---

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

---

---

Congenital Uterine Anomalies - Postgraduate Level

---

1. Embryological Basis

STEP 1: Organogenesis
Mullerian ducts form lateral to Wolffian ducts (weeks 6-9)
         ↓
STEP 2: Lateral Fusion (Canalization)
Both ducts elongate caudally and fuse in the midline (weeks 9-12)
         ↓
STEP 3: Septal Resorption
Intervening septum resorbs to give single cavity (by week 20)

• Failure of organogenesis → Agenesis/Hypoplasia (Class I)
• Failure of one duct to form → Unicornuate (Class II)
• Failure of lateral fusion → Didelphys (Class III) or Bicornuate (Class IV)
• Failure of septal resorption → Septate (Class V) or Arcuate (Class VI)
• Drug-induced disruption → DES-related (Class VII)

---

2. Classification Systems

2.1 AFS/ASRM Classification (Buttram & Gibbons, 1979 - most widely used clinically)

2.2 ESHRE/ESGE Classification (2013 - newer, more detailed)

Cervix and vagina are sub-classified separately (C0-C2, V0-V2)

---

3. Diagrammatic Representations

Types of Congenital Uterine Anomalies

• A: Uterus didelphys with double vagina
• B: Uterus didelphys with single vagina
• C: Bicornuate uterus (two horns)
• D: Bicornuate uterus with rudimentary left horn
• E: Septate uterus (normal external contour, internal division)
• F: Unicornuate uterus (banana-shaped, one horn)

---

Hysterosalpingogram Appearances

• A: Normal uterine cavity with bilateral tubal spill
• B: Bicornuate uterus - two horns with wide intercornual angle
• C: Uterus didelphys - two completely separate uterine cavities
• D: Uterus didelphys with double vagina

---

4. Individual Anomalies - Detailed Description

---

CLASS I: Mullerian Agenesis / MRKH Syndrome

• Absent uterus (or rudimentary uterine remnants)
• Absent upper two-thirds of vagina
• Normal fallopian tubes and ovaries (ovaries are of mesonephric origin - unaffected)

• Type I (Isolated/Classic MRKH): Uterovaginal aplasia alone
• Type II (MRKH + MURCS Association): With renal anomalies (absent, pelvic, horseshoe kidney), skeletal anomalies, cardiac defects, hearing impairment

• Primary amenorrhea
• Normal breast development, normal pubic/axillary hair (estrogen from normal ovaries)
• Absent or short (2-3 cm) vaginal dimple on examination
• No uterus on pelvic imaging
• Normal secondary sexual characteristics
• Cyclic pelvic pain if any functioning uterine tissue present

• Karyotype: 46,XX (rules out AIS which is 46,XY)
• Pelvic MRI: confirms absent uterus, characterises any remnants
• Renal USS: horseshoe kidney, renal agenesis in ~30%
• FSH, LH, estradiol: normal
• Testosterone: normal female range (distinguishes from complete AIS where T is male-range)
• Bone survey for skeletal anomalies (in suspected MURCS)

• Vaginal creation (primary goal - no curative surgery exists for the uterus):
  • Frank's progressive dilation: First-line; 80-90% success; 10-20 minutes daily with graduated dilators over 3-6 months
  • McIndoe vaginoplasty: Split-thickness skin graft over mold if dilation fails
  • Vecchietti procedure: Laparoscopic traction-based elongation of vaginal dimple - faster (1-2 weeks)
  • Davydov procedure: Laparoscopic creation using peritoneum
• Fertility: IVF with oocyte retrieval from own ovaries + gestational surrogate (own genetic child possible)
• Uterus transplantation: Experimental; first live births reported - may become viable option

---

CLASS II: Unicornuate Uterus

• Communicating (with endometrial cavity connected to main uterus)
• Non-communicating with endometrium (most dangerous - can cause ectopic pregnancy or hematometra)
• Non-communicating without endometrium (solid remnant - least problematic)
• Absent (pure unicornuate)

• Often asymptomatic and discovered incidentally
• Cyclic dysmenorrhea if rudimentary horn has non-communicating functional endometrium
• Hematometra in non-communicating horn with endometrium
• Ectopic pregnancy within rudimentary horn (life-threatening - rupture at 10-20 weeks due to greater distensibility than fallopian tube)
• Recurrent miscarriage, preterm birth
• Banana-shaped uterine cavity on HSG or MRI

• MRI (gold standard): characterises the rudimentary horn precisely
• 3D transvaginal USS
• HSG: shows single banana-shaped cavity (cannot visualise non-communicating horn)
• Laparoscopy: confirms external morphology
• Renal USS mandatory

