This document provides information on the normal female pelvis and contracted pelvis. It describes the boundaries, diameters, and planes of the true and false pelvis as well as the pelvic inlet, cavity, and outlet. It discusses anatomical landmarks like the sacral promontory, pubic bones, and ischial spines. Common causes of a contracted pelvis like rickets are mentioned. The Caldwell-Moloy classification system divides pelves into gynecoid, anthropoid, android, and platypelloid types based on transverse diameters.

1. CONTRACTED PELVIS

2. PPRROOFF.. MM..CC.. BBAANNSSAALL
MM..BB..BB..SS ,, MM..SS.. ,, MM..II..CC..OO..GG,, FF..II..CC..OO..GG..
FFoouunnddeerr PPrriinncciippaall&& CCoonnttrroolllleerr;;
JJhhaallaawwaarr MMeeddiiccaall CCoolllleeggee aanndd HHoossppiittaall JJhhaallaawwaarr..
EExx.. PPrriinncciippaall && CCoonnttrroolllleerr;;
MMaahhaattmmaa GGaannddhhii MMeeddiiccaall ccoolllleeggee AAnndd HHoossppiittaall,, SSiittaappuurraa,, JJaaiippuurr..
DDRR.. RRIIDDHHII KKAATTHHUURRIIAA

3. The pelvic cavity is a body cavity that is
bounded by the bones of the pelvis.
Its oblique roof is the pelvic inlet
(the superior opening of the pelvis).
Its lower boundary is the pelvic floor.
The pelvic cavity primarily
contains reproductive organs,
the urinary bladder, the pelvic colon,
and the rectum.

4. NNOORRMMAALL FFEEMMAALLEE PPEELLVVIISS
 From obstetrical view, the bony pelvis is to be considered as a whole unit.
 An articulated pelvis consists of- two innominate bones, sacrum, coccyx.
 These are joined together at 4 joints-a.
2 Sacro-iliac joints.
b. Sacro-coccygeal joints.
c. Symphysis pubis.

5.  Pelvis is anatomically divided into – TRUE PELVIS & FALSE PELVIS,
the boundary line being the brim of the pelvis.
 BBrriimm OOff TThhee PPeellvviiss from anterior to posterior on each side are-a.
Pubic Symphysis
b. Pubic Crest
c. Pubic Tubercle
d. Pectineal Line
e. Ilio-pubic Eminence
f. Ilio-pectineal Line
g. Sacroiliac Joint
h. Anterior border of ala of sacrum
i. Sacral Promontory

7.  Greater pelvis (or "false pelvis") is the space enclosed by the pelvic
girdle above and in front of the pelvic brim.
 Boundaries: 1. Lateral : Iliac Fossa
2. Posterior : Lumbar Vertebra
3. Anterior : Inner portion of the abdominal wall
 Little obstetrical significance.
 Only obstetric function- Support The Enlarged Uterus During Pregnancy.

8. Intercristal diameter [IC =29 cm]:
widest point on lateral aspect of iliac
crest
Interspinous diameter [IS =26 cm]:
distance between the lateral tips of
the anterior superior iliac spines
External conjugate [AP] diameter
[EC =20 cm]: distance between apex
of spine of 5th lumbar vertebra and
centre of the superior border of
symphysis pubis.

10.  It is the obstetrically significant pelvis.
 Forms the canal through which the fetus has to pass.
 Bounded above by : Promontory And Alae Of The Sacrum
Linea Terminalis
Upper Margins Of The Pubic Bones
 Bounded below by : Pelvic Outlet
 Cavity is obliquely truncated, bent cylinder with anterior wall
measuring 5 cm, and posterior wall is about 10 cm

11. Pelvic Brim or Pelvic inlet :
formed by the upper
margins of pubic bones, the
ilio-pectineal lines and the
anterior upper margin of the
sacrum.
Cavity: formed by the pubic
bones, ischium, ilium, and
sacrum
Outlet: diamond-shaped
made up of the pubic bones,
ischium, ischial tuberosities,
sacrotuberous ligament, and
5th segment of sacrum

12. Four Imaginary Planes
1.Plane of the pelvic inlet— The Superior Strait
2.Plane of the pelvic outlet— The Inferior Strait
3.Plane of the midpelvis— The Least Pelvic Dimension
4.Plane of greatest pelvic dimension— No obstetrical significance

13. BBoouunnddaarriieess
•Sacral Promontory
•Alae Of The Sacrum
•Sacroiliac Joints
•Iliopectineal Lines
•Iliopectineal Eminencies
•Upper Border Of The Superior Pubic Rami
•Pubic Tubercles
•Pubic Crests
•Upper Border Of Symphysis Pubis.

