A bicornuate bicollis uterus is a congenital uterine malformation in which the uterus has two separate horns (cornua) and two separate cervices, rather than the single pear-shaped cavity and single cervix most women are born with. It belongs to a broader family of Müllerian duct anomalies and sits in an unusual spot between the more commonly discussed bicornuate unicollis uterus (two horns, one cervix) and the uterus didelphys (two fully independent uterine bodies). Many people who have one go years without knowing it, often learning about it only during pregnancy or a workup for recurrent losses.
How a Bicornuate Bicollis Uterus Forms
During early fetal development, two tube-like structures called Müllerian ducts normally fuse together and then remodel into a single uterine cavity, a single cervix, and the upper portion of the vagina. When this fusion process is incomplete at the top but proceeds normally at the bottom, you get a bicornuate uterus with one cervix. When the lower portion also fails to fully unify, you end up with two cervices as well, producing the bicornuate bicollis variant. The fusion and reabsorption steps can be disrupted to different degrees along the length of the ducts, which is why the spectrum of anomalies is so wide and why some cases do not fit neatly into any single classification box.1PubMed Central. Müllerian anomalies “without a classification”: from the didelphys-unicollis uterus to the bicervical uterus with or without septate vagina
A longitudinal vaginal septum frequently accompanies the bicollis form, dividing the vaginal canal partially or completely. One case report describes the full picture as a bicornuate bicollis uterus with a complete longitudinal vaginal septum, classified under the European Society of Human Reproduction and Embryology (ESHRE/ESGE) system as U3b/C2/V1 and under the 2021 American Society for Reproductive Medicine (ASRM) system as bicornuate bicollis with complete longitudinal vaginal septum.2PubMed Central. An Uncommon Encounter: Obstetric Management of a Bicornuate Bicollis Uterus With a Longitudinal Vaginal Septum That string of alphanumeric codes matters mainly to your clinical team; what matters to you is that the condition involves a deep split at the top of the uterus, two cervical openings, and sometimes a divided vagina.
Where It Sits Among Uterine Anomalies
The newer ESHRE/ESGE classification system refers to what was traditionally called a bicornuate uterus as a “bicorporeal” uterus.3PubMed Central. Mullerian anomalies: revisiting imaging and classification The bicollis variant specifically is one where the two-cervix feature pushes it close to the territory of uterus didelphys, which also has two horns and two cervices but is defined by a more complete separation of the uterine bodies. In practice, the distinction can be subtle enough that imaging alone sometimes cannot tell them apart, and the clinical overlap is substantial. Twin pregnancies occurring with one fetus in each horn (called dicavitary twins) can happen in both didelphys and bicornuate bicollis uteri, and the management principles are similar.4PubMed Central. Dicavitary twin pregnancy in patient with bicornuate bicollis uterine anomaly
The practical takeaway is that if you have been told you have a bicornuate bicollis uterus, your doctors may also discuss findings in didelphys-related literature because the two conditions share many of the same pregnancy risks and management strategies.
How It Gets Diagnosed
A bicornuate bicollis uterus can be discovered incidentally during a pelvic exam (when a clinician notices two cervical openings), during imaging for another reason, or during a surgical procedure. Historically, the gold standard for diagnosing uterine anomalies was a combined laparoscopy and hysteroscopy, but that requires going into the operating room.5PubMed Central. Diagnosis of Congenital Uterine Abnormalities: Practical Considerations Three-dimensional ultrasound has largely taken over as the first-line tool because it is noninvasive, relatively inexpensive, and quite accurate.
