Forehead, frontal and facial presentation of the fetus

The anterolateral, frontal and facial presentations are called extensor, formed in total in 0.5-1% of cases.

[1], [2], [3], [4]

Causes of extensor presentation of the fetus

The causes of the formation lie in the characteristics of the pregnant and fetus organisms, because of which the present part of the fetus can not properly settle above the entrance to the small pelvis.

For maternal reasons include overgrowth of the uterus, polyhydramnios, multiple births, multiple births, irregular shape of the uterus - saddle, two-partedness, the presence of septum in the cavity, fibromyoma.

Fruit causes are small or too large fetal head sizes (prematurity, anencephaly, microcephaly, hydrocephalus), the presence of cervical teratomas, thyroid tumors.

An important reason for the extensor insertion of the head is a clinical mismatch between the size of the head and pelvis, in particular with narrow basins, large fruits, tumors of the soft and bony tissues of the pelvis.

Biomechanism of labor in all types of extensor presentation has common features: in all variants of extensor presentation, births are possible only under the condition of forming a rear view, which is especially important for labor in facial presentation.

[5], [6]

Anterior preposition

Anteroplegia often occurs with a flat pelvis, that is, with reduced, straight dimensions of the pelvic planes with normal transverse planes. In such cases, the head is long above the entrance to the pelvis with a swept suture in a transverse dimension, both fontanels are on the same level. If, due to adaptive movements, the fetal head will unbend (the first moment of the birth biomechanism), then the large fontanel will become the leading point and first fall into the small pelvis. A large segment of the head in this case will correspond to the circle by its straight size (12 cm). A generic tumor is formed in the region of a large fontanel, the head acquires a tower configuration.

When going from a wide to a narrow part of the small pelvis, the head begins an internal turn (the second moment of the birth biomechanism), completed in the plane of exit from the pelvis with the formation of a rear view. The recognition lines on the presenting part will be the swept seam and part of the frontal suture.

The first fixation point is formed on the present part, between the nose bridge and the lower edge of the pubic bone. The occipital part of the head under the action of expulsive forces directed along the axis of the spine, continues to move forward. This is the third point in the biomechanism of labor - the flexion of the head. Clinically, this moment corresponds to the birth of a large fontanel and parietal: bugra. Head eruption with a straight size with a circumference of 34 cm is often accompanied by trauma to the head and soft tissues of the birth canal.

After passing through the head of the exit plane of the small pelvis, the nose bridge slides out from under the bosom, and the occipital part of the head is fixed at the tip of the coccyx or sacrococcygeal articulation, forming the second fixation point with the suboccipital fossa. The fourth moment of the biomechanism of sorts begins - the extension of the head, which clinically corresponds to the birth of the fetus from under the fetus. The fifth moment of the biomechanism of births - the internal turn of the shoulder girdle - does not differ from that in the occipital presentation.

The course of labor with anterior preposition, even in the case of normal fetal and pelvic dimensions, is lengthy, requiring a significant head configuration and vigorous labor.

For the diagnosis of anterolateral insertion in labor, the methods of external obstetric research are poorly informative, although Leopold's third and fourth methods sometimes determine the degree of extension of the head.

With sufficient opening of the cervix and absent fetal bladder, the most important diagnostic value is internal obstetric research. The basis for diagnosing an anterolateral presentation (insertion) is the location on the leading axis of the pelvis of the large fontanel and easily accessible for palpation of the arrow-shaped suture.

In parturient women with normal fetal and pelvic dimensions, uncomplicated obstetrical anamnesis and regular labor activity, the births in the anterolateral presentation take place expectantly through the natural birth canal. With a burdened obstetric anamnesis and with the slightest deviations from the normal course of labor, the delivery by cesarean section is indicated.

Frontal presentation

The frontal presentation is a significant danger in childbirth. It is formed as a transition from the head to the front. Spontaneous delivery is extremely rare premature with a low body weight or a dead fetus with autolysis phenomena.