• Miscarriage rate ~36%
• Preterm delivery ~20%
• IUGR, malpresentation
• Rudimentary horn ectopic: extremely dangerous rupture

• Rudimentary horn with endometrium (communicating or non-communicating): MUST be excised laparoscopically on diagnosis - risk of ectopic pregnancy and hematometra
• Rudimentary horn without endometrium: excision optional (to confirm diagnosis and prevent torsion)
• Pure unicornuate: conservative management; enhanced antenatal surveillance for preterm birth
• Cervical cerclage: may be considered for cervical incompetence
• No surgical unification available for the main uterine horn

---

CLASS III: Uterus Didelphys

• Two complete, separate uterine bodies
• Two separate cervices (bicollis)
• Often two vaginas (divided by a longitudinal septum)

• Often asymptomatic - discovered incidentally
• Dyspareunia if longitudinal vaginal septum present
• Two cervical os on speculum examination
• May present with obstructed hemivagina in Herlyn-Werner-Wunderlich (OHVIRA) syndrome:
  • Uterus didelphys + obstructed hemivagina + ipsilateral renal agenesis
  • Presents at menarche with cyclic pain but apparent normal menstruation (from non-obstructed side)
  • Hematocolpos on obstructed side

• Pelvic MRI or 3D USS: two complete uterine bodies, two cervices
• HSG: shows two completely separate cavities
• Renal USS (especially if OHVIRA suspected)

• Unification surgery (Strassman metroplasty) is NOT recommended for didelphys - outcomes do not improve and risks are significant
• Longitudinal vaginal septum: Excision if causing dyspareunia or obstructed delivery - otherwise can be left
• OHVIRA syndrome: Surgical excision of vaginal septum/drainage of obstructed hemivagina urgently (to prevent pyocolpos, endometriosis, retrograde flow)
• Enhanced antenatal surveillance for preterm birth

---

CLASS IV: Bicornuate Uterus

• Two uterine horns joined at the lower uterine segment/cervix
• Single or double cervix (bicollis or unicollis)
• External fundal indentation/cleft >1 cm on laparoscopy/MRI

BICORNUATE                  SEPTATE
   __  __                   ________
  /  \/  \                 /        \
 |    /\  |               |   /\    |
  \__/  \__/               \__/  \__/
Indented fundus          Normal/convex fundus
Two cavities             Two cavities

• Recurrent miscarriage (particularly second trimester)
• Preterm delivery
• Abnormal fetal presentation at term
• Cervical incompetence

• MRI (gold standard): Fundal contour + internal morphology; T2-weighted images distinguish myometrium from fibrous septum
• 3D transvaginal USS: Comparable to MRI, emerging first-line
• HSG: shows two cavities but cannot characterise external contour
• Combined laparoscopy + hysteroscopy: traditional gold standard; visualises external fundal contour and internal cavity simultaneously

• Miscarriage ~36%, preterm birth ~23%, malpresentation ~40%

• Strassman metroplasty (abdominal unification of the two horns): Controversial; evidence for improved outcomes is limited and surgery carries risk of uterine rupture in subsequent pregnancies
• Most recent evidence (RCOG 2025): Surgical treatment for bicornuate uterus is not usually recommended - risks outweigh potential benefits
• Enhanced antenatal surveillance
• Cervical cerclage if recurrent second trimester loss
• Progesterone supplementation for recurrent miscarriage

---

CLASS V: Septate Uterus (Most Common Clinically Significant Anomaly)

• Complete septum: Extends from fundus to internal or external cervical os (may divide cervix too)
• Partial/Subseptate: Extends from fundus but does not reach internal os
• Very rarely: Complete cervicovaginal septum as well

• Highest rate of reproductive failure of all uterine anomalies
• Recurrent first trimester miscarriage (the predominant presentation)
• Infertility (less common - may be discovered on workup)
• Second trimester loss
• Preterm labour
• Malpresentation
• Often entirely asymptomatic until reproductive failure occurs

• 3D transvaginal USS: Best initial investigation - normal external contour with internal division
• MRI: Confirms normal external contour; T2 shows low signal fibrous septum vs. intermediate myometrial signal in bicornuate
• Sonohysterography (SIS + 3D): Excellent for delineating septum
• HSG: Shows two cavities with acute angle between them; cannot characterise external contour
• Hysteroscopy: Visualises septum directly; gold standard for cavity assessment
• Combined laparoscopy + hysteroscopy: To confirm normal external contour if doubt remains

