A bicornuate uterus or bicornate uterus (from the Latin ''cornū'', meaning "horn"), is a type of Müllerian anomaly in the human

uterus The uterus (from Latin ''uterus'', : uteri or uteruses) or womb () is the hollow organ, organ in the reproductive system of most female mammals, including humans, that accommodates the embryonic development, embryonic and prenatal development, f ...

, where there is a deep indentation at the fundus (top) of the uterus.

Pathophysiology

A bicornuate uterus develops during

embryogenesis An embryo ( ) is the initial stage of development for a multicellular organism. In organisms that reproduce sexually, embryonic development is the part of the life cycle that begins just after fertilization of the female egg cell by the male ...

. It occurs when the proximal (upper) portions of the

paramesonephric ducts The paramesonephric ducts (or Müllerian ducts) are paired ducts of the embryo in the reproductive system of humans and other mammals that run down the lateral sides of the genital ridge and terminate at the sinus tubercle in the primitive urogen ...

do not fuse, but the distal portions that develops into the lower uterine segment, cervix, and upper vagina fuse normally.

Diagnosis

Diagnosis of bicornuate uterus typically involves imaging of the uterus with 2D or 3D

ultrasound Ultrasound is sound with frequency, frequencies greater than 20 Hertz, kilohertz. This frequency is the approximate upper audible hearing range, limit of human hearing in healthy young adults. The physical principles of acoustic waves apply ...

hysterosalpingography Hysterosalpingography (HSG), also known as uterosalpingography, is a radiology, radiologic procedure to investigate the shape of the uterine cavity and the shape and patency of the fallopian tubes. It is a special x-ray procedure using Contrast ...

, or

magnetic resonance imaging Magnetic resonance imaging (MRI) is a medical imaging technique used in radiology to generate pictures of the anatomy and the physiological processes inside the body. MRI scanners use strong magnetic fields, magnetic field gradients, and ...

(MRI). On imaging, a bicornuate uterus can be distinguished from a septate uterus by the angle between the cornua (intercornual angle): less than 75 degrees in a septate uterus, and greater than 105 degrees in a bicornuate uterus. Measuring the depth of the cleft between the cornua (fundal cleft) may also assist in diagnosis; a cleft of over is indicative of bicornuate uterus.

Classification

Bicornuate uterus is typically classified based on whether or not the division extends to the external cervical os. Bicornuate uteri with a division above the os are called ''bicornuate unicollis'' and those with a divided os are called ''bicornuate bicollis.'' There is a continuous range of the degree and location of the fusion of the

, and existence of a spectrum, rather than a fixed number of types corresponding to strict medical definitions. Two processes that occur during the embryonic development of the paramesonephric ducts — fusion and reabsorption — can be affected to different degrees. There is also a ''hybrid bicornuate uterus:'' External fundal depressions of variable depths associated with a septate uterus can be seen by laparoscopy, indicating the coexistence of the two anomalies. These cases are candidates for hysteroscopic metroplasty under appropriate sonographic and/or laparoscopic monitoring. An ''obstructed bicornuate uterus'' showing uni or bilateral obstruction might also be possible. The unilateral obstruction is more difficult to diagnose than the bilateral obstructive. A delay in the diagnosis can be problematic and compromise the reproductive abilities of those cases.

Treatment

Bicornuate uterus typically requires no treatment. In those who do need treatment,

metroplasty Metroplasty (also called Strassman metroplasty, uteroplasty or hysteroplasty) is a reconstructive surgery used to repair congenital anomalies of the uterus The uterus (from Latin ''uterus'', : uteri or uteruses) or womb () is the hollow org ...

is the surgical correction of choice. Women who have recurrent miscarriage with no other explanation may benefit from surgery.

Epidemiology

The occurrence of all types of paramesonephric duct abnormalities in women is estimated around 0.4%. A bicornuate uterus occur in 0.4% of the general population.

In pregnancy

A bicornuate uterus is an indication for increased surveillance of a pregnancy, though most women with a bicornuate uterus are able to have healthy pregnancies. Women with a bicornuate uterus are at an increased risk of

recurrent miscarriage Recurrent miscarriage or recurrent pregnancy loss (RPL) is the spontaneous loss of 2-3 pregnancies that is estimated to affect up to 5% of women. The exact number of pregnancy losses and gestational weeks used to define RPL differs among medic ...

, preterm birth, malpresentation, disruptions to fetal growth, premature rupture of membranes,

placenta previa Placenta praevia or placenta previa is when the placenta attaches inside the uterus but in a position near or over the cervical opening. Symptoms include antepartum bleeding, vaginal bleeding in the second half of pregnancy. The bleeding is bright ...

and retained placenta (which can lead to

postpartum hemorrhage Postpartum bleeding or postpartum hemorrhage (PPH) is often defined as the loss of more than 500 ml or 1,000 ml of blood following childbirth. Some have added the requirement that there also be signs or symptoms of low blood volume fo ...

