The document discusses the fetal skull and pelvis and their relation to labor and delivery. It defines the bones that make up the bony pelvis and describes the shapes of the pelvis. It also defines the diameters of the fetal skull and describes how the skull bones mold during labor to accommodate the birth canal. Moulding involves the skull bones overlapping as the head descends through the pelvis. The degree of moulding is assessed from 0 to 3.

1. FETUS AND GYNAECOID PELVISFETUS AND GYNAECOID PELVIS
DR.TARIG MAHMOUD
MD SUDAN
HAIL UNIVERSITY KSA

2. THE BONY PELVISTHE BONY PELVIS
WHICH BONES COMPOSE THE
BONY PELVIS?
I ) 2 Innominate bones :
a) Illium
b) Ischium
c) Pubis
II) Sacrum
III) Coccyx

3. THE BONY PELVISTHE BONY PELVIS
WHAT IS THE PELVIC BRIM?
 It is the inlet of the pelvis which divides the pelvic cavity
into false & true pelvis
Is bounded in front by the symphysis ,on each side by the
upper margin of the pubic bone, the ileopectineal line
and the ala of the sacrum, and posteriorly by the
promontory of the sacrum.
 The plane of the brim is 60 C° above the horizontal line

4. False pelvisFalse pelvis
The false pelvis is bounded
posteriorly by the lumbar
vertebra and laterally by the
iliac fossa. In front, the
boundary is formed by the
lower portion of the anterior
abdominal wall.

6.  The brim is oval in shape:
Anterioposterior diameter (true conjugate)------- 11 cm
Transverse diameter ------ 13.5 cm
The pelvic cavity
 The pelvic canal is curved , the post wall is longer than
the anterior
 The most roomy zone with almost round shape D--12cm

7. THE PELVIC OUTLET
 Lower border of the symphysis pubis, ischial tuberosities
& tip of the coccyx

8. THE pelvic OUTLET
 Oval shaped
 Anterioposterior diameter -----lower border of the
symphysis pubis to last fixed point of the sacrum-----
13.5 cm
 Transverse diameter ------ 11 cm

9. PELVIC SHAPEPELVIC SHAPE
After you activate your
book, you will get
The four basic pelvic types. The dotted line indicates the
transverse diameter of the inlet. Note that the widest
diameter of the inlet is posteriorly situated in an android or
anthropoid pelvis. The gynecoid pelvis illustrates the
location of the sacrosciatic notch, present in all pelvic types.
Printed from: Hacker & Moore's Essentials of Obstetrics
and Gynecology 5e (on 05 January 2013)
© 2013 Elsevier

10. PELVIC SHAPEPELVIC SHAPE
1-GYNECOID
Typical female pelvis found in 50% of
women
Rounded—slightly oval inlet
Straight pelvic sidewalls with roomy
pelvic cavity
Good sacral curve
Ischial spines are not prominent
Pubic arch is wide

11. PELVIC SHAPEPELVIC SHAPE
2-ANDROID
Typical male pelvis found in 1/3
white women 1/6 non-white
Pelvic brim is heart shaped
Pelvis funnels from above
downwards (convergent sidewalls)
Narrow pubic arch
Prominent spines

12. PELVIC SHAPEPELVIC SHAPE
3-ANTHROPOID
25% white women & 50%
nonwhite
Pelvic brim APD > TD
Long & narrow pelvic canal
with long sacrum
Straight pelvic sidewalls

13. PELVIC SHAPEPELVIC SHAPE
4-PLATYPELLOID
3% of women
Pelvic brim TD >>>APD 
kidney shape
Sacral promontory pushed
forwards

14. ADEQUACY OF THE PELVIS TO ACHIEVEADEQUACY OF THE PELVIS TO ACHIEVE
VAGINAL DELIVERYVAGINAL DELIVERY
WHAT IS MEANT BY CLINICALLY FAVORABLE
PELVIS?
 Sacral promontory can not be felt
 Ischial spines are not prominent
 Subpubic arch accept 2 fingers
 Intertuberous diameter accept 4 knuckles on pelvic exam

15. CONJUGATE

16. WHAT IS THE OBSTETRIC CONJUGATE?
The shortest APD between sacral promontory & symphysis
pubis
Can only be measured radiologically
N ≥ 10 cm