• Septum depth >50% of uterine wall thickness on 3D USS
• Fundal internal indentation >10 mm (AFS criterion)

1. Hysteroscopic septal incision using scissors, monopolar/bipolar electrosurgery, or Holmium:YAG laser
2. No uterine wall incision; outpatient or day procedure
3. Recovery within days; pregnancy allowed after 1-3 menstrual cycles
4. Concomitant laparoscopy may be done to confirm normal external contour

• Hysteroscopic metroplasty significantly reduces rates of pregnancy loss in septate uterus
• Does NOT significantly improve infertility rates
• Post-operative miscarriage rate drops from ~60% to ~10-15%

---

CLASS VI: Arcuate Uterus

• Usually clinically insignificant
• Live birth rates comparable to women with normal uteri
• May be a normal variant - considered borderline between normal and abnormal
• Some studies suggest mild increase in second trimester loss (controversial)

---

CLASS VII: DES-Related Anomaly (Diethylstilbestrol)

• T-shaped uterus (characteristic)
• Hypoplastic uterine cavity
• Constriction rings
• Irregular contour

• Infertility
• Recurrent miscarriage
• Ectopic pregnancy (7-fold increased risk)
• Second trimester loss
• Cervical incompetence
• Preterm labour
• Clear cell adenocarcinoma of vagina/cervix (daughters of DES-exposed mothers)

---

5. Prevalence and Reproductive Impact Summary

---

6. Investigations - Systematic Approach

Step 1: Clinical Evaluation

• History: menstrual pattern, obstetric history (recurrent miscarriage, preterm birth), pain
• Examination: cervical os assessment (single or double), vaginal assessment

Step 2: Imaging

ALGORITHM FOR DIAGNOSIS:

2D Transvaginal USS
(sensitivity only 44% for malformations - limited)
         ↓ If abnormality suspected
3D Transvaginal Ultrasound
(first-line confirmatory - comparable to MRI, non-invasive)
         ↓ If complex anomaly or doubt
Pelvic MRI (Gold standard overall)
• Distinguishes septate vs. bicornuate
• Characterises rudimentary horns  
• Evaluates renal anatomy simultaneously
         ↓ For cavity evaluation
Hysteroscopy (gold standard for cavity)
         ↓ If combined external + internal characterisation needed
Laparoscopy + Hysteroscopy combined

Step 3: Mandatory Associated Investigations

• Renal USS (mandatory for any Mullerian anomaly - renal agenesis in 30-40%)
• Karyotype (if primary amenorrhea - to exclude AIS, Turner syndrome)
• Hormonal profile: FSH, LH, E2, AMH (assess ovarian reserve)
• HSG: useful for tubal assessment concomitantly

Imaging Comparison Table

2025 evidence: A meta-analysis (PMID 40628082) confirms 3D TVS performs comparably to MRI for diagnosing and classifying congenital uterine anomalies - positioning it as the preferred non-invasive first-line confirmatory test.

---

7. Management Overview

Conservative (Most Anomalies)

• Reassurance
• Enhanced antenatal surveillance (preterm birth risk)
• Progesterone supplementation in recurrent miscarriage
• Cervical cerclage for mid-trimester losses with cervical insufficiency

Surgical Indications and Procedures

RCOG 2025 Key Guidance (Scientific Impact Paper No. 62):

• Surgical treatment may be considered for septate uterus with recurrent miscarriage
• Evidence is inconclusive and conflicting for improved live birth rates - counsel women accordingly
• Surgical treatment for other CUAs is not usually recommended - risks outweigh benefits
• All women with CUAs should receive preterm birth surveillance protocols
• Women with CUAs should be screened for renal anomalies

---

8. Obstetric Complications and Antenatal Care

• Recurrent first/second trimester miscarriage
• Preterm premature rupture of membranes (PPROM)
• Preterm birth (even after surgical correction of septate uterus)
• IUGR and fetal growth restriction
• Pre-eclampsia
• Fetal malpresentation (especially breech) - increased caesarean rate
• Placenta praevia, placenta accreta
• Retained placenta, postpartum haemorrhage
• Uterine rupture (particularly with rudimentary horn pregnancy)

Antenatal Surveillance Protocol:

1. Early USS to confirm intrauterine location and viability (exclude ectopic)
2. Serial cervical length monitoring from 16 weeks (preterm risk)
3. Serial fetal growth scans from 24 weeks
4. Presentation assessment from 36 weeks
5. Delivery planning: vaginal delivery possible in most; caesarean if malpresentation or uterine rupture risk

---

9. Key Differentiating Points (Exam Focus)

---

---

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)