Narrow pelvis

In obstetrics female pelvis, anatomically narrow and clinically. The pelvis, whose outer conjugate less than 18 cm or at least one of the other major smaller than most 2 cm (see Midwifery research. The pelvis, female)is anatomically narrow pelvis. The concept of clinically narrow basin means the discrepancy between the head of the foetus and the pelvis women regardless of the size of the last detected only in the process of childbirth. Thus, anatomically narrow pelvis not necessarily clinically narrow, i.e. preventing the delivery through the birth canal.
Anatomical narrow pelvis may be caused by: impaired fetal development or diseases of bones and joints, women in childhood, in the period of growth and formation of the pelvis, sometimes a fracture of the pelvis in adulthood.


Fig. 1. The entrance to the pelvis in normal conditions and in its various anomalies: 1 - normal pelvis; 2 - observeronly; 3 - a simple flat; 4 - flat-rachitic; 5-obesogenic flat pelvis.

Fig. 2. Sacral diamond: 1 - the woman has the right body; 2 - when deformed pelvis.

Anatomically narrow pelvis form are distinguished: observeronly, flat (plain and flat rachitic) and obesogenic flat. Less common are: kolomesnky, poperechnogo, osteomalaciei (Fig. 2, 2.).
Observeronly basin is characterized by the reduction of all sizes, the form of the pelvis normal (Fig. 1.1 and 2). The approximate size of the pelvis: distantia spinarum - 23 sm, distantia cristarum - 26 sm, distantia trochanterica - 29 cm, conjugate externa - 18 cm, conjugate diagonalis - 11 cm, conjugate vera - 9 see
Simple flat pelvis (energiticheskogo, davinteresdi) is characterized by a significant approximation of the sacrum to the front wall of the pelvis, resulting in the direct size of the pelvic cavity shortened especially true conjugate (Fig. 1, 3). Approximate size of their respective is 28-31-18-11-9 see
Flat-rachitic pelvis characteristic deformation: plane entrance has a kidney-shaped form of cross located oval deeply behind the Cape; the rump flattened and rejected backwards; direct the size of the entrance of the pelvis shortened significantly (Fig. 1, 4). The approximate size of the pelvis: 26-26-31-17-9-7 see
Obesogenic flat pelvis. All dimensions of the pelvis reduced, especially direct the size of the entrance to the pelvis (Fig. 1, 5). The approximate size of the pelvis: 23-26-29-16-9-7 see
Largest real conjugates determine the degree of narrowing anatomically narrow pelvis: 1 from 9 to 11 cm cm; 2-I - 7 cm to 9 cm; 3-I - from 5 cm to 7 cm; 4-I-5 cm or less.
At 1-St degree of narrowing, if no other complicating circumstances, childbirth usually occur normally; 2-nd degree they can also end up safely to the mother and fetus, but the delivery is longer, often require the use of obstetric surgery (caesarean section, vacuum extractor and others); 3-rd degree of narrowing of the vaginal delivery can be extracted dead fetus in pieces (embryotomy), lively and full-term fetus can be extracted only by caesarean section; 4-th degree - the only possibility of delivery is a cesarean section.
On the anatomy of the narrowing of the pelvic indicates growth , below 145 see Scoliosis (see), kyphosis (see), lordosis (see), shortening of one leg indicate past rickets and tuberculosis (the most frequent causes deformation of the pelvis). The top corner of the sacral diamond (diamond Michaelis) usually corresponds spinous process at the lumbar vertebrae, lower the top of the sacrum, the side corners - top-rear awn Ilium. The more is composed of the woman, the more the diamond shape is nearly a square, (Fig. 2,1). With a simple flat pelvis shortened the distance between the top and bottom corner of the diamond; rachitic deformed pelvis diamond loses its shape.
If the degree of anatomical narrow pelvis allows for a normal delivery, the delivery mechanism determined by the shape of the pelvis.
Forecast births in anatomically narrow pelvis depends on the functional usefulness of the pelvis: about 70-73% of cases anatomically narrow pelvis not create obstacles for the passage of the head of the fruit, and generations pass without complications.

  • The course of pregnancy and childbirth with a narrow pelvis