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How to define a normal or abnormal nuchal translucency measurement can be difficult. The use of a single millimeter cutoff (such as 2.5 or 3.0 mm) is inappropriate because nuchal translucency measurements normally increases with gestational age (by approximately 15% to 20% per gestational week from 10 to 13 weeks). [10]
Perhaps the most common such test uses a measurement of the nuchal translucency thickness ("NT-test", or "Nuchal Scan"). Although 91% of fetuses affected by Down syndrome exhibit this defect, 5% of fetuses flagged by the test do not have Down syndrome. Ultrasound may also detect fetal organ anomaly.
Pelvimetry is the measurement of the female pelvis. [1] It can theoretically identify cephalo-pelvic disproportion, which is when the capacity of the pelvis is inadequate to allow the fetus to negotiate the birth canal. However, clinical evidence indicate that all pregnant women should be allowed a trial of labor regardless of pelvimetry ...
An ultrasound showing an embryo measured to have a crown-rump length of 1.67 cm and estimated to have a gestational age of 8 weeks and 1 day. Crown-rump length (CRL) is the measurement of the length of human embryos and fetuses from the top of the head (crown) to the bottom of the buttocks (rump).
By comparison, in the same 4000 women, a screening test that has a 99% sensitivity and a 0.5% false positive rate would detect all 10 positives while telling 20 normal women that they are positive. Therefore, 30 women would undergo a confirmatory invasive procedure and 10 of them (33%) would be confirmed as positive and 20 would be told that ...
Increased nuchal translucency or other abnormal ultrasound findings; Family history of a chromosomal abnormality or other genetic disorder; Parents are known carriers for a genetic disorder; Advanced maternal age (maternal age above 35). AMA is associated with increase risk of Down's syndrome and at age 35, risk is 1:400.
An AFI between 8 and 18 cm is considered normal. [5] Median AFI level is approximately 14 cm from week 20 to week 35, [6] when the amniotic fluid begins to reduce in preparation for birth. An AFI smaller than 5–6 cm is considered as oligohydramnios. [3] The exact number can vary by gestational age.
Nicolaides has developed methods of (i) screening for premature birth (which is the main cause of perinatal morbidity and mortality) by measurement of cervical length and prevention through the use of vaginal progesterone, [9] (ii) screening for pre-eclampsia (which is one of the main causes of maternal mortality) by measurement of blood flow ...