The 18th week of pregnancy is a time of relative calm. Painful bouts of toxicosis have receded, the feeling of heaviness has not yet appeared. The mood of the expectant mother is excellent. It is during this period that she can receive a referral for an ultrasound scan. What the diagnostics will show for such a period and what to prepare for, we will tell in this article.
Objectives of the survey
The concept of "screening" is already familiar to the expectant mother, because in the first trimester she already underwent an ultrasound scan and donated blood for laboratory biochemical research. At 18 weeks she will have another screening, the second in a row. The Ministry of Health recommends that it be carried out from 18 to 21 weeks, so now is the right time to re-look at the long-awaited baby.
Screening ultrasound is supported by data obtained from the laboratory. According to the results of both studies, one can judge about possible pathological conditions, some malformations of the fetus.
Ultrasound examination at 18 weeks has an important goal - identify problems in the development of the baby... But this is not the only reason why the scan is done. At this time, an ultrasound scan helps to navigate the timing of pregnancy, if they are not fully clarified, and also to set the expected date of birth.
During this period already you can try to see the gender of the child, because the external genitals are fully formed.
If the baby is not shy and shows the doctor his gender, the woman will be able to find out who she expects - a son or a daughter.
The issues that are resolved during the screening do not imply gender determination, therefore this service is paid, while all other diagnostic measures within the framework of prenatal diagnostics are completely free for all women in an “interesting position”.
An unscheduled ultrasound scan at 18 weeks can be done according to indications - these are sudden pain sensations, discharge that cannot be considered normal for pregnant women, a discrepancy between the height of the bottom of the uterus and the obstetric period.
Preparation for the procedure and features of the procedure
Ultrasound at week 18 can be performed in two ways - internal or external. The internal one, called transvaginal, gives a good view through the vaginal wall if it is obstructed through the peritoneum. It may be difficult for a doctor to see a child if the expectant mother is the owner of extra pounds and fat folds on her stomach.
The vaginal probe is also indispensable for the threat of termination of pregnancy, as it allows you to more clearly see the cervix and cervical canal at 18 weeks.
If a woman has a normal or thin physique, this week of pregnancy, you can conduct a transabdominal study - through the abdomen. Preparation for an ultrasound scan is not required, no matter how it is carried out. No need to drink water or tea to fill up your bladder, there is no need to follow a diet that reduces flatulence in the intestines.
What is seen on an ultrasound scan?
At 18 weeks, the baby looks like a small person, but his head is still disproportionately large. The growth of the crumbs from heels to crown is almost 20 centimeters, and its weight approaches 200-240 grams. Such dimensions allow him to roll freely, swim, push off from the walls of the uterus, make a variety of movements with his arms and legs. It is at this time that some pregnant women begin to feel the first movements. Basically, these are women expecting twins or triplets, as well as multiparous.
Even if the woman does not yet feel the movements, you can enjoy the baby's movements during the ultrasound procedure. The baby's skin is still very thin, blood vessels can be seen through it. The brain is developing rapidly, this week the endocrine system begins to work. This ultrasound scan, of course, will not show.
But the mother will be able to see the little heart, listen to how it beats, if the level of the equipment allows, then you can see how the baby clenches and unclenches his fists, spreads his fingers.
The baby already distinguishes sounds. He was already accustomed to the beating of his mother's heart, the murmur of blood in her vessels, but everything new, what comes from outside, interests and frightens him at the same time. Therefore, the baby can liven up at the unfamiliar voice of the health worker who is conducting the research, or, on the contrary, he can be frightened and quiet down.
The genitals are clearly visible at this time, if the baby is located conveniently for examination. It is possible that the umbilical cord will be clamped between the legs. And then the girl can be confused with the boy. Shy little boys can hide their "dignity" between their legs and they can easily be mistaken for a girl. The percentage of error, however, is not large at this time - no more than 2-4%.
Norms and decoding
The description is compiled in three main areas - the size of the fetus (fetometric indicators), the anatomy of the fetus (the presence and correct formation of internal organs), as well as a description of the auxiliary organs and environments - the placenta, umbilical cord, amniotic fluid surrounding the toddler. In addition, the doctor assesses the state of health of the woman herself - whether everything is in order with her reproductive organs, whether there is a threat of termination of pregnancy.
Fetometry of the fetus
It is possible to draw conclusions about how the child's head is developed by two parameters, their diagnosticians measure first of all. These are the longitudinal (LZR) and transverse dimensions (BPR). The head circumference completes the picture. The size such as the circumference of the baby's abdomen. At this time, measurements of paired bones are also carried out - the femur, the bones of the lower leg, shoulder and forearm. At 18 weeks, the bones of the nose are also measured.