Studies comparing 3D ultrasound to MRI for classifying Müllerian anomalies find strong agreement between the two methods. One retrospective study reported concordance between 3D ultrasound and MRI at about 96% when using the ESHRE/ESGE classification.6PubMed. The accuracy of three-dimensional ultrasonography in the diagnosis of Müllerian duct anomalies and its concordance with magnetic resonance imaging MRI does hold an edge in overall diagnostic accuracy. A comparative study found MRI had a sensitivity of about 95% and specificity of about 90%, while 3D ultrasound came in at roughly 89% and 85%, respectively.7PubMed Central. Comparing the Diagnostic Efficacy of 3D Ultrasound and MRI in the Classification of Müllerian Anomalies For the bicorporeal (bicornuate) subtype specifically, 3D ultrasound showed a sensitivity of about 83% but perfect specificity, meaning it rarely called something bicorporeal when it was not.8Ultrasound in Obstetrics & Gynecology. Accuracy of three‐dimensional ultrasound compared with magnetic resonance imaging in diagnosis of Müllerian duct anomalies using ESHRE–ESGE consensus on the classification of congenital anomalies of the female genital tract
In many clinical pathways, an abnormal finding on 3D ultrasound prompts a confirmatory MRI, especially when the exact subtype affects management. In the bicollis case described earlier, the two cervices were visible on speculum exam, and MRI confirmed the full anatomy of the malformation.9PubMed Central. An Uncommon Encounter: Obstetric Management of a Bicornuate Bicollis Uterus With a Longitudinal Vaginal Septum
Kidney and Other Associated Conditions
Because the Müllerian ducts and the kidneys develop in close proximity during fetal life, uterine anomalies often come with kidney abnormalities. Among women with a complete bicornuate uterus, about a quarter in one study had unilateral renal agenesis, meaning one kidney never formed. In two of those cases, the missing kidney was on the same side as an obstructive vaginal septum. Partial bicornuate uteri had a much lower rate of kidney problems, closer to 4%.10Clinical Obstetrics, Gynecology and Reproductive Medicine. Renal tract malformations associated with Müllerian duct anomalies For this reason, if you are diagnosed with a bicornuate bicollis uterus, your doctor will likely order imaging of your kidneys as well.
Endometriosis is another condition that may be more common or more severe in the presence of uterine malformations. The altered uterine anatomy can promote retrograde menstruation, where menstrual blood flows backward through the fallopian tubes into the pelvis instead of out through the cervix. One documented case involved a woman with a bicornuate uterus and left renal agenesis who had years of painful periods and pain during sex; imaging revealed an associated endometriotic mass.11Clínica e Investigación en Ginecología y Obstetricia. Description of a case of endometriosis associated with a bicornuate uterus: Role of uterine malformations in endometriosis When both conditions coexist, symptoms tend to be severe and may appear at a younger age than typical endometriosis.
Effects on Fertility
The evidence on whether a bicornuate uterus lowers your chances of getting pregnant is not as clear-cut as many online sources imply. Some older data suggested that bicornuate, didelphic, unicornuate, and septate uteri all produce lower pregnancy rates with assisted reproduction compared to a normal uterus.12Europe PMC. Reproductive outcomes in women with uterine anomalies But a more recent study looking specifically at IVF and related treatments found no significant differences in ovarian response, pregnancy rates, or obstetric outcomes between women with a bicornuate uterus and those with a normal one.13PubMed. Effects of bicornuate uterus on pregnancy and obstetric outcomes of in vitro fertilization / intracytoplasmic sperm injection
That said, other research paints a less optimistic picture. A study using frozen embryo transfers found that women with a bicorporeal uterus had a live birth rate of about 24% per cycle compared to about 35% in matched controls.14Human Reproduction. Impact of uterine malformations on pregnancy and neonatal outcomes of IVF/ICSI–frozen embryo transfer A separate retrospective study found that women with “unification defects” (the category that includes bicornuate uteri) had lower clinical pregnancy rates, lower live birth rates, and higher early miscarriage rates compared to women with normal uteri.15European Journal of Medical Research. Impact of congenital uterine anomalies on reproductive outcomes of IVF/ICSI-embryo transfer: a retrospective study
The conflicting data probably reflects differences in study design, patient populations, and how “bicornuate uterus” is defined across classification systems. The honest summary is that a bicornuate bicollis uterus does not make pregnancy impossible, but it likely shifts the odds somewhat, particularly around miscarriage risk and the chance of carrying to term.