14. IINNCCLLIINNAATTIIOONN
 In erect posture, the pelvis is tilted forward.
 Such that the plane of inlet makes an angle of 55 degrees with the
horizontal, c/d as TThhee AAnnggllee ooff IInncclliinnaattiioonn.

15.  When the angle of inclination is increased due to sacralisation of the
L5, it is c/d HHiigghh IInncclliinnaattiioonn.
 High inclination has obstetrical significances:-
a. There is delay in engagement as uterine axis fails to coincide
with the inlet.
b. It favours Occipito-posterior position.
c. Difficulty in descent of head due to long birth canal & flat
sacrum not allowing internal rotation.
 Angle of inclination may be lessened in case of lumbarisation of S1.
It has no obstetrical significance.
It actually favours early engagement.

19. 11.. TTRRUUEE CCOONNJJUUGGAATTEE // CCOONNJJUUGGAATTEE VVEERRAA
(11cm)
Distance b/w midpoint of sacral promontory to the
inner of upper border of symphysis.
22.. OOBBSSTTEETTRRIICC CCOONNJJUUGGAATTEE
(10cm)
Distance b/w midpoint of sacral promontory to
prominent bony projection in midline on
inner surface of symphysis.
33.. DDIIAAGGOONNAALL CCOONNJJUUGGAATTEE
(12cm)
Distance b/w lower border of symphysis to
midpoint on sacral promontory

20.  Obstetric conjugate is the most obstetrically significant.
 It is also the shortest diameter.
 Only, the Diagonal conjugate can be clinically assessed on a P/V exam.
Remaining are calculated based on it.
 DDCC == 1122 ccmm..
 AACC == DDCC -- 11..22 ccmm
 OOCC == DDCC –– 11..5 ttoo 22 ccmm..
For practical purposes, if the middle finger of
the examining finger fails to reach the
promontory or reaches with difficulty, the pelvis
is likely to be adequate.

21. 11.. AANNAATTOOMMIICCAALL TTRRAANNSSVVEERRSSEE DDIIAAMMEETTEERR ==1133CCMM
Between the farthest two points on the iliopectineal lines.
It lies 4 cm anterior to the promontory and 7 cm behind the symphysis.
Divides pelvis to Anterior & Posterior segments.
It is the largest diameter in the pelvis.
22.. OOBBSSTTEETTRRIICC TTRRAANNSSVVEERRSSEE DDIIAAMMEETTEERR
It bisects the true conjugate and is slightly shorter than the anatomical
transverse diameter.
Head negotiated the brim through it.

22. PPOOSSTTEERRIIOORR
SSAAGGIITTTTAALL
DDIIAAMMEETTEERR OOFF TTHHEE
IINNLLEETT
AANNTTEERRIIOORR SSAAGGIITTTTAALL
DDIIAAMMEETTEERR OOFF TTHHEE
IINNLLEETT

23. a. RIGHT OOBBLLIIQQUUEE DDIIAAMMEETTEERR ==1122 CCMM
from the right sacroiliac joint to the left iliopubic eminence.
a. LLEEFFTT OOBBLLIIQQUUEE DDIIAAMMEETTEERR == 1122 CCMM
from the left sacroiliac joint to the right iliopubic eminence.
a. SSAACCRROO--CCOOTTYYLLOOIIDD DDIIAAMMEETTEERRSS == 99--99..5 CCMM
from the promontory of the sacrum to the right and left iliopectineal
eminence, so the right diameter ends at the right eminence and vice
versa.

24. • It is a segment, the boundaries of which are:
1.Roof - plane of pelvic brim
2.Floor - plane of least pelvic dimension
3.Anteriorly - shorter symphysis pubis
4.Posteriorly - longer sacrum

25. Anterior posterior diameter:
From midpoint on posterior surface of symphysis pubis to junction of S2 and
S3.
Oblique diameter:
Lower end of sacroiliac joint to the centre of obturator membrane.
Transverse diameter:
Across the lateral bony walls of pelvic cavity.
Cant be accurately measured.

