After each ultrasound procedure, pregnant women receive a study protocol in their hands, which contains important information on the development of the baby. One of the most important parameters of the fetus is the biparietal size of the head, or BPR. What is the BDP of the fetus and for what it is needed, how BDP and pregnancy are related, what are the norms of biparietal head size for weeks - you will learn all this from our article.
БПР - decoding
During the ultrasound, special attention is paid to the study of the baby's head. This is not surprising: the brain is the most important organ, the growth and development of which directly affect the fetus. Determine the size of the head, and hence the level of brain development will help BDP. Biparietal size is a kind of "width" of the head, measured along the minor axis, from the temple to the temple.
In addition to the BPR, the frontal-occipital size (LZR) is also defined - along the major axis, from the forehead to the occiput. However, the main parameter remains biparietal size: it is used to determine the duration of pregnancy. With special accuracy, this can be established in the period of 12-28 weeks.
The values of BDP are also important for determining the possibility of physiological delivery. If the size of the fetal head does not correlate with the dimensions of the birth canal, a decision is made about the planned cesarean section.
Biparietal size of the head - norm
For the evaluation of BDP fetus for a week, special tables have been developed, which indicate the average indices of the biparietal size of the fetal head and its permissible fluctuations. In BDP tables, fetal head size values are represented as percentiles. This is a special way of representing medical statistics, which, as a rule, indicates the average value (50th percentile), as well as the lower (5th percentile) and upper (95th percentile) boundaries of normal values.
In order to use this table and determine the norm of the BDP of the fetus for weeks, it is necessary to find the value of the 50th percentile, the remaining values determine the boundaries of normal indications. For example, at 12 weeks the norm of the BDP is 21 mm, with tolerances of 18-24 mm. This means that when the BPR value of 19 mm to the future mother is not worth worrying about - this is most likely a feature of the development of the baby.
BDP fetus in the table - deviation from the norm
It happens that BDP indicators go beyond acceptable limits. What does this mean? First, in order to be convinced of the absence of pathology, the physician should evaluate other parameters of the fetus (length of the thigh, abdominal circumference). If all of them exceed the norm for one or several weeks, then it can talk about a large fruit. If other values of fetometry are normal, then it is possible that the baby is growing jumpwise, and after a couple of weeks all parameters are leveled.
Nevertheless, significant deviations in the values of BDP from the norm may indicate serious problems. Thus, an increased biparietal size is observed in tumors of the brain or skull bones, as well as in cerebral hernia and hydrocephalus . In all these cases, with the exception of hydrocephalus, the pregnant woman is offered to interrupt pregnancy, since these pathologies are incompatible with life. When hydrocephalus is detected, antibiotics are administered and only in rare cases (in the absence of the effect of treatment) resort to abortion.
The significantly reduced size of the fetal head also does not bode well: as a rule, this means underdevelopment of the brain or the absence of some of its structures (the cerebellum or the cerebral hemispheres). In this case, at any time the pregnancy is interrupted.
In the third trimester, a reduced BDP indicates the presence of a syndrome of intrauterine growth retardation. Treatment is carried out with drugs that improve uterine-placental blood flow (kurantil, actovegin, etc.).