17.  WHAT IS THE TRUE (ANATOMIC)CONJUGATE?
 APD between promontory of the sacrum & superior
margin of the symphysis pubis 11cm
or diagonal conjugate – 1.5cm
 WHAT IS THE DIAGONAL CONJUGATE?
 Distance between sacral promontory & inferior margin of
the symphysis pubis 12.5cm?
 Measured clinically

18. FETAL SKULLFETAL SKULL
The skull is formed of the face , the vault & the base
The bones that form the skull are : two frontal bones, two
parietal bones, two temporal bones wings of the
sphenoid & occipital bone
The bones of the face & base are heavy & fused
The bones of the vault are 2 frontal ,2 parietal & occipital
The bones of the vault are not joined thus changes in the
shape of the fetal head during labor and called moulding.

19. FETAL SKULL DEFINITIONSFETAL SKULL DEFINITIONS
Bregma 
 Anterior fontanelle
Brow 
 lies between bregma &root of the nose
Face 
 lies between chin & suborbital ridges
Occiput 
 boney prominence behind posterior fontanelle
Vertex 
 diamond shaped area between anterior & posterior
fontanelles & parietal eminences

20. FETAL SKULL SUTURESFETAL SKULL SUTURES
 Frontal suture 
between 2 frontal bones
 Sagittal suture 
between 2 parietal bones
 Coronal suture 
between parietal & frontal
 Lambdoid suture 
between parietal & occipital
 Temporal suture 
between inferior margin
of the parietal & temporal

21. FETAL SKULLFETAL SKULL
FONTANELLESFONTANELLES
Anterior fontanelle :
diamond shaped
space between coronal &
sagittal suture,
ossifies at 18 - 20 month
Posterior fontanelle
(lambda) :
triangle shaped space
between sagittal &
lambdoid suture

22. Diameteres of the fetal skullDiameteres of the fetal skull
Biparietal diameter = 9.5cm
Suboccto-bregmatic diameter =
9.5cm
Occipito-frontal diameter =
11.5cm
(occipito-posterior position)
The suboccipito-frontal
diameter= 10 cm
(1st
diameter passes through
vulval orifice)

23. Diameteres of the fetal skullDiameteres of the fetal skull
Mento-vertical diameter =13cm
(Brow presentation)
Submento-bregmatic diameter =
9.5cm
(face presentation)
Bis-acromial diameter =12cm
(diameter of the shoulder)
Bitrochanteric diameter =10cm
(Diameter of the breech)

24. FETAL SKULL DIAMETERSFETAL SKULL DIAMETERS
 Biparietal diameter 9.5 cm. 
between parietal eminences The greatest transverse
diameter
 Suboccipitobregmatic 9.5 cm. 
middle of the bregma to undersurface of the occipital
bone at the neck
The presenting diameter of the well flexed head in labour
 Suboccipitofrontal 10.5 cm 
root of the nose to undersurface of the occipital bone at
the neck
The presenting diameter of the partially flexed head

25. FETAL SKULL DIAMETERSFETAL SKULL DIAMETERS
 Occipitofrontal 11.5 cm 
Root of the noose to the most prominent point of the
occiput
A defelexed head presents with this diameter
 Mentovertical 13 cm 
Chin to most prominent point of the vertix.
The presenting diameter in brow presentation
The largest diameter of the fetal head
 Submentobregmatic 9.5 cm 
Below the chin to middle of bregma
The presenting diameter in face presentation

26. MOULDING OF THE HEADMOULDING OF THE HEAD
 Occurs with descent of the fetal head into the pelvis to
reduce the head circumference
 Frontal bones slip under parietal bones
 Parietal bones override each other
 Parietal bones slip under the occipital bone

27. VERTIXVERTIX
 The area of the fetal skull bounded by the two partietal
emineces and the anterior and the posterior fontanelles.

28. MOULDING OF THE HEADMOULDING OF THE HEAD
DEGREE OF MOULDING
Assessed vaginally
 0 
suture lines are separate
 +1 
suture lines meet
 +2 
suture lines overlap but can be reduced by gentle
digital pressure
 +3 
overlap irreducible

29. Thank you