26. ANATOMICAL OUTLET
It is lozenge-shaped bounded by:-
Front - lower border of symphysis pubis
& pubic arch
Laterally - ischial tuberosities,
sacrotuberous and sacrospinous
ligaments
Posterior - tip of the coccyx.
OBSTETRIC OUTLET
It is a segment, the boundaries of
which are:
Roof - plane of least pelvic
dimension
Floor - anatomical outlet
Anteriorly - lower border of
symphysis pubis
Posteriorly - Saccrum.
Laterally - ischial spines.

28. ANTERO -- PPOOSSTTEERRIIOORR DDIIAAMMEETTEERRSS::
a. Anatomical Antero-posterior Diameter =11cm
from the tip of the coccyx to the lower border of symphysis
pubis.
b. Obstetric Antero-posterior Diameter = 13 Cm
from the tip of the sacrum to the lower border of symphysis
pubis as the coccyx moves backwards during the second stage of
labour.
TTRRAANNSSVVEERRSSEE DDIIAAMMEETTEERRSS:
1. Bituberous diameter = 11 cm
between the inner aspects of the ischial tuberosities.
2. Bispinous Diameter = 10.5 Cm
between the tips of ischial spines.

29. Inferio
r View

32. OBSTETRIC AXIS
It is an imaginary line representing the way passed by the head during
labour.
It is J shaped
Passes downwards and backwards along the axis of the inlet till the
ischial spines where it passes downwards and forwards along the axis
of the pelvic outlet.

33. ANATOMICAL DEFINITION
It is a pelvis in which one or more of its diameters is reduced below the
normal by one or more centimeters.
OBSTETRIC DEFINITION
It is a pelvis in which one or more of its diameters is reduced so that it
interferes with the normal mechanism of labour.

34. HISTORY
PPRREELLIIMMIINNAARRYY
DDIIAAGGNNOOSSIISS
* Rickets: is expected if there is a history of delayed walking and
dentition.
* Trauma or diseases: of the pelvis, spines or lower limbs.
* Bad obstetric history: e.g. prolonged labour ended by;
• difficult forceps,
• caesarean section or
• still birth.

35. EXAMINATION
General examination
1.Gait: abnormal gait suggesting abnormalities in the pelvis, spines or
lower limbs.
2. Stature: women with less than 5feet height / shoe size less than 4 usually
have contracted pelvis.
3. Spines and lower limbs: may have a disease or lesion.

36. 4. Manifestations of rickets
* Square head
* Rosary beads in the costal ridges
* Pigeon chest
* Harrison’s sulcus & Bow legs
5. Dystocia dystrophia syndrome: the woman is
* Short
* Stocky
* Subfertile
* Android pelvis
* Masculine hair distribution
* History of delayed menarche.
* More exposed to occipito-posterior position and dystocia.

37. ABDOMINAL EXAMINATION
Nonengagement of the head - in the last 3-4 weeks in primigravida.
 Pendulous abdomen - in a primigravida.
 Malpresentations - are more common.

38. CALDWELL AND MOLOY CCLLAASSSSIIFFIICCAATTIIOONN
• Divided pelvis into anterior and posterior segments based on the
greatest transverse diameters of the inlet.
• Posterior segment determines the type of pelvis.
• Anterior segment determines the tendency.
• Many pelvis are not pure but of mixed types.
Eg. A gynaecoid pelvis with an android tendency

40. GGYYNNAAEECCOOII
DD
((5500%%))
AANNTTHHRROOPPOOIIDD
((2255%%))
AANNDDRROOIIDD
((2200%%))
PPLLAATTYYPPEELLLLOOIIDD
((55%%))

41. o 50%
o It is the normal female type.
o Inlet is slightly transverse oval.
o Sacrum is wide with average
concavity and inclination.
o Side walls are straight with blunt
ischial spines.
o Sacro-sciatic notch is wide.
o Sub pubic angle is 90-100 degrees.

