Antenatal Diagnosis of Thanatophoric Dwarfism: About a Case Report and Review of the Literature

    

    

    Figure 2: Showing a characteristic aspect of thanatophoric dysplasia.
    

Results

Diagnostic approach: ultrasonography at 38 SA revealed a female fetus with a BIP of 102.5 mm greater than 90 of gestational age, a poorly developed thorax an abdomen of normal volume (DAT=107.7, CA=360.1 mm greater than 90 of gestational age) and, above all, shortening of the bones of all four limbs with femurs that are curved: LF= 50.1 mm below the 10 percentile of gestational age and with an LF/PIED ratio <0.8, note the presence of hydramnios with a large cistern at 100mm. There were no other associated morphological abnormalities. The diagnosis of type II TD was made on the basis of these findings, and the couple was informed.

Therapeutic intervention and follow-up: delivery was via a high route for a borderline pelvis and unfavorable bi-spinous BIP confrontation, giving birth to a female newborn, PDN= 2600g ap 10, who presented respiratory distress for which she was hospitalized in the neonatal intensive care unit.

Discussion

NT is a major and lethal fetal malformation. According to Machado et al [1], the term thanatophore is derived from the Greek myth "thanatos" and means personified death. The life expectancy of newborns with NT is estimated at around one hour after birth by Noe et al. [2], who have evoked some rare cases of survival up to five and eight years. In our observation, the newborn with NT presented respiratory distress. This will be related to the narrowness of the rib cage with a lack of lung development would be involved according to Pietryga et al. [3].

Our patient was 25 years old with no particular history. The notion of consanguinity or related couple noted in the literature was not found in our case. In the study by Lahmar-Boufaroua in Tunisia, consanguinity was found in 61% of cases.

Antenatal diagnosis of fetal malformations whether lethal or not should be the haunt of every sonographer. To this end, some authors recommend early morphological anomaly detection during firsttrimester ultrasound [4]. This ultrasound should insist on nuchal clarté. According to Tonni et al [5], nuchal hyperclarity is an early sign of NT. In our observation, the sonographer had only measured the thickness of the nuchal translucency without evoking its echogenicity.

We believe that the quantity of amniotic fluid should also be taken into account in ultrasound exploration during the prenatal check-up. Indeed, hydramnios is a clinical and ultrasound sign consistently found in the literature as part of the signs associated with NT [5]. We observed it, in our case.

Signs of NT and classification as type I or II are evident from the second trimester onwards on two-dimensional ultrasound. These include macrocrania, a narrow thorax, a prominent abdomen and extremely short limbs. In type I, the femur is curved, whereas in type II it is not. Recent advances in technology, with the advent of threedimensional ultrasound, have further facilitated the diagnosis of NT [6]. However, the fear of making a mistake or confusing NT with achondroplasia, osteogenesis imperfecta, achondrogenesis or any other non-lethal micromelia means that ultrasound must be coupled with molecular biology, which provides a diagnosis of certainty [7]. In its absence, it would be advisable to combine ultrasound with an X-ray of the uterine contents [8]. Noe et al [9] estimated vertebral compression and shortening at around one hour after birth, and reported rare cases of survival up to five and eight years. According to Pietryga et al.[10], severe respiratory distress linked to the narrowness of the thoracic cage and lack of lung development is the cause.

Acknowledgements

To all the authors who have contributed to the completion of this work.

Declarations

Funding: This work received no funding,

Conflict of interest: The authors declare no conflicts of interest,

Ethical approval: Informed consent has been obtained from the patient.

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