General information about straightened abnormal presentations head of the fetus (Deflexio capitis)

The reasons. The head of the fetus often comes at the entrance of the pelvis not in a bent, and in opened position. Depending on the degree of extension of the head (moderate, average and maximum) there is some kind of presentation, namely prednisolone, frontal or front previa (Fig. 77, 78, 79).

Fig. 77. Beginning extension head (I degree) - prednisolone presentation.
Fig. 78. The progressive extension of head (II degree) - frontal presentation.
Fig. 79. Full extension head (III degree) - face presentation.

If biomechanism of labor in the occipital previa flexion of the head is the adaptation of its dlinnie to the curvature of the birth canal, the last extension (only on the first two degrees) commits such a device, and thus difficult for labor.
It is known that in biomechanism of labor plays a significant role installing heads in the birth canal is the ratio of the line head of curvature line pelvic curvature (match or mismatch). This provision equally applies to the occipital, and to the personal abnormal presentations (C. D. Mikhnov).
Head in front previa, as in the occipital, has kidney-shaped form; favorable biomechanism passing head through the pelvis is created when the line is head of curvature coincides with the line of the curvature of the birth canal; otherwise, the translational motion of the head touches an obstacle.
When the front previa a match head of curvature with pelvic curvature (generic tube) is created when chin turned to the front. S. D. Mikhnov indicates that in this case the head will go through the cross-section birth canal from the same planes of the same its fan-shaped inclined to each other cross-sections, which it passes and in the occipital, but only in reverse order.
Depending on the degree of extension of the heads will be celebrated on certain features and biomechanism of labor (see table. 19). Causes of prednisolone, the skull and facial abnormal presentations are similar, because the case is about the same movement of the head (extension); the difference is only in degree extension.
In appearance these abnormal presentations plays the role of some factors (basic and additional), which often can be combined. Among them are: the narrowing of the size of the birth canal, lowering the tone of the muscles of the uterus and, in particular, the lower segment of the latter, the state (turgor of tissues of the fetus, increased the size of the head of the fetus, especially in the presence of strongly outstanding neck (dolichocephaly) and so on. However, a number of researchers (C. S. Gruzdev, E. Bumm) consider dolichocephalic form of head phenomenon is of a secondary nature, resulting from the configuration and the strangulation of the skull in the back of the front direction, which entails the extension of the head toward the back of the head. On the material of our clinic facial previa was observed in 92,5% at normal pelvis, 6.3% in a simple flat and very rarely in obsesiones flat pelvis. Favorable factor for the development of personal presentation should also be considered as a large weight of the fetus, polyhydramnios, the presence of multiple pregnancy (twins), and other
However, not only the large size of the head, but also the small size of the fetus can contribute to the establishment of the head in front previa. It is necessary to consider also possible random disturbance in clearspring fetus (drooping of the pens by the neck, and so on). Finally, the cause of the extensor abnormal presentations can be congenital abnormalities in the cervical parts of the spine of the fetus (avilable atlantization joint impeding the bending of the head).
Among these factors the status of plastic tone muscles of the uterus has, in our opinion, the primary importance, because by using the muscles of the uterus is carried out correction of the position of the fetus and presentation.
A significant role in the emergence of the extensor of presentation and, in particular, facial plays state of the abdomen of a pregnant woman. Loose flabby belly and the displacement of the uterus side (usually the right) lead to the fact that the axis of the uterus, and with it the axis of the fetus (spine) do not coincide with the axis of the pelvis. As a result, the head departs in one of the lateral parts of the pelvis, and in those cases, when the trunk of a fetus "roll" toward the back of the head, chin is removed from the breast, and there is a flattening of the head. Flew belly, and therefore the extension of the head is also promoted by the deformation of skeleton in the mother (kyphosis) and, in particular, the architecture of the pelvis. Straighten heads favoured also by premature rupture of the amniotic fluid. It is possible that when potoshopshi waters of this kind anomalies are temporary; in the period of the opening direction of the axis of the fetus may change and this creates an opportunity to lower the back of the head.
The view that straightened presentation occur more frequently from the second occipital presentation (due to more private abnormalities of the uterus to the right), we clinical material cannot confirm; first and second frontal presentation was observed in the same number. Incorrect insertion of the head may occur when there is a slanting position of the fetus with the onset of labor activity, when the contractions lead to fix this complication.
We watched the front previa after transfer of the fruit of the cross of the provisions in the second longitudinal.
The emergence of the extensor abnormal presentations contributes inferiority soft - tissue generic ways, in particular of the tissues of the pelvic floor. Only elastic pelvic floor muscles contributes to the bending of the head and adapting it to the spatial characteristics of the pelvic outlet.

