Abnormal labourAbnormal labour

ObjectivesObjectivesAt the completion of this presentation, the participant should At the completion of this presentation, the participant should knowknow::

11 – – Definition of abnormal labour and its causesDefinition of abnormal labour and its causes..22 – – Abnormalities of the various stages( first and second) and Abnormalities of the various stages( first and second) and

phases of labour ( latent and active phase)phases of labour ( latent and active phase)..33 – – Uterine dysfunction and its various types (hypertonic, Uterine dysfunction and its various types (hypertonic,

hypotonic ,ect)hypotonic ,ect)44 – – What is cephalopelvic disproportion(CPD)What is cephalopelvic disproportion(CPD)..

55 – – Risk factors for poor progress in labourRisk factors for poor progress in labour..66 – – Dystocia due to pelvic contraction(inlet midpelvis and outlet)Dystocia due to pelvic contraction(inlet midpelvis and outlet)..

77 – – Various methods of estimation of pelvic capacityVarious methods of estimation of pelvic capacity..88 – – Fetal and maternal effect of abnormal labourFetal and maternal effect of abnormal labour..

DystociaDystocia Dystocia : Literally , difficult labour. Characterized by Dystocia : Literally , difficult labour. Characterized by

abnormally slow progress of labour.abnormally slow progress of labour.

Labour become abnormal when there is poor progress ( as Labour become abnormal when there is poor progress ( as evidenced by a delay in cervical dilatation or descent of The evidenced by a delay in cervical dilatation or descent of The presenting part, and / or the fetus shows signs of presenting part, and / or the fetus shows signs of compromise ,similarly by definition, if there is compromise ,similarly by definition, if there is malpresentation ,a multiple gestation, a uterine scar ,or if malpresentation ,a multiple gestation, a uterine scar ,or if labour has been induced , can not be considered normal. labour has been induced , can not be considered normal.

Causes :Causes : 4 distinct abnormalities that may exist singly or in 4 distinct abnormalities that may exist singly or in combination.combination.

1 – 1 – Abnormalities of the expulsive forces (power) either uterine Abnormalities of the expulsive forces (power) either uterine force insufficiently strong or inappropriately coordinated to force insufficiently strong or inappropriately coordinated to efface or dilate the cervix. ( Uterine dysfunction ) , or efface or dilate the cervix. ( Uterine dysfunction ) , or inadequate voluntary muscle effort during the second stage of inadequate voluntary muscle effort during the second stage of labour.labour.

2 – 2 – Abnormalities of presentation, position, or development of Abnormalities of presentation, position, or development of the fetus( the passenger).the fetus( the passenger).

3 – 3 – Abnormalities of the maternal boney pelvis i.e pelvic Abnormalities of the maternal boney pelvis i.e pelvic contraction (passages).contraction (passages).

4 – 4 – Abnormalities of birth canal that form an obstacle to fetal Abnormalities of birth canal that form an obstacle to fetal descend (passages). descend (passages).

Normal labour usually divided into :Normal labour usually divided into :1 – 1 – Latent phase : usually little cervical dilatation but Latent phase : usually little cervical dilatation but

considerable changes taken place in the connective tissue considerable changes taken place in the connective tissue components of the cervix.components of the cervix.

2 – 2 – Active phase : Friedman subdivided the active phase into Active phase : Friedman subdivided the active phase into acceleration phase, phase of maximum slope and the acceleration phase, phase of maximum slope and the deceleration phase.deceleration phase.

Latent phase :Latent phase : Friedman defined it as the point at which the mother perceives regular Friedman defined it as the point at which the mother perceives regular

uterine contraction along with cervical softening and effacement and uterine contraction along with cervical softening and effacement and ends at 3 cm dilatation.ends at 3 cm dilatation.

Prolonged latent phase :Prolonged latent phase : Defined ( 1963 ) by Friedman and Sachtleben to be greater than 20 Defined ( 1963 ) by Friedman and Sachtleben to be greater than 20

hours in the nullipara and 14 hours in the paras women. These are the hours in the nullipara and 14 hours in the paras women. These are the 9595thth percentage. percentage.