The causes of frontal insertion are similar to those of other extensor insertions. A large segment corresponds to a large oblique head size (13.5 cm, 39-41 cm in circumference).

The first moment of the biomechanism of birth is also the extension of the head. The leading point is the middle of the frontal suture, which first enters the plane of the entrance to the small pelvis. A generic tumor forms on the joint, and the head acquires a pyramidal shape.

The second moment of the birth biomechanism - the inner turn of the head - also ends in the pelvic floor with the formation of a rear view. The first fixation point is formed between the upper jaw of the fetus and the lower edge of the womb. The third moment of the biomechanism of labor is performed - the flexion of the head. The birth of the head is similar to that described in front of the headless presentation with a similar second fixation point and the fourth moment of the biomechanism of the genus. The humeral girdle is born as in the occipital presentation,

Timely diagnosis of the frontal presentation is extremely important, because even with normal pelvic dimensions, the birth of the fetus is alive through the natural birth canal: the large oblique head size, which is inserted, exceeds any other size in the small pelvis. Therefore, in order to avoid maternal traumatism in the cases of the formation of frontal presentation, emergency delivery by the cesarean section is necessary. In the case of fetal death, the labor is terminated with a fruit-destroying operation.

The diagnosis of frontal presentation is based on the data of external and internal obstetric research, auscultation and ultrasonic fetoscopy.

With external obstetric examination, Leopold's 3rd and 4th techniques allow you to define the chin in the form of a sharp protruding part on the head, and on the opposite side - a hollow between the fetal back and its occiput. Palpitation of the fetus will be better heard from the side of the breast.

Internal obstetric examination allows palpating the frontal suture, the superciliary arches, the nose bridge and the frontal back of the fetus.

Face presentation

The facial presentation is the most favorable variant, since the vertical size of the head corresponding to the large segment in front presentation is commensurate with the small oblique size of the fetal head - 9.5 cm. The chin becomes the leading point. Recognize this presentation on the vertical line of the face, when it becomes available palpation.

The biomechanism of labor in facial presentation mirrors the biomechanism of the occipital presentation. The first moment - extension of the head - begins above the entrance to the small pelvis, reaches a maximum on the pelvic floor, resulting in the leading point becomes the chin of the fetus. The inner turn (the second moment) ends at the pelvic floor with the formation of a rear view (on the back).

In the case of turning into the rear view, a fixation point is formed between the lower edge of the womb and the hyoid bone, around which the head is bent - the third moment of the birth biomechanism. It should take into account the high incidence of injuries to the crotch tissue due to eruption head size close to the large oblique. The fourth moment of the biomechanism of labor with facial presentation - the inner turn of the shoulders and the external turn of the head - occurs as with all the head.

Diagnosis of facial presentation is based on data from external and internal obstetric studies, on ultrasound data. X-ray examination has not lost its meaning.

Differential diagnostics of facial and purely gluteal presentation is extremely important. At the face presentation, the height of the standing of the uterine fundus corresponds to the period of pregnancy, with the pelvic presentations it is somewhat larger. In the face of the uterus, with a facial presentation, a large loose part is found, with pelvic a round, dense ballistic head. Above the entrance to the small pelvis, with facial presentation, palpation is determined by the chin and the nape of the fetus. 

In case of internal obstetric examination, in case of facial presentation, the chin and the front line are determined. Palpation of the jaws and palate complements the diagnosis. With gluteal presentation, the tip of the coccyx is found, the interyagodular crease. To enter a finger into the anus is not due to the high probability of trauma to the perineum of the fetus.

Natural delivery is possible only if the rear view is formed. Keeping of expectant mothers, in case of minor complications, for example, premature rupture of the bladder, weakness of labor activity, perform cesarean section. Formation of the front view is unacceptable, requires urgent delivery by caesarean section, since with the head extended at the pelvic floor in the forward view, further forward movement and extension are impossible (the head has already been maximized!) And threatens with fetal death and uterine rupture.

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