Increased nuchal translucency observed in the 13th week of fetal ultrasound is characteristic of?

JODHPUR AIIMS SNO-2018

Obstetrics & Gynaecology

Easy

Appeared in: JODHPUR AIIMS SNO-2018

Explanation

Increased nuchal translucency (NT) is the term for the fluid collection at the back of the fetal neck, visible on ultrasound.
This measurement is a key component of first-trimester screening (11-14 weeks) for chromosomal abnormalities.
While it can be associated with several conditions, an increased NT is most strongly and characteristically linked to Down's syndrome (Trisomy 21).
The finding is a screening marker, not a diagnosis, and indicates the need for genetic counseling and discussion of further diagnostic testing like CVS or amniocentesis.

Option A: While Turner's syndrome (45,X) can present with an increased NT, sometimes leading to a cystic hygroma, it is a less common cause than Down's syndrome.
Option B: Klinefelter's syndrome (47,XXY) is not typically associated with increased nuchal translucency. The link is weak and not considered a primary characteristic.
Option C: Hydrocephalus is the buildup of cerebrospinal fluid within the ventricles of the brain, leading to an enlarged head. This is an entirely different anatomical location and pathology from the fluid collection in the nuchal region.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Interpretation of first-trimester ultrasound findings, specifically nuchal translucency, and its association with chromosomal abnormalities as background academic context rather than a clinical decision trigger.
Nurses play a vital role in patient education, explaining that an increased NT is a screening result, not a definitive diagnosis. This helps manage parental anxiety and prepares them for discussions about further diagnostic options.
It is crucial to ensure the patient understands the difference between a screening test (which assesses risk) and a diagnostic test like amniocentesis or CVS (which can confirm a condition).
Accurate dating of the pregnancy is essential, as NT measurement is only valid between approximately 11 and 14 weeks of gestation.

How to Approach the Question

First, identify the key clinical finding in the question: 'increased nuchal translucency' at the '13th week'.
Recognize this as a specific marker from a first-trimester prenatal screening ultrasound.
Recall the purpose of first-trimester screening, which is primarily to assess the risk for common chromosomal abnormalities (aneuploidies).
Evaluate the given options. Differentiate between the chromosomal syndromes (Turner's, Klinefelter's, Down's) and the structural brain defect (Hydrocephalus).
Immediately eliminate Hydrocephalus, as it involves fluid in the brain's ventricles, not the nuchal fold.
Consider the remaining chromosomal syndromes. Recall or deduce that while increased NT can be linked to several aneuploidies, it is most famously and strongly characteristic of Down's syndrome (Trisomy 21).

Concept Tested & Keywords

Concept Tested: Interpretation of first-trimester ultrasound findings, specifically nuchal translucency, and its association with chromosomal abnormalities.
Stem keywords: nuchal translucency, 13th week, fetal ultrasound
Lead-in keywords: characteristic of
Clinical cues: First-trimester screening finding (13th week)
Clinical cues: Ultrasound measurement (nuchal translucency)