Embryogeneisis OverviewMullerian Duct Anomalies (MDAs)

• 1-5% of the general population and 13-25% of patients with infertility or recurrent pregnancy loss (1)
• Affecting fallopian tubes, uterus, cervix, and proximal 2/3 of the vagina
• Normal ovaries and distal third of vagina
• Three stages: ductal development, ductal fusion, and septal resorption (2)

Ductal Development

Ductal Fusion

Septal resorption

Hysterosalpingography (HSG)

• Limited utility in characterizing Mullerian anomalies since only lumen visualized.
• Pearls: divergent angle of less than 75 degrees between endometrial horns suggesting septate uterus and angle of greater than 105 degrees suggesting bicornuate configuration,
• Pitfalls: overlap between these two entities with majority of cases falling within this range and masses such as adenomyomas or fibroids mimicking these findings (3).

Ultrasound (US)

• 3D imaging useful for visualization of exterior surface of uterine fundus.
• Pearls: imaging during secretory phase preferred when endometrium thicker.

Magnetic resonance (MR)

• Modality of choice since external surface and internal architecture of uterus well depicted.
• T2 weighted sequences for visualization of anatomy–ideally coronal and axial imaging planes prescribed from sagittal images, parallel and perpendicular to body of uterus.
• T1 weighted sequences useful for identification of blood products.
• Large field of view images enabling visualization of kidneys and ureters and any concurrent urinary tract anomalies.

Agenesis or Hypoplasia: Mayer-Rokitansky-Kuster-Hauser Syndrome

• Hypoplasia or agenesis of uterus and upper 2/3 of vagina.
• 5-10% of MDA cases.
• Occurring in 1 out of 4000 females, second most common cause of primary amenorrhea (9).
• Often presenting as primary amenorrhea with normal external characteristics because ovaries functioning normally.
• Rudimentary uterine tissue, if present, always caudal to ovaries which may be ectopic in location (8).
• Once diagnosed, surgery enabling normal sexual function and reproduction occurring with assistance.

Agenesis

Vaginal and cervical agenesis
Left renal agenesis in same patient

Hypoplasia

Presumed fibroid (star) stable in size for 14 years and strand of tissue (arrow) which may represent rudimentary uterine tissue
Normal ovaries more superiorly in same patient

Unicornuate Uterus

Unicornuate Uterus without Rudimentary Horn

HSG of right unicornuate uterus with patent endometrial cavity and fallopian tube
T2 axial MR of left unicornuate uterus
US of right unicornuate uterus
Intrauterine pregnancy in same patient at later date

Unicornuate Uterus with Rudimentary Horn

Right unicornuate uterus with rudimentary left horn attached by fibrous tissue (arrow), possible endometrial tissue (arrowhead), and no communication with right endometrial canal

Uterine Didelphys

• Near complete failure of Mullerian duct fusion
• Results in two endometrial cavities, cervixes, and proximal vaginas
• 5% of MDAs (3)
• Pearl: external uterine fundal contour distinguishing fusion failures from incomplete resorption of septum. Bicornuate and didelphys uteri with less than 5 mm myometrium above level of endometrial horns or apex of fundus located below level of horns

Uterine Didelphys

Two endometrial horns (top) Two cervixes (bottom), patient has two proximal vaginas more inferiorly (not pictured)
Different patient with fluid collection adjacent to obliterated right hemivagina (arrow), patient subsequently underwent right hysterectomy and salpingectomy

Bicornuate Uterus

• Incomplete fusion of Mullerian ducts at level of uterine fundus
• Second most common anomaly for MDA infertility patients, accounting for 10% of MDA cases
• Pearl: external uterine fundal contour distinguishing fusion failures from incomplete resorption of septum. Bicornuate and didelphys uteri with less than 5 mm myometrium above level of endometrial horns or apex of fundus located below level of horns
• Pearl: Upper vaginal septa occuring in about 25% of cases and when associated with bicornuate bicollis configuration, difficult to distinguish from didelphys uteri

