The position of the fetus plays a huge role in the mechanism of childbirth. There are head presentation of the fetus during pregnancy and pelvic, depending on this, we can talk about the natural course of childbirth or the need for surgical intervention (cesarean section).
Fetal presentation options
Normal in obstetrics is considered the head presentation of the fetus during pregnancy. In the anterior view, which begins from the occipital presentation, the most favorable parameters are formed between the size of the fetal head and the small pelvis of the woman in labor. The rear view, which refers to the occipital presentation and is the initial stage of the extension of the head, suggests that much more labor will be needed, since the fetus passes through the birth canal with large head sizes. Complications in the form of asphyxia and weak labor are possible.
Frontal presentation is the II degree of extension of the head, when the foremost part is the foremost. In this case, the delivery is delayed. If the pelvic ring is normal or large, then independent delivery is allowed. The period of exile, the third period of childbirth, lasts a long time. There may be complications in the form of asphyxia and fetal death, deep ruptures of the perineum, uterine ruptures.
With facial presentation or III degree extension, the face becomes the lower part. A favorable course of labor is possible if the ratio between the pelvis and the fetus is optimal. Rarely there is a complication in which a posterior view of facial presentation occurs (the forehead is facing the symphysis, and the chin to the sacrum). In such cases, perforation of the head or cesarean section are mandatory.
The high standing of the head indicates that the entrance to the small pelvis is an arrow-shaped seam. With the correct ratio of the size of the head and pelvis, a strong bending of the head occurs when passing through all the planes of the pelvis. Approaching the bottom, the head enters the suboccipital fossa into the pubic arch and performs extension.
At the highest or, on the contrary, upright standing of the head, there may be complications in the form of weak labor, the head does not advance, soft tissues are compressed and fetal asphyxiation occurs. The anterior view, which refers to the high upright standing of the head, usually ends in spontaneous delivery, and in the posterior view, a cesarean section or craniotomy is most often done.
Causes of incorrect insertion of the fetal head during childbirth
Obstetricians identify the following reasons:
- placenta previa;
- narrow pelvis;
- uterine fibroids;
- heredity;
- abnormal structure of the uterus;
- polyhydramnios.
At various stages of pregnancy, the above pathologies can cause miscarriage or premature birth.
What you need to know with low cephalic previa
At a period of 20-36 weeks, pregnant women can find out about the low position of the fetus. But do not worry, this situation is quite common and can be controlled. Therefore, it is important to follow the recommendations of the doctor who monitors the course of your pregnancy.
The doctor's recommendations for low placenta previa are as follows:
- not to run;
- rest more often;
- abandon physical activity;
- use a special antenatal bandage.
Almost always, childbirth in such cases passes safely and without complications.
Asynclitism or incorrect insertion of the head
Asynclitic insertion is considered abnormal, during which the head is inserted not into the large but into the small pelvis, but the sagittal suture deviates forward or backward from the center of the midline. So, one of the parietal bones falls below the other. Weak asynclitism does not adversely affect the course of childbirth. Asynclitic insertion of the head sometimes positively affects the course of labor. But if asynclitism is strongly expressed, then this prevents the head from moving.
Causes of Asynclitic Insertion of the Head
Off-axis insertion of the head into the pelvis may be due to the following reasons:
- The flaccid state of the abdominal wall, which does not restrain the fundus of the uterus protruding forward, forms an anteroposterior insertion.
- A weak lower segment of the uterus, which is not able to withstand the head protruding forward, forms a posterior insertion.
An important factor is that the size of the fetal head and the small pelvis of the woman in childbirth may not fit together and hamper the mechanism of childbirth.
Clinical picture
Determining the asynclitic insertion of the head using external palpation is quite difficult. A vaginal examination is considered decisive , with the help of it a suture is felt on the skull of the fetus and the approach to the womb or to the cape is determined. With pronounced asynclitism, it is possible to feel the ear or cheek of the fetus, such a presentation is called ear or buccal.
Types of Asynclitism
In the normal mechanism of labor, the fetal head may be above the pelvis and the swept suture coincides with the wireline of the pelvis. This insertion is called axial or synclitic, favorably affects the passage of the head through the birth canal.
A moderately expressed asynclitic insertion of the head is characterized by the fact that the fetal head is uneven at the entrance to the pelvis and the anterior bone is lower than the posterior.
Obstetricians distinguish the following types of asynclitism:
- Front - sagittal suture is located next to the sacrum, the anterior or parietal bone is lower and is the leading point.
- Back - the seam on the skull of the fetus is deflected forward to the fold, and the posterior parietal bone appears first in the pelvic plane.
Thanks to the front insertion, the conditions for the passage of the head through the narrow birth canal become optimal. More often in childbirth, posterior asynclitism occurs.