Maternofetal

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Anatomy scan: late fetal health and risks

Ultrasound sequence, minimal fetal sonography suggested by the American College of Obstetricians and Gynecologists (ACOG) for the evaluation of the second and third trimester fetuses; it is the continuation of the evaluation of structures not visible during the first trimester and the obtaining of functional data and prediction of risks such as preeclampsia and premature delivery. It must include fetal echocardiography, so it is suggested that the sonographer have solid knowledge in this area.

Typical study: minimum evaluation

The study begins by determining the position of the fetus within the womb, determination of sex and the indemnity of the face to rule out labiopalatal clefts. We observe the amount of amniotic fluid

Fetal position

Evaluation of the fetal head and its dimensions. Hydrocephalus and many other congenital disorders present in the region are ruled out. Indirectly we can suspect the presence of Spina Bifida if it exists

Measurement of intracerebral structures, healthy baby

Presence of the four limbs (Arms and Legs) and their long bones (Humerus, Ulna, Radius, Femur, Tibia and Fibula) and their measurements

Measurement of the 4 main bones and comparison between them

Cross section of the fetal abdomen and we measure its circumference while evaluating stomach, spleen, liver, gall bladder, kidneys, adrenal, intestines and bladder. The two measurements (abdomen and femur) provide the fetal weight of the moment.

Abdominal circumference and femur: obtaining fetal weight

Systematic anatomical review starting from the head where we review the profile, the orbits and fetal eyes and measurement of the nasal bones (known marker of Down syndrome when they are very small or non-existent)

Orbits and nasal bones

Evaluation of the spine from the cervical region to the sacrum, with special emphasis on the lumbar region as the favorite site for the appearance of Spina Bifida. The presence of encephalocele, another form of Neural Tube Defect, is also ruled out.

Fetal column and sacrum

Thoracic evaluation, ribs, lung characteristics and heart determining activity data, orientation, cardiac axis (VN 20-70 degrees), presence, quality of the four cardiac chambers and their partitions and the exit of the great vessels (aorta and pulmonary). The normal vision of the 4 cameras discards 60% of the major cardiac malformations, the large vessels the remaining 40%

Study of the fetal thorax, detail of the baby's heart and diaphragm

Legs and feet: It is very important to evaluate the relationship of the foot and leg joint to rule out equine foot disorders and deformities. Here we observe a correct alignment of the foot and the leg. The sole of the foot detects local problems and may indicate chromosomal alterations: equine foot, positional deformities of the foot and leg, joint disorders and markers such as the heel in rocking chair (trisomy 18) and the sign of the sandal (trisomy 21)

Evaluation of legs and feet

Detail of feet and hands to determine the presence of 5 fingers, their relations between them, as well as the presence of the phalanges of the fingers. The aberrant position of the fingers, the shape of the fist, the number of fingers, the sequence of opening and closing of the hand are details of careful study since they can indicate the presence of abnormal conditions

Evaluation of the fingers and toes

Evaluation of the placenta, its location, appearance, structural changes and thickness. Placenta previa is ruled out

Placenta and its cord inserted into it

The umbilical cord is evaluated to show the presence of its three normal components and we follow it all the way to its origin in the fetus, around the bladder. In this case we verify it using the Doppler, see the two arteries

Origin of the cord arteries in the fetal pelvis flanking the bladder

The presence of cord circles in the fetal neck and the presence of true cord knots are discarded (color Doppler)

Cervical circular double cord demonstrated by Doppler

Normal Doppler of the Umbilical Cord: correlates directly with fetal oxygenation (placental function)

Normal Doppler

The study is complemented by verifying the flow pattern of the Middle Cerebral Artery, this provides us with direct evidence of cerebral oxygenation. The study of both circulations gives us the Cordo-Cerebral Pattern, index that effectively indicates health or progressive fetal commitment

Average normal brain

To finish the Doppler evaluation of the baby, the uterine flow pattern of the mother is studied to predict the risk of Preeclampsia.

Uterine without risk of HIE

Even without risk factors for premature birth or when the patient has contracted uterine contractions or discomfort, a brief transvaginal evaluation of the cervix is ??performed for the prediction of a premature birth.

It is routine between weeks 20-24

Normal, long 41mm uterine neck. No risk of premature delivery

The second trimester runs from week 14 to week 26, by this time the baby has already acquired its final human form and all its organs are fully formed. This is a relatively boring period because the dramatic changes to which the embryo / fetus used to be during the First Trimester will no longer be observed, but thanks to the growth of the organs it is possible to complete the anatomical study of those structures that for their small Size could not be seen in more detail. This is the case of the fetal heart, whose early evaluation was superficial and insufficient.

This is the period of easiest to perform an ultrasound study since the baby is large enough to look very well through the Surface Ultrasound (Transabdominal), is small enough to cover it very well within the ultrasound image and the amniotic fluid is comparatively abundant so that the baby is comfortable and has plenty of room to move and allow us to see it in great detail from many angles.

Anatomical Eco of the week 18-23: in our Service we established the evaluation scheme proposed by the Foundation of Fetal Medicine of the United Kingdom so that after the study of 11 to 14 weeks follows the anatomical evaluation of 18-23 weeks. As already said, this period has a series of advantages that allow us to carry out a study that complements or replaces the genetic evaluation of the First Trimester if this could not be carried out at the time. Unfortunately, if there are severe problems and the screening is done towards the end of the period, the possibility of performing diagnostic studies such as amniocentesis will be compromised.

Anatomic scan (Genetic) Second Trimester: Between weeks 16 and 20 we perform the genetic evaluation of the fetus making the screening of multiple risk markers for chromosomal disease, genetic syndromes and congenital anomalies if they exist. If there are risk markers, an Amniocentesis or similar procedure will be suggested. If we can diagnose a particular disease, the patient will go to Genetic or Perinatological Counseling to evaluate the prognosis, treatment (if any) and future recurrence of the detected condition. In our experience, the results of the first trimester and the second trimester are similar with the advantage that starting from week 16 we can already make an unequivocal diagnosis of fetal sex.

The third trimester corresponds to the last 13 weeks of pregnancy and goes from week 27 to 40 (up to 42 according to the World Health Organization). The main characteristic of this period is the growth and fetal maturation and the appearance of maternal diseases such as Pregnancy-Induced Hypertension (HIE, Preeclampsia), Pregnancy Diabetes (Gestational Diabetes, DG) and Gestational Dermatoses , among others. frequent

At the beginning of the period it is easy to perform an ultrasound due to the conditions described for the end of the second trimester but as we approach the end of pregnancy the size and the agglomeration of fetal parts make accurate anatomical diagnosis difficult, so in some cases the diagnostic sensitivity drops considerably It is for this reason that the ideal time for the three-dimensional Eco is at the beginning of this period: Between weeks 26-29 of pregnancy are given the conditions to make a study with excellent conditions of technical resolution of the team (clear and very detailed images) as shown in the sequential images (see below) of what corresponds to a good quality study; In addition, the Doppler study (included in the 3D assessment scheme) of Fetal and Maternal circulation allows us to detect problems early or predict them before they occur to take the necessary preventive or therapeutic measures.

Optionally we obtain 3D images of significant elements such as the face or the genitals.