An increased NT has been strongly associated with many genetic,
cardiovascular and structural anomalies.
Is the sonographic appearance of the amount of nuchal fluid behind the cervical spine that can be identified and measured in virtually all fetuses between the 10th and 14th week of gestation.
Fig. 1: Increased nuchal translucency at first trimester ultrasound (12 weeks) proven to be a Down syndrome.
Cystic hygromas are congenital malformations of the lymphatic system,
characterized by fluid filled lesions at sites of lymphatic–venous connections along the posterior neck and back,
and in which septations may develop.
Cystic hygroma may be considered a markedly increased nuchal translucency.
Fig. 3: Large cystic hygroma (arrows). First trimester ultrasound (12 weeks), axial plane at cranium base. Proven to be a case of Turner syndrome.
Other anomalies of the lymphatic system are jugular lymphatic sacs which are fluid filled pouches found at the lateral jugular regions.
These are commonly found in association with cystic hygroma.
Fig. 2: Bilateral lateral neck cysts (arrows). Same case as above.
In some cases the cystic hygroma extends to the dorsal and cephalic regions and can be accompanied by diffuse subcutaneous edema.
Fig. 4: Coronal plane of a Down syndrome case where a massive cystic hygroma involves the hole cranium. (11 weeks gestation).
Fig. 5: Mid-sagital plane at first trimester pregnancy. Note the cervical cystic hygroma extending to the dorsal region (arrows). Chorionic villus sampling revealed a Down syndrome.
PATHOLOGIES ASSOCIATED WITH INCREASED NT OR CYSTIC HYGROMA
Aneuploidies:
- Trisomies (e.g.
21,
18,
13)
- Monosomy X
- Triploidy
Other genetic syndromes and sequences:
- Perlman syndrome
- Simpson–Golabi–Behmel
- Foetal akinesia deformation sequence (FADS)
- Noonan syndrome
- Multiple pterygium syndrome
- Smith-Lemli-Optiz syndrome
- Beckwith-Wiedemann syndrome
- Meckel-Gruber syndrome
- Hydrolethalus
- Fryns syndrome
- Neu-Laxova syndrome
- Bone and cartilage disorders (e.g.
osteochondrodysplasias,
bone dysplasias and achondrogenesis)
- Polycystic kidney disease
- Arthrogryposis
Cardiovascular anomalies (isolated or integrated in a syndrome):
- Cardiac septa defects
- Complex cardiopathy (e.g.
tetralogy of Fallot)
- Aortic arch pathology (e.g.
coarctation)
- Transposition of great arteries
- Left superior vena cava
- Aortic valve stenosis
- Pulmonary stenosis
- Tricuspid regurgitation
- Hipoplastic left heart
- Intrauterine Wolff-Parkinson-White syndrome