[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Embryology](https://durgical.com/en/embryology/) › [Urogenital system](https://durgical.com/en/embryology/#a-urogenital) › Uterine anomalies: bicornuate, septate, didelphys, Müllerian agenesis [Embryology](https://durgical.com/en/embryology/) · [Urogenital system](https://durgical.com/en/embryology/#a-urogenital) # Uterine anomalies: bicornuate, septate, didelphys, Müllerian agenesis - Malformation The uterus forms when two tubes join; if they never join, join halfway or never form, the uterus ends up double, divided or absent. Updated 2026-11-01 **See it in 3D:** [Body of uterus](https://durgical.com/en/anatomy/body-of-uterus/) · [Fundus of uterus](https://durgical.com/en/anatomy/fundus-of-uterus/) · [Cervix](https://durgical.com/en/anatomy/cervix-of-uterus/) · [Vagina](https://durgical.com/en/anatomy/vagina/) · [Uterine tubes](https://durgical.com/en/anatomy/uterine-tube/) · [Ovaries](https://durgical.com/en/anatomy/ovary/) · [Kidneys](https://durgical.com/en/anatomy/kidney/) ## Key points - Failure of formation: agenesis (MRKH) if both ducts are missing; unicornuate uterus if one is. - Failure of fusion: uterus didelphys (no fusion, two cervices) or bicornuate (partial fusion, fundus with an external cleft). - Failure of septal resorption: septate uterus, the commonest and the one with most pregnancy losses. - MRKH: 46,XX, normal ovaries, normal secondary sex characteristics, primary amenorrhoea. - They are associated with same-side kidney anomalies, such as renal agenesis. - Fetal exposure to diethylstilbestrol produces a T-shaped uterus. ## What it is Müllerian anomalies are errors in the formation, fusion or septal resorption of the paramesonephric ducts. They range from the septate uterus, the commonest, to complete agenesis of the uterus and upper vagina (Mayer-Rokitansky-Küster-Hauser syndrome). They usually show up as amenorrhoea, infertility, pregnancy loss or preterm birth, and often come with kidney anomalies. ## Embryological cause - Weeks 6–8: the Müllerian ducts form beside the Wolffian ducts; if one fails to form or elongate, a unicornuate uterus results. - Weeks 9–12: the caudal ends fuse in the midline; absent fusion gives uterus didelphys and partial fusion a bicornuate uterus. - After fusion, the septum between them must resorb from below upward; if it persists, the uterus is septate or arcuate. - MRKH: the Müllerian ducts fail to develop; the ovary, of separate origin, is normal. The genes involved are not fully known; WNT4 explains one form with hyperandrogenism. - Closeness to the Wolffian duct explains the link with renal agenesis or ectopia. ## Markers - HOXA10 - HOXA13 - WNT4 ## How it presents - MRKH: a teenager with normal breasts and hair and primary amenorrhoea; short or absent vagina. - Septate uterus: recurrent miscarriage, especially in the second trimester. - Bicornuate or didelphys uterus: preterm birth, malpresentation; sometimes a double vagina. - Obstructed hemivagina: cyclic pain and a pelvic mass after menarche. - Many mild anomalies cause no symptoms and are found during fertility work-up. ## Diagnosis - 3D ultrasound: shows the outer contour of the uterine fundus and the cavity. - MRI: the standard for classifying and planning; separates septate (smooth outer fundus) from bicornuate (external cleft). - Hysterosalpingography and hysteroscopy: cavity and septa. - Renal ultrasound in every Müllerian anomaly; karyotype in primary amenorrhoea without a uterus to separate MRKH from androgen insensitivity. ## Memory aid “Three mistakes of two tubes: not forming (agenesis, unicornuate), not joining (didelphys, bicornuate) or not clearing the wall (septate).” ## Test yourself Think of the answer, then tap the question to see it. ## Which embryological failure produces a septate uterus? Failure to resorb the septum left between the Müllerian ducts after they fuse. ## How is a septate uterus told apart from a bicornuate uterus on imaging? The septate uterus has a smooth or nearly smooth outer fundal contour; the bicornuate uterus shows an external fundal cleft. ## What separates MRKH from complete androgen insensitivity when both have primary amenorrhoea without a uterus? In MRKH the karyotype is 46,XX with normal ovaries and pubic hair; in complete insensitivity it is 46,XY, with testes and sparse hair. ## Why is a renal ultrasound requested for a Müllerian anomaly? Because the Müllerian ducts depend on the Wolffian duct, which gives rise to the ureteric bud, and renal agenesis or ectopia often coexists. [Add to my cards (4)](https://durgical.app/estudiar/?add=/en/embryology/uterine-anomalies-bicornuate-septate-didelphys-mullerian-agenesis/) ## See it in 3D The structures of Durgical's 3D anatomy where it is found. - [Body of uterus](https://durgical.com/en/anatomy/body-of-uterus/) - [Fundus of uterus](https://durgical.com/en/anatomy/fundus-of-uterus/) - [Cervix](https://durgical.com/en/anatomy/cervix-of-uterus/) - [Vagina](https://durgical.com/en/anatomy/vagina/) - [Uterine tubes](https://durgical.com/en/anatomy/uterine-tube/) - [Ovaries](https://durgical.com/en/anatomy/ovary/) - [Kidneys](https://durgical.com/en/anatomy/kidney/) ## Related - [Genital ducts: Wolffian (mesonephric) and Müllerian (paramesonephric)](https://durgical.com/en/embryology/genital-ducts-wolffian-and-mullerian/) - [Sex determination: SRY, anti-Müllerian hormone and testosterone](https://durgical.com/en/embryology/sex-determination-sry-anti-mullerian-hormone-and-testosterone/) - [Renal agenesis and the Potter sequence](https://durgical.com/en/embryology/renal-agenesis-and-the-potter-sequence/) - [Differences of sex development: CAH, AIS and 5α-reductase](https://durgical.com/en/embryology/differences-of-sex-development-cah-ais-and-5-reductase/) - [Androgens, diethylstilbestrol and other hormones](https://durgical.com/en/embryology/androgens-diethylstilbestrol-and-other-hormones/) [← All of embryology](https://durgical.com/en/embryology/) Educational content on embryonic development; not a guide to prenatal diagnosis or to medicines in pregnancy and no substitute for a health professional's advice. No doses are given. Sources: [Mayer-Rokitansky-Küster-Hauser syndrome: MedlinePlus Genetics](https://medlineplus.gov/genetics/condition/mayer-rokitansky-kuster-hauser-syndrome/) (MedlinePlus, U.S. National Library of Medicine, 2024); [Embryology, Sexual Development - StatPearls - NCBI Bookshelf](https://www.ncbi.nlm.nih.gov/books/NBK557601/) (StatPearls Publishing (NCBI Bookshelf), 2023). ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/embryology/uterine-anomalies-bicornuate-septate-didelphys-mullerian-agenesis/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/embryology/uterine-anomalies-bicornuate-septate-didelphys-mullerian-agenesis/