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CONTRACTED PELVIS
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DEFINITION
Anatomical definition:
It is a pelvis in which one or more of its main
diameters are reduced below average normal by one
or more centimetres
Obstetric definition:
It is a pelvis in which one or more of its main
diameters are reduced to the extent that interferes
with the normal mechanism of labour
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ETIOLOGY
1. Developmental causes Small gynaecoid -- generally contracted pelvis
Small android
Small anthropoid Small flat platypelloid pelvis
Naegeles pelvis
Roberts pelvis
High assimilation pelvis Low assimilation pelvis
Split pelvis
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NAEGELES PELVIS
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ROBERTS PELVIS
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FAULTY DEVELOPMENT
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2. Diseases of the pelvic bones and joints
Metabolic diseases ---- Rickets, Osteomalacia
Bone tuberculosis
Severe malnutrition
Poliomyelitis
Hipjoint disease
Fractures of the pelvic bones, tumours of the pelvic
bones
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Rachitic pelvis Osteomalacic pelvis
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3. Causes in the spine
Scoliosis
Kyphosis
Spondylolisthesis
Coccygeal deformity
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Kyphotic pelvis Scoliotic pelvis
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DIAGNOSING CONTRACTED PELVIS
1. HISTORY:
GENERAL: Rickets, Osteomalacia,
Poliomyelitis, TB, fracture
OBSTETRIC: Previous prolonged labour,
difficult vaginal delivery, perineal tear,
vesico-vaginal or recto-vaginal fistula
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2. PHYSICAL EXAMINATION
Height: high risk
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Dystocia - dystrophia syndrome:
short and obese
stocky
broad shoulders and short thighs
sub-fertile
has android pelvis
masculine hair distribution
with history of delayed menarche
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3. ABDOMINAL EXAMINATION
4. PELVIMETRY
* Clinical
* Imaging - X- Ray, CT, MRI
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Data Findings
Forepelvis (pelvic brim) RoundDiagonal conjugate 11.5 cmAnterposterior diameter of outlet 11.0 cm
Symphysis Average thickness, parallel to sacrumSacrum Hollow, average inclinationSide walls StraightIschial spines BluntInterspinous diameter 10.0 cmSacrosciatic notch 2.5 -3 finger - breadthsSubpubic angle 2 finger - breadthsBituberous diameter 4 knuckles (> 8.0 cm)Coccyx Mobile
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Degrees of Contracted Pelvis
Minor degree: The true conjugate is 9-10 cm
Moderate degree: The true conjugate is 8-9 cm
Severe degree: The true conjugate is 6-8 cm
Extreme degree: The true conjugate is less than6 cm.
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MECHANISM OF LABOUR
1. Flat rachitic pelvis
Engagement : with the sagittal suture in the
transverse diameter
Asynclitism with anterior parietal bone
presentation
Lateral displacement of the head
Deflexion of the head and descent
Rotation of the occiput 2/8 circle anteriorly
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2. Simple Flat Pelvis
Persistent flattening of the pelvis
Contracted outlet
No internal rotation and descent
Obstructed vaginal delivery
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3. Contracted Outlet ( Funnel Pelvis )
Normal descent and engagement
Extreme flexion and moulding of the head at
ischial spines
Narrow subpubic angle causes the head to push
backward
Face to pubis position is more favourable
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CEPHALOPELVIC DISPROPORTION
The disparity in the relation between the head and
the pelvis which may be either due to an average size
baby with a small pelvis or due to a big baby with
normal size pelvis (hydrocephalus) or due to a
combination of both.
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CAUSES OF HIGH HEAD AT TERM
Occipito-posterior position - deflexion
Deflexed head
Multipara
Halffull bladder
Mistaken maturity
Twin, hydramnios, placenta praevia
Increased angle of inclination
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DIAGNOSING CPD
1.Abdominal method ( Pinards method )
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2. Abdomino-vaginal method (Muller-Munro
Ken)
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EFFECTS OF CONTRACTED PELVIS
1. On pregnancy
2. On labour* maternal
* fetal
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MANAGEMENT OF CONTRACTED
PELVIS
INLET CONTRACTION
Preterm induction of labour
Elective Caesarean section at term
Trial labour
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TRIAL LABOUR
The conduction of spontaneous labour in a
moderate degree of cephalo-pelvic disproportion,
in an institution under supervision with watchful
expectancy, hoping for a vaginal delivery
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CONTRAINDICATIONS
Associated mid-pelvic and outlet contraction
Elderly primigravida
Mal-presentation
Post-maturity
Post caesarean pregnancy
Pre - eclampsia
Medical disorders like heart disease, DM, TB
Unavailability of facilities for caesareansection
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GUIDELINES FOR TRIAL LABOUR
Selection of patients
Monitoring progress
Augmentation of labour
After rupture of membranes
Termination
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Favourable features of trial labour
Unfavourable features
Advantages
Disadvantages
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MID-PELVIC AND OUTLET
CONTRACTION
Cephalopelvic disproportion at the outlet is
defined as one where the biparietal - suboccipito-
bregmatic plane fails to pass through the
bispinous and antero-posterior planes of the
outlet.
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MANAGEMENT
Elective Caesarean section --- In case of
contraction of both the transverse and A-P
diameters of the mid-pelvic plane
Vaginal delivery --- In uncomplicated cases with
minor contraction
*by forceps or ventouse with deep episiotomy to
prevent per ineal injur ies
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