Pregnancy Risks
The most consistently documented risks for pregnant women with a bicornuate uterus are miscarriage, preterm birth, and fetal malpresentation (such as breech). Congenital uterine anomalies as a group are associated with recurrent pregnancy loss in both the first and second trimesters.16PubMed. Uterine factor in recurrent pregnancy loss One analysis specifically found that women with a bicornuate uterus had significantly more second-trimester miscarriages, at roughly 14%, compared to about 1% in controls.17PubMed. The pattern of pregnancy loss in women with congenital uterine anomalies and recurrent miscarriage
Congenitally malformed uteri are also linked to intrauterine growth restriction, premature rupture of membranes, and stillbirth.18PubMed Central. Corrected evaluation of the breech presentation outcome based on etiology of this presentation in congenitally malformed uterus The limited space inside each horn can restrict the baby’s ability to turn head-down, which explains the higher rate of breech positioning. One case report of a bicornuate bicollis uterus described a history of cesarean delivery due to low amniotic fluid, followed in a later pregnancy by a ruptured ectopic pregnancy, illustrating the range of complications that can arise across multiple pregnancies.19PubMed Central. An Uncommon Encounter: Obstetric Management of a Bicornuate Bicollis Uterus With a Longitudinal Vaginal Septum
Uterine Rupture in a Bicornuate Uterus
One of the more alarming risks, though uncommon, is uterine rupture. In a normal uterus, rupture almost always happens at the site of a prior surgical scar, such as a previous cesarean incision. In a bicornuate uterus, rupture can happen spontaneously, even without any prior surgery, because the wall of the malformed horn may thin out unevenly as the pregnancy grows.20International Medical Case Reports Journal. Second Trimester Spontaneous Fundal Rupture of Unscarred Bicornuate Uterus in Primipara: A Case Report and Literature Review The fibrous band connecting the two horns can also limit expansion, putting extra stress on the uterine wall.21Case Reports in Women’s Health. Mid-trimester spontaneous rupture of a bicornuate uterus: A case report
Case reports have documented rupture at various gestational ages, including one at around 30 weeks triggered by prostaglandin induction in a patient with eclampsia, where the right horn tore from the top downward about 8 cm along the back wall.22PubMed Central. Rupture of bicornuate uterus These reports are rare, but they underscore why pregnancies in women with known bicornuate uteri are monitored more closely than average and why labor induction decisions need careful thought.
Cervical Cerclage and Preterm Birth Prevention
Because preterm birth is one of the main threats, cervical cerclage (a stitch placed around the cervix to help keep it closed) is sometimes used in women with Müllerian anomalies who have a history of preterm delivery or cervical insufficiency. The evidence here is limited to small studies and case reports, but what exists is encouraging. In one study of women with a bicornuate uterus, those who received a cerclage delivered at term about 76% of the time, compared to only about 27% of those who did not receive one.23PubMed Central. The Role of Cervical Cerclage in Pregnancy Outcome in Women with Uterine Anomaly
A case report further illustrates the potential benefit: a woman with a bicorporeal uterus and two prior preterm births (at 23 to 24 weeks and 28 to 29 weeks) received a cerclage at around 14 weeks of her third pregnancy. She made it to 36 to 37 weeks before delivering a healthy baby by emergency cesarean.24SAGE Open Medical Case Reports. Usage of cervical cerclage in pregnancy with Mullerian anomalies and cervical insufficiency: A case report The report notes that roughly half of pregnancies in a bicorporeal uterus reach term, and the other half end as early preterm losses, making the potential gain from cerclage significant for the right patients. Guidelines for cerclage use in Müllerian anomalies are not well established, so the decision remains a case-by-case judgment.
