Abnormal Delivery1

Abnormal delivery Liu Yuling 刘玉凌 Department Of Obstetrics & Gynecology Renmin Hospital Wuhan University Email: [email protected]

M.D.

DYSTOCIA  Definition ＆ Classification  Abnormal Patterns of Labor  Pathogenesis ＆ Treatment

Definition  Dystocia is defined as difficult labor  It may associated with various

abnormalities that prevent or deviate from the normal course of labor and delivery

These abnormalities are classified into 3 general categories that are often interrelated   

A contracted pelvis may increase the likelihood of fetal malpresentation Malpresentation or excessive fetal size may be related to ineffective uterine action Disproportion between pelvic architecture and the presenting part often accompanies uterine dysfunction

Classification I. II. III.

Abnormalities of the Powers Abnormalities of the Passage Abnormalities of the Passenger

Abnormalities of the Powers  Constitute uterine dystocia 

That is uterine activity that is in effective in eliciting the normal progress of labor

 Characteristic of ineffective uterine action   

Hypertonic activity Hypotonic activity Discoordinated uterine activity

 Lack of voluntary expulsive effort during the

second stage may also impede the normal course of delivery

Abnormalities of the Passage  Constitute pelvic dystocia

That is aberrations of pelvic architecture and its relationship to the presenting part  Be related to 

  

Size or configurational alterations of the bony pelvis Soft tissue abnormalities of the birth canal Reproductive tract masses or neoplasia Aberrant placental location

Abnormalities of the Passenger  Be known as fetal dystocia 

That is that are caused by abnormalities of the fetus.

 Common fetal abnormalities leading to

dystocia include    

Excessive fetal size Malposition Congenital anomalies Multiple gestation

Abnormal Patterns of Labor  Prolonged latent phase  Protraction disorders  

Protracted active-phase dilatation Protracted descent

 Arrest disorders    

Prolonged deceleration phase Secondary arrest of dilatation Arrest of descent Failure of descent

 Precipitate labor disorders

Abnormal Patterns of Labor

Labor Labor is a dynamic process characterized by uterine contraction that increase in regularity intensity duration to cause progressive dilatation and effacement of the cervix and permit descent of the fetus through the birth canal

Stages of labor  1st stage of labor

begin of contraction to full cervical dilatation  2nd stage of labor from full dilatation to the birth of the baby  3rd stage of labor the time from the birth of the baby to the expulsion of the placenta and membranes

Labor  Stage One

(Dilatation)  Stage Two (Expulsion)  Stage Three (Placental Stage)

Evaluate the progress of labor  Estimate of cervical dilatation  Estimate of descent of the fetal

presenting part

Pattern of Cervical Dilatation 2 phases of cervical dilatation  latent phase  

Begins with the onset of regular uterine contractions Extends to the beginning of the active phase of cervical dilatation(2cm )

 active phase

from a 2cm dilatation of the cervix until the point when the cervix is fully dilated (approximately 10 cm)  Acceleration phase  Phase of maximum slope  Deceleration phase

1st & 2nd stage of normal labor

Abnormal Patterns of Labor  Prolonged latent phase  Protraction disorders  

Protracted active-phase dilatation Protracted descent

 Arrest disorders    

Prolonged deceleration phase Secondary arrest of dilatation Arrest of descent Failure of descent

 Precipitate labor disorders

Prolonged latent phase

 The duration of the latent phase  

average 6.4 hours in nulliparas average 4.8 hours in multiparas

Definition  Prolonged Latent Phase 

The latent phase is abnormally prolonged It lasts more than 20 hours in nulliparas 14 hours in multiparas

Causes  Excessive sedation or sedation  

 

given before the end of the latent phase The use of conduction or general anesthesia before labor enters the active phase Labor that begins with an unfavorable or unripe cervix, ie, one that is long, closed, rigid, and thick ( a low Bishop score) Uterine dysfunction Fetoplevic disproportion

Treatment Treatment should acknowledge that  These patients tend to be physically exhausted and emotionally discouraged by their lack of progress  They are suffering from fluid and electrolyte imbalance

Prolonged Latent Phase

Treatment

Therapeutic Rest Regimen

Narcotic agent

Oxytocin Infusion

Hydration

Therapeutic Rest Regimen A regiment of rest is recommended in the absence of any risk factors    

Premature rupture of the membrane Amnionitis Pre-eclampsia eclampsia

Narcotic agent Purpose  to arrest uterine contractions temporarily  to provide from 6 to 12 hours of rest Methods  morphine sulfate given subcutaneously  given in doses large enough an initial dose of 8-12 mg (depending in the patient’s weight)  given and additional 4 mg of morphine  

no cervical changes have occurred if uterine contractions persist after 20 minutes

Oxytocin Infusion  Be recommended as the primary

treatment  Disadvantage 

Decrease the time available  To

correct fluid and electrolyte imbalances  To meet the patient’s psychological needs 

No opportunity to identify patients in false labor

Oxytocin Infusion  Advantage

To be treatment of choice if immediately delivery is required such as preeclampsia and amniotitis

Prognosis The prognosis for vaginal delivery after these therapeutic measures is excellent. 

