Prenatal diagnosis of caudal regression syndrome and omphalocele in a fetus of a diabetic mother

The caudal regression syndrome is defined as total or partial agenesis of the sacrum and lumbar spine, frequently associated with other developmental malformations (orthopedic, neurological, genito-urinary, gastrointestinal…). Prenatal diagnosis is possible through fetal ultrasound (US) and magnetic resonance imaging (MRI). A case of fetal caudal regression syndrome with omphalocele from a diabetic mother is presented, demonstrating the sonographic, MRI, CT and X-Ray features diagnostic. We will also discuss neonatal findings, risk factors and prognosis of this condition.


Introduction
The caudal regression syndrome is a rare congenital malformation [1]. Defined as total or partial agenesis of the sacrum and lumbar spine, frequently associated with other developmental malformations (orthopedic, neurological, genito-urinary, gastrointestinal...). Prenatal diagnosis is possible through fetal ultrasound and MRI [1,2]. The etiopathogenesis of this condition is not univocal [2], maternal diabetes appears to be among the major risk factors [3]. This anomaly is not lethal but the prognosis depends on the associated malformations. We report a case of this syndrome suspected at 28 weeks of gestation ultrasound and confirmed by fetal MRI.

Patient and observation
A 24-year-old woman, gravida 3, para 3, asthmatic for 13 years and diabetic with high dose of insulin for 2 years. The current unplanned pregnancy was poorly followed. The first ultrasound was performed There was also a moderate ventriculomegaly, measured at 12 mm.
A fetal MRI was then performed ( Figure 2). Its objective was to study the spine and the spinal cord and to seek an etiology for ventriculomegaly. It confirmed the omphalocele and its content. It Apgar was five in the first minute and then seven in the fifth minute. The clinical examination found a weight at 3600 g, a small size at 36 cm, and a macrocrania with a cranial perimeter at 38 cm.
The omphalocele was found to be 10 cm in diameter ( Figure 3).
There was also a micromyelia of the two lower limbs, feet bots, paraplegia of the two lower limbs and peripheral axial hypotonia, a polypnea at 80 cycles/min and a generalized cyanosis. Cardiac auscultation was normal. The thoraco-abdominal radiograph showed cardiomegaly, digestive clarity in the omphalocele and lumbosacrococcygeal agenesis ( Figure 4). The karyotype was normal (46, XY). The evolution was marked by the death after five hour of life by neonatal respiratory distress.

Discussion
The lumbosacral agenesis also known as caudal regression syndrome is an abnormality of placement of the terminal part of the fetal spine occurring before the 9th week of development [1,2] .Embryology it is either an early disappearance of the caudal appendix (exaggeration of a normal process) or an absence of development of the caudal appendix (caudal bud abortion). The consequence of the absence of the caudal bud is the approximation and fusion of the rudiments of the lower limbs up to the sirenomelia. The frequency of caudal regression syndrome is 0.1 to 0.4 per 10,000 births [2]. The sex ratio is estimated at 3 boys for a girl [4]. This condition is not described as a hereditary condition.
Indeed, the risk of recidivism is very low [3]. bones of lower limbs [6]. Our newborn seems to carry caudal regression syndrome type 4. Antenatal diagnosis can be suspected in the first trimester and confirmed in the second trimester of gestation. In the first trimester, lumbosacral agenesis will result in a decrease in cranio-caudal length [7]. During the second trimester, there was a lack of visualization of the sacrum and / or lumbar spine with abrupt interruption of the image of the rachis more or less extended during the study of the spine. The lower limbs, generally immobile, present a characteristic position: in "frog", characteristic [7]. Their echostructure is also a peculiar testimony to the hypotrophy of the muscular-cutaneous masses. This was the case of our observation or we observed an anomaly of echogenicity of the musculoskeletal tissues of the lower limbs that can be explained by a neurological origin [8]. The morphological ultrasound is oriented towards the diagnosis and helps to count the other frequently associated malformations. There is a spectrum of malformations affecting the caudal end of the trunk ranging from isolated and partial agenesis of the sacro-coccygeal spine to more severe malformations. Urogenital, gastrointestinal malformations, respiratory diseases and congenital cardiac abnormalities may be associated. In our case, the omphalocele is the sign of major ultrasound call that led us to detect the other malformations as the amputation of the spine and the right clubfoot.
Fetal MRI makes it possible to confirm the diagnosis and to determine the level of the terminal medullary cone, which will be a major prognostic factor [9].

Competing interests
The authors declare no competing interest.

Authors' contributions
All the authors have read and agreed to the final manuscript.