1. Department of Obstetrics and Gynaecology,Kwong Wah Hospital, Hong Kong SAR, China;
2. Department of Obstetrics and Gynaecology, Princess Margaret Hospital, Hong Kong SAR, China.

Case report

A 32-year old women (G1P0), from a non/consanguineous couple and with non-contributive history, presented with polyhydramnios (amniotic fluid index = 32cm) at 34 weeks of her gestation.  Her second trimester scan at 19 weeks was reported to be normal.

2D and 3D ultrasound examinations performed at 34 weeks revealed significant micrognathia and dysmorphic facial features (Images 1-3). An elective lower segment caesarean section was performed at 38 weeks due to the polyhydramnios and unstable fetal position. The neonate (boy), weighing 2.73 kg, with Apgar scores of 8, 9 (in the first and fifth minutes respectively) was delivered.

His characteristic dysmorphic facial features were nearly identical with the 3D render mode ultrasound images: bilateral down-slanting palpebral fissures, malar hypoplasia and micrognathia. There was no cleft lip/palate or coloboma of eyelids. The diagnosis of Treacher Collins Syndrome with upper airway obstruction and conductive hearing deficit was confirmed.

Image 1: 2D image showing the abnormal facial profile of the fetus with micrognathia.

Images 2, 3: 3D images showing the abnormal facial profile of the fetus: bilateral down-slanting palpebral fissures, malar hypoplasia and micrognathia. 

Discussion

Prenatal diagnoses of the Treacher Collins Syndrome by conventional 2D ultrasound have been reported [1-3]. Downward palpebral fissures were detected by 2D scans, but the images were suboptimal [3]. Retrognathia (dorsally positioned mandible) and micrognathia (small size of the mandible) could be assessed by 3D ultrasound and measuring of the inferior facial angle and the mandible width to maxilla width ratio respectively [4]. The characteristic facial features, as shown in our case, could be well discerned on 3D scans [5, 6]. Therefore, 3D ultrasound imaging may be helpful in the prenatal diagnosis and counseling of the affected pregnancies.

References

1. Meizner I, Carmi R, Katz M. Prenatal ultrasonic diagnosis of mandibulofacial dysostosis (Treacher Collins syndrome). J Clin Ultrasound 1991; 19: 124–127.
2. Cohen J, Ghezzi F, Goncalves L, Fuentes JD, Paulyson KJ, Sherer DM.
Prenatal sonographic diagnosis of Treacher Collins syndrome: a case and review of the literature. Am J Perinatol 1995; 12: 416–419.
3. Ochi H, Matsubara K, Ito M, Kusanagi Y. Prenatal sonographic diagnosis of Treacher Collins syndrome. Obstet Gynecol. 1998; 91:862.
4. Rotten D, Levaillant JM, Martinez H, Ducou le Pointe H, Vicaut E.The fetal mandible: a 2D and 3D sonographic approach to the diagnosis of retrognathia and micrognathia. Ultrasound Obstet Gynecol. 2002; 19(2):122-130.
5. Hsu TY , Hsu JJ, Chang SY , Chang MS. Prenatal three-dimensional sonographic images associated with Treacher Collins syndrome. Ultrasound Obstet Gynecol 2002; 19: 413–414.
6. Tanaka Y, Kanenishi K, Tanaka H, Yanagihara T, Hata T. Antenatal three-dimensional sonographic features of Treacher Collins syndrome.
Ultrasound Obstet Gynecol.2002 ;19(4):414-415.
Lower Segment Caesarean Section.