Facial previa

Only a small number of cases, facial previa can be primary, if it is determined by the beginning of birth (congenital goiter, tumors in the neck of the fetus); most often to the beginning of childbirth head a little bent and slated to be actually forehead. So the current presentation is more often secondary, i.e. arises from the skull, usually after rupture of membranes, with well-pronounced labor activity.
The biomechanism of labor. When the front previa first time instead of the usual bending head is its extension; the fourth point is the teething is committed through the bend, and not the extension, as it is observed in the occipital previa (table. 28).

Promoting head through the birth canal is of the form: at the entrance to the pelvis head inserted in diameter, occupies a middle position between the chin-occipital and chin-parietal; this amount equals 12.5 cm and is usually located in the transverse size of the entrance to the pelvis; chin (wired point) is to the right or to the left. Front line is in the transverse size. Chin and a large fontanel stand at the same height (or chin is slightly higher). Forehead as part of a head, deeper, less accessible to research than the chin. After rupture of membranes extension head maximally increases, chin drops below than a large fontanel. From that moment the front previa quite installed; at the entrance to the pelvis, the head is fixed more convenient diameter - chin-parietal, which equals 10 - 10,8 see In this position the person falls into the cavity and small pelvis. Cheek, turned to the front wall of the pelvis, in the study achieved easier than facing the sacral depression. On the side of the face turned toward the front, formed edema, which is often difficult to study. Thus, the first point is the extension of the head, and the second is in progress it at the entrance of the pelvis, i.e. the head sinks into the pelvic cavity using sacral rotation, and reaches its bottom.
Once the cylinder reaches the bottom of the pelvis, begins the internal rotation her, which was caused by the same factors that determine the biomechanism of labor when occipital abnormal presentations. Internal rotation of the face is that of a wired point - to-chin - goes straight to the size of the cavity, pelvis and is under the pubic joint. This turning down the exit of the pelvis. In rare cases, internal rotation is completed already during the eruption. The person falls to until erupt chin, and the angle between the lower jaw and neck of the fetus fit under the bottom edge of the symphysis.
Thus, a commit point is between the lower jaw and neck of the fetus, i.e. in the area of the hyoid bone (Fig. 91).

Fig. 91. Personal presentation. The cutting head.

Fig. 92. Personal presentation. Front view (chin turned backwards).

From the moment of approach of the chin under the pubic arch start teething face and dismissal of the head. First, from under the pubic arc cut through the chin. After the liberation under the goatee the front surface of the neck rests in the pubic arch? after this starts flexing heads, during which consistently born forehead, crown and nape.
The cutting head is committed by a circle passing through the hyoid bone and crown (circumferentia sublingulo-parietalis), equal to 34.7 see the Internal rotation of the torso and external; head rotation is performed the same way as when the occipital previa.
Deviations in biomechanism of labor is possible within any moment. On the one hand, may delay the extension of the head, causing slowing and even the suspension of its translational motion; on the other hand, can disrupt the process of internal rotation of the head: the chin or remains at the origin, or turns back to the sacrum (Fig. 92), or does not reach the pubic joint. The first two anomalies extremely unfavorable; birth in most cases are suspended, and the mother and the fetus is in danger. When the third birth anomalies sometimes (very rarely) over yourself.
Personal presentation detected 0.25% (1 per 400) births and mainly among multiparous. The primary facial previa observed in 34% of cases, and secondary - in 13% of cases arising from the skull, previa (G. I. Molchanova).
Depending on the position backrest of the fetus, there are I or II position; the frequency of their nearly identical. However, what matters is not so much the position, and then, where in the pelvic cavity turn wired point (chin), as spontaneous labor, as already mentioned, is possible only under condition of rotation of the chin to the front - fold (rear view of the front of presentation).
The recognition. The diagnosis can be made on the basis of the external examination, as the head is in a state of great extension, therefore, between the back and the neck of the fetus is formed as a deep impression. Breast fetus is closer to the wall of the uterus than the bridge. So heart tones of fruit clearer heard from breast fetus.
Vaginal examination greatly facilitates the diagnosis. When probed on the one hand chin, and with another - the root of the nose and eyebrows, and on the front lines is the mouth and forehead of the fetus, the existence of personal presentation undoubtedly.
The forecast. If the forecast births in the frontal previa is unfavorable, then this cannot be said regarding personal presentation. Spontaneous delivery occurs in 95.7% of operative intervention is required only 4.3% (I. I. Yakovlev, and O. Sheveleva).
The maternal mortality ratio in our material (94 case facial abnormal presentations) were observed. Of perineum was 20%.
The prediction for the fetus relatively favourable, but the incidence of stillbirths higher than in the occipital previa. In the emergence of personal presentation, as well as in the death of the fetus, the important role played cord entanglement around the neck of the fetus. According to our observations, the length of the cord more than 50 cm in front abnormal presentations was in 47% of cases.
Strictly expectant management of labour at the front previa dramatically reduces the number of stillbirth; delayed surgery (forceps delivery attempts to repair presentation), undoubtedly, contributes to the increase of death rate.
The skull of a child born in the face previa, it is spherical (Fig. 93); the onset swelling is usually located on the chin, lips and eyes.

Fig. 93. Head of the newborn, who was born in the front previa.

When I face previa it is more expressed on the right, and when II - on the left side of the face. A generic tumor join significant bleeding, especially on the eyelids and lips, which greatly distort the face of the child. Generic tumor often captures the language and bottom of the mouth, resulting in newborns in the first days of often poorly suck.