). This is due to the distortion of the normal shape of the uterus, distortion of the cervix leading to cervical insufficiency, or under-vascularization of the

endometrium The endometrium is the inner epithelium, epithelial layer, along with its mucous membrane, of the mammalian uterus. It has a basal layer and a functional layer: the basal layer contains stem cells which regenerate the functional layer. The funct ...

as the pregnancy requires more blood supply. In some cases, the nonpregnant horn can rupture during labor, necessitating emergency surgery. Fetuses developing in bicornuate uteri are more likely to present breech or

transverse Transverse may refer to: *Transverse engine, an engine in which the crankshaft is oriented side-to-side relative to the wheels of the vehicle *Transverse flute, a flute that is held horizontally * Transverse force (or ''Euler force''), the tangen ...

, with the fetal head in one horn and the feet in the other. This will often necessitate cesarean delivery. If the fetus is vertex (head down), the two horns may not contract in coordination, or the horn that does not contain the pregnancy may interfere with contractions and descent of the fetus, causing

obstructed labor Obstructed labour, also known as labour dystocia, is the baby not exiting the pelvis because it is physically blocked during childbirth although the uterus contracts normally. Complications for the baby include Perinatal asphyxia, not getting e ...

Effect on intrauterine device usage

Usage of intrauterine device (IUD) with copper requires one IUD in each horn to be effective in case of bicornuate uterus. The same practice is generally applied when using

IUD with progestogen A hormonal intrauterine device (IUD), also known as an intrauterine system (IUS) with progestogen and sold under the brand name Mirena among others, is an intrauterine device that releases a progestogenic hormonal agent such as levonorgestre ...

due to lack of evidence of efficacy with only one IUD. Evidence is lacking regarding progestogen IUD usage for

menorrhagia Heavy menstrual bleeding (HMB), previously known as menorrhagia or hematomunia, is a menstrual period with excessively heavy flow. It is a type of abnormal uterine bleeding (AUB). Abnormal uterine bleeding can be caused by structural abnorm ...

in bicornuate uterus, but a case report showed good effect with a single IUD.

Uterus bicornis in mammals

A double uterus is the normal female anatomy in many

mammals A mammal () is a vertebrate animal of the class Mammalia (). Mammals are characterised by the presence of milk-producing mammary glands for feeding their young, a broad neocortex region of the brain, fur or hair, and three middle e ...

. In

insectivores A robber fly eating a hoverfly An insectivore is a carnivorous animal or plant which eats insects. An alternative term is entomophage, which can also refer to the human practice of eating insects. The first vertebrate insectivores wer ...

, certain species of

primates Primates is an order of mammals, which is further divided into the strepsirrhines, which include lemurs, galagos, and lorisids; and the haplorhines, which include tarsiers and simians ( monkeys and apes). Primates arose 74–63 ...

i.e.

lemurs Lemurs ( ; from Latin ) are wet-nosed primates of the superfamily Lemuroidea ( ), divided into 8 families and consisting of 15 genera and around 100 existing species. They are endemic to the island of Madagascar. Most existing lemurs are s ...

, furthermore in

carnivores A carnivore , or meat-eater (Latin, ''caro'', genitive ''carnis'', meaning meat or "flesh" and ''vorare'' meaning "to devour"), is an animal or plant whose nutrition and energy requirements are met by consumption of animal tissues (mainly mu ...

, and in

whales Whales are a widely distributed and diverse group of fully Aquatic animal, aquatic placental mammal, placental marine mammals. As an informal and Colloquialism, colloquial grouping, they correspond to large members of the infraorder Cetacea ...

the uterus bicornis a part of their healthy morphological structures.

Health issues

The risk of cancer is ''not'' increased in the case of uterus bicornis.

Endometrial carcinoma Endometrial cancer is a cancer that arises from the endometrium (the lining of the uterus or womb). It is the result of the abnormal growth of cells that can invade or spread to other parts of the body. The first sign is most often vaginal ...

s are very rare. If the presence of a uterus bicornis is not yet known and there is clinical suspicion of a carcinoma, which cannot be confirmed by the

histological Histology, also known as microscopic anatomy or microanatomy, is the branch of biology that studies the microscopic anatomy of biological tissue (biology), tissues. Histology is the microscopic counterpart to gross anatomy, which looks at large ...

findings,

sonography Medical ultrasound includes diagnostic techniques (mainly imaging) using ultrasound, as well as therapeutic applications of ultrasound. In diagnosis, it is used to create an image of internal body structures such as tendons, muscles, joints ...

and

provide diagnostic possibilities, as the cause may lie in a second uterine horn. Approximately 15% of all ovarian tumours and 8% to 10% of epithelial ovarian tumours are mucinous cyst adenomas, which can also arise in a normally developed uterus.V. More, H. Warke, N. M. Mayadeo, M. N. Satia:
Large Bilateral Mucinous Cystadenoma Of Ovary
'. In: ''Journal of Postgraduate Gynecology & Obstetrics''. Volume 2, Issue 4, April 2015.

References

External links

{{DEFAULTSORT:Bicornuate Uterus Congenital malformations of uterus and cervix