Sagittal (B) CECT images in a patient with history of colon cancer s/p partial colectomy. There is a large heterogeneously Transverse grayscale (A) and color doppler (B) ultrasound images demonstrate a hypervascular, lobulated, hypoechoic mass involving the lower uterine segment and cervix. Axial (C) and sagittal (D) contrast enhanced CT images demonstrate a homogenously enhancing lobulated mass centered enhancing myometrial mass. The distal ileum is adherent anteriorly (red in the lower uterine segment/cervix (red arrow). No regional lymphadenopathy identified. Coronal fused PET/CT (E) image after hysterectomy arrows) and sigmoid colon is adherent posteriorly (blue arrows). Not demonstrates no regional or distant hypermetabolic lymph nodes suggesting no extra-uterine involvement (Primary uterine lymphoma). pictured here were multiple other sites of metastasis including mesenteric lymph nodes, anterior abdominal wall, and lungs.

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Conclusion References

1. Kido A, Togashi K, Koyama T, etal. Diffusely enlarged uterus: Evaluation with MR imaging. Radiographics 2003; 23: 1423-2439. 2. Hann LE, Giess CS, Bach AM, Tao Y, Baum HJ, Barakat RR. Endometrial thickness in Tamoxifen-treated patients: Correlation with clinical and pathologic findings. AJR 1997; 168: 657-661. Enlargement of the uterus is an abnormal finding that radiologists 3. Lyons EA, Taylor PJ, Zheng XH, Ballard G, Levi CS, Kredentser JV. Characterization of subendometrial myometrial contractions throughout the in normal fertile women. Fertile Steril 1991; 55(4): 771-774. encounter frequently in their daily practice. Knowing the key 4. Huang MW, Muradali D, Thurston WA, Burns PN, Wilson SR. Uterine arteriovenous malformations: gray-scale and doppler US features with MR imaging correlation. Radiology 1998; 206: 115-123. 5. Umeoka S, Koyama T, Togashi K, Kobayashi H, Akuta K. Vascular dilatation in the pelvis: Identification with CT and MR imaging. distinguishing features between various uterine processes across Radiographics 2004; 1: 193-208. 6. Sala E, Wakely S, Senior E, Lomas D. MRI of malignant neoplasms of the uterine corpus and cervix. AJR 2007; 188: 1577-1587. multiple modalities will simplify the diagnostic approach to this 7. Beddy P, Moyle P, Kataoka M, Yamamoto AK, Joubert I, Lomas D, Crawford R, Sala E. Evaluation of depth of myometrial invasion and overall staging in : comparison of diffusion weighted and dynamic contrast-enhanced MR imaging. Radiology traditionally difficult topic. 2012; 262(2): 530-537. 8. Lien HH, Nome O, Berner A. Lymphoma of the uterus: Findings on MR imaging. AJR 1994; 163(4): 996. 9. Tsoi D, Buck M, Hammond I, White J. Gastric adenocarcinoma presenting as uterine metastasis – A case report. 2005; 97(3): 932-934. 10. Reinhold C, Tafazoli F, Mehio A, Wang L, Atri M, Siegelman ES, Rohoman L. Uterine adenomyosis: Endovaginal US and MR imaging features with histopathologic correlation. Radiographics 1999; 19: 147-160. 11. Behr SC, Courtier JL, Qayyum A. Imaging of Mullerian Duct Anomalies. Radiographics 2012; 32: 233-250. 12. Willms AB, Brown ED, Kettritz UI, Kuller JA, Semela RC. Anatomic changes in the pelvis after uncomplicated vaginal delivery: evaluation with serial MR imaging. Radiology 1995; 195:91-94. 13. Noonan JB, Coakley FV, Qayyum A, Yeh BM, Wu L, Chen LM. MR imaging of retained products of conception. AJR 2003; 181(2): 435- 439. 14. Durfee SM, Frates MC, Luong A, Benson CB. The sonographic and color Doppler features of retained products of conception. J Ultrasound Med 2005; 24(9): 1181-1186. 15. Allen SD, Lim AK, Seckl MJ, Blunt DM, Mitchell AW. Radiology of gestational trophoblastic neoplasia. Clinical Radiology 2006; 61(4): 301-313.

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