Mullerian Duct Anomalies

Introduction & Embryology

• They are named after Johannes Peter Müller, a physiologist who described these ducts in his text “Bildungsgeschichte der Genitalien” in 1830.
• Paired ducts derived from intermediate mesoderm.
• Known as a paramesonephric duct. 
• Mullerian ducts form as buds of coelomic epithelium.
• Grows downward & lateral to corresponding Wolffian ducts.
• Turn inwards & crosses anterior to it joining its fellow from the opposite side.
• Structure developing from the Mullerian duct in males is a Prostatic utricle.
• The development of the paramesonephric (Müllerian) ducts is controlled by the presence or absence of Anti- Mullerian Hormone (AMH) 
• In male embryogenesis: The developing testes produce AMH causing regression of paramesonephric ducts.
• In female embryogenesis: The absence of AMH results in the development of the paramesonephric ducts into the uterine tubes, uterus, & upper 2/3 of the vagina. 

 Parts 

• Upper vertical part lateral to Wolffian duct → fallopian tube
• Middle horizontal part crossing Wolffian duct → remaining part of the fallopian tube
• Lower vertical part fusing to the opposite part → uterus, cervix, upper 1/3 rd. of the vagina
• In forming the uterus, the Mullerian duct fuses from below upwards.

Classification Of Mullerian Duct Anomalies/Lateral Fusion Defects 

They are due to the failure of Mullerian ducts either to unite or defect in the dessostuning of septa.

S. No.	Anomaly	Defect
1.	Mullerian Agenesis	Here both Mullerian ducts are absent. Hence both Fallopian tubes, uterus, cervix and upper vagina are absent. The Ovary and lower vagina are Present. It shows Normal breast development. Androgen Insensitivity Syndrome & Primary amenorrhoea is associated with agenesis.
2.	Unicornuate Uterus	It does not represent a defect in the fusion of the ducts, rather here one of the Mullerian ducts is completely absent and so there is only 1 fallopian tube. Uterus, cervix, and vagina though appear to be normal are only half of the Fully developed organ. Second, most commonly associated with miscarriages.  Common on right side Associated with renal anomalies, cryptomenorrhea & primary infertility NOTE; Patients with a unicornuate uterus have increased incidence of infertility, endometriosis, and dysmenorrhea.
3.	Uterus Didelphys	It is a condition where there is a failure of fusion along the whole length of the Mullerian duct resulting in 2 vaginae, 2 cervices, and 2 uteri. Mostly asymptomatic but Dyspareunia may be seen as a result of vaginal septum. Note; This is the only condition where 2 vaginas are present
4.	Bicornuate uterus A. Uterus bicornis Unicollis	In this condition only the lower part of the ducts fuse leaving the cornua separate, so always there is a single vagina. commonly associated with abortions. Here, vagina and cervix are fused, i.e. Single vagina, single cervix but 2 Uterus
	B. Uterus bicornis Bicollis	Here, the vagina is fused but cervix and uterus are not fused, i.e. Single vagina,2 cervices, and 2 uterus
5.	Septate/Subseptate Uterus	In this condition; both MD fuse & form septa but septa fail to resolve. So the uterus is outwardly normal but contains a complete or incomplete septum inside. most common congenital anomaly associated with abortion.
6.	Arcuate uterus	Here the fundus of the uterus remains flat & does not become dome-shaped. Least commonly associated with reproductive failure.

WHO classification of Mullerian duct anomalies 

1.      Class I Mullerian agenesis (MRKH- Mayer Rokitansky Kuster Hauser Syndrome)

2.      Class II Unicornuate uterus

3.      Class III Didelphys uterus

4.      Class IV Bicornuate uterus

5.      Class V Septate uterus

6.      Class VI Arcuate uterus

7.      Class VII DES related abnormalities/T shaped uterus

T-shaped uterus:

•  It is associated with in utero exposure to diethylstilbestrol (DES), which is a synthetic nonsteroidal estrogen and a known teratogen.

Clinical Implications

• Pelvic pain following the menarche.
• Dysmenorrhea and an increase in abdominal volume. 
• Primary amenorrhea.
• Vaginal agenesis presents with primary amenorrhea and dyspareunia. 
• Hematometra and hematocolpos are frequent findings.
• History of repeated miscarriage or infertility.

 Diagnosis of Mullerian Duct Anomalies

• HSG: Hysterosalpingogram (HSG) is mainly preferred in uterine anomalies but it cannot distinguish between a septate and bicornuate uterus. Hence it is not the IOC.done between day 5 and day 11 of the menstrual cycle (Best done on D-10)- In the preovulatory phase
• Other diagnostic tests:
  • MRI: Imaging modality of choice for septate uterus
  • Radiograph
  • Ultrasound: Important in Uterus didelphys & Septate uterus

Hysterosalpingogram:

• Unicornuate uterus: Fusiform shaped endometrial cavity tapering apex and draining into a single fallopian tube
• Uterus didelphys(IOC): 2 separate endocervical canals open into separate fusiform endometrial cavities, without communication between the two horns. Each endometrial cavity ends in a solitary fallopian tube.
• Bicornuate uterus: Divided uterus
• Septate uterus: An angle of less than 75° between the uterine horns is suggestive of a septate uterus, and an angle of more than 105° is more consistent with bicornuate uteri.
• T-shaped uterus: Opacified endometrial cavity appears small, with a shortened upper uterine segment, resulting in the characteristic T-configuration.

Management of Bicornuote or Septate Uterus

• The presence of uterine malformation per se is not an indication of surgical correction. 
• Unification operation is indicated in otherwise unexplained cases of infertility or if it has to lead to >3 abortions.
• Options Include For bicornuate uterus: (and if needed for Didelphys uterus). Unification surgery is done either hysteroscopically (preferred) or by abdominal route, e.g. Straussman metroplasty.
• For septate uterus: Earlier: Jones/Tompkins Metroplasty was done.
• Nowadays: Hysteroscopic resection of septa is being done after inducing endometrial atrophy by administering the GnRH analogue for 2 months.
• Main complications: Uterus perforation and fluid overload.

                           

                    

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