In these malformations the external contours of the uterus are normal. On a coronal section the fundal serosa is rectilinear or with mild invagination (less than 1cm). The single uterine cavity is divided by a bridge of fibrous myometrium. The septum is in generally hypovascularized in comparison to the adjacent myometrium.
These malformations are very rare. The uterus has an isthmic communication between the cavities of the bicornuate or septate uterus. The diagnosis can be done by hysterography or by 3D sonography and MRI.
The two facts are important to realize:
More than 50% of women with malformed uterus will stay completely asymptomatic from the obstetrical point of view;
Anatomical aspect and clinical outcomes can be different and influenced by other, not so striking, associated anomalies like anomalies of endometrium, vascularization, myometrial compliance, cervical competence and others.
The prevalence of uterine malformations in the infertile patients is very variable according to all studies, but does not seem to be significantly different from the prevalence observed in the general population. The uterine malformations are not the only factor responsible for the infertility, but it should be taken into account that some of them can increase the risk of a endometriosis. The finding of an uterine malformation must be integrated to the consideration about the obstetrical prognosis.
All uterine malformations can be responsible for early abortions. The frequency of abortions is doubled compared with the women with normal uterus. The incidence of the miscarriages seems to be highest in the case of septate uterus when the trophoblast invades the badly vascularized area of the septum with defective structure of the endometrium.
The frequency of the ectopic pregnancies in the cases of malformed uteri does not seem to be different from that found in the general population. Nevertheless, the place of ectopic gravidity is important prognostic factor. When not recognized early, the ectopic pregnancies localized in a rudimentary horn of the unicornuate uteri (type II A or IIB) or asymmetrical septate uteri can lead to serious uterine ruptures.
Late abortions or premature birth
These complications are often secondary to premature rupture of the membranes or to a cervical incompetence and can be associated with all types of uterine malformations. The rate of childbirth at term in cases of uterine malformations is only 50%. There is also a higher risk of late fetal losses and very premature childbirths.
The risk of IUGR appears to be increased in cases of uterine malformation. Some studies described 50% risk of IUGR in the case the unicornuate uterus and some authors found an increase rate of preeclampsia and placental abruption, probably as a consequence of abnormal placentation.
Anomaly of presentation
The risk of abnormal presentation (breech or transverse presentation) is higher in cases of uterine malformations due to mechanical factors that impede normal rotation of the fetus in the uterine cavity.
MANAGEMENT OF UTERINE MALFORMATIONS
The management of the uterine malformations before pregnancy comprises the surgical treatment if it is possible and necessary. Some of the malformations remain out of surgical capabilities (unicornuate uterus, didelphys uterus), but surgical procedures can prevent ectopic pregnancy for example in cases of the unicornuate uteri of the type IIa or IIb (excision of the rudimentary horn).
In the bicornuate uteruses type VI, hysteroplastic is theoretically possible in case of symptomatic malformation, but as this malformation is usually more complex, this procedure is done only seldom.
The septate uteri (type V) are the only uterine malformations whose surgical treatment is relatively simple by hysteroscopic excision. This treatment is addressed to the symptomatic patients that had had an obstetrical complication before. However some authors recommend preventive treatment after the anomalies had been diagnosed. Hysteroscopic treatment can be proposed to patients with some types of the bicornuate uteri and arcuate uteri.
However, the two important facts must be taken into account in the surgical treatment of uterine malformations:
The restoration of normal cavity anatomy is not guarantee of a good obstetrical prognosis (abnormal uterine vascularization, compliance etc.);
To the contrary with the generally accepted idea, the number of pregnancies doesn"t improve obstetrical prognosis in women with untreated uterine malformations.
During the pregnancy
When the diagnosis of uterine malformation is made at the beginning of pregnancy, the treatment can be only preventive (setting at rest, sonographic monitoring of the fetal growth and the cervical competence). Cervical cerclage should be proposed only in the case of proved cervical incompetence observed in 1/3 to 1/4 of uterine malformations.