What is a didelphys uterus?

Didelphys Uterus: Definition and Clinical Significance

Didelphys uterus (uterus didelphys) is a congenital Müllerian duct anomaly characterized by complete duplication of the uterus, resulting in two separate, non-communicating uterine horns, each with its own cervix, and often accompanied by a double vagina or longitudinal vaginal septum. 1, 2, 3

Embryologic Basis

• This anomaly occurs due to complete failure of fusion of the paired Müllerian (paramesonephric) ducts during embryonic development 2, 4
• Each uterine horn has its own cervix and fallopian tube 3, 5
• Vaginal duplication may be present, with either two separate vaginas or a longitudinal vaginal septum dividing the vaginal canal 6, 4
• Uterus didelphys constitutes approximately 5-11% of all Müllerian duct anomalies 5

Clinical Presentation

• Most women with uterus didelphys are asymptomatic and the condition is often discovered incidentally during pregnancy, gynecologic examination, or imaging for other indications 2, 6, 4
• When symptomatic, patients may experience dysmenorrhea, dyspareunia, or vaginal bleeding 1, 4
• The anomaly may be associated with infertility, though many women conceive naturally 6, 4

Diagnostic Approach

MRI is the gold standard for diagnosing and classifying uterus didelphys with 100% accuracy in surgically proven Müllerian duct anomalies, as recommended by the American College of Radiology. 7

• 3D transvaginal ultrasound (TVUS) serves as an excellent alternative with 92% accuracy in classification of Müllerian duct anomalies 7
• Hysterosalpingography (HSG) has poor accuracy (only 16.7%) and cannot reliably differentiate between septate and bicornuate uterus, making it inadequate for diagnosing uterus didelphys 7
• On imaging, uterus didelphys shows two completely separate uterine horns with two cervices, distinguishing it from other anomalies like septate or bicornuate uterus 1

Key Imaging Features

• Two distinct endometrial cavities that do not communicate 1
• Two separate cervical canals 3, 6
• Fundal cleft depth helps differentiate from bicornuate uterus: a cleft >1 cm suggests bicornuate rather than septate uterus, though didelphys shows complete separation 7
• Vaginal septum or complete vaginal duplication may be visualized 6, 4

Obstetric Implications and Management

Pregnancies in women with uterus didelphys are considered high-risk due to increased rates of miscarriage, preterm labor, fetal malpresentation (especially breech), and need for cesarean delivery. 3, 4

Pregnancy Complications

• Higher risk of preterm labor and delivery 3, 4
• Increased incidence of fetal growth restriction 6
• Breech presentation is common due to limited uterine cavity space 6, 4
• Risk of cervical insufficiency requiring cerclage 3, 6
• Rare possibility of pregnancy in one uterus with prolapse of the other 2
• Extremely rare occurrence of twin pregnancy with one fetus in each uterine cavity (approximately 1 in 1,000) 5

Pregnancy Management Considerations

• Cervical length monitoring is essential, with cerclage considered for short cervix (<2.5 cm) 6
• Progesterone supplementation may be used for cervical insufficiency 6
• Cesarean section should be strongly considered, particularly when vaginal septum is present, as it can obstruct vaginal delivery 3, 4
• Close prenatal monitoring is required throughout pregnancy 3, 6

Clinical Pitfalls

• The condition may be missed on routine examination if not specifically evaluated 6, 4
• During cesarean section, surgeons must be aware that a second gravid uterus may be present if twin pregnancy exists in both cavities 5
• Proper imaging terminology should specify gestational sac location relative to the uterine anomaly (e.g., "GS in right horn of didelphys uterus") rather than using imprecise terms 7
• The presence of a vaginal septum can complicate vaginal examination and delivery, requiring surgical consideration 6, 4

Prognosis

• Despite the anatomic abnormality, successful pregnancy outcomes with term delivery are achievable with appropriate prenatal care and monitoring 2, 3, 6
• Uterus didelphys is associated with better reproductive outcomes compared to other Müllerian duct anomalies 3
• Decreased live birth rates compared to normal uterine anatomy, but many women achieve successful pregnancies 4