Surgical Correction With Metroplasty
For women with a bicornuate uterus who experience repeated pregnancy losses and have no other identifiable cause, surgical correction through a procedure called Strassman metroplasty may be considered. The surgery unifies the two horns into a single, more spacious cavity. It has been performed as both an open abdominal procedure and laparoscopically. One report describes a woman who had six miscarriages and secondary infertility before undergoing laparoscopic metroplasty, then went on to deliver a baby by cesarean section.25PubMed Central. Successful Reproductive Outcome After Laparoscopic Strassmann’s Metroplasty Another documents a successful term pregnancy after open metroplasty.26PubMed Central. Successful Pregnancy Outcome after Open Strassman Metroplasty for Bicornuate Uterus
Metroplasty is not without its own risks. A pregnancy after the procedure carries a scar on the uterine wall, and the uterus may not contract or respond to contraction-inducing medications as effectively during labor. One case report documented placenta percreta (where the placenta grows through the uterine wall) after metroplasty of a complete bicornuate uterus, leading to severe postpartum hemorrhage.27BMC Pregnancy and Childbirth. Placenta percreta after Strassman metroplasty of complete bicornuate uterus: a case report For this reason, any pregnancy after metroplasty is treated as high-risk, and cesarean delivery is typically planned well in advance.
Delivery Planning
Even without prior surgery, cesarean delivery is common in pregnancies complicated by a bicornuate bicollis uterus. The reasons accumulate: breech presentation, the nongravid horn potentially obstructing the birth canal, and the elevated risk of rupture during labor all tilt the balance toward a planned cesarean. In one reported case, the nongravid side of a bicornuate bicollis uterus obstructed the lower segment of the gravid side, causing the cervix to prolapse and making cesarean delivery the only safe option.28Case Reports in Obstetrics and Gynecology. Bicornuate Bicollis Uterus with Obstruction of the Lower Uterine Segment and Cervical Prolapse Complicating Pregnancy
When twins develop with one in each horn, the delivery picture becomes more complex. One case documented an uncomplicated spontaneous vaginal delivery of the first twin followed by a delayed spontaneous delivery of the second, which is unusual and reflects the essentially independent labor dynamics of two separate uterine cavities.29Journal of Medical Case Reports. Peripartal management of dichorial twin pregnancy in a bicornuate bicollis uterus: a case report and review of the literature Still, careful planning around mode of delivery and type of uterine incision (if cesarean is chosen) is always necessary.30PubMed Central. Dicavitary twin pregnancy in patient with bicornuate bicollis uterine anomaly
Contraception Considerations
If you have a bicornuate bicollis uterus and are considering an intrauterine device (IUD) for contraception, there are some practical wrinkles worth knowing about. A review of available evidence on IUD use in women with uterine anomalies found that pregnancies sometimes occurred in the horn opposite the one containing the IUD, suggesting that a single IUD may not effectively cover both cavities.31International Journal of Gynecology & Obstetrics. Use of intrauterine devices in women with uterine anatomic abnormalities That means some clinicians will place an IUD in each horn when the anatomy allows it.
Expulsion rates are also higher than in women with a normally shaped uterus. A small case series following IUD use in uterine anomalies reported a 40% expulsion rate, with all expulsions happening within the first four weeks of placement. The authors pointed out that early expulsion of an IUD could itself be a clue to an undiagnosed uterine anomaly.32PubMed. Levonorgestrel Intrauterine Device Placement in Uterine Anomalies: A Case Series Ultrasound or hysteroscopy at the time of placement helps confirm the IUD is positioned correctly within the available cavity, and follow-up imaging within the first month is a reasonable precaution.
Symptoms Outside of Pregnancy
Many women with a bicornuate bicollis uterus have no symptoms at all outside of reproductive challenges. Some, however, experience heavy or prolonged periods, pelvic pain, or dysmenorrhea (painful periods), particularly when a vaginal septum is present and partially obstructs menstrual flow from one side. When the anatomy promotes retrograde menstruation, endometriosis can develop, sometimes at a younger age and with more intense symptoms than in women without uterine malformations.33Clínica e Investigación en Ginecología y Obstetricia. Description of a case of endometriosis associated with a bicornuate uterus: Role of uterine malformations in endometriosis If you have been diagnosed with this anomaly and experience worsening pelvic pain, it is worth raising the possibility of endometriosis with your gynecologist, since the two conditions can compound each other.