CPD, or cephalopelvic disproportion, occurs when the fetal head is too large to pass through the mother's pelvis during labor. It can be caused by a large baby, abnormal fetal position, or a contracted pelvis. A contracted pelvis is a permanent deformity where one or more pelvic diameters are smaller than normal, which can cause dystocia or difficult labor. Clinical methods like abdominal palpation and Munro-Kerr-Muller are used to assess CPD, but imaging like X-ray or MRI can provide more accurate measurements. While elective c-section is preferred for severe CPD, a trial of vaginal delivery may be attempted for mild cases in a hospital

1. CPD & CONTRACTED PELVIS

2. CEPHALOPELVIC
DISPROPORTION
 CPD- disproportion between diameters of fetal
head & maternal pelvis for that pregnancy, with
that head and under the given circumstances.
 CPD need not recur in subsequent pregnancies
 CPD is best assessed only at the onset of labour

3. Causes for CPD
 Large baby due to :
- hereditary factors
- diabetes
- post maturity
- multiparity
 Abnormal fetal position
 Contracted pelvis
 Abnormally shaped pelvis

4. Contracted pelvis
 Anatomical definition: One or more diameters in one
or more of the planes of the pelvis may be shorter
than normal.
 Obstetric definition: alteration in size / shape of pelvis
of sufficient degree to alter the normal mechanism of
labour in an average sized baby
 Permanent deformity of the pelvis
 Recurrent cause for dystocia in subsequent labour
 Contracted pelvis could be a cause of CPD, all CPDs
are not due to contracted pelvis
 Contraction may be at the level of pelvic
brim/cavity/outlet
 It may be symmetrical or asymmetrical and it may
affect either antero posterior / transverse diameter or
both

5. Factors influencing the size & shape
of pelvis
 Developmental factor- hereditary/ congenital
 Racial factor
 Nutritional factor- malnutrition leads to small
pelvis
 Sexual factor- excess androgen may produce
android pelvis
 Metabolic factor- Rickets / osteomalacia
 Trauma/ diseases/ tumors of bony pelvis/
legs/spines

6. Etiology of contracted pelvis
 Causes in pelvis
 DEVELOPMENTAL( congenital)
-Small gynaecoid pelvis( generally contracted
pelvis)
-Small android / anthropoid pelvis
-Small platypelloid pelvis(simple flat pelvis)
- NAEGELE’S PELVIS- absence of one sacral ala
- ROBERT’s pelvis- absence of both sacral ala
- SPLIT pelvis- splitted pubic symphysis
- HIGH assimilation pelvis-sacrum composed of 6
vertebrae
- LOW assimilation pelvis- sacrum composed of 4

7. Contd.,
 Causes in spines:
 Lumbar kyphosis/ lumbar scoliosis/
spondylolisthesis
 L5 vertebra is pushed forward along with the
above vertebral column while the promontory is
pushed backwards & tip of the sacrum is pushed
forwards leading to outlet contraction
 Causes in lower limbs
 Dislocation of one or both femur
 Atrophy of one or both lower limbs
 Diseases / tumors/ fracture affecting one side

8. Diagnosis of CPD/ Contracted pelvis
 HISTORY
 h/o Rickets- if there delayed dentition/ walking
 h/o trauma/diseases of pelvis/spines/ lower limbs
 In a parous women – h/o previous deliveries
-safe/vaginal delivery of normal size/live/undamaged
babies at term- normal pelvic capacity
-BOH- difficult vaginal delivery which ended in stillbirth/
neonatal death/ C- section/ forceps delivery
-prolonged labour/ perineal tears/PPH/VVF/RVF & size
of baby /neurological sequelae
In LSCS- Emergency lscs followed by prolonged labour due
to CPD/ h/o malpresentations/ blood transfusions

9. Examination
 General examination:
 Gait – abnormal gait( limping/waddling gait)
associated with abnormalities in pelvis/LL/ spines
 HEIGHT-
-SHORT STATURE (<135 cm) have smaller
pelvis and in many cases babies are too small
-Pelvic dystocia is more common in a women
who are less than average height
- shortening of lower limbs due to
fracture/surgery
 Spines/lower limbs- lesion/
diseases(kyphosis/polio/TB)

10. Contd.,
 Rickets manifestations- pigeon chest/ ricketic
rosary in costal ridges/ Harrison’s sulcus/ bow
legs
 DYSTOCIA DYSTROPHIA SYNDROME-
 Short /obese
 Subfertile / android type of pelvis
 Male distribution of hair

11. Abdominal examination
 UNENGAGED or FLOATING head in PRIMI at
term
 Pendulous abdomen – CPD due to inlet
contraction
 Mal presentations are more common
 Deflexed attitude of head prior to the
commencement of labour should be ruled out
 Deflexed head may simulate or exaggerate
disproportion

