Congenital Anomalies of the Female Reproductive Tract

1. Embryological Basis

1. The Mullerian ducts elongate toward the midline
2. They fuse in the midline
3. The intervening septum undergoes resorption

• Upper vagina
• Cervix
• Uterine corpus
• Fallopian tubes

2. Classification and Prevalence

• Rises to 5-10% in women with early pregnancy loss
• Up to 25% in women with second and third trimester pregnancy losses

AFS/ASRM Classification (American Fertility Society)

3. Outflow Tract Anomalies (Transverse Blockages)

• Hematocolpos (blood in vagina)
• Hematometra (blood in uterus)
• Hemoperitoneum
• Endometriosis (retrograde flow)

3.1 Imperforate Hymen

• The most distal outflow obstruction
• Most are not diagnosed until hematocolpos forms
• Clinically: bluish bulging membrane at introitus, cyclic pelvic pain, primary amenorrhea
• Treatment: Cruciate incision to open the vaginal orifice
• Caution: Do NOT place a needle into a hematocolpos without completely removing the obstruction - a pyocolpos may result

3.2 Transverse Vaginal Septum

• Results from failure of canalisation between the Mullerian tubercle and the sinovaginal bulb
• Distribution: 46% in the upper third vagina; 40% in the middle third
• Clinical features: same obstructive picture as imperforate hymen
• Treatment: Surgical removal of the septum; vaginal dilators must be used post-operatively to prevent adhesions and re-obstruction
• Prognosis: Patients with repaired transverse septum in middle/upper vagina may have increased infertility risk, but some studies show normal conception rates after surgical repair

3.3 Absent/Hypoplastic Cervix

• Rare, difficult to treat
• Previously required hysterectomy
• Current first-line: Conservative laparoscopic uterovaginal anastomosis
• Endometriosis is a common finding
• If hysterectomy is required, ovaries should be retained (for IVF/gestational carrier option)

4. Vaginal Anomalies

4.1 Vaginal Agenesis - MRKH Syndrome

• Karyotype: 46,XX (normal female)
• Accounts for 10-15% of all cases of primary amenorrhea
• Features: vaginal agenesis with variable uterine development

1. Type I (Isolated): Mullerian aplasia only - absent or rudimentary uterus and upper vagina
2. Type II (MURCS association): Mullerian anomaly + associated anomalies:
   • Renal malformations (absent, pelvic, horseshoe, or double collecting system)
   • Skeletal abnormalities
   • Congenital heart defects
   • Hearing impairment

• Progressive dilation (Frank's/McIndoe dilators) - successful in most cases
• If dilation fails: McIndoe split-thickness skin graft technique, Vecchietti procedure, or other surgical approaches
• Post-surgical dilators are mandatory to maintain vaginal patency

5. Uterine Anomalies

5.1 Mullerian Agenesis (Class I)

• Absent uterus with variable development
• Only anomaly closely associated with infertility - affected women can have genetically related children only through IVF + gestational carrier

5.2 Unicornuate Uterus (Class II)

• One Mullerian duct fails to develop
• Banana-shaped uterus
• May have a rudimentary horn (communicating or non-communicating)
• Non-communicating rudimentary horn with functioning endometrium: Risk of:
  • Hematometra
  • Endometriosis
  • Ectopic pregnancy within the horn (life-threatening)
• Management: Rudimentary uterine horns require removal on diagnosis (laparoscopic excision)

5.3 Uterus Didelphys (Class III)

• Complete failure of lateral fusion - two separate uteri, two cervices, often two vaginas (with longitudinal septum)
• Associated with obstructed hemivagina + ipsilateral renal agenesis (Herlyn-Werner-Wunderlich syndrome / OHVIRA)
• Generally best obstetric outcomes among fusion defects
• Surgical unification (Strassman metroplasty) rarely indicated

5.4 Bicornuate Uterus (Class IV)

• Incomplete fusion at the fundal level
• Two uterine horns joined at the lower uterine segment/cervix
• Bicollis (two cervices) or unicollis (one cervix)
• Associated with: recurrent pregnancy loss (especially second trimester), preterm delivery
• Metroplasty (Strassman procedure via laparotomy) for recurrent losses - though evidence is debated

5.5 Septate Uterus (Class V) - Most Common Anomaly

• Commonest Mullerian anomaly (accounts for ~35% of all uterine anomalies)
• Results from failure of resorption of the midline septum after fusion
• Septum can be partial (subseptate) or complete
• Associated with highest rate of reproductive failure - early pregnancy loss (up to 60-65%), preterm labor
• External uterine contour is normal (differentiates from bicornuate on MRI)
• Treatment: Hysteroscopic metroplasty - significantly reduces rates of pregnancy loss (but not infertility). This is the standard of care - straightforward, minimally invasive
• Diagnosis: 3D transvaginal ultrasound or MRI (gold standard)

5.6 Arcuate Uterus (Class VI)

• Mildest anomaly - near-complete septal resorption with only a fundal indentation
• Generally: live birth rates comparable to women with normal uteri
• Often considered a normal variant

5.7 DES-Related Anomaly (Class VII)

• In utero exposure to diethylstilbestrol (DES)
• DES was banned in 1971 - number of affected reproductive-age patients is declining
• Associated with: T-shaped uterus, hypoplastic uterus, uterine anomalies
• Higher rates of: ectopic pregnancy, preterm labor, miscarriage, cervical incompetence
• Women whose mothers (not the women themselves) were exposed to DES have higher rates of these malformations

6. Diagnosis and Imaging

• Differentiating septate (normal external contour) from bicornuate (heart-shaped external contour) uterus
• Characterizing rudimentary horns
• Evaluating renal anomalies simultaneously

7. Androgen Insensitivity Syndrome (Structural Mimicker)

• Complete AIS: 46,XY with absent Mullerian structures (Mullerian regression by AMH from testes), absent Wolffian structures (androgen insensitivity), female phenotype, absent uterus and upper vagina, blind vaginal pouch
• Presents as primary amenorrhea with normal breast development
• Axillary and pubic hair absent/sparse
• Gonads (testes) in inguinal canal or labia
• Management: Gonadectomy after pubertal development (to prevent malignant degeneration - ~14% develop gonadoblastoma, ~50% of which are malignant dysgerminomas)

8. Associated Anomalies

• Renal anomalies: Renal agenesis (especially with didelphys + obstructed hemivagina), pelvic kidney, horseshoe kidney, duplex collecting system
• Skeletal anomalies (in MRKH Type II)
• Cardiac anomalies (in MRKH Type II)
• Auditory defects (in MRKH Type II)

9. Obstetric Implications

10. Summary of Surgical Management

Recent Evidence Updates

• A 2025 meta-analysis (PMID 40628082) found that 3D transvaginal ultrasound performs comparably to MRI for diagnosing and classifying congenital uterine anomalies, potentially positioning 3D TVS as the preferred first-line modality
• ART outcomes in women with uterine anomalies continue to be studied - a 2024 systematic review (PMID 39227392) evaluates IVF outcomes in this population

What Was Covered

• The widely-used AFS/ASRM (Buttram & Gibbons) Classes I-VII
• The newer ESHRE/ESGE U0-U6 system with cervical/vaginal sub-classification

• Embryological defect
• Anatomy and sub-types
• Clinical features
• Associations (especially renal anomalies)
• Investigations with an algorithmic approach
• Obstetric risks with data
• Management (including when surgery is/is not indicated)