LABOURLABOURPRESENTEd by,SiNmayEE dEviaSST. PRof.(ob&G)l.j.m coN bbSR , odiSha

DEFINITIONDEFINITION

Series of events that take place in the Series of events that take place in the genital organs in an effort to expel the genital organs in an effort to expel the viable products of conception out of the viable products of conception out of the womb through the vagina into the outer womb through the vagina into the outer world is called LABOR.world is called LABOR.

Difference between Normal Labor and Difference between Normal Labor and Abnormal LaborAbnormal Labor

NORMAL NORMAL LABORLABOR Spontaneous in onset and at Spontaneous in onset and at

termterm With vertex presentationWith vertex presentation Without undue pronlongationWithout undue pronlongation Natural termination with Natural termination with

minimal aidsminimal aids Without having any Without having any

complications affecting the complications affecting the health of the mother and/or health of the mother and/or the baby. the baby.

ABNORMAL LABORABNORMAL LABOR Onset is pre or post term.Onset is pre or post term. Presentation other than Presentation other than

vertex or having some vertex or having some complications even with complications even with vertex presentation.vertex presentation.

Prolongation in labor.Prolongation in labor. Modification in the nature Modification in the nature

of terminationof termination Adversely affecting the Adversely affecting the

maternal and/or fetal maternal and/or fetal prognosis.prognosis.

FEATURES OF LABOR PAINFEATURES OF LABOR PAIN

TRUE LABOR PAINTRUE LABOR PAIN

Painful uterine contraction Painful uterine contraction at regular intervalat regular interval

Contraction with increasing Contraction with increasing intensity and durationintensity and duration

Show (expulsion of cervical Show (expulsion of cervical mucus plug, mixed with mucus plug, mixed with blood)blood)

Progressive effacement Progressive effacement and dilatation of the cervixand dilatation of the cervix

Formation of “bag of water”Formation of “bag of water”

FALSE LABOR PAINFALSE LABOR PAIN

Pain is dull in nature and Pain is dull in nature and usually confined to the usually confined to the lower abdomen and groinlower abdomen and groin

Continuous and unrelated Continuous and unrelated with hardening of the with hardening of the uterusuterus

No effect on dilatation of No effect on dilatation of the cervix.the cervix.

Unusually relieved by Unusually relieved by enema and administration enema and administration of a sedative.of a sedative.

STAGES OF LABORSTAGES OF LABOR FIRST STAGE FIRST STAGE – – It starts from the onset of true It starts from the onset of true

labour pain and ends with full dilatation of the cervix. labour pain and ends with full dilatation of the cervix. Its average duration is 12 hrs in primigravidae and 6 Its average duration is 12 hrs in primigravidae and 6 hrs in multiparae.hrs in multiparae.

SECOND STAGE SECOND STAGE - - It starts from the full It starts from the full dilatation of the cervix and ends with expusion of the dilatation of the cervix and ends with expusion of the fetus from the birth canal. Its average duration is 2 fetus from the birth canal. Its average duration is 2 hrs in primigravidae and 30 min in multiparae.hrs in primigravidae and 30 min in multiparae.

THIRD STAGE THIRD STAGE – – It begins after expulsion of the It begins after expulsion of the fetus and ends with expusion of the placents and fetus and ends with expusion of the placents and membranes. Its average duration is about 15 min in membranes. Its average duration is about 15 min in both primi gravidae and multiparae.both primi gravidae and multiparae.

PHYSIOLOGY OF FIRST PHYSIOLOGY OF FIRST STAGE OF LABORSTAGE OF LABOR

Phases of the first stagePhases of the first stage Latent phaseLatent phase: started when the cervix dilatated : started when the cervix dilatated

slowly and reached to about 3cm.slowly and reached to about 3cm.A.A. in primigravida = 8hin primigravida = 8hB.B. in multigravida = 4hin multigravida = 4h

Active phase: Active phase: rapid dilatation of the cervix to rapid dilatation of the cervix to reach 10cm reach 10cm

A.A. in primigravda = 4hin primigravda = 4hB.B. in multigravida =2h in multigravida =2h