Factors that affect the duration of the latent phase include :Factors that affect the duration of the latent phase include : 1 – 1 – Excessive sedation : conduction analgesia.Excessive sedation : conduction analgesia. 2 – 2 – Poor cervical conduction : ( eg. Thick , uneffaced or undilated )Poor cervical conduction : ( eg. Thick , uneffaced or undilated ) 3 – 3 – False labour. False labour.

Rest is preferable for correcting prolonged latent labour Rest is preferable for correcting prolonged latent labour because unrecognized false labour was common, with because unrecognized false labour was common, with strong sedation 85 % of females begin active labour and strong sedation 85 % of females begin active labour and 10 % cease contraction ( false labour ) and 5 % develop 10 % cease contraction ( false labour ) and 5 % develop recurrent abnormal latent labour and require oxytocin recurrent abnormal latent labour and require oxytocin stimulation. stimulation.

Active labour :Active labour : It beginsIt begins when the cervix is 3 cm dilated.when the cervix is 3 cm dilated. ** active phase abnormalities are the most common abnormalities active phase abnormalities are the most common abnormalities

of labour about 25% of nullipara and 15% of multipara.of labour about 25% of nullipara and 15% of multipara. * * Friedman subdivided active phase problems into Friedman subdivided active phase problems into protraction protraction

and arrest disorders. and arrest disorders. * Protraction defined as a slow rate of cervical dilatation or * Protraction defined as a slow rate of cervical dilatation or

desent. desent. i.e < 1.2 cm dilatation / hour or < 1 cm / hour for nullipara or < i.e < 1.2 cm dilatation / hour or < 1 cm / hour for nullipara or <

1.5 cm / hour or < 2 cm / hour for multipara.1.5 cm / hour or < 2 cm / hour for multipara. * Arrest of dilatation defined as 2 hr with no cervical change or * Arrest of dilatation defined as 2 hr with no cervical change or

arrest of descent as 1 hour without fetal descent.arrest of descent as 1 hour without fetal descent.

Factors contributing to both protraction and arrest Factors contributing to both protraction and arrest disorders were :disorders were :

1 – Excessive sedation.1 – Excessive sedation. 2 – Conduction analgesia.2 – Conduction analgesia. 3 – Fetal malposition eg. Persistant occipito – posterior.3 – Fetal malposition eg. Persistant occipito – posterior.

In both protraction and arrest disorders, fetopelvic In both protraction and arrest disorders, fetopelvic examination done to diagnose CPD.examination done to diagnose CPD.

Second stage of labour :Second stage of labour : ***The second stage of labour begin when cervical dilatation is ***The second stage of labour begin when cervical dilatation is

complete and ends with fetal expulsion. complete and ends with fetal expulsion. ***The length of the second stage of labour in nullipara was ***The length of the second stage of labour in nullipara was

limited to 2 hours and extended to 3 hours when regional limited to 2 hours and extended to 3 hours when regional analgesia was used. For multipara 1 hour was the limit analgesia was used. For multipara 1 hour was the limit extended to 2 hours with regional analgesia. extended to 2 hours with regional analgesia.

***The causes can be classified also as abnormalities of the ***The causes can be classified also as abnormalities of the powers, the passenger and the passages.powers, the passenger and the passages.

***Three options to treat :• Continued observation. • Attempt at operative vaginal delivery • Cesarean delivery

Uterine dysfunction :Uterine dysfunction : This is the most common cause of poor progress in This is the most common cause of poor progress in

labour. Uterine dysfunction in any phase of cervical labour. Uterine dysfunction in any phase of cervical dilatation is characterized by lack of progress, for one of dilatation is characterized by lack of progress, for one of the prime characteristic of normal labour is its the prime characteristic of normal labour is its progression. progression.

However, one of the most common error is to treat However, one of the most common error is to treat women for uterine dysfunction who are not yet in active women for uterine dysfunction who are not yet in active labour. labour.

It is more common in primigravida and in older women. It is more common in primigravida and in older women.

There have been 3 significant advances in the treatment of There have been 3 significant advances in the treatment of uterine dysfunction :uterine dysfunction :

1 – realization that undue prolongation of labour may 1 – realization that undue prolongation of labour may contribute to perinatal morbidity and mortality. contribute to perinatal morbidity and mortality.

