Both of malformations and for damage to the brain is a threshold dose of 100 mSv. To radiation must be fatal in fetal life, is the threshold of 200 mSv in the first trimester and over 500 mSv later in pregnancy. It is dose sizes extremely rarely achieved by radiographic examination.
Radiation doses in various studies
There are studies that show made radiation dose in mSv on fetus for part studies carried out on the mother. Different ways to take pictures of and differences in equipment and techniques means that doses may vary somewhat. On average, the leading x-ray of head or x-ray of the lungs to less than 0.01 mSv. X-ray of the kidneys (urography) and x-ray study of lumbar spine average 1.7 mSv (maximum 10 mSv). Candling of the colon leads to average 6.8 mSv (max. 24 mSv).
mSv definitions: http://www.abbreviationfinder.org/acronyms/msv.html
CT study of the head causes less than 0.005 mSv and CT examination of lungs 0.06 mSv. CT of the entire stomach area (abdomen) gives the radiation dose on average 8.0 mSv (max. 49 mSv), CT of spine 2.4 mSv (max 8.6), while CT of pelvis allows the average radiation dose to the fetus at 25 mSv (max 79 mSv).
CT definitions: http://www.abbreviationfinder.org/acronyms/ct.html
Ultrasound examination or MRI examinations do not entail any x-ray radiation.
MRI definitions: https://en.wikipedia.org/wiki/MRI
Pregnant women should only be taken as a starting point, the x-rays, if it has therapeutic impact of pregnancy. It follows the general principle that pregnant for the sake of the fetus should be spared as much as possible. There are situations where x-ray photography is recommended, even if the patient is pregnant. One example is the x-ray of the lungs where there is suspicion of tuberculosis.
If there are good medical reasons to carry out x-ray examinations of pregnant or if there will be taken pictures without being known to the pregnancy, it may be helpful to read the instructions from the National Institute of radiation protection (SIS).
SIS says on the basis of international recommendations, that there will never be any reason to recommend abortion, if the radiation dose to the foetus is estimated to be less than 100 mSv. Usually there is no radiographic examination, which comes up in such radiation doses.
There can often be the concerns of parents who have been exposed to radiation of ovaries or testes before fertilization. Conclusion based on the available knowledge is that this does not result in increased risk of malformation, abnormalities in mental development or increased cancer risk in the child.
The ultrasound 32 weeks is the exam most important during the 3rd quarter, and provides key information to ascertain the evolution of the foetus.
The ultrasound 32 weeks , or an ultrasound of the 3rd quarter is an examination of prenatal diagnosis that essentially serves to evaluate the development of the fetus, through the study (doppler) of fetal circulation and the placenta, as well as to exclude possible malformations that can arise in this final stage of pregnancy.
According to the recommendations of the World Health Organization (WHO), the pregnant woman should perform an ultrasound by quarter to evaluate the well-being of the fetus and its development.
This ultrasound is not as exciting for parents as to the previous, due to the fact that at this stage, the majority already know the sex of the baby and how the baby is already relatively large, it is more difficult to view the baby in their entirety, as well as watching him move, because it already occupies the large part of the amniotic sac.
1. WHEN SHOULD YOU CARRY OUT?
The ultrasound 32 weeks should always be carried out between the 30th and 32nd week + 6 days of pregnancy.
2. WHY IS IT SO IMPORTANT TO ULTRASOUND 32 WEEKS?
This examination is important because it provides valuable information to the medical expert that will be fundamental in the follow-up of the remainder of the time of gestation, as well as during the time of the birth.
The objectives of this exam are:
- Determine the position of the fetus (which, probably, will already be in position cephalic, or head down), so as to assist the physician in the decision of what type of delivery the mother should have;
- Determine the amount of amniotic fluid existing, since a small amount of liquid may induce a premature birth;
- Check if the fetus is developing correctly:
- Measurement of the length of the femur;
- Assessment of head circumference and abdominal circumference;
- Approximate determination of the size and weight of the baby at the time, and the expected size at the time of delivery.
- Assess the location and status of the placenta, this is important as your pregnancy progresses and the placenta also grows old, but in some cases it ages more quickly, which can affect the ability to nourish and provide oxygen to the baby at all. If the placenta is not well-located you may need a caesarean section;
- Detect fetal abnormalities , the onset late;
- Evaluate the fluxometria of the umbilical cord and the fetus (evaluation of the movement placentar and fetal).
3. HOW IS IT PERFORMED THE ULTRASOUND?
This examination is carried out in the same way that the 1st or the 2nd ultrasound scan of the pregnancy, that is, the realization of this ultrasound does not require any preparation or care prior.
The woman should remain lying down during the examination and will be placed a ecógrafo on the abdomen, after the application of a gel that facilitates the transmission and reception of ultra-sounds.
4. WHAT ARE THE RISKS ASSOCIATED?
For the case of an examination non-invasive and painless, where there is no emission of radiation, this test does not present risks for both the fetus as to the mother and can be performed as often as necessary throughout the pregnancy.
After 32 weeks, in the case of situations of high risk pregnancy (hypertension, diabetes, delay of intrauterine growth, etc.) you may justify doing more of the scans, however, this decision will be up to your obstetrician.
There may be the need to perform other complementary diagnostic tests for clarification of the clinical situations detected.