4.2

Question 1

What bones make up the bony pelvis?

Answer 1

Ilium, ischium, pubic (innominate hip bones)
Sacrum
Coccyx

Question 2

Give some palpable structure of the pelvic girdle

Answer 2

Iliac crest
Arcuate line + pectineal line + pubic crest = linea terminals
Ischial spine (greater and lesser sciatic notches)
Ischial tuberosity

Promontory of sacrum
Anterior superior edge of S1

Question 3

Joints of the bony pelvis

Answer 3

Sacroiliac joint

Pubic symphysis

Question 4

What is a good pelvis for childbirth?

Answer 4

Round inlet
Straight side walls
Ischial spines not too prominent
Well-rounded greater sciatic notch
Well curved sacrum (to fit with foetal head)
Sub-purbic arch > 90 degrees

Question 5

Give differences in pelvic inlet, pelvic outlet, pubic arch, obturator foramen, acetabulum and greater sciatic notch in males/females.

Answer 5

M 
pelvic inlet = narrow, heart shaped
Pelvic outlet = Small
Pubic arch = Narrow  80 degrees
Obturator foramen = oval
Acetabulum = small
Greater sciatic notch - almost 90 degrees

Question 6

What forms the pelvic inlet? Draw

Answer 6

Superior pelvic aperture

Promontory and ala of the sacrum posteriorly
- Superior surface of lateral part, adjacent to body of sacrum

Right and left linea terminals anteriorly

• Arcuate line on inner surface of ilium
• Pectineal line and pubic crest

Question 7

How is the pelvic inlet assessed clinically?

Answer 7

Anatomic conjugate
Obstetric conjugate
Diagonal conjugate

Question 8

What is the anatomic conjugate?

Answer 8

Length from sacral promontory to the superior border of pubic symphysis

Question 9

What is the obstetric conjugate?

Answer 9

Sacral promontory to the midpoint of pubic symphysis

minimum diameter of the canal, as this is where pubic bone is thickest

Question 10

What is the diagonal conjugate?

Answer 10

Sacral promontory to the inferior border of the pubic symphysis.

Question 11

How is the mid-pelvis assessed

Answer 11

Check for straight side-walls

Check the distance between the ischial spines

Question 12

How is the pelvic outlet assessed?

Answer 12

Infrapubic angle (>90degrees)
Distance between the ischail tubertosities

Question 13

Which conjugate is most important and how long is it?

Answer 13

Obstetric conjugate from midpoint of pubis to sacral promontory.
Narrowest AP diameter that fetus passes through
10cm

Question 14

Why do clinicians use the diagonal conjugate instead of obstetric? How?

Answer 14

Obstetric can only be assessed using imagine.
To measure diagonal, 2 fingers into vagina and palpate sacral promontory, noting where one’s hand is under the edge of the pubix
11.5cm

Question 15

What forms the pelvic outlet?

Answer 15

Pubic arch anteriorly
ISchial tuberosities laterally
Inferior margin of the sacrotuberous ligament posterolaterally - ligament is stretch and softens in childbirth due to progesterone.
Tip of the coccyx posteriorly

Question 16

What is the false pelvis??

Answer 16

Greater pelvis

superior to pelvic inlet
NBoudned by the iliac alas posterolaterally
Bounded by anterosuperior aspect of S1 posteriorly
Occupied by abdominal viscera

No obstetric relevance

Question 17

What is the true pelvis?

Answer 17

Lesser pelvis
Bony canal which is solid and immovable between pelvic inlet and outs let
Inferior to linea terminalis
Bounded by pelvic surfaces of hip bones, sacrum, coccyx

Major obstetric significance.

Question 18

Give full assessment of bony pelvis

Answer 18

Bimanual exam
Palpate ischial spines
Assess inter tuberous distance
Assess suprapubic arch
Assess diagonal conjugate