2 – Use of dilute intravenous infusion of oxytocin in the 2 – Use of dilute intravenous infusion of oxytocin in the treatment of certain types of uterine dysfunction.treatment of certain types of uterine dysfunction.

3 – More frequently use of cesarean section delivery 3 – More frequently use of cesarean section delivery rather than difficult midforceps delivery when oxytocin rather than difficult midforceps delivery when oxytocin fail or its use is inappropriate. fail or its use is inappropriate.

****Assessment of uterine contraction most commonly carried out Assessment of uterine contraction most commonly carried out

By clinical examination and by using external uterine By clinical examination and by using external uterine tocography, but this only provide information about the tocography, but this only provide information about the frequency and duration of uterine contraction. frequency and duration of uterine contraction.

**Intrauterine pressure catheters are available and these give **Intrauterine pressure catheters are available and these give

accurate measurement of the pressure generated by the accurate measurement of the pressure generated by the contraction but these rarely necessary. contraction but these rarely necessary.

**A frequency of 4 – 5 contractions per 10 minutes is usually **A frequency of 4 – 5 contractions per 10 minutes is usually

considered ideal.considered ideal.

Types of uterine contractions :Types of uterine contractions : **Uterine contractions of normal labour are charecterized by **Uterine contractions of normal labour are charecterized by

gradient of myometrial activity being greater and lasting gradient of myometrial activity being greater and lasting longer at the fundus ( fundal dominant ) and diminished longer at the fundus ( fundal dominant ) and diminished towards the cervix.towards the cervix.

Usually the exciting stimulus starts in one cornue and then Usually the exciting stimulus starts in one cornue and then several milliseconds later in the other. The excitation waves several milliseconds later in the other. The excitation waves then join and sweeping over the fundus and down the uterus.then join and sweeping over the fundus and down the uterus.

** Normal spontaneous contractions often exert pressures of ** Normal spontaneous contractions often exert pressures of

about 60 mm Hg.about 60 mm Hg.

There are 3 types of uterine dysfunction :There are 3 types of uterine dysfunction :1 – 1 – Hypotonic uterine dysfunction :Hypotonic uterine dysfunction : No basal hypertonus and uterine contraction is have a normal No basal hypertonus and uterine contraction is have a normal

gradient pattern ( synchronus ) but the slight rise in pressure gradient pattern ( synchronus ) but the slight rise in pressure during a contraction is insufficient to dilate the cervix.during a contraction is insufficient to dilate the cervix.

Treatment : Treatment : 1 – Matrenal rehydration. 1 – Matrenal rehydration. 2 – ARM.2 – ARM. 3 – Good pain relief and emotional support.3 – Good pain relief and emotional support. 4 – IV oxytocin ( syntocinon ), continuous EFM is necessary. 4 – IV oxytocin ( syntocinon ), continuous EFM is necessary.

**If progress fails to occur despite 4-6 hour of agumentation with **If progress fails to occur despite 4-6 hour of agumentation with oxytocin, a C/S will usually be recommended.oxytocin, a C/S will usually be recommended.

2 –2 – Hypertonic uterine dysfunction : Hypertonic uterine dysfunction : Either basal tone is elevated appreciably or pressure gradient is Either basal tone is elevated appreciably or pressure gradient is

distorted, perhaps by contraction of the mid – segment of the distorted, perhaps by contraction of the mid – segment of the uterus with more force than the fundus. uterus with more force than the fundus.

3 – 3 – Incoordinated uterine dysfunction : Incoordinated uterine dysfunction : complete asynchronism of the impulses originating in each complete asynchronism of the impulses originating in each

cornue. cornue. Sometimes combination of the last 2 types. Sometimes combination of the last 2 types. Treatment :Treatment : Sometimes oxytocin effective in coordinating these contractions.Sometimes oxytocin effective in coordinating these contractions.

**Dystocia can result from several distinct abnormalities involving the **Dystocia can result from several distinct abnormalities involving the cervix, uterus,cervix, uterus, the fetusthe fetus ,,otherother obstruction in the birth canal or in the obstruction in the birth canal or in the maternal bony pelvis. Quit often combination of these interaction to maternal bony pelvis. Quit often combination of these interaction to produce dysfunction labour. Recently term such as cephalopelvic produce dysfunction labour. Recently term such as cephalopelvic disproportion and failure to progress are often used to describe these disproportion and failure to progress are often used to describe these dysfunctional labours when cesarean section delivery is necessory.dysfunctional labours when cesarean section delivery is necessory.