12. Causes for MOBILE head
(Primi /at term)
 Wrong dates
 Prematurity
 Placenta previa
 Polyhydraminos
 Cord around the neck
 Multiple pregnancy
 CPD/ contracted pelvis
 Tumors in LUS
 Fetal cause- hydrocephalus

13. Clinical methods for diagnosing CPD
 ABDOMINAL method- Screening method
 Difficult in obese/ deflexed head/ floating head
 Procedure
 After emptying the bladder, in dorsal position with
thighs and knees are semi flexed & abducted.
 Left hand is used to grasp the fetal head
 Middle finger & index finger of right hand is
placed above the pubic symphysis, keeping the
inner surface of the middle finger in line with
pubic symphysis

14. Contd.,
 Head is pushed downwards into pelvis
 Fingers of right hand placed on pubic symphysis
will assess CPD
 Interpretation
 Head can be pushed down into pelvis- NO CPD
 Head is flushed with pubic symphysis- MILD
degree of CPD
 Head cannot be pushed down & there is over
riding of head over pubic symphysis- MAJOR
degree of CPD

15. Contd.,
 Ian Donald method:
 In dorsal position, pt’s knee is not fully raised but
widely separated
 Using 3rd, 4th, 5th fingers of both hands , head is
grasped at sinciput & occiput
 Index finger reaches pubic symphysis
 Thumbs of both hands are placed over parietal
eminence
 Thumbs on parietal eminence press the head
downwards & index fingers on pubic symphysis
can assess the degree of CPD

16. Pelvic assessment
 Pelvimetry –
 Assessment of pelvic diameters & capacity done
at 38-39 weeks of gestation. It includes,
 CLINICAL PELVIMETRY-
Internal pelvimetry External pelvimetry
Inlet/ cavity/ outlet Inlet / outlet

17. Pre requisites for assessing CPD
 Explain the procedure to the patient
 Bladder should be empty
 Patient should be in dorsal position
 Done under aseptic precautions, internal
examination should be gentle
 Pelvic capacity can be estimated clinically by
evaluating various measurements with middle /
index finger of right hand during bimanual
examination

18. Vaginal examination
 Sacral promontory- reached easily or not
 Sacral curvature-well curved or not
(from promontory to tip of sacrum – if it is well
developed at the level of mid pelvic / higher level
,bone can be reached with difficulty)
 Flattening of sacrum- unfavourable sign-
transverse arrest
 Sacro sciatic notch-admits 2 fingers or not
Adequacy of pelvis at the lower level can be
assessed.
Less space – narrowing of sacrosciatic foramen &
diminished capacity of lower pelvis.

19. Contd.,
 Pelvic sidewalls- parallel/ divergent /
convergent(dangerous)
 Ischial spines- prominent or not. It should be
reached when fingers are spanned.
 Sub pubic arch/ sub pubic angle-acute/obtuse.
( corresponds to angle substended by fully
abducted thumb/index finger)
 Ischial tuberosities-admits 4 knuckles when
clenched fist is kept between ischial tuberosities
 Coccyx –mobile or tipped

20. Diagonal conjugate
 DC- is the distance between lower border of
pubic symphysis to sacral promontory(12.5 cm)
Procedure
 Under SAP, pt in dorsal position, after emptying
the bladder
 Introduce index finger/ middle finger of right hand
into vagina until middle finger reaches sacral
promontory
 Index finger of left hand marks off the lower
border of pubic symphysis over the right hand
 Right hand is withdrawn & distance between the
tip of middle finger and point marked by index

21. True conjugate
 TC is estimated by deducting 1.5-2cm from DC
(10.5 cm)
 Accuracy depends on
 Depth of pubic symphysis-If it is deeper, more
must be deducted
 Inclination of pubic symphysis-if it is obtuse, more
must be deducted
 Height of promontory- if it is higher, more must be
deducted
However DC and through that TC are not assessed
as a routine

22. Munro-Kerr-Muller method
 Abdomino pelvic method
 Assess the relative size of fetal head and
maternal pelvis
Procedure
 After emptying the bladder, in dorsal lithotomy
position with thigh /knee are semi flexed
 Obstetrician stands on right side
 Grasps the fetal head with the left hand & pushes
it into pelvic brim
 Middle /index fingers of right hand are kept at the
level of ischial spines and thumb of right hand is
kept over the pubic symphysis

23. Contd.,
 Extent of fetal head into maternal pelvis or degree
of over riding of head over symphysis, severity of
CPD can be assessed.
 If the head could be pushed down
 upto the level of ischial spines & there is no
overlapping of parietal bone over pubic
symphysis- NO CPD
 Not upto the level of ischial spines & parietal
bone is flushed with pubic symphysis- MINOR
CPD
 When head could not be pushed down and there
is marked over riding of head on thumb- MAJOR
CPD

