Maternal Pelvis Flashcards
What is the true pelvis?
The bony canal that the foetus passes through, divided into:
- pelvic brim
- pelvic cavity
- pelvic outlet
What is the false pelvis?
An area above the pelvic brim formed by the flared portions of the iliac bones to protect abdominal organs
What are the 4 areas that make up the pelvic girdle?
- Ilium
- Ischium
- Sacrum
- Coccyx
What are the pelvic joints?
- Symphysis pubis (between 2 pubic bones)
- Sacroiliac joints x 2 (between sacrum and ilium and connect spine to pelvis)
- Sacrococcygeal joint (between the coccyx and sacrum)
What changes occur to the joints in pregnancy?
Softened by hormone called relaxin
What are the 4 types of pelvis?
- Gynaecoid
- Android
- Anthropoid
- Platypelloid
Describe a gynaecoid pelvis
- Ideal for childbearing
- Round brim
- Round cavity
- Subtle sacral promontory
- Curve of Carus
- Blunt ischial spines
Describe an android pelvis
- Male pelvis usually
- Triangular shape
- Prominent ischial spines
- Straight sacrum
Describe an anthropoid pelvis
- Oval brim
- Side walls divergent
- Sacrum long and concave
- Blunt ischial spines
- Large area
- Common in African women
Describe a platellypoid pelvis
- Kidney-shaped brim
- Side walls divergent
- Sacrum flat
- Blunt ischial spines
What is the Curve of Carus?
An imaginary line made up of the axes of the pelvic canal that direct the foetal head upwards, causing lateral flexion in 2nd stage
What is asynclitism?
Lateral tilting of the head to allow the biparietal diameter to pass the narrowest pelvic diameter
What is a Rachitic pelvis?
- Deformed by rickets
- Flat pelvic brim
- May need CS as foetus will enter the pelvis in asynclitic position
What is a Naegele’s pelvis?
- Missing 1 sacral ala
- Sacrum is fused to the ilium
- CS required as head cannot engage
Which pelvic type usually results in a very quick labour?
Anthropoid
