Nuchal fold
Updates to Article Attributes
TheNuchal nuchal fold thickness is a parameter thatnormal fold of skin seen at the back of the fetal neck during the second trimester of pregnancy. Increased thickness of the nuchal fold is a soft marker associated with multiple fetal anomalies, and is measured on an obstetric a routine second-trimester scan trimester ultrasound. (at ~18-22 weeks) and
It should not be confused with nuchal translucency (which, which is measured in the first trimester).
Pathology
The proposed aetiology of increased nuchal thickness is the result of hydrops or lymphatic obstruction.
Associations
The predominant reason for measuring the nuchal fold is that it is a soft marker for aneuploidy. As an isolated finding, it has a likelihood ratio of 3.25 for Down Syndromesyndrome9.
Other associations include:
- Turner syndrome
- congenital heart disease
- Klippel-Feil syndrome
- Zellweger syndrome
- Cumming syndrome
- Robert syndrome 7
Natural course
An abnormally thickened nuchal fold or even a cystic hygroma may resolve, especially toward the third trimester; however, the risk of karyotypic abnormalities is not reduced.
Radiographic features
Antenatal ultrasound
Nuchal fold thickness of > 6 mm is abnormal on a routine morphology ultrasound performed at 18-22 weeks.
The nuchal fold is known to increase throughout the second trimester in a normal pregnancy, and may be measured during a broader window of 14 and 24 weeks when required. There is some controversy regarding the normative thresholds at the earlier and later gestations - some authors advocating the use of a normogram10, others suggest that the 6mm upper limit may be appropriate up to 24 weeks11.
Technical considerations
Nuchal fold thickness is measured on an axial section through the head at the level of the thalami, cavum septi pellucidi, and cerebellar hemispheres (i.e. in the same plane that is used to assess the posterior fossa structures). One calliper should be placed on the outer edge of the skin, and the other against the outer edge of the occipital bone. The ideal angle of insonation is at approximately 30 degrees to the horizontal. This plane is less likely to produce a false positive thickened NF.
Nuchal fold thickness of > 6 mm is considered abnormal:
-
NF >6 mm: sensitivity 12%, specificity 99%, PPV 13%, NPV 99% for trisomy 21ref
See also
-<p><strong>Nuchal fold thickness</strong> is a parameter that is measured on an obstetric <a href="/articles/second-trimester-ultrasound-scan">second-trimester scan</a> (at ~18-22 weeks) and should not be confused with <a href="/articles/nuchal-translucency-1">nuchal translucency</a> (which is measured in the <a href="/articles/first-trimester">first trimester</a>). </p><h4>Pathology</h4><p>The proposed aetiology of increased nuchal thickness is the result of hydrops or lymphatic obstruction. </p><h5>Associations</h5><p>The predominant reason for measuring the nuchal fold is that it is a soft marker for aneuploidy. As an isolated finding, it has a likelihood ratio of 3.25 for Down Syndrome<sup>9</sup>.</p><p>Other associations include:</p><ul>- +<p>The<strong> nuchal fold</strong> is a normal fold of skin seen at the back of the fetal neck during the second trimester of pregnancy. Increased thickness of the nuchal fold is a soft marker associated with multiple fetal anomalies, and is measured on a routine second trimester ultrasound. </p><p>It should not be confused with <a href="/articles/nuchal-translucency-1">nuchal translucency</a>, which is measured in the <a href="/articles/first-trimester">first trimester</a>. </p><h4>Pathology</h4><p>The proposed aetiology of increased nuchal thickness is the result of hydrops or lymphatic obstruction. </p><h5>Associations</h5><p>The predominant reason for measuring the nuchal fold is that it is a soft marker for aneuploidy. As an isolated finding, it has a likelihood ratio of 3.25 for <a href="/articles/down-syndrome">Down syndrome</a><sup>9</sup>.</p><p>Other associations include:</p><ul>
