Mechanisms Of labour Flashcards
(15 cards)
How would you Introduce yourself to Ana?
Primigravida 39 weeks attending midwife only unit. Mentor asks you to explain and demonstrate the mechanisms of Labour
Introduce myself: Chelsea, Student Midwife
Confirm her name DOB/CHI verbally and against notes
Perform 5 WHO moments and 7 Steps of hand hygiene. Use alcohol gel is hands visibly clean
Explain here to explain and demonstrate mechanisms of labour - gain informed consent/ is this okay?
Discuss the approach you would take to delivering antenatal education?
Take an assets based approach - what does she know about labour if anything?
If she said incorrect information, I can correct her and explain in detail throughout the session
Have my tools to educate - doll and pelvis
What is the definition of the mechanisms of labour?
Widest diameter of the fetal head successfully negotiates the widest diameter of the maternal pelvis
Describe the basic anatomy of the pelvis?
False pelvis - flared upper regain above the pelvic brim - doesn’t have anything to do with labour itself
True pelvis - everything involved with the labour and birth process, begins with the pelvic brim which is Ovoid in shape -
Also includes the pelvic cavity in the middle, and the pelvic outlet at the bottom
Beginning with the pelvic brim describe the anatomy and the diameters
Vertebraes at bottom of spine connected here is the Sacrum, 8 landmarks (go clockwise) and begin with the
1) Sacral Promontory
2) Sacral Ala - wing like
3) Sacroiliac Joint - between Sacrum & Illium
4) Iliopectineal line - not a real line
5) Iliopectineal Eminence - rougher area of the pelvis when the faux line ends
6) Upper borders of the Superior Pubic Rami
7) Upper borders of the Pubic Arch
8) Symphysis Pubis - front of body
Pelvis brim has an
Anterior-Posterior Diameter of 11 cm
Oblique Diameter of 12 cm
Transverse Diameter of 13cm
Ovoid in shape. Helps us determine which way baby is lying during antenatal exams and labour.
Describe the Pelvic Cavity and the diameters
The pelvic cavity is the internal area of the pelvis, it’s circular in shape -
shorter at the front as it’s bordered by the symphysis pubis
Longer at back bordered by Sacrum and finishes at the coccyx (aka tailbone)
As it’s circular diameters are all the same:
12 cm Anterior Posterior
12 cm Oblique
12 cm Transverse
Sacrum also forms the curve of carus
Describe the Pelvic outlet and the diameters
Outlet is situated at the bottom, and partially bordered by ligaments, but can’t see them on this pelvis
Has a diamond shape, formed by the coccyx, and lower part of the symphysis pubis and the ligaments.
Diameters are
13 cm Anterior Posterior
12 cm Oblique
11 cm Transverse
Outlet is the last part of the pelvis the baby has to negotiate before they are born
Ask if they have a question?
Describe and demonstrate the mechanisms of labour in a logical manner
Descent - fetal head moves toward the pelvic brim
For primigravida women and first time mothers descent can take place from 36 weeks gestation because of food unterine tone and Braxton hicks contractions
Parous or multiparous women who have birthed before descent and engagement may not start until the onset of Labour.
Fundal contractions against fetal axis pressure encourage descent
Widest part of the fetal head has entered the maternal pelvis we talk about the head being engaged.
During an antenatal examination of we can feel 3/5 or less on your abdomen, will talk about the fetal head being engaged
Next stage is Flexion
This happens due to increased descent - Good contractions and Fundal dominance (pressure from the top of the uterus uses fetal axis pressure)
Fetus meets the resistance of the pelvic floor
Increases it’s flexion - chin will tuck onto its chest
Presenting part of the fetal head now has smaller diameters
Making it easier to negotiate through the pelvic brim
Progress with labour
Internal Rotation
Next stage of MOL
Pelvic floor - is gutter shaped - with continued contractions and the presenting part of the fetus meets the gutter shape of the pelvis - forces an internal rotation of the fetus.
Internally rotate from a transverse position into an anterior position as it’s negotiating through the pelvic cavity.
Crowning
Next stage of MOL
Continued descent, and as this is ongoing the fetal head will slip forwards and back until it’s over the curve of carus.
When the widest part of the fetal head comes through the vulva and no longer retracts with contractions
This stage is called crowning.
It can be very uncomfortable, aka ring of fire, but your midwife can give soothing remedies for this.
Extension
Head is born by a process of extension
Neck will pivot on the subpubic arch
Baby’s head is born starting with the forehead sweeping along the perineum, then the nose and the chin and gradually the whole head
Neck extends upwards against the pubic arch - that’s extension
Restitution
Followed by Extension -
If the baby entered the pelvis at a Right Anterior Position,
The head needs to realign with it’s body. Realign towards the maternal right and turn an 1/8th of a circle.
External Rotation of the head
Internal rotation of the shoulders
After restitution and after a few more strong contractions the external rotation of the head and the internal rotation of the shoulder happens at the same time
Shoulders rotate into the widest diameter of the pelvic outlet to facilitate birth
The fetal head will rotate around to face the maternal thigh.
Whichever way the fetus entered the pelvis right or left occiput anterior - head will face that maternal thigh.
Baby is almost born. If your midwife has supported you with a hands on approach, will help with Lateral Flexion
Lateral Flexion
Hands on approach, using a chin occiput grip or bi-parietal hold
Once the baby’s anterior shoulder is visible, help pull downwards, following the curve of carus to laterally sweep baby onto mother’s chest using traction and the posterior shoulder gliding over perineum.
Dry baby, facilitate skin to skin / start of golden hour
Provide optimal cord clamping.
ASK IF ANY QUESTIONS
SUPERVISOR CAN CONCLUDE VISIT
WISH HER GOOD LUCK