Baby head sizes:
Sizes of paired bones and bones of the nose:
Anatomical features
The baby in the womb is already large enough for the doctor to examine its internal organs. During the study, the heart is examined, excluding possible defects of this organ and large vessels. Doctors are also interested in the kidneys, bladder of a child, intestines, stomach, lungs, gallbladder, brain structures and cerebellum.
In the absence of defects and visible problems, the doctor indicates that the internal organs of the toddler do not have any peculiarities.
Placenta, umbilical cord, amniotic fluid
The rates and deviations are compared with this table:
The diagnostician be sure to note where the placenta is located. In most pregnant women, this temporary organ, responsible for supplying the baby with everything necessary for 9 months, is located along the posterior uterine wall, however, the anterior location should not be surprising either. This is a variant of the norm, only requiring more careful management of pregnancy by the attending physician.
Possible problems
During the ultrasound scan at 18 weeks, some pathological conditions may become apparent. Let's talk about the most common ones:
Child's size is lagging or outstripping
Any discrepancies with the standards that are inherent in fetuses for a certain period of time require careful study by doctors. Small lags or advances - can be caused by completely harmless reasons - heredity, peculiarities of the baby's body constitution. Skinny parents usually have the same children.
Situations where the sizes deviate in one direction or another for 2 weeks or more deserve additional examination.
In this case, you should pay attention to exactly which sizes exceed the norm, whether the process is symmetrical (when all sizes are increased), or there is an asymmetry (only one part of the body or one size is increased).
An increase and decrease in a child's head can be a sign of genetic malformations, hydrocephalus, or microcephalus. If the dimensions are enlarged symmetrically, then there is a possibility that a woman is carrying a fetus with a tendency to a large weight (more than 4 kilograms) or to a gigantic weight (more than 5 kilograms).
Symmetrical decrease may indicate trouble, which is experienced by the crumb, right up to intrauterine growth retardation.
However, there is no need to rush to conclusions - children grow in the womb in "leaps", and it is possible that on the control ultrasound in a couple of weeks the baby will "align" in the parameters.
Nose bones are lagging behind
The length of the nose bones is a marker of chromosomal abnormalities. In children with Down, Patau, Turner syndromes and other incurable diseases, the face profile is flattened, the nose is much smaller than that of healthy peers. This fact is taken as the basis for measuring this parameter. A slight lag in the length of the nasal bones should not be too worrisome either.
Rather, this is a reason to look carefully in the mirror for the mother herself and study the appearance of her relatives. Maybe in the family, small noses are a hereditary feature.
From the same point of view, a moderate increase in the size of the nose of the crumbs should not cause panic.
When measuring this parameter, errors and inaccuracies very often occur, which are a consequence of the fact that the equipment on which the diagnostics are carried out is outdated and has a low resolution.
If the diagnostician is still inclined to consider the deviation significant, and blood tests confirm an imbalance of hormones and proteins in the body, then this is - a reason to see a geneticist and, possibly, undergo invasive procedures - amniocentesis or chorionic biopsy in order to know with more than 99% accuracy whether the child is healthy.
The placenta is low
The diagnostician's verdict on the low location of the placenta should not enter the pregnant woman into a stupor. Pregnancy has not yet reached even half, the most intensive growth of the uterus is yet to come. The "child's place" has every chance to rise higher together with the growing uterine wall. In most cases, this is what happens.
However, the established low placentation imposes a number of restrictions on a woman - she should not lift weights, bend over and squat sharply, she should take vitamin complexes, eat well, avoid fast walking, fatigue, and often lie in a horizontal position. In some cases, doctors offer hospitalization in the department of gynecology or pathology of pregnant women, and you should not refuse it.
Ultrasound pictures
Even on a conventional two-dimensional ultrasound at 18 weeks, you can see not only the baby's profile, but also the spine, ribs, fingers. A three-dimensional ultrasound scan can be performed at this time, but so far nothing particularly interesting can be found in 3D images. The baby is not yet grimacing, not "posing". To get bright and emotional "photos" it is better to visit a 3D ultrasound after 21 weeks.
If the doctor manages to "get close" with the sensor from below, then in such a projection you can clearly see the sexual characteristics - a boy and a girl from this angle can be distinguished from each other with the naked, unprofessional eye.
If you want to save a photo from this ultrasound for history, you should ask the doctor for a digital copy, since ultrasound images tend to quickly discolor and lose image contrast.