-</ul><h5>Natural course</h5><p>An abnormally thickened nuchal fold or even a <a href="/articles/cystic-hygroma-1">cystic hygroma</a> may resolve, especially toward the third trimester; however, the risk of karyotypic abnormalities is not reduced.</p><h4>Radiographic features</h4><h5>Antenatal ultrasound</h5><p>Nuchal fold thickness is measured on an axial section through the head at the level of the <a href="/articles/thalamus">thalami</a>, <a href="/articles/cavum-septum-pellucidum-3">cavum septi pellucidi</a>, and cerebellar hemispheres (i.e. in the same plane that is used to assess the posterior fossa structures). One calliper should be placed on the outer edge of the skin, and the other against the outer edge of the occipital bone. The ideal angle of insonation is at approximately 30 degrees to the horizontal. This plane is less likely to produce a false positive thickened NF.</p><p>Nuchal fold thickness of > 6 mm is considered abnormal:</p><ul><li>NF >6 mm: sensitivity 12%, specificity 99%, PPV 13%, NPV 99% for trisomy 21 <sup>ref</sup>-</li></ul><h4>See also</h4><ul>- +</ul><h5>Natural course</h5><p>An abnormally thickened nuchal fold or even a <a href="/articles/cystic-hygroma-1">cystic hygroma</a> may resolve, especially toward the third trimester; however, the risk of karyotypic abnormalities is not reduced.</p><h4>Radiographic features</h4><h5>Antenatal ultrasound</h5><p>Nuchal fold thickness of > 6 mm is abnormal on a routine morphology ultrasound performed at 18-22 weeks.</p><p>The nuchal fold is known to increase throughout the second trimester in a normal pregnancy, and may be measured during a broader window of 14 and 24 weeks when required. There is some controversy regarding the normative thresholds at the earlier and later gestations - some authors advocating the use of a normogram<sup>10</sup>, others suggest that the 6mm upper limit may be appropriate up to 24 weeks<sup>11</sup>.</p><h6>
- +<sup></sup>Technical considerations</h6><p>Nuchal fold thickness is measured on an axial section through the head at the level of the <a href="/articles/thalamus">thalami</a>, <a href="/articles/cavum-septum-pellucidum-3">cavum septi pellucidi</a>, and cerebellar hemispheres (i.e. in the same plane that is used to assess the posterior fossa structures). One calliper should be placed on the outer edge of the skin, and the other against the outer edge of the occipital bone. The ideal angle of insonation is at approximately 30 degrees to the horizontal. This plane is less likely to produce a false positive thickened NF.</p><p> </p><h4>See also</h4><ul>
References changed:
- 10. Goynumer G, Arisoy R, Turkmen O, Yayla M. Fetal nuchal skin-fold thickness during the 2nd trimester of pregnancy. (2015) Journal of obstetrics and gynaecology : the journal of the Institute of Obstetrics and Gynaecology. 35 (2): 111-4. <a href="https://doi.org/10.3109/01443615.2014.937681">doi:10.3109/01443615.2014.937681</a> - <a href="https://www.ncbi.nlm.nih.gov/pubmed/25093251">Pubmed</a> <span class="ref_v4"></span>
- 10. Goynumer G, Arisoy R, Turkmen O, Yayla M. Fetal nuchal skin-fold thickness during the 2nd trimester of pregnancy. (2015) Journal of obstetrics and gynaecology : the journal of the Institute of Obstetrics and Gynaecology. 35 (2): 111-4. <a href="https://doi.org/10.3109/01443615.2014.937681">doi:10.3109/01443615.2014.937681</a> - <a href="https://www.ncbi.nlm.nih.gov/pubmed/25093251">Pubmed</a> <span class="ref_v4"></span>
- 11. Singh C, Biswas A. Impact of gestational age on nuchal fold thickness in the second trimester. (2014) Journal of ultrasound in medicine : official journal of the American Institute of Ultrasound in Medicine. 33 (4): 687-90. <a href="https://doi.org/10.7863/ultra.33.4.687">doi:10.7863/ultra.33.4.687</a> - <a href="https://www.ncbi.nlm.nih.gov/pubmed/24658949">Pubmed</a> <span class="ref_v4"></span>
- 10. Singh C, Biswas A. Impact of gestational age on nuchal fold thickness in the second trimester. (2014) Journal of ultrasound in medicine : official journal of the American Institute of Ultrasound in Medicine. 33 (4): 687-90. <a href="https://doi.org/10.7863/ultra.33.4.687">doi:10.7863/ultra.33.4.687</a> - <a href="https://www.ncbi.nlm.nih.gov/pubmed/24658949">Pubmed</a> <span class="ref_v4"></span>
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