The active phase is divided into:The active phase is divided into:1.1. Accelerative phaseAccelerative phase2.2. Slopping phaseSlopping phase3.3. Decelerative:Decelerative:

PROCESS OF LABORPROCESS OF LABOR

I. UTERINE ACTIONI. UTERINE ACTION

i . Fundal Dominancei. Fundal DominanceEach uterine contraction starts in Each uterine contraction starts in

the fundus near one cornua and the fundus near one cornua and spreads across and downwards. The spreads across and downwards. The contraction lasts longest in the fundus contraction lasts longest in the fundus where it is also more intense, but peak where it is also more intense, but peak is reached simultaneously over the is reached simultaneously over the whole uterus and the contraction fades whole uterus and the contraction fades from all parts together. This pattern from all parts together. This pattern permits the cervix to dilate and the permits the cervix to dilate and the strongly contracting fundus to expel strongly contracting fundus to expel the fetus.the fetus.

ii. Polarityii. Polarity

There is some co ordination between There is some co ordination between fundal contraction and cervical dilatation fundal contraction and cervical dilatation called called “polarity of uterus”“polarity of uterus” . During each . During each uterine contraction these two poles act uterine contraction these two poles act harmoniously. The upper pole contracts harmoniously. The upper pole contracts strongly and retracts to expel the fetus, the strongly and retracts to expel the fetus, the lower pole contracts slightly and dilates to lower pole contracts slightly and dilates to allow expulsion to take place. allow expulsion to take place.

iii. Uterine Contraction and Retractioniii. Uterine Contraction and Retraction

Uterine muscle has a unique property. During Uterine muscle has a unique property. During labour the contraction does not pass off entirely, but labour the contraction does not pass off entirely, but muscle fibres retain some of the shortening of muscle fibres retain some of the shortening of contraction instead of becoming completely relaxed contraction instead of becoming completely relaxed this is called this is called retractionretraction . It assist in progressive . It assist in progressive expulsion of the fetus, the upper segment of the expulsion of the fetus, the upper segment of the uterus becomes gradually shorter and thicker and its uterus becomes gradually shorter and thicker and its cavity diminishes. cavity diminishes.

At the beginning of first stage, the uterine At the beginning of first stage, the uterine contraction may occur every 15 – 20 minutes and contraction may occur every 15 – 20 minutes and last for 30 sec. By the end of first stage they occur at last for 30 sec. By the end of first stage they occur at 2 – 3 min and last for 50 – 60 sec and are very 2 – 3 min and last for 50 – 60 sec and are very powerful.powerful.

iv. Formation of upper and lower uterine iv. Formation of upper and lower uterine segmentsegment

During labour, the uterus is divided in two During labour, the uterus is divided in two parts. The upper uterine segment, having parts. The upper uterine segment, having been formed from the body of the fundus, been formed from the body of the fundus, which is only concerned for contraction and which is only concerned for contraction and retraction; it is thick and muscular.retraction; it is thick and muscular.

The lower uterine segment is formed of The lower uterine segment is formed of the isthmus and the cervix, and is about 8 – the isthmus and the cervix, and is about 8 – 10 cm in length. The lower segment is 10 cm in length. The lower segment is prepared for distension and dilatation. prepared for distension and dilatation.

v. The Retraction Ringv. The Retraction Ring

A ridge forms between the upper and A ridge forms between the upper and lower uterine segments is known as lower uterine segments is known as retraction ring or physiological ring.retraction ring or physiological ring.

The physiological ring gradually rises as The physiological ring gradually rises as the upper uterine segment contracts and the upper uterine segment contracts and retracts and the lower segment thins out to retracts and the lower segment thins out to accommodate the descending fetus. Once accommodate the descending fetus. Once the cervix is fully dilated and the fetus can the cervix is fully dilated and the fetus can leave the uterus, the retraction ring rises no leave the uterus, the retraction ring rises no further.further.

Sequence of development of segment & ring Sequence of development of segment & ring in uterus in pregnancy women at term & in in uterus in pregnancy women at term & in

laborlabor

vi. Cervical Effacementvi. Cervical Effacement

Effacement is the process by which the Effacement is the process by which the muscular fibers of the cervix are pulled muscular fibers of the cervix are pulled upward and merges with the fibers of the upward and merges with the fibers of the lower uterine segment. It is determined by lower uterine segment. It is determined by the length of the cervical canal in the the length of the cervical canal in the vagina.vagina.

