What is the shortest anteroposterior diameter of the pelvic inlet?
The obstetric conjugate: Measured from the sacral promontory to the point bulging the most on the back of the symphysis pubis, located about 1 cm below its upper border. It measures 10.5 cm on average; it is the lesser anteroposterior diameter.
What is the narrowest diameter of the pelvic inlet?
The narrowest diameter for the fetus to pass through is the pelvic outlet, which is only 11 cm wide in the average female pelvis.
What is the smallest AP diameter of the fetal head?
The smallest circumference, corresponding to the plane of the suboccipitobregmatic diameter, is 32 cm (13 in). The bones of the cranium are normally connected only by a thin layer of fibrous tissue that allows considerable shifting or sliding of each bone to accommodate the size and shape of the maternal pelvis.
What is the most important diameter of pelvic inlet?
The transverse diameter of the pelvic inlet measures 13.5 cm. Midpelvis: The midpelvis is the distance between the bony points of ischial spines, and it typically exceeds 12 cm. Pelvic outlet: The pelvic outlet is the distance between the ischial tuberosities and the pubic arch. It usually exceeds 10 cm.
What is the narrowest transverse diameter of the pelvis that the fetal head must pass?
The narrowest distance that the head of the child must pass through during vaginal birth is the interspinous distance, which typically measures around 10 centimeters, is called station 0. However, this space is not a fixed distance due to pubic symphysis loosening during labor.
Which plane has least pelvic dimensions?
n. The plane that extends from the end of the sacrum to the lower border of the pubic symphysis, bounded posteriorly by the end of the sacrum, laterally by the ischial spines, and anteriorly by the lower border of the pubic symphysis.
What are the 3 diameters of the pelvic outlet?
Antero -posterior diameters: Anatomical antero-posterior diameter (true conjugate) = 11cm. from the tip of the sacral promontory to the upper border of the symphysis pubis.
What should be the pelvic size for normal delivery?
The diagonal conjugate is the measurement from your pubic symphysis, aka the pubic bone, to your sacral promontory, aka the tail bone. Ideally, this distance should be roughly 11-12 cm. Assuming that a baby’s head is ~10cm, a baby should fit through the pelvic outlet if the diagonal conjugate is 11-12cm.
What is the pelvic inlet?
The pelvic inlet is oval shaped and is widest from side to side. It divides the bony pelvis into the false pelvis above (made up mainly of the ala of the ilium on each side which forms the lower lateral portion of the abdomen), and the true pelvis below (the pelvic cavity).
Which is the highest diameter of the female pelvis?
Dimensions in number:
- Pelvic cavity is almost round with both AP and transverse diameter 12 cm.
- Both the oblique diameters of inlet and pelvic cavity are 12 cm.
- AP diameter – 11, 12, 13 from up to down.
- Transverse diameter: 13, 12, 11 from up to down.
Does a small pelvis mean C-section?
We use this term when we deem that your pelvis is too small to deliver your baby vaginally. Often, this is the case when the baby has a high estimated fetal weight and the mom is petite. If your physician believes this to be the case, you will be offered a cesarean section.
What is the normal pelvic diameter?
On the other hand, in the normal female pelvis the plane of the superior strait is described as more oval, the transverse diameter averaging 13 cm. and the anteroposterior 11 cm.