The importance of screening ultrasound between weeks 11 and 14 by gynecologist Yolima Martinez
Gynecology
Author: Yolima Martínez Velásquez Modified date:
What is the screening ultrasound from week 11 to 14?
The screening ultrasound is an ultrasound that is performed on the mother at 3 months of pregnancy, specifically between weeks 11 to 13 6/7, in order to assess the baby's risk of suffering from in the number of chromosomes, such as trisomy 21 or Down syndrome (the best known), trisomy 13, and trisomy 18.
How is screening done from week 11 to 14?
Genetic screening from week 11 to 14 can be performed with ultrasound alone or by combining ultrasound with the triple serum marker, the latter approach has a higher detection rate (92%). An ultrasound is performed through the maternal abdomen looking for specific markers of the baby and a blood sample is taken from the mother, to evaluate the levels of three substances that are normally found in pregnancy, but whose concentrations may be affected in cases of mothers who carry babies with chromosomal alterations in their womb or mothers who at older gestational ages will present pre-eclampsia (high blood pressure in pregnancy).
What can be seen in the screening from week 11 to 14?
In this ultrasound the size of the baby is evaluated from head to tail, the gestational age is calculated in a very reliable way. The thickness of the fluid in the neck of the baby (nuchal translucency), the blood that passes through a vein in the abdomen, which is called the ductus venosus, the presence of the nasal bone and the competence of one of the heart valves (tricuspid) is determined. . It is usual for babies with Down syndrome to show altered some of these markers. Additionally, the mother's blood is evaluated in the uterine arteries, through Doppler, to determine the risk of pre-eclampsia. And depending on the position of the baby, in some cases we could evaluate the probability of fetal sex.
What happens if the 11-14 week screening is not done?
If the 11-14 week screening is not performed, the opportunity to establish the risk of Down syndrome in the baby is lost. Given that at other gestational ages, these specific ultrasound markers cannot be taken, nor can the risk of this disease be calculated, in order to know if it is necessary to perform other invasive tests (taking fluid from the amniotic sac) to confirm if there is any alteration of the chromosome type.
What happens if screening is done after week 14?
If screening is done after week 14, we can establish the risk of Down syndrome until the baby's head-to-tail (CCL) measurement is 84 mm. Above this value, which is equivalent to a gestational age greater than 14 weeks, there are no tables to extrapolate the ultrasound findings into risk probabilities, so we cannot establish whether the pregnancy is at high risk for chromosomal alterations or not.
What can be detected in the 11-14 week screening?
At the 11-14 week screening, ultrasound findings may be found to suggest that the baby is highly likely to have Down syndrome. Some early major malformations can be evaluated, some of these incompatible with life, such as the absence of the skull (acrania-anencephaly), the absence of the sternum bone in the baby's chest (ectopia cordis), hernias of the abdominal wall ( omphalocele, gastroschisis), absence of limbs and problems associated with large bladder (megabladder), among others.
Why is it important to be screened between weeks 11-14?
Screening between weeks 11 and 14 is one of the most important ultrasounds together with ultrasound of anatomical detail from weeks 20 to 24. With this screening, it is possible to know early and with a detection rate close to 80% , if the baby may be suffering from Down syndrome and thus be able to carry out tests that confirm it before the baby is born. It is an aid to counseling parents about the risk of pregnancy.
How much does a screening ultrasound cost between weeks 11-14?
The cost of the screening ultrasound varies depending on many factors, such as social security affiliation, city in which you are located, professional who performs it and it will depend on whether you perform the combined screening of the ultrasound with the blood sample maternal. The most important thing to keep in mind is that this ultrasound is performed by qualified personnel in this area, the most suitable person will always be the specialist in Maternal Fetal Medicine or Perinatology, who has the training to look for ultrasound markers in your baby, extensive knowledge in prenatal diagnosis and diseases of both the mother and the babies in the womb, which will be able to guide you regarding what other tests or procedures are required, explaining the implications and prognosis of your pregnancy.