5 Anatomy of the Female Pelvis and Partuition Flashcards
What makes up the pelvic inlet?
sacral promontory
margin of ala
linea terminalis
superior pubic symphysis
What comprises the pelvic outlet?
pubic symphysis ischiopubic rami ischial tuberosity sacrotuberous ligament coccyx
Which of the pelvic inlet or outlet is bigger?
the pelvic outlet is smaller
how can the parietal bone move?
they can move on top of each other, elongating the skull
What can be measured on MRI pelvimetry?
sagittal pelvic inlet diameter
transverse inlet diameter
bispinous outlet
sagittal pelvic outlet
What is the smallest diameter in the pelvis, what is the significance of this?
bispinous outlet (10.5)
child can arrest here
What is the shape of the pelvic inlet?
wide transverse and narrower AP diameter
What is the shape of the pelvic outlet?
narrow transverse and wide AP diameter
What are the front and back of the foetal skull referred to as?
occiput
sinciput
What is the widest part of the foetal skull?
biparietal diameter at 9.5cm
What are the 3 layers to the uterine wall?
endometrium
myometrium
perimetrium
What are the layers of the myometrium?
internal muscle middle muscle (thick, spiral arrangement) external muscle (longitudinal)
Going down, what are the parts of the uterus?
fundus corpus anatomical internal os isthmus histological internal os cervix
What is the difference in composition of the fundus compared to the cervix?
fundus is 90% muscle
cervix is 10% and hence much more collagenous
What happens to the uterine wall over pregnancy?
first 20 weeks - hypertrophy of muscle wall
next 20 weeks - distension, decrease in thickness
How does the weight of the uterus change over pregnancy?
50g to 950g
What is the height of the uterus at 12 weeks?
pubic symphysis
What is the height of the uterus at 20 weeks?
umbilicus
What is the height of the uterus at 36 weeks?
xiphisternum
What is significant about uterus size at 24 weeks?
from this point onwards, the accurate gestational age estimate can be taken
What is aortocaval compression?
how can this be avoided?
reduction in venous return to the heart
women are advised to sleep on their left to avoid this
What is Potters’ syndrome?
in some chemical kidey diseases causing impaired urine production, the uterus can be smaller
What arteries are associated with female genitalia?
ovarian artery, which anasotmoses with the uterine artery
vaginal artery
What is significant about the structure of the uterine artery?
tortuous path to allow for expansion
What are the 3 main phases of childbirth?
dilation of cervix
expulsion of foetus
afterbirth of placenta
What facilitates dilation of the cervix?
relaxin
What is the cranial position when the cervix dilates?
normally right or left occipitotransverse
What is the state of the histological internal os at 36 weeks?
full of mucous
What are the phases of foetus expulsion?
engagement descent flexion medial rotation extension lateral rotation expulsion
What happens in engagement?
biparietal diameter enters pelvic inlet
What happens in descent?
head goes through pelvic cavity
What happens in flexion?
neck flexes
head forced anteriorly under force of contraction
What happens in medial rotation?
the baby changes from lateral facing to occipitoanterior position, via a wave of uterine contraction
What happens in extension?
head extends around the pubic symphysis
What happens in lateral rotation?
face turns laterally, so the anterior shoulder can expel and then the posterior shoulder
When does labour technically start?
when the mucous of the histological internal os is no more
How is haemorrhage avoided in placenta delivery?
rapid involusion of the fetus disrupts the plaenta ad tears the blood vessels, fibres the pinch off the arterioles
What is a 3rd degree pelvic tear?
tearing the rectal sphincter
What is a 4th degree pelvic tear?
tearing of the rectal sphincter with rectal mucosa involvement
What nerve can be damaged during childbirth?
the pudendal nerve
What is the function of an episotomy?
prevention of tears progressing to 3rd or 4th degree and vaginal prolapse
Name 2 types of episotomy
midline episotomy
mediolateral episotomy
What do you have to do if a woman presents with abdominal pain?
if they are of childbearing age, you have to rule out ectopic pregnancy
