Case 14- Childbirth Flashcards
How the female pelvis assists in childbirth
The fetus rotates to align with the widest section of the female pelvis. The pelvic floor acts like a funnel to guide the fetal head through the birth canal. The rotation of the fetal head is due to the resistance from the pelvic floor.
Most common presentation in childbirth
Longitudinal cephalic line
Cardinal movements of childbirth
1) Engagement
2) Descent
3) Flexion
4) Internal rotation
5) Crowning
6) Extension
7) External rotation and restitution
Fetal position prior to descent
The body is facing head down towards. The back is curved and flexed, with their knees drawn into their chest.
Cardinal movement- Engagement
Largest diameter of the fetus head fits into the largest diameter of the maternal pelvis. Then moves towards the pelvis brim in either the left or right occipto-transverse position.
Cardinal movements- Descent
The baby descends through the pelvic inlet towards the pelvic floor. Occurs due to uterine contraction, amniotic fluid pressure and abdominal muscle contractions.
Cardinal movements- Flexion
The fetal head meets the pelvic floor and cervical flexion occurs. Allows foetus to be sub-occipito bregmatic. In this position the fetal skull has the smallest diameter
Cardinal movements- Internal rotation
The pelvic floor has a gutter shape (forward and downward slope), causes the head to rotate from a left or right occipto-transverse position to an occipto-anterior position.
Cardinal movement- Crowning
The largest diameter of the fetal head goes through the narrowest part of the bony pelvis. The head is visible at the vulva and no longer retreats between contractions.
Cardinal movements- Extension
The occiput slips beneath the suprapubic arch as the head extends, the nape of the neck pivots against the arch. Extension of the head causes stretching of the perineum.
Cardinal movements- External rotation and restitution
The head externally rotates to face the right or left medial thigh of the mother. The shoulders rotate from a transverse position to an anterior-posterior position. The re-alignment of the shoulders with the head is restitution.
Partuition
Delivery
Delivery of a baby
- Uterine contractions causes flexure of the uterine neck, this means the smallest diameter of the fetal skull is presented.
- The fetus moves further down the pelvis and the Occiput meets the pelvic floor, there is rotation of the fetal skull.
- The shoulders do not rotate and are misaligned to the skull.
- Causes the Occiput to present (crowning).
- The fetal face is birthed and the shoulders realign in a process called restitution. The anterior shoulder moves below the subpubic arch and is delivered first
- The midwife will do lateral flexion to release the posterior shoulder
- Following normal labour the placenta is birthed.
How is the sacrum adapted for childbirth
It is curved (curve of carus)
Foetal skull
Near the end of pregnancy the cartilaginous neurocranium ossifies to form the adult skull. At the calvaria (skull cap), flat bones are separated by dense connective tissue membranes that eventually form sutures (fibrous joints). Large fibrous areas called fontanelles are located between certain sutures (anterior, posterior, sphenoid, and mastoid). They are because the bones have not completely fused, they allow the bones to slide over each other (molding), aids in partition.
Symmetry in the foetal skull
All the bones are paired and you have one on each side i.e. a left and right frontal bone
Foetal skull- sutures
- The frontal suture is between the two frontal bones fuse after 2-3 months
- The coronal suture is between the frontal and parietal bone.
- The sagittal suture is between the two parietal bones
- The lanmboid suture is between the Occiput and parietal bone
Role of fontanelles in the fetal skull
Allow the skull bones to move over each other during birth, to aid passage of the fetal skull through the narrow pelvis. It allows for rapid stretching as the brain grows
Divisions of the fetal skull
Down from the Glabella is the face. The underside of the skull is the base of the skull. The remained of the skull is classified as the vault. The Clavaria is the top part of the skull. Compared to an adult skull the face is a lot smaller then the vault
What bones are in the Clavaria
Frontal, Parietal, Temporal and Occipital
The Fontanelles in the fetal clavaria
- Anterior fontanelle- bounded by the coronal, frontal and sagittal suture. Fuses after 18 months
- Posterior fontanelle- bounded by the sagittal and lambdoid suture, it fuses after 3 months
- Sphenoidal fontanelle- fuses after 6 months, lateral side
- Mastoid fontanelle- lateral backside, fuses between 6-18 months.
Cleidocranial dysplasia (CCD)
Anterior fontanelles dont fuse, causes lack of clavicles, supernumerary teeth