The Latin word “cornu” means horn. A bicornuate uterus, a fused type of uterine malformation in humans is “normal” amongst other mammals like rats, mice and pigs. Tubal Mullerian anomaly accounts for bicornuate 39%, arcuate 7%, septated-uterus 34%, aplastic > 5% and other uterine structural defects  . Bicornuate uterus being a disorder of Mullerian ducts  is distinct from type II uterine didelphys which sometimes have two vaginas/external genitalia.
There are reported cases of IVF failure in a bicornuate uterus and some increased incidence of ectopic pregnancy complications  . Kumar et al. (2008)  in a study reported that MRI showing bicornuate uterus exposed cervical agenesis. Some studies  have cited septate uterus as the 2nd most common uterine anomaly after bicornuate uterus  . Surgically treated didelphic uterus according to Heinonen (2000)  has encouraging fertility prognosis when compared to a bicornuate uterus. Pregnancy rarely occurs in the horn of a unicornuate uterus  .
A longitudinal study  observed that antenatal women with monitored (ultrasound) history were at lower risk of having uterine anomalies. Accurate statistical percentage and incidence of Mullerian abnormality in a population is difficult to estimate due to its rarity  . Malfusion of the mesonephric duct (Müllerian) in utero results in different uterine anomalies  . Data linking Caesarian sections, PROM (premature rupture of membrane), breach-lie/presentations to uterine anomalies are mostly from case reports, structural anatomic variations or micro-studies    . Advances in 3D and 4D (i.e., 3D in real-time) ultrasound have led to non-invasive observations of these anomalies  .
2. Case Report
A middle-aged woman suspected to be from a high-socio-economic background reported at the Radiological Department of Crystal Specialist Hospital (CSH), Dopemu-Akowonjo, Lagos, Nigeria. Ultrasound was performed with a Logic 3―Pro General Electric (GE) ultrasound machine (made in USA); 3.5 MHz curvilinear transducer. She had a turbulent menstrual cycle, with fluctuating amenorrhea and sometimes/occasional episodes of excessive bleeding. “Frozen” sonograms confirmed bicornuate uterus; though the (bilateral) ovaries were distal in position, they appeared normal in collaboration with structural anatomical plane.
Oral-patient interaction yielded no significant family history of rhesus-factor incompatibility, or consanguineous marriage by relatives. According to medical-records, the patient was nulliparous, weighed 61 kg and had copious “whitish” discharge noted by the attending physician during speculum examination of the cervix and external os. Informed consent was sought from patient and granted by Crystal Specialist Hospital for documentation of this case in line with the 1975 Helsinki Declaration on patient-rights and confidentiality.
Surgical treatment of the patient was not done or carried out in our hospital (CSH); however, information reached us that her postoperative recovery was uneventful with skin stitches removed after 8 days. Follow-up data also revealed dressing was done on the 2nd postoperative day and patient discharged on the 9th day.
Diagnosis of a bicornuate uterus in other to differentiate it with split-uterine-didelphys can be by hysteroscopy, ultrasound, HSG and laparoscopy. It should be noted that in a septated uterus, a thick persistent longitudinal septum partially separates the uterine cavity superiorly as opposed to a bicornuate variation (Figure 1). Our ultrasound findings are in agreement with a retrospective study  on didelphys uterus and bicornuate uteri; they (researchers) noted patients with the anomalies required sustained infertility treatments. Parallel to Jayasinghe et al. (2005)  and majority of obstetricians, if a confirmed diagnosis of cyesis occurs in the rudimentary horn (see Figure 2, u2), immediate surgery must be performed. Since there is a failure in the complete development of both Mullerian ducts with incomplete fusion, the fused lower portion forms the main cervical and uterovaginal area (Figure 2, u1).
Figure 1. The 2 uterine cavities are separated at an angle of approximately 78˚ anteflexed. Observe the pressure indentation on posterior-inferior wall of urinary bladder (B).
Figure 2. B mode-split image of (Figure 1) above. Note the supra-fundal area with the second horn (u2) mimicking a fibroid (benign) tumor (anteriorly).
Severe dysmenorrhea, occasional cervical duplication  make gravidae a daunting task in women with the bicornuate uterus; being mostly in “compressed” form of birth defects. A plausible explanation for irregular uterine anomalies is decreased muscle mass and blood flow in uterine arteries. Incidence of this rare anomaly varies and may affect gynecological structure and obstetric outcome  . Greater than 60% of women with malformed uterus may stay completely asymptomatic. Cephalic part of the bicornuate uterus appears bifurcated (Figure 1) while the caudal part is normal. The symmetry of uterine cavities in bicornuate uterus creates certain fissional communication inferiorly. In the branched horn (Figure 1) if the angle of one uterine cavity is equal or less than 75 degrees, a septate uterus is formed  . Likely haematometra and cryptomenorrhea is a chronology likely to develop in the rudimentary horn (Figure 2, u2).
In agreement with Reuter et al., (1989)  sonography will rule-out pressure of pedunculated/fistulic or septated uterine component; since it is at a wide angle 75˚ - 102˚. In contrast to our case report, unicornuate uterus indicates “single-horned” with a RT or LT adnexae, with a small AP diameter parallel to the cervix; while a didelphic variant exhibits 2 (cervical and endometrial) canals    . Paired mesonephric ducts are incompletely fused in a “dented” fundus. Bicornuate uterus can also be caused by resorption defects, malrotation fusions during embryonic stage, with an angle separating the 2 horns not greater than (>) 105˚  ; as opposed to a normal uterus (control) seen in Figure 3, marked probe tenderness was present in the right fornix. Normal uteri women have better reproductive outcome and higher pregnancy rate compared with those with anomalies. Without a doubt, they belong to a high- risk group and it is of great importance for sonologists to detect reproductive tract anatomic variations by ultrasound early. The widely divergent apices and bi-fundus of the bicornuate uterus makes hysteroplastic unity a theoretical possibility.
Figure 3. Control/normal longitudinal section of a non-gravid anteverted uterus (U) free of any pedunculated mass or attachment.
Conception and fertility in bicornuate uteri remains a controversial topic among radiologists and gynecologists. Elusive data on surgical correction: (partial) hysterectomy, metroplasty or myomectomy (as the case may apply) remains sparse.
Strassman’s utriculoplasty surgery could be helpful in correcting women with a bicornuate uterus. This procedure will allow for fusion of the bi-uterine cavity and fundus. Incision for uniting uterine cavity improves parturitional outcome in bicornuate patients who had earlier suffered abortions. Real-time ultrasound should be considered to exclude Herlyn-Werner-Wunderlich (HWW) syndrome.