* *Cephalopelvic disproportion ( CPD ) :* *Cephalopelvic disproportion ( CPD ) : Abnormal labour due to disparity between the dimensions of the fetal Abnormal labour due to disparity between the dimensions of the fetal

head and maternal pelvis, as to preclude vaginal delivery. It can be head and maternal pelvis, as to preclude vaginal delivery. It can be due to a large head, small pelvis or a combination of the two. due to a large head, small pelvis or a combination of the two. Originally describe for overt pelvic contracture due to rickets, Originally describe for overt pelvic contracture due to rickets, however now such true CPD is rare and most disproportions are due however now such true CPD is rare and most disproportions are due to malpositions of the fetal head- asynchtisim or extension of the bony to malpositions of the fetal head- asynchtisim or extension of the bony diameters of the fetal head, or to ineffective uterine contraction. diameters of the fetal head, or to ineffective uterine contraction.

****Women of small stature ( < 1.60 m ) with a big baby in their first Women of small stature ( < 1.60 m ) with a big baby in their first

pregnancy are candidate to develop this abnormality. Sometimes pregnancy are candidate to develop this abnormality. Sometimes the pelvis is unusually small due to previous fractures or metabolic the pelvis is unusually small due to previous fractures or metabolic bone disease. Rarely a fetal anomaly may contribute to CPD as bone disease. Rarely a fetal anomaly may contribute to CPD as hydrocephaly, fetal thyroid and neck tumor. hydrocephaly, fetal thyroid and neck tumor.

CPD is suspected if there is :CPD is suspected if there is : 1 – Progress is slow or arrest despite efficient uterine 1 – Progress is slow or arrest despite efficient uterine

contraction. contraction. 2 – The fetal head is not engaged.2 – The fetal head is not engaged. 3 – Vaginal examination shows severe moulding and caput 3 – Vaginal examination shows severe moulding and caput

formation.formation. 4 – The head is poorly applied to the cervix. 4 – The head is poorly applied to the cervix.

Risk factors for poor progress in labour :Risk factors for poor progress in labour : 1 – Small women.1 – Small women. 2 – Big baby.2 – Big baby. 3 – Malpresentation.3 – Malpresentation. 4 – Malposition.4 – Malposition. 5 – Early rupture of membrane.5 – Early rupture of membrane. 6 – Soft tissue / pelvic malformation.6 – Soft tissue / pelvic malformation. 7 – Dysfunctional uterine activity.7 – Dysfunctional uterine activity.

Failure to progress, this term used to indicate lack of progressive Failure to progress, this term used to indicate lack of progressive cervical dilatation or lack of descent. So it is an observation cervical dilatation or lack of descent. So it is an observation rather than a diagnosis. rather than a diagnosis.

Dystocia due to pelvic contraction :Dystocia due to pelvic contraction : Any contraction of the pelvic diameters that diminishes the Any contraction of the pelvic diameters that diminishes the

capacity of the pelvic can create dystocia during labour. Pelvic capacity of the pelvic can create dystocia during labour. Pelvic contractions may be classified as follows :contractions may be classified as follows :

1 – Contraction of the pelvic inlet.1 – Contraction of the pelvic inlet. 2 – Contraction of the mid pelvis.2 – Contraction of the mid pelvis. 3 – Contraction of the pelvic outlet.3 – Contraction of the pelvic outlet. 4 – Generally contracted pelvis ( Combination of the above ).4 – Generally contracted pelvis ( Combination of the above ).

Abnormalties in the uterus and cervix can also delay labour. Abnormalties in the uterus and cervix can also delay labour. Unsuspected fibroid in the lower uterine segment can prevent Unsuspected fibroid in the lower uterine segment can prevent the descent of the fetal head.the descent of the fetal head.

**Delay can also be caused by “cervical dystocia” , a term used to describe a non- compliant cervix which effaces but fail to dilate because of severe scarring usually as a result of a

previous cone biopsy .

**It is rare for soft tissues of the pelvic floor to cause significant delay in labour .