Patients with a prolonged latent phase of labor who respond to rest can be expected to delivery vaginally in nearly all cases.



After abnormalities in the latent phase have been corrected, patients are not at any greater risk of developing subsequent labor disorders than the patients who have experienced a normal latent phase.

Abnormal Patterns of Labor  Prolonged latent phase  Protraction disorders  

Protracted active-phase dilatation Protracted descent

 Arrest disorders    

Prolonged deceleration phase Secondary arrest of dilatation Arrest of descent Failure of descent

 Precipitate labor disorders

Protraction disorders  Definition  Causes  Treatment  Prognosis

Definition  The protraction disorders are constituted

of  

Protracted active-phase dilatation Protracted descent of the fetus

 Common characteristics 



An abnormally slow rate for dilatation in the active phase A abnormally slow rate of descent

(cm/hr)

In nulliparas

In multiparas

Protracted dilatation

≤1.2

≤ 1.5

Protracted descent ≤ 1

≤

2

Causes  Fetopelvic disproportion 

This is encountered in about one-third of patients

 Minor malpositions (occiput posterior)  Improperly administered conduction anesthesia 

 

Epidural anesthesia administered above dermatome T10 or given before the onset of the active phase or in the presence of other inhibitory factors

 Excessive sedation  Pelvic tumors obstructing the birth canal

Treatment Evaluation of fetopelvic relationships Physical examination Possibly by x-ray examination

Fetoplevic disproportion is present

Fetoplevic disproportion is absence

Cesarean section

Conservative Management

Conservative Management  Supportive measure  Inhibitory factors should be avoided  Oxytocin infusion or other forms of

stimulation of labor

Supportive measure  Special attention should be paid to  

fluid and electrolyte balance the patients’ emotional and physical needs

 It is possible to enhance uterine

contractility, progression of dilatation may not improve

Inhibitory factors  Inhibitory factors should be avoided  

Administering excessive sedation Regional block anesthesia

Oxytocin  Patients experiencing protraction

disorders generally do not respond to oxytocin infusion or other forms of stimulation of labor if their contractions are already adequate  Other authorities recommend active intervention with oxytocin in nulliparas with protraction disorders, and equally successful outcomes are reported

Prognosis  Depends on the presence or absence

of fetopelvic disproportion

Prognosis  The prognosis for the fetus is closely

related to the quality of delivery 



These infants seem particularly sensitive to instrumental vaginal delivery The most crucial factor favoring a good outlook for the fetus  

Spontaneous vaginal delivery One achieved with minimal manipulation

Abnormal Patterns of Labor  Prolonged latent phase  Protraction disorders  

Protracted active-phase dilatation Protracted descent

 Arrest disorders    

Prolonged deceleration phase Secondary arrest of dilatation Arrest of descent Failure of descent

 Precipitate labor disorders

Arrest disorders  Definition  Causes  Treatment  Prognosis

Characters of Arrest Disorders Prolonged The deceleration phase lasts deceleration phase

Secondary arrest of dilatation

≥ 3 hours in nulliparas ≥ 1 hour in multiparas

No progressive cervical dilatation in the active phase of labor ≥ 2 hours

Arrest of descent Descent fails to progress

≥ 1 hour

Failure of descent Descent during fails to occur the deceleration phase of dilatation and during the second stage

Causative factors  About 50% patients demonstrate

fetopelvic disproportion  Various fetal malpositions    

Occiput posterior Occiput transverse Face brow

 Inappropriately administered anesthesia

or excessive sedation

Treatment Thorough evaluation of fetopelvic relationships

Fetoplevic disproportion exits

Fetoplevic disproportion is absence

Cesarean section

Oxytocin stimulation

Prognosis  A poor prognosis for vaginal delivery  Increased perinatal morbidity

Abnormal Patterns of Labor  Prolonged latent phase  Protraction disorders  

Protracted active-phase dilatation Protracted descent

 Arrest disorders    

Prolonged deceleration phase Secondary arrest of dilatation Arrest of descent Failure of descent

 Precipitate labor disorders

Precipitate labor disorders  Definition  Causes  Treatment  Prognosis

Definition In primigravidas In multigravidas

Precipitate dilatation

A maximum ≥ 5 cm/ h slope

≥ 10 cm/ h

Precipitate descent

Descent of the≥ 5 cm/ h fetal presenting part

≥ 10 cm/ h

Causes  Extremely strong uterine contraction 



Occasionally be associated with administration of oxytocin May accompany abruption placentae

 Low birth canal resistance

Treatment  oxytocin administration may be stopped  Decrease the uterine contractions   

