Dystocia
Second part,abnormalities of birth
canal
Pelvic contraction
?Birth canal
– bony canal
– soft canal
?abnormal bony canal,pelvic contraction
– any contraction of the pelvic diameters that
diminishes the capacity of the pelvis can creat
dystocia during labor
Classification
?Contraction of the pelvic inlet
?contraction of the midpelvis and pelvic
outlet
?general contraction of the pelvis
?pelvic deformities
Contracted pelvic inlet
?Anteroposterior d<10cm
?diagonal conjugate d<11.5cm
?external conjugate d<18cm
– simple flat pelvis
– rickets flat pelvis
Contracted midpelvis
?Midpelvis,from inferior margin of the
symphysis pubis through the ischial
spines,touches the sacrum near the junction
of the 4th and 5th vertebrae
?contraction,interischial spinous diameter is
smaller than 8cm(spines are prominent,the
pelvic side walls converge or the
sacrosciatic notch is narrow)
Contracted pelvic outlet
?Defination,diminition of the interischial
tuberous diameter to 8cm or less.
?2 triangles:
– baseof both,interischial tuberous diameter
– anterior triangle
– posterior triangle
picture1
Outlet contraction without concomitant
midplane contraction is rare
?Funnel shaped pelvis
?transversely contracted pelvis
?General contraction of the pelvis
?2cm or more shorter than normal
?Pelvic deformities
?osteomalacic pelvis
?obliquely contracted pelvis
Effects on mather and fetus
?MOTHER:Inlet
– Malpresentation and malposition
– prolonged labor
– insufficient uterine contraction
?midpelvis and outlet
– persistant occipitotransverse or
occipitoposterior position
– fistula formation
– intrapartum infection
– threatening rupture or rupture
fetus
?PROM
?Prolapse
?Distress
?Death
?Injury
?Infection
Soft birth canal
?Lower segment of uterus
?cervix
?vaginal
Fetal malposition
?Occipitoanterior position 90%
?malposition 10%
? abnormal cephalic posion 6-7%
? breech presentation 3-4%
? others
Persistant occipitoposterior
(transverse) position
?Causes
– abnormal pelvis:transverse narrowing of the
midpelvis
– flexion not well
– hypotonic uterine dysfunction
Breech presentation
?Incidence
– breech presentation is common remote from
term.
– 3-4% of singleton deliveries
?Position
– LSA,LST LSP,RSA,RST,RAP
Causes
?Uterine relaxation
?limited uterine cavity
?fetal head obstructed
classification
?Frank breech p
– the lower extremities are flexed at the hips and
extended at the knees,and thus the feet lie in
close proximity to the head.
– It appears most commonly
?complete breech p
– differs in that one or both knees are flexed.
?Incomplete breech p
– one or both hips are not flexed and one or both
feet or knees lie below the breech,that is,a foot
or knee is lowermost in the birth canal.
Incomplete breech presentation
Effects
?Maternal
– greater frequency of operative delivery
– higher maternal morbidity and slightly higher
mortality
– PROM
– secondary hypotonic uterine dysfunction
– puerperium infection
– postpartum haemorrhage
– laceration of cervix
Effects
?Fetus
– PROM
– cord prolapse
– fetal distress even death
– newborn asphyxia
– brachial plexus injury
– IVH
Fa
ce pre
sen
tat
ion
Compound presentation
Second part,abnormalities of birth
canal
Pelvic contraction
?Birth canal
– bony canal
– soft canal
?abnormal bony canal,pelvic contraction
– any contraction of the pelvic diameters that
diminishes the capacity of the pelvis can creat
dystocia during labor
Classification
?Contraction of the pelvic inlet
?contraction of the midpelvis and pelvic
outlet
?general contraction of the pelvis
?pelvic deformities
Contracted pelvic inlet
?Anteroposterior d<10cm
?diagonal conjugate d<11.5cm
?external conjugate d<18cm
– simple flat pelvis
– rickets flat pelvis
Contracted midpelvis
?Midpelvis,from inferior margin of the
symphysis pubis through the ischial
spines,touches the sacrum near the junction
of the 4th and 5th vertebrae
?contraction,interischial spinous diameter is
smaller than 8cm(spines are prominent,the
pelvic side walls converge or the
sacrosciatic notch is narrow)
Contracted pelvic outlet
?Defination,diminition of the interischial
tuberous diameter to 8cm or less.
?2 triangles:
– baseof both,interischial tuberous diameter
– anterior triangle
– posterior triangle
picture1
Outlet contraction without concomitant
midplane contraction is rare
?Funnel shaped pelvis
?transversely contracted pelvis
?General contraction of the pelvis
?2cm or more shorter than normal
?Pelvic deformities
?osteomalacic pelvis
?obliquely contracted pelvis
Effects on mather and fetus
?MOTHER:Inlet
– Malpresentation and malposition
– prolonged labor
– insufficient uterine contraction
?midpelvis and outlet
– persistant occipitotransverse or
occipitoposterior position
– fistula formation
– intrapartum infection
– threatening rupture or rupture
fetus
?PROM
?Prolapse
?Distress
?Death
?Injury
?Infection
Soft birth canal
?Lower segment of uterus
?cervix
?vaginal
Fetal malposition
?Occipitoanterior position 90%
?malposition 10%
? abnormal cephalic posion 6-7%
? breech presentation 3-4%
? others
Persistant occipitoposterior
(transverse) position
?Causes
– abnormal pelvis:transverse narrowing of the
midpelvis
– flexion not well
– hypotonic uterine dysfunction
Breech presentation
?Incidence
– breech presentation is common remote from
term.
– 3-4% of singleton deliveries
?Position
– LSA,LST LSP,RSA,RST,RAP
Causes
?Uterine relaxation
?limited uterine cavity
?fetal head obstructed
classification
?Frank breech p
– the lower extremities are flexed at the hips and
extended at the knees,and thus the feet lie in
close proximity to the head.
– It appears most commonly
?complete breech p
– differs in that one or both knees are flexed.
?Incomplete breech p
– one or both hips are not flexed and one or both
feet or knees lie below the breech,that is,a foot
or knee is lowermost in the birth canal.
Incomplete breech presentation
Effects
?Maternal
– greater frequency of operative delivery
– higher maternal morbidity and slightly higher
mortality
– PROM
– secondary hypotonic uterine dysfunction
– puerperium infection
– postpartum haemorrhage
– laceration of cervix
Effects
?Fetus
– PROM
– cord prolapse
– fetal distress even death
– newborn asphyxia
– brachial plexus injury
– IVH
Fa
ce pre
sen
tat
ion
Compound presentation