42.  Male-type pelvis favouring OP positions
and apt to cause deep transverse arrest of
head.
 Brim heart-shaped
 Sacrum curved
 Ischial spines prominent
 Long-cone funnel pelvis
 Acute greater sciatic notch
 Oval obturator foramen
 Sub-pubic arch very narrow
[Gothic arch]

43.  Ape-like pelvis favouring OP
positions often requiring operative
vaginal
deliveries.
 Brim AP oval
 Sacrum very slightly curved
 Ischial spines prominent
 Long-cone funnel pelvis
with straight sidewalls
 Obtuse greater sciatic notch
 Oval obturator foramen
 Sub-pubic arch narrow

44.  Leads to cephalo-pelvic
disproportion.
 Brim oval transversely
 Sacrum very slightly curved
 Ischial spines prominent
 Short-cone shallow pelvis
 Acute greater sciatic notch
 Triangular obturator foramen
 Wide arch

45. GYNAECOID ANDROID ANTHROPOID
PLATYPELLOID
SHAPE
INLET
CAVITY
OUTLET

46. ABNORMALITIES DUE TO DISEASE / INJURY AAFFFFEECCTTIINNGG PPEELLVVIICC
BBOONNEESS && HHIIPP JJOOIINNTTSS
11..RRiicckkeettss-- FFllaatt RRaacchhiittiicc PPeellvviiss
Brim outlines ‘figure of 8’ or Reniform outline.
Sacral promontory is displaced downwards and forwards.
Sharp bending of sacrum at level of S4 and S5.
Increased interspinous diameter.
Wide subpubic angle.

47. 22.. SSccoolliioo--rraacchhiittiicc PPeellvviiss
If there is, any marked lateral spinal curvature, it produces such a
pelvis.
33.. OOsstteeoommaallaacciiaa PPeellvviiss == BBeeaakkeedd ppeellvviiss == RRoossttrraattee == TTrriirraaddiiaattee
Commonly found in women abiding by the Purdah System.
Promontory pushed downwards & forwards.
Lateral pelvic walls pushed inwards.
Anterior wall pushed forwards to form a beak.
Brim assumes ‘trifoliate’ shape.
Sub pubic angle narrowed.
Swinging gait.

48. 33.. PPoolliioo
44.. CChhaannggeess wwiitthh ppoossttuurree

49. ABNORMALITIES DUE TO DEVELOPMENTAL FFAAUULLTTSS
11.. NNaaeeggeellee’’ss PPeellvviiss == OObblliiqquueellyy CCoonnttrraacctteedd
Arrested development of one ala of the sacrum.
Straightening of iliopectineal line of the same side, with narrow
sacral bay.
Conjugate diameter little affected.
Oblique diameters unequal.
Transverse diameter much reduced.

50. 22.. RRoobbeerrtt’’ss PPeellvviiss == TTrraannssvveerrsseellyy CCoonnttrraacctteedd
Double Naegele pelvis.
Both alae are ill formed.
Rarest form of deformity.
33.. SSpplliitt PPeellvviiss
Physiological separation b/w pubic bones during later months of
pregnancy.
Extreme cases gap may be as large as 10cm with fibrous band
covering it.
Ectopia of bladder may occur.

51. 44.. AAssssiimmiillaattiioonn PPeellvviiss
Variation in number/type os sacral bones fusing to form a sacrum.
Low Assimilation – sacrum has 4 bones.
High Assimilation – sacrum consists of 6 bones.
Obliquity of Plane of Brim is effected.
Low type- low obliquity. So head enters brim easily.
High type- increased obliquity. Thus, head enters with difficulty.

52. ABNORMALITIES OF THE VVEERRTTEEBBRRAALL CCOOLLUUMMNN
aa))KKyypphhoossiiss
bb))SSccoolliioossiiss
cc))SSppoonnddyylloolliisstthheessiiss
dd))CCooccccyyggeeaall ddeeffoorrmmiittyy..
AABBNNOORRMMAALLIITTIIEESS OOFF DDIISSEEAASSEE OORR DDEEFFOORRMMIITTYY OOFF LLOOWWEERR
LLIIMMBB
11))HHiipp jjooiinntt ddiisseeaassee..
22))DDiissllooccaattiioonn ooff ffeemmuurr..
33))AAttrroopphhyy oorr lliimmbb lloossss..

53. PPEELLVVIIMMEETTRRYY
CCLLIINNIICCAALL PPEELLVVIIMMEETTRRYY
A. Internal pelvimetry
1. Inlet
2. Cavity
3. Outlet
BB.. EExxtteerrnnaall ppeellvviimmeettrryy
1. Inlet
2. Outlet

54. IIMMAAGGIINNGG PPEELLVVIIMMEETTRRYY
a) X-ray.
b) Computed Tomography (CT).
c) Magnetic Resonance Imaging (MRI) .
CT and MRI are recent and accurate but expensive and not always available so
they are not in common use.

