S10- Anatomy of Pregnancy and Childbirth Flashcards
Where is the mot common site for fertilisation?
The ampulla of the uterine tubes
On what day does implantation into the endometrial wall typically occur?
Implantation occurs on day 8-9
What are the two main periods of pregnancy?
Embryonic period-weeks 1-8
Foetal period- weeks 8 to term
When does labour normally occur?
Assuming a normal implantation it will occur between 37-42 weeks gestation.
How often and for what duration do uterine contractions occur?
They occur every 2-3 mins and typically last around a minute.
What are the three main stages of labour?
- The cervix opens up to full dilation
- Foetus is delivered
- Placenta is delivered
What features of the foetal head make it more suitable for being given birth to?
Bones of the cranial vault aren’t fused at birth.
Skull is more oblong shaped than an adult skull.
Fontanelles can be moulded during delivery.
Which way does the doetus engage during delivery and why is this?
It engages so the foetus is facing laterally. This is because the transverse diameter of the pelvic inlet is greater than the antero-posterior diameter.
What happens to the orientation of the foetus as it is delivered?
As the head descends the neck flexes and the head rotates 90 degrees as the AP diameter is slightly bigger in the pelvic outlet. The head faces the sacrum and is delivered. The shoulders now need to do the same so the torso rotates back to its original position facing laterally so the shoulders can fit through.
What changes occur to the pelvic canal before childbirth and why?
The canal increases in diameter by around 15% due to relaxation of pelvic joints and ligaments. This is due to the action of the sex hormone relaxin which loosens collagen of all the ligaments.
What are the different degrees of perineal tearing during birth?
First degree-superficial
Second degree-Include perineal muscles
Third degree-Includes anal sphincter
Forth degree-Includes anal mucosa
What limits the lateral distension of the vagina during childbirth?
The Ischial spines and the sacrospinal ligaments.
What is the course of the pudendal nerve?
It originates in the sacral plexus (S2-S4)
Leaves pelvis through the lower part of the greater sciatic foramen and crosses ischial spine.
Re-enters the pelvis through the lesser sciatic foramen.
Then accompanies internal pudendal vessels superiorly and anteriorly.
Where would anaesthetic for the pudendal nerve be administered?
Feel for the sacrospinous ligament near to which the pudendal nerve runs
What can be the result of compression of the ureters during pregnancy?
It can cause a build up of pressure that causes hydronephrosis leading to post-renal failure.