24. Limitations
 If done before labour, a deflexed head may
simulate disproportion and gives wrong prediction
 It assess only contraction at the level of pelvic
brim
 Once ACTIVE LABOUR starts , the preliminary
adjustment between head & brim occurs, mild
disproportion is usually corrected, thereby
accuracy of this method is enhanced
 Inspite of limitations, it must be essential part of
routine antenatal examination near term in all
 Primigravidas with unengaged head
 Multigravidas with BOH

25. Contracted pelvis
Contracted inlet Contracted midpelvis Contracted outlet
If AP diameter<10cm
If DC< 11.5 cm
Complications :
Early spontaneous
ROM
Slow dilatation of cervix
Malpresentations
If interischial diameter
<10cm
Ischial spines are
prominent
Converging sidewalls
Narrow sacro sciatic
notch
More common than
inlet contraction
Malrotation of fetal
head
Deep transverse arrest
If intertuberus diameter
<8cm
Isolated outlet
contraction is rare.
commonly associated
with midpelvis
contraction

26. IMAGING PELVIMETRY
To supplement the observations obtained on
clinical examination
X ray CT MRI USG
For pelvis
assessment
/ CPD
Lateral view-
AP
diameters of
pelvis/ sacral
curvature/
pelvis brim/
sacroscaitic
notch
-More
accurate
-Restricted
use because
of
unnecessary
radiation
exposure
Advantages
-No ionising
radiation
-Fetus can
be
completely
imaged
-Soft tissue
dystocia can
be
diagnosed
-Biparietal
diameter can
be measured
accurately
-Occipito
frontal
diameter
-Head
circumferenc
e

27. Management of labour
 Early diagnosis & proper management influence
the maternal/ fetal prognosis
 All cases of suspected contracted pelvis/ CPD
should be delivered only in well equipped centres
 In modern obstetrics, ELECTIVE C-section is the
method of choice for contracted pelvis
 Trial of labour can be attempted when there is
Minor CPD, in a well equipped facility & well
experienced Obstetrician & team is available

28. Trial of labour
Definition –
 Trial of labour is conducted in a woman with
minor degree of CPD with vertex presentation,
with no obstetric or medical complications in an
attempt to deliver vaginally.
Pre requistes for Trial of labour
 Should be conducted in an institution with
facilities for LSCS
 Counselling of the
woman(advanatges/disadvanatges & it may end
up in LSCS)
 Monitor with PARTOGRAM

29. Factors affecting TOL
 TOL is dependent on 3 factors that cannot be
assessed before labour
 Uterine contractions
 Moulding of fetal head leading to decrease in
diameters of fetal head
 Yield of the pelvis at the sacroiliac joints / pubic
symphysis with resultant increase in pelvic
dimensions and giving up of perineum

30. Contd.,
Indications Contra indications
Minor or first degree CPD Elderly woman
Average size fetus Outlet contraction
No obstetric complications True conjugate<9cm
Medical /obstetric complications of
pregnancy

31. Outcome of TOL
SUCCESSFUL TRIAL FAILED TRIAL
Vaginal delivery
Normal /assisted with
forceps/vaccum
Good maternal/ fetal outcome
LSCS /vaginal delivery
With poor maternal/fetal outcome

32. Conduct of TOL
 During trial labour, adeqaute hydration/ nutrition
and analgesia should be maintained
 Informed consent
 Nil oral, only IV fluids
 Analgesia – Epidural
 Progress of labour can be monitored by
Partogram
 If inadequate uterine contractions- oxytocin drip
can be started
 Apply forceps when needed
 AMTSL

33. Termination of TOL
 LSCS- if there is fetal/ maternal distress
-inadequate progress of labour
 Trial FORCEPS- tentative attempt in MILD CPD
 it should be attempted in OT after informed consent,
to expedite the delivery
 Abandon the procedure , if there is difficulty in
application while locking/ traction then proceed to C-
section.
FAILED FORCEPS-
Error in judgement of CPD
Failure to deliver fetus vaginally after applying forceps

34. Role of ELECTIVE LSCS in CPD
Indications
 MAJOR degree of CPD
 CPD associated with
-BOH
-APH
-Pre eclampsia
-GDM
-FGR
-Prolonged pregnancy

35. Signs in progression of TOL
Favourable signs Unfavourable signs
Good uterine contractions- 3 in 10
mins each lasting for 30-45 secs
Ineffective uterine contractions
Early engagement of head in OA
position
Head remaining high at full cervical
dilatation
Occipito posterior position
Closely applied cervix( well thinned
out & effaced)
Loosely hanging cervix not applied
to head
Rupture of membranes after full
dilatation of cervix
Early rupture of membranes

36. Complications of CPD
Maternal complications Fetal complications
PROM/ Cord prolapse Fetal hypoxia
Prolonged labour Birth asphyxia/ intrapartum death
Obstructed labour leads to uterine
rupture/VVF/sepsis
Cephalhematoma
High chance for instrumental
delivery
Hypoxic ischemic
encephalopathy(HIE)
PPH(atonic/ traumatic) Multiple fractures