55. CLINICAL AASSSSEESSSSMMEENNTT BBYY
BBOODDYY SSTTRRUUCCTTUURREE

56. Best done beyond 37 weeks or better at start of labour.
11..SSAACCRRUUMM – smooth, well curved, seldom reached beyond lower 3
pieces.
2.SACRO-SCIATIC NOTCH – is sufficiently wide such that 2 fingers can
be easily placed over sacrospinous ligament, covering the notch.
3.ISCHIAL SPINES – difficult to tough tips of both fingers at the same
time.
4.ILIO-PECTINEAL LINES- note for any beaking.

57. 5. SIDE WALLS - normally not palpable by sweeping fingers, unless
convergent.
6.POSTERIOR SURFACE OF PUBIC SYMPHYSIS - smooth rounded.
Any beaking or angulation is abnormal.
7.SACRO-COCCYGEAL JOINT - mobility noted.
8.PUBIC ARCH - normally rounded accommodating palmar aspect of two
fingers.
9.DIAGONAL CONJUGATE
10. PUBIC ANGLE - inferior pubic rami of females is well defined.
11.TRANSVERSE DIMAETER OF OUTLET – place knuckles of clinched
fist b/w ischial tuberosities.

60. DISPARITY IN RELATION B/W THE FETAL
HEAD AND THE MATERNAL PELVIS.
ᴥ May be due to average size baby with a small pelvis, or big baby with
normal pelvis.
ᴥ Clinical assessment can be done with :-
a)CLINICAL
b)IMAGING TECHNIQUES
c) CEPHALOMETRY- Ultrasound, MRI, X-Ray

61.  Patient made to lie in dorsal position, with thighs slightly flexed &
separated.
 Head grasped with left hand.
 Index & Middle fingers of the right hand placed above symphysis,
keeping inner surface of fingers in line with anterior surface of symphysis,
to judge degree of overlapping.

62. 1. Head can be pushed down without overlapping- NO
DISPROPORTION.
2. Head can be pushed down with slight overlapping- MODERATE
DISPROPORTION.
3. Head cant be pushed down, with overhanging of parietal bones-
SEVERE DISPROPORTION.

63. Patient evacuates her bladder and rectum.
Placed in semi-sitting position to bring the foetal axis perpendicular
to the brim.
Left hand pushes the head downwards and backwards into the pelvis
while the fingers of the right hand are put on the symphysis to detect
disproportion.

66. I. Head can be pushed down upto level of ischial spines without
overlapping of parietal bone over symphysis- NNoo DDiisspprrooppoorrttiioonn.
II. Head can be pushed a little but not upto level of the spines, with mild
overlapping- Mild / Moderate Disproportion.
III. Head cant be pushed, and instead parietal bone overhangs the
symphysis, replacing the thumb- Severe Disproportion.

68. PPRREETTEERRMM IINNDDUUCCTTIIOONN
• Only for mild degree of
contraction.
• Not favoured in present day
practice.
• In multigravidae, with prior
history, done 2-3 weeks prior to
due date.
EELLEECCTTIIVVEE CCSS AATT
TTEERRMM
 Major inlet
contraction
 Moderate degree
with complications.
 With doubtful
maturity, withheld till
pains start or ROM,
whichever is early.
TTRRIIAALL LLAABBOOUURR
 Conducting
spontaneous labour in
moderate
disproportion under
supervision, with
facilities of
intervention available
at hand.

69. MALE FEMALE
Bone are taller, heavier, and thicker Bones are lighter and less dense
Illiac fossa is more concave and the anterior
superior iliac spine is inturned.
Illiac fossa is shallow and anterior superior
illiac spine is straight forward.
Acetabular cavity is large. Acetabualr cavity is shallow.
Obturator foramen is large and oval. Obturator foramen is small and triangular.
Pelvic inlet is heart shaped Round in shaped and diameters are longer than
male.
Pelvic cavity longer and more conical Pelvic cavity shorter and more conical.
Symphysis pubis and body of the pubis are
Symphysis pubis and body are short.
elongated.
Pelvic outlet is small and 1” lesser than
diameters of female.
Pelvic outlet is wide and anterior posterior
diameter is longest.
Sub-pubic angle is narrow and measures 50°-
60°
Sub-pubic angle is wide and measures about
80°-90°.
Angle and depth of greater sciatic notch are
narrow.
Angle and greater sciatic notch are wide.
Ischial spine are inturned Ischial spines are out turned.
Curvature of the pelvic surface of sacrum is
uniformly concave.
The upper part is more flat and lower part is
abruptly concave.