Dystocia（ii）

Dystocia(II) An hongmin Department Of Obstetrics & Gynecology

Definition Dystocia literally means difficult labor and it is characterized by abnormally slow progress of labor It is the consequence of four distinct abnormalities that may exist singly or combination

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Categories of dystocia Abnormal of the powers(uterine contractility and maternal expulsive effort) Abnormalities of the passage (the birth canal) Abnormalities of passenger (the fetus)

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Hypotonic dysfunction

Hypertonic dysfunction Uncoordinated dysfunction

Hypotonic dysfunction is uterine activity characterized by contraction of the uterus with insufficient force( ＜ 24mmHg), irregular or infrequent rhythm, or both. Hypotonic dysfunction responds well to oxytocin.

Hypertonic uterine contractions and uncoordinated contraction often occur together and are characterized by elevated resting tone of the uterus and frequent intense uterine contractions. Oxytocin administration is generally of no value. Sedation is generally effective in converting hypertonic contractions to normal labor patterns.

Dystocia Second part: abnormalities of the passage and the passenger

Abnormalities of the passage ◆

Bony abnormalities

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Soft tissue obstruction of the birth canal

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Abnormal placental location

Pelvic types

Pelvimetry( 骨盆测量 ) X-ray pelvimetry

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 9

Pelvic contraction classification Contraction of the pelvic inlet contraction of the midpelvis and pelvic outlet general contraction of the pelvis pelvic deformities

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Abnormalities of birth canal 1.Bony pelvic 1)Contracted pelvic inlet simple flat pelvis （单纯性扁平性骨盆） rachitic flat pelvis( 佝偻病性扁平性骨盆 )

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Contracted pelvic inlet Anteroposterior （前后径） d<10cm diagonal conjugate （对角径） d<11.5cm external conjugate( 骶耻外径 ) d<18cm

2)Contracted midpelvis (anthropoid pelvis 类人猿型骨盆 ) interischial spinous diameter is smaller than 8cm(spines are prominent, the pelvic side walls converge or the sacrosciatic notch is narrow)

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3)Contracted pelvic outlet (funnel shaped pelvis 漏斗型骨盆 ) diminition of the interischial tuberous diameter to 8cm or less.

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4) Generally contracted pelvis 2cm or more shorter than normal

5) Pelvic deformities osteomalacic （骨软化的） pelvis obliquely contracted pelvis ( 斜狭骨盆 )

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Clinical signs of contracted pelvis 2) Contracted pelvic inlet 3) Contracted midpelvis 4) Contracted pelvic outlet

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Diagnosis : History Physical examination Pelvimetry external pelvimetry internal pelvimetry diagonal conjugate 12.5~13cm bi-ischial diameter 10cm incisura ischiadica 5~6cm angle of subpubic arch 90 17

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 18

Fetus Prom Prolapse Distress Death Injury Infection

2. Abnormal of soft birth canal

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2. Abnormal of soft birth canal Lower segment of uterus cervix vaginal

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Abnormal of soft birth canal Congenital anomalies Scarring of the birth canal Pelvic masses Low-lying placenta

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Fetal malposition Occipitoanterior position 90% malposition 10% abnormal

cephalic posion 6-7% breech presentation 3-4% others

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Abnormalities of the passenger A. malposition and malpresentation a. vertex malposition persistent occiput posterior persistent occiput transverse 5% sincipital presentation 1.08% anterior asynclitism( 前不均 位 ) posterior asynclitism （ 后不均 位） 0.5%~0.81% b. brow presentation 0.03%~0.1% c. face presentation 0.08%~0.27% d. breech presentation 3%~4% e. abnormal fetal lie transverse or oblique lie 0.25% 23

Persistant occipitoposterior (transverse) position Causes  abnormal pelvis:transverse narrowing of the midpelvis  flexion not well  hypotonic uterine dysfunction

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Face presentation 27

Breech presentation Incidence  breech presentation is common remote from term.  3-4% of singleton deliveries

Position  LSA, LST LSP. RSA, RST, RAP

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Causes Uterine relaxation limited uterine cavity fetal head obstructed

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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

Breech presentation

complete(mixed) breech presentation frank breech presentation （伸腿臀先露） incomplete breech presentation knee or footling presentation differs in that one or both knees are flexed 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 30 lowermost in the birth canal

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 31

Effects Fetus     

PROM cord prolapse fetal distress even death newborn asphyxia brachial plexus injury 32

Extraction of breech

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Compound presentation 36

B. Fetal macrosomia large for gestational age(LGA) ≥400 0g shou lder dystosia

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C. Fetal malformation

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Operative delivery 1)forceps operations 2)Vacuum extractor

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2)Vacuum extractor

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3)Cesarean section

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Main point of dystocia managemnet

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思考题 : 1.The definition and classification of dystosia 2.How to deal with uterine inertia during the first stage of labor ?

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THANKS FOR YOUR ATTENTION

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