The recognition. On the extensor abnormal presentations judge, on the one hand, according to the external examination, listening to the fetal heart, and on the other, on the results of the study of vaginal.
External study reveals only a clear degree of extension of the head; when a thin, loose abdominal wall should identify the location of the forehead and chin. In most cases through the external examination (feelings) only define longitudinal position and cranial presentation. Only the attendant circumstances (pendulous abdomen, narrow pelvis and others) can reinforce the assumption about the extensor previa head.
The heartbeat of the fetus when Prednisolonum previa usually heard from the back, but can be caught and the location of small parts; on the contrary, when severe extension heart tones are heard from the side of the breast (small parts); due lordosis of the spine. In doubtful cases the recognition extensor presentation usually helps vaginal examination. Depending on what part of the head felt by wire axis pelvis, is determined by the particular type of presentation (figure. 80, 81, 82, 83, 84). So, if by wire axis is determined by a large fontanel, while small fontanel almost or completely unattainable, we can talk about the first stage extensor state head - on Prednisolonum previa. If a field of study is determined forehead with his seam, and on one side there is the bridge of his nose, and with another - a large fontanel, while no mouth, no chin to achieve finger fails, we can speak only about the frontal previa head - on the second stage of the extensor state. Finally, by definition, on the one hand, chin and mouth, and with another - eye hollows root of the nose and perenosa can with certainty to speak about full extension head - on the personal presentation.

Fig. 80. Front view occipital presentation.

Fig. 81. Rear view occipital presentation.

Fig. 82. Prednisolone presentation.
The arrows show the direction of movement of the head through the birth canal.

Fig. 83. Frontal presentation.
The designations are the same as in Fig. 82.

Fig. 84. Personal presentation.
The designations are the same as in Fig. 83.

To avoid errors vaginal examination must be thorough, but at the same time careful not to put the fruit of severe injuries (such as the eye). Errors occur due to mixing gluteal presentation of face, as at a long presence of the head in generic ways the outline of the face so distorted generic tumor that when inattentive study it can be taken for the buttocks of the fetus. You need to know the signs for the persons of the fetus, and be able to distinguish them from the signs of pelvic presentation. It is necessary, in particular, to be able to distinguish between the anus from the mouth during vaginal examination. The mouth has two solid arc upper and lower jaw; the anus as it appears in the form of a uniformly soft, compressible elastic ring.
Recognition accuracy type extension is of great importance when forceps delivery, as produced by them traction are some differences.

The forecast. From all kinds extensor abnormal presentations the most favourable is the face (chin, turned toward the front)as it features the most advanced installation heads in the birth canal; the head is cut through predation-parietal plane (planum sublinguo-parietale), having in circumference 34,7 see Less favorable labor at Prednisolonum inserted when the head is cut through by a circle, the corresponding direct size and is equal to 34 see Even less favorable prognostic labor at Calvary previa, when the head comes into the pelvis its largest size - maxillo-occipital (from the chin to the most outstanding parts of the nape), the circle which is 35 see
Adverse effects atypical inserting impact on the condition of the mother and foetus.
Soft generic parts sexual tract overly stretched and injured due to the long standing head in the birth canal. Particularly strong tension in the transverse direction is exposed crotch. This explains the large number of soft-tissue injuries sexual tract; when straightened abnormal presentations of perineum happens much more frequently than when bent. The difficulty of promoting head through the birth canal, of course, increases the duration of labour.
For births in the extensor abnormal presentations can adversely affect the fetus (asphyxia, cerebral edema, intracranial hemorrhage). These complications can cause fetal death.
The prediction for the mother is determined not only by the existence of atypical presentation, but also often related complications (delayed discharge of water, rigidity of soft tissues sexual apparatus and so on).