Bicornuate Uterus

Apex of fundus below level of uterine horns, two cervixes, and no vaginal septum
Left renal agenesis in same patient
MR and HSG on same patient with wide divergence of endometrial horns on HSG (arc)
US on different patient with external surface of uterine fundus below level of endometrial horns (arrowheads)

Septate or Subseptate Uterus

• Normal external contour of uterine fundus
• 55% of MDA cases, poorest reproductive outcome regardless of size of septum (3)
• When complete, extending from uterine fundus through cervix
• Pearl: external uterine fundal contour distinguishing fusion failures from incomplete resorption of septum.
• Septate, subseptate, and arcuate uteri having 5 mm or more of myometrium above level of endometrial horns
• Treatment: Surgical resection of septum
• No residual septum or septum less than 1 cm considered optimal for reproduction

Complete Septum

Septum extending from fundus through cervix
Same patient with findings more difficult to visualize on coronal CT reformats

Subseptate Uterus

Normal external contour of uterine fundus and divergence of endometrial horns on short axis T2 MR and 3D US

Post Septate Resection

No residual septum or septum less than 1 cm considered optimal for reproduction	1. 2.67 cm 2. 1.10 cm 1. 2.81 cm 2. 0.98 cm
Preoperative MR (left) Postoperative HSG (right) with improved septal abnormality

Arcuate Uterus

• Near complete septal resorption
• May be normal variant
• Mild broad indentation of fundal portion of endometrium
• No defining depth to distinguish from broad septum (3)
• Up to 3.9% of general population with no increased prevalence in high risk groups (7)
• Pearl: external uterine fundal contour distinguishing fusion failures from incomplete resorption of septum.
• Septate, subseptate, and arcuate uteri having 5 mm or more of myometrium above level of endometrial horns

Arcuate Uterus

Same patient on MR and 3D US with subtle broad indentation of fundal portion of endometrium with normal external contour of uterine fundus

1. Behr SC, Courtier, JL, Qayyum A. Imaging of Mullerian duct anomalies, Radiographics 2012:32(6)
2. Robbins JB, Parry JP, Guite KM et al. MRI of pregnancy-related issues: müllerian duct anomalies. AJR Am J Roentgenol 2012;198(2):302–310.
3. Trolano RN, McCarthy SM. Mullerian duct anomalies: imaging and clinical issues. Radiology 2004; 233(1):19–34.
4. The American Fertility Society classifications of adnexal adhesions, distal tubal obstruction, tubal occlusion secondary to tubal ligation, tubal pregnancies, Müllerian anomalies and intrauterine adhesions. Fertil Steril 1988; 49:944–955.
5. Olpin JD, Heilbrun M. Imaging of müllerian duct anomalies. Clin Obstet Gynecol 2009;52(1):40–56.
6. Li S, Qayyum A, Coakley FV, Hricak H. Association of renal agenesis and mullerian duct anomalies. J Comput Assist Tomogr 2000;24(6):829–834
7. Chan YY, Jayaprakasan K, Zamora J, Thornton JG, Raine-Fenning N, Coomarasamy A. The prevalence of congenital uterine anomalies in unselected and high-risk populations: a systematic review. Hum Reprod Update 2011;17(6):761–771.
8. Hall-Craggs MA, Williams CE, Pattison SH, et al. Mayer-Rokitansky-Kuster-Hauser syndrome: diagnosis with MR imaging. Radiology 2013;269(3).
9. Giusti S, Fruzzetti E, Perini D, Fruzzetti F, Giusti P, Bartolozzi C, et al. Diagnosis of a variant of Mayer-Rokitansky-Kuster-Hauser syndrome: useful MRI findings. Abdom Imaging. 2011;36:753–55.
10. Fedele L, Bianchi S, Marchini M, Mezzopane R, DiNola G, Tozzi L. Residual uterine septum of less than 1 cm after hysteroscopic metroplasty does not impair reproductive outcome. Hum Reprod 1996; 11:727–729.