Parenteral epinephrine Magnesium sulfate Various tocolytic agents

Prognosis Maternal complications  Postpartum hemorrhage  Uterine rupture or Lacerations of the birth canal  Antecedents of maternal amniotic fluid embolism

Perinatal mortality  Hypoxia  Possible intracranial hemorrhage  Unattended delivery

Abnormal labor pattern Labor pattern

Diagnostic criteria Nulliparas

Multiparas

> 20 hr

>14hr

< 1.2 cm/hr < 1.0 cm/hr

< 1.5 cm/hr < 2 cm/hr

> 3 hr > 2 hr > 1 hr No descent in deceleration phase or second stage

> 1 hr > 2 hr > 1 hr

Prolongation disorder (Prolonged latent phase) Protraction disorders 1. Protracted active phase dilatation 2. Protracted descent Arrest disorders 1.Prolonged deceleration phase 2. Secondary arrest of dilatation 3. Arrest of descent 4. Failure of descent

Precipitate labor disorders Precipitate dilatation Precipitate descent

≥ 5 cm/ h ≥ 5 cm/ h

≥ 10 cm/ h ≥ 10 cm/ h

Pathogenesis ＆ Treatment  Abnormalities of the Powers  Abnormalities of the Passage  Abnormalities of the Passenger

Abnormalities of the Powers

Normal Uterine Activity in Labor 

Fundal dominance 



The value of the intensity of contractions  



The relative intensity of contractions is greater in the fundus than in the midportion or lower uterine segment The average value of the intensity of contractions is more than 24 mmHg In the active phase of labor. Pressures often increase to 40 – 60 mmHg

Contractions are well synchronized in different parts of the uterus

Normal Uterine Activity in Labor The basal resting pressure of the uterus is between 12 and 15 mmHg  The frequency of contractions progresses from 1 every 3 – 5 minutes to 1 every 2 – 3 minutes during the active phase  The duration of effective contraction in active labor approaches 60 seconds  The rhythm and force of contractions areregular 

Abnormalities of the Powers  Abnormal Uterine Activity  

Hypotonic dysfunction Hypertonic and uncoordinated dysfunction

 Inadequate Expulsive Efforts

Hypotonic dysfunction  Uterine activity characterized by 



contraction of the uterus with insufficient force (<24 mmHg) irregular of in frequent rhythm or both

Causative factors  Excessive sedation  Early administration of conduction

anesthesia  Twins  Polyhydramnios  Overdistention of the uterus

Management  Rule out abnormalities of the passage

or passenger requiring cesarean section   

Physical examination Ultrasonography Sometimes x-ray

Oxytocin  Pure hypotonic patterns may be effectively

treated with oxytocin augmentation of labor 





Intravenous administration of a dilute oxytocin solution through an in fusion pump A used dilution is 10 U of oxytocin per liter of balanced salt solution. The in vivo half-life of oxytocin is about 5 minutes.

Oxytocin 





With intravenous administration, a steadystate plasma level is achieved 40-60 minutes The response of each patient to a given dosage is unpredictable and must be titrated Overzealous administration may lead to hypertonic uterine action, precipitate labor, fetal distress or hypoxia, or uterine rupture

Protocols for administration of oxytocin  A starting dose of 1 -2 mU/min  Increasing in fractional fashion every 15

minutes to achieve the desired response

Seitchik and Castillo(1983) recommend a lower dosage of oxytocin and report similar efficacy  starting doses of 1 mU/min  be increased at intervals of not less than 30 minutes  satisfactory cervical dilatation in more than 90% of patients at dosage of 4 mU/min or less  with fewer adjustments for hypertonic patterns of fetal distress

Hypertonic and uncoordinated dysfunction  Be less common than hypotonic

dysfunction  Often occur together  Be characterized by  



elevated resting tone of the uterus dyssynchronous contractions with elevated tone in the lower uterine segment frequent intense uterine contractions

Causative factors  abruptio placentae  overzealous use of oxytocin  cephalopelvic disproportion  fetal malpresentation  the latent phase of labor

Manifestation  Constant pain when the resting tone

of the uterus is 25 mmHg or more  The uterus is generally painful to palpation  A constriction ring may develop at the level of the isthmus and further obstruct the progress of labor

Treatment  Oxytocin administration is generally

of no value  Sedation is generally effective in converting hypertonic contraction normal labor patterns

Prognosis  Precipitate labor disorders  Fetal intracranial hemorrhage  Fetal distress  Neonatal injury or depression  Birth vaginal lacerations from rapid

deliver

Inadequate Expulsive Efforts  Inadequate pushing in the second stage

of labor is common

Causative factors  conduction anesthesia  oversedation  exhaustion  neurologic dysfunction such as

paraplegia or hemiplegia of various causes  psychiatric disorders

Treatment  Mild sedation or a waiting period to

permit analgesic or anesthetic agent to wear off may improve expulsive effort.  Outlet forceps delivery may be affected in selected cases.

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