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ABNORMAL LABOUR
DR. CHINTAMANI MOHANTA
ASSOCIATE PROF. (O&G)
PRMMCH, BARIPADA

OBJECTIVES
• Definitions of abnormal labour and it’s causes
• Abnormalities of various Stages(1st & 2nd ) and Phases(Latent/Active)
of Labour
• Uterine dysfunction and its various types (Hypotonic/Hypertonic)
• What is Cephalo Pelvic Disproportion(CPD)
• Risk factors for poor progress of labour
• Dystocia due to pelvic contraction (Inlet/Midpelvis/Outlet)
• Various methods of estimation of pelvic adequacy
• Fetal and Maternal effect of abnormal Labour

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

Dystocia = Causes
Dystocia: Literally, difficult labour
Characterized by abnormally slow progress of labour.
Causes: 4 distinct abnormalities that may exist singly or in combination
• 1. Abnormalities of the Uterine Expulsive forces
• either uterine force insufficiently strong or in appropriately co ordinated to efface or dilate the
cervix (UTERINE DYSFUNCTION)
• Inadequate voluntary muscle effort during the second stage of labour
• 2. Abnormalities of presentation, position , or development of fetus
• 3. Abnormalities of the maternal bony pelvis (i.e. pelvic contraction)
• 4. Abnormalities of birth canal other than the bony pelvis that form an obstacle to the fetal descend.

UTERINE DYSFUCTION
Uterine dysfunction is common whenever there is disproportion between the
presenting part of the fetus and the birth canal
NORMAL LBOUR usually divided into:
1: Latent phase- usually little
cervical dilatation but
considerable changes taken place
in the connective tissue
components of the cervix
2: Active phase- Friedman
subdivided the active phase into
• acceleration phase,
• phase of maximum slope and
• the deceleration phase.

Latent phase
Friedman defined it as the point at which the mother perceives regular uterine contraction
along with cervical softening and dilatation with effacement and ends at between 3 and 5 of
dilatation.
Prolonged latent phase:
• Defined (1963) by Friedman and Sachteben to be greater than 20 hours in the nullipara and 14 hours in paras woman (95th
percentile)
Factors that affect the duration of the latent phase include:
• 1- Excessive sedation : conduction analgesia.
• 2- Poor cervical conduction eg. Thick, uneffaced or undilated)
• 3- False labour

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

Active labour :
• It begins when the cervix is 3 to 4 cm dilated.
• * active phase abnormalities are the most common abnormalities of labour about 25% of nullipara and 15%
of multipara.
• * Friedman subdivided active phase problems into protraction and arrest disorders.
• * Protraction defined as a slow rate of cervical dilatation or desent.
• i.e < 1.2 cm dilatation / hour or < 1 cm / hour for nullipara or < 1.5 cm / hour or < 2 cm / hour for multipara.
• * Arrest of dilatation defined as 2 hr with no cervical change or arrest of descent as 1 hour without fetal
descent.

Factors contributing to both protraction and arrest disorders were :
• 1 – Excessive sedation.
• 2 – Conduction analgesia.
• 3 – Fetal malposition eg. Persistant occipito – posterior.
• In both protraction and arrest disorders, fetopelvic examination done to diagnose CPD.
• Recommended therapy for protraction disorder was expectant management, whereas oxytocin was advised
for arrest disorders in the absence of CPD.

Second stage of labour :
• The second stage of labour begin when cervical dilatation is complete and ends with fetal expulsion. It needs
duration 50 min for nullipara and 20 min for multipara. But it is also highly viable.
• the length of the second stage of labour in nullipara was limited to 2 hours and extended to 3 hours when
regional analgesia was used. For multipara 1 hour was the limit extended to 2 hours with regional analgesia.

Uterine dysfunction
• This is the most common cause of poor progress in labour. Uterine dysfunction in any phase of cervical
dilatation is characterized by lack of progress, for one of the prime characteristic of normal labour is its
progression. However, one of the most common error is to treat women for uterine dysfunction who are not
yet in active labour. It is more common in primigravida and in older women. There have been 3 significant
advances in the treatment of uterine dysfunction :
• 1 – realization that undue prolongation of labour may contribute to perinatal morbidity and mortality.
• 2 – Use of dilute intravenous infusion of oxytocin in the treatment of certain types of uterine dysfunction.
• 3 – More frequently use of cesarean section delivery rather than difficult midforceps delivery when oxytocin
fail or its use is inappropriate.

• Assessment of uterine contraction most commonly carried out By clinical examination and by using external
uterine tocography, but this only provide informations about the frequency and duration of uterine
contraction. Intrauterine pressure catheters are available and these give accurate measurement of the
pressure generated by the contraction but these rarely necessary.
• A frequency of 4 – 5 contractions per 10 minutes is usually considered ideal.

Types of uterine contractions :
• Uterine contractions of normal labour are charecterized by gradient of myometrial activity being greater and
lasting longer at the fundus ( fundal dominant ) and diminished towards the cervix.
• Usually the exciting stimulus starts in one cornue and then several milliseconds later in the other. The
excitation waves then join and sweeping over the fundus and down the uterus.
• * Normal spontaneous contractions often exert pressures of about 60 mm Hg.

There are 3 types of uterine dysfunction :
• 1 – Hypotonic uterine dysfunction :
• No basal hypertonus and uterine contraction is have a normal gradient pattern ( synchronus ) but the slight
rise in pressure during a contraction is insufficient to dilate the cervix.
• Treatment :
• 1 – Matrenal rehydration.
• 2 – ARM.
• 3 – IV oxytocin ( syntocinon )

• 2 – Hypertonic uterine dysfunction :
• Either basal tone is elevated appreciably or pressure gradient is distorted, perhaps by contraction of the mid
– segment of the uterus with more force than the fundus.
• 3 – Incoordinated uterine dysfunction :
• complete asynchronism of the impulses originating in each cornue.
• Sometimes combination of the last 2 types.
• Treatment :
• Sometimes oxytocin effective in coordinating these contractions.

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

* Cephalopelvic disproportion ( CPD ) :
• Describe abnormal labour due to disparity between the dimensions of the fetal 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.
Originally describe for overt pelvic contracture due to rickets, however now such true CPD is rare and most
disproportions are due to malpositions of the fetal head- asynchtisim or extension of the bony diameters of
the fetal head, or to ineffective uterine contraction.

• Women of small stature ( < 1
• Women of small stature ( < 1.60 m ) with a big baby in their first pregnancy are candidate to develop this
abnormality. Sometimes the pelvis is unusually small due to previous fractures or metabolic bone disease.
• CPD is suspected if there is :
• 1 – Progress is slow or arrest despite efficient uterine contraction.
• 2 – The fetal head is not engaged.
• 3 – Vaginal examination shows severe moulding and caput formation.
• The head is poorly applied to the cervix.

Risk factors for poor progress in labour :
• 1 – Small women.
• 2 – Big baby.
• 3 – Malpresentation.
• 4 – Malposition.
• 5 – Early rupture of membrane.
• 6 – Soft tissue / pelvic malformation.
• Failure to progress, this term used to indicate lack of progressive cervical dilatation or lack of descent. So it is
an observation rather than a diagnosis.

Dystocia due to pelvic contraction :
• Any contraction of the pelvic diameters that diminishes the capacity of the pelvic can create dystocia during
labour. Pelvic contractions may be classified as follows :
• 1 – Contraction of the pelvic inlet.
• 2 – Contraction of the mid pelvis.
• 3 – Contraction of the pelvic outlet.
• 4 – Generally contracted pelvis ( Combination of the above ).

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