In nulliparous woman the cervix will not In nulliparous woman the cervix will not dilate untill it is fully effaced, where as in dilate untill it is fully effaced, where as in parous woman effacement and dilatation parous woman effacement and dilatation occur simultaneously. It is expressed in occur simultaneously. It is expressed in terms of percentage. terms of percentage.

Cervix near end of pregnancy before labor

Beginning effacement of Cervix

Cervical canal obliterated

Further effacement of Cervix

vii. Cervical Dilatationvii. Cervical Dilatation

Dilatation of the cervix is the process of Dilatation of the cervix is the process of enlargement of the os uteri from a tightly enlargement of the os uteri from a tightly closed aperture to an opening large closed aperture to an opening large enough to permit passage of the fetal enough to permit passage of the fetal head. It is measured in centimeters and head. It is measured in centimeters and full dilatation is equate to about 10 cm.full dilatation is equate to about 10 cm.

CERVICAL EFFACEMENT AND CERVICAL EFFACEMENT AND DILATATION DURING LABORDILATATION DURING LABOR

II. MECHANICAL FACTORII. MECHANICAL FACTORi . Formation of fore wateri. Formation of fore water

As the lower uterine segment forms As the lower uterine segment forms and stretches, the chorion become and stretches, the chorion become detached from it and the increased detached from it and the increased intrauterine pressure causes this intrauterine pressure causes this loosened part of the sac of f luid to bulge loosened part of the sac of f luid to bulge downward into the internal so, to the downward into the internal so, to the depth of 6 – 12 mm. The well f lexed head depth of 6 – 12 mm. The well f lexed head fits into the cervix and cutt off the f luid in f its into the cervix and cutt off the f luid in front of the head from that which front of the head from that which surrounds the body. The former is know surrounds the body. The former is know as forewater and later is known as as forewater and later is known as hindwater.hindwater.

The effect of separation of the forewater The effect of separation of the forewater prevents the pressure that is applied to the prevents the pressure that is applied to the hind waters during uterine contraction from hind waters during uterine contraction from being applied to the forewater. This helps being applied to the forewater. This helps to keep the membrane intact and prevent to keep the membrane intact and prevent from natural infection.from natural infection.

FORMATION OF FORE WATER AND HIND WATER

ii. General Fluid Pressureii. General Fluid PressureWhile the membrane remain intact, the While the membrane remain intact, the pressure of the uterine contractions is pressure of the uterine contractions is exerted on the fluid and as fluid is not exerted on the fluid and as fluid is not compressible, the pressure is equalized compressible, the pressure is equalized throughout the uterus and over the fetal throughout the uterus and over the fetal body , it is known as body , it is known as general f luid general f luid pressure.pressure.

iii. Rupture of the membraneiii. Rupture of the membraneThe optimum physiological time for the The optimum physiological time for the

membranes to rupture spontaneously is at membranes to rupture spontaneously is at the end of the first stage of labour after the the end of the first stage of labour after the cervix becomes fully dilated.cervix becomes fully dilated.

With the rupture of membrane, variable With the rupture of membrane, variable amount of liquor escape out through the amount of liquor escape out through the vagina and often there is acceleration of vagina and often there is acceleration of uterine contraction uterine contraction

iv. Fetal axis pressureiv. Fetal axis pressureDuring each contraction the uterus During each contraction the uterus

rises forward and the force of the fundal rises forward and the force of the fundal contraction is transmitted to the upper pole contraction is transmitted to the upper pole of the fetus, down the long axis of the of the fetus, down the long axis of the fetus and applied by the presenting part to fetus and applied by the presenting part to the cervix. This is known as the cervix. This is known as fetal axis fetal axis pressure pressure and becomes much more and becomes much more significant after rupture of the membrane significant after rupture of the membrane and during second stage of labour.and during second stage of labour.

Fundal height Fundal height

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First Leopold Second Leopold

Third Leopold Fourth Leopold