Bicornuate uterus is a congenital anomaly of the anatomical structure of the uterus, consisting in splitting a single cavity into two horns that merge in the lower parts. The presence of a bicornuate uterus manifests itself as dysmenorrhea, abnormal uterine bleeding, miscarriage or infertility. Diagnosis of the bicorn uterus includes ultrasound, hysterosonography, hysteroscopy, laparoscopy. If necessary, correction is performed endoscopic interventions to restore the uterine cavity, Strassmann surgery. Pregnancy and childbirth with a bicornular uterus are possible, although they are associated with increased risks.
Q51.3 Bicornuate uterus
Among the anomalies of the uterus, bicornuate uterus is the most common, but in general it is diagnosed only in 0.1-0.5% of women. The formation of a bicornuate uterus is associated with disorders of intrauterine development. Pathology develops due to incomplete fusion of the Muller ducts at 10-14 weeks of embryogenesis, which leads to the division of the uterine cavity into two niches.
More often, with a bicornuate uterus, there is one neck and one vagina, but it is also possible to double the neck and have an incomplete vaginal septum. One horn in a bicornuate uterus may be rudimentary. In the case of attachment of a fetal egg in a rudimentary horn, pregnancy proceeds according to the type of ectopic with a rupture of the horn and intra-abdominal bleeding. In other cases, both horns are developed correctly, and in each of them full uterine cycles can occur, pregnancy may occur, ending in childbirth.
The formation of a bicornuate uterus in a female fetus can be facilitated by the action of various damaging factors in the first months of pregnancy, when the organs of the child are laid and develop. Such teratogenic factors include various kinds of intoxication (alcohol, nicotine, drugs, drugs, chemical agents), vitamin deficiency, mental trauma during pregnancy, endocrine diseases (diabetes mellitus, thyrotoxicosis) or heart defects in the mother.
Infectious agents – causative agents of measles, rubella, influenza, toxoplasmosis, syphilis and other diseases have a damaging effect on the embryo. Chronic fetal hypoxia, the course of pregnancy with toxicosis adversely affects the process of organogenesis. A two—horned uterus can be combined with some other anomalies, most often with defects of the urinary system.
Anatomical variants of a bicornuate uterus
The bicornuate uterus is characterized by the division of the cavity into two parts, which merge in the lower parts at different levels. Depending on the size of the cleavage of the uterine cavity, gynecology distinguishes a full, incomplete and saddle-shaped bicornuate uterus.
In the full version of the bicornuate uterus, the separation of the cavity and the departure of the horns in different directions begins at the level of the utero-sacral ligaments; at the same time, the angle between the two horns may be different. The pronounced separation of the uterine cavity leads to the presence of separate niches resembling two one-horned uterus, which are located very close to each other. Pregnancy in this case can develop normally in the niche of one of the existing horns.
An incomplete version of a bicornuate uterus is characterized by a cleavage of the cavity in the upper third and a shallow opening between the two horns. In this case, the shape and size of both uterine horns are usually the same. With a saddle-shaped bicornuate uterus, there is a slight depression in the area of its bottom, shaped like a saddle. Conception with a saddle uterus is not excluded, however, in the presence of concomitant defects, spontaneous termination of pregnancy may occur. A two-horned saddle-shaped uterus in combination with a narrow pelvis can cause an incorrect fetal position, which excludes the possibility of independent childbirth.
The presence of a bicornuate uterus may not be accompanied by pronounced clinical manifestations. Sometimes with a bicornuate uterus, dysmenorrhea, uterine bleeding is noted. Spontaneous abortions or infertility are often observed in women with a bicornuate uterus. However, it is possible that pregnancy and childbirth will proceed without complications.
With a two–horned uterus, pregnancy usually develops in one of the available horns, in rare cases – simultaneously in both horns. Pregnancy with a bicornuate uterus is often associated with risks of termination, which requires careful medical supervision. Spontaneous abortions with a bicornuate uterus usually occur in the first trimester, since the growth of the embryo is hindered by insufficient blood supply and a small volume of the internal cavity of the uterine horn.
In addition, with a bicornuate uterus, anomalies of the placenta location (presentation or low placement) are often found, fraught with its premature detachment and bleeding. The presence of a bicornuate uterus increases the likelihood of isthmic-cervical insufficiency, pelvic presentation of the fetus, premature birth and violation of contractile activity of the muscles of the uterus, postpartum bleeding. With an oblique or transverse position of the fetus, a caesarean section is indicated.
The presence of a bicornuate uterus may be suspected by a gynecologist with typical complaints – algodismenorrhea, abnormal bleeding, habitual miscarriages, infertility. During the gynecological examination of the patient, a clarifying probing of the uterine cavity is carried out, which allows determining its shape and the presence of an anatomical two-horned structure.
The bicornuate uterus is detected during pelvic ultrasound with a vaginal or abdominal sensor; the results of ultrasound-hysterosalpingoscopy, hysterosalpingography, MRI, hysteroscopy and laparoscopy contribute to the confirmation of the diagnosis. On hysterograms or tomograms with a bicornuate uterus, the presence of two mouths of the fallopian tubes is revealed; the bottom of the uterus is pushed into the uterine cavity to varying degrees in the form of a ridge. When examining patients, a differential diagnosis is made between the intrauterine septum and the bicorn.
Surgical tactics with is indicated only in the case of habitual miscarriage (2-3 miscarriages in a row) or infertility. The purpose of surgery for bicornuate uterus is to restore a single full-fledged uterine cavity. Most often in operative gynecology, they resort to extirpation of the rudimentary horn or removal of the septum separating the cavity (Thompson, Strassman operations).
The standard intervention is the Strassmann operation, which consists in laparotomy, dissection of the uterine fundus by a transverse incision, excision of the median septum, followed by stitching of the uterine membranes. In addition, surgical correction with a bicornuate uterus can be performed using a hysteroscopic technique. After surgical restoration of a single uterine cavity, an IUD is installed for 6-8 months.
With sufficient capacity of the uterine cavity, pregnancy can occur without complications. With a pronounced degree of bifurcation of the uterine cavity, the risk of spontaneous abortion or premature birth increases. The management of pregnancy in patients requires the prevention of miscarriage, the development of isthmic-cervical insufficiency, bleeding.
When there is a threat of termination of pregnancy at a late date (after 26-28 weeks of gestation), a caesarean section is performed to preserve the fetus. In case of full-term pregnancy, the issue of delivery is resolved taking into account various factors (the position and presentation of the fetus, concomitant pathology in the pregnant woman, etc.). After surgical correction of the bicornuate uterus, the risk of miscarriage decreases from 90% to 30%. In women with insufficient volume of the uterine cavity or with miscarriage remaining after surgical treatment, motherhood is possible thanks to assisted reproductive technologies, namely IVF under the surrogacy program. Artificial insemination of the patient’s egg is performed using ICSI or IMSI technology (if necessary using donor sperm), after the cultivation stage, embryos are transplanted into the uterus of the surrogate mother.