Ultrasound of the Siren Syndrome (Sirenomelia) in the District of Bamako Apropos of a Case

Sirenomelia is a rare fetal malformation with more or less complete fusion of both lower limbs consistently associated with bilateral renal abnormalities. The positive diagnosis can be made antenatally by ultrasound during the first trimester of pregnancy but often before the 22 weeks of amenorrhea. The ob-jective was to think about the possible diagnosis by ultrasound in front of the urinary anomalies and the ologiamnios during the morphological study of the second trimester of pregnancy. We report a case of sirenomelia in a 25-year-old lady as part of the routine prenatal assessment suspected and confirmed during the morphological ultrasound of the second trimester of pregnancy and confirmed after the termination of pregnancy in Mali in the Health Center of Reference of commune III of the district of Bamako. The morphological ultrasound made it possible to diagnose the malformation of the urinary tract, the amniotic fluid and to make the therapeutic decision of medical termination of pregnancy at the end of confirming the siren syndrome.


Introduction
Sirenomelia is a fetal malformation characterized by a variable degree of fusion of the lower limbs. It is a rare form of caudal dysgenesis described for the first time by Rocheus in 1542 and then by Polfyr in 1553. Its prevalence is estimated at 1 per 100,000 live births. This pathology is not compatible with life and is much more often associated with other fetal malformations, especially renal [1] [2]. The positive diagnosis is therefore based on ultrasound, which visualizes the malformation and specifies the different associations of the sequence and it is in the first trimester (12)(13) that the diagnosis should be made, with the help of a probe. Endovaginal [3] very few cases have been reported in Africa, especially in Mali, with a single case in the Sikasso region [4] [5] [6]. We report our case of sirenomelia observed in Mali in commune III of the District of Bamako. The spine is visualized over its entire length.

Observation
At the chest level: the 4 cavities were symmetrical, the septum intact, the departure of the large vessels was normal, the aorta at 5.4 mm, the pulmonary artery at 5.6 mm. The diaphragm was present. N terms of the abdomen: the abdominal wall was continuous, the liver, the gallbladder, and the normal stomach.
The bladder is not seen, supposedly empty or absent. There was an agenesis of a kidney and the other kidney carrier of multiple cysts ( After the interruption of pregnancy, delivery by the low way, we observed: a fusion of the lower limbs associated with a shortening of the humerus and an anomaly of form and number of the fingers and toes making evoke a sirènomelie ( Figure 4).
The mother is doing well physically. She is followed by a psychologist from the health center on the mental level for better socio-cultural integration.     The association with a long bone anomaly such as the shortening of the humerus has been seen in our case; radial agenesis is rarely described in the literature [3] [11] [12]. Sirenomelia, apart from its prenatal diagnosis, is a malformation incompatible with life and survival after birth is very short. The positive diagnosis is therefore based on ultrasound, which visualizes the malformation and specifies the different associations. It is in the first trimester (12 -13 SA) that the diagnosis should be made, with the help of an endovaginal probe while the amniotic fluid is still normally present, favoring the visualization of MI and its movements [2] [13] [14]. In case of doubt, an ultrasound around 17 -18 SA is necessary, but usually, it is before the first warning sign that represents the oligo-anamnios (consequence of renal agenesis [13] [15]) that the diagnosis is made in the 2nd trimester. In our observation, he had not had a first trimester ultrasound like many pregnant women across Mali, despite the incredible accessibility of technical and financial means these days. This may most likely be due to the lack of information or the quality of the information provided to our pregnant women.

O. Diarra et al. Open Journal of Medical Imaging
The examination looks for this unilateral or bilateral renal agenesis, the bladder, as well as the other malformations listed above. Amnioinfusion may be necessary to recognize fused lower limbs with little or no mobility. Color Doppler ultrasound is essential as it can circumvent the difficulty due to oligohydramnios [3] [16]. It studies the abdomino-pelvic vascularization, the aspect of the abdominal aorta (complete or partial atresia) and can make it possible to verify the absence of renal vessels. In renal agenesis alone, the aortic bifurcation is always observed [16] [17].
On ultrasound, sirenomelia can cause diagnostic difficulty with caudal regression syndrome (CRS). The distinction between these entities is important, especially for genetic counseling and the obstetrical future of these patients [3]. On ultrasound, in the CRS, we will find the classic V-shaped aspect of the femurs in abduction, the fetus in Buddha, normal abdominal fluid, no renal abnormality, and the presence of the two umbilical arteries. Maternal diabetes should be sought in principle [3]. On the other hand, a few cases of diabetic mothers have been described in sirenomelia in the literature, 10% to 15% of cases [1]. Mermaid syndrome is a sporadic malformation (unlike caudal regression syndrome [3] [18]).

Conclusion
Sirenomelia is a rare congenital malformation that must be considered as much

Conflicts of Interest
The authors declare no conflicts of interest regarding the publication of this paper.

Consent
The parents were informed and they gave their informed consent.