Tag: Stages of Normal Labour

Stages of Normal Labour

Stages of Normal Labour


INTRODUCTION:

  • PARTURITION is defined as the process of bringing forth of young which comprises of multiple transformations in both uterine and cervical functions

There are four phases :

  • Quiescence
  • Activation phase
  • Stimulation phase
  • Involution phase

FIRST STAGE OF LABOUR:

Following are the major events during labour:

  • Gradually increasing uterine contractions
  • Retraction
  • Dilatation of cervix
  • Effacement of cervix
  • Lower uterine segment formation

DILATATION OF THE CERVIX:

  • Structural components of the cervix
  • Smooth muscle (5–20%)
  • Collagen 
  • Ground substance.

Predisposing factors:

  • Softening of cervix
  • Fibromusculoglandular hypertrophy
  • Increased vascularity
  • Accumulation of fluid in between collagen fibers
  • Breaking down of collagen fibrils by enzymes collagenase and elastase
  • Change in GAGs

FACTOR RESPONSIBLE:

Uterine contraction and retraction:

  • Polarity of uterus i.e. co-ordination between fundal contraction and cervical dilatation.
  • Upper segment contracts→ lower segment and cervix dilate

Fetal axis pressure:

  • Contractions of the circular muscle of uterus→fetal podalic pole→vertebral column→well-fitted fetal head→stretching of lower segment →dilatation of  cervix

Bag of membranes:

  • Uterine contractions→ hydrostatic pressure in forewaters→dilatation of  cervix

Vis-a-tergo:

  • Downward thrust of the presenting part of the fetus and upward pull of the cervix over the lower segment

EFFACEMENT:

  • Muscles of cervix are pulled upward and merges with lower uterine segment.
  • Primigravidae:effacement precedes  cervix dilatation
  • Multiparae:effacement & cervix dilatation occurs simultaneously
  • Lead to expulsion of mucus plug

LOWER UTERINE SEGMENT:

Anatomical Features :

  • Developed from the isthmus of uterus

Boundries:

  • Above:Physiological retraction ring(in labor)
  • Below:Fibromuscular junction of cervix and uterus(in labor)
  • Anteriorly:peritoneum
  • Size and Shape:7.5–10 cm,cylindrical 
  • Poor retractile property

Thining of wall:

  • Relaxation of muscle fibers to allow elongation
  • Contraction and retraction during labor
  • Descent of the presenting part

Clinical Significance:

  • Receptive relaxation→ formation of complete birth canal along with fully dilated cervix→expulsion of the fetus
  • Through this segment cesarean section is done
  • Implantation of placenta in lower segment 
  • Poor decidual reaction in this segment facilitates morbid adherent placenta
  • Obstructed labor, the lower segment is very much stretched and thinned out and ruptures
  • Postpartum hemorrhage if placenta is implanted over

EVENTS IN SECOND STAGE OF LABOR:

2 stages:

  • Propulsive: From full dilatation until head touches the pelvic floor
  • Expulsive:Since the time mother has irresistible desire to “bear down” and push until the baby is delivered.
  • Latent phase of labour is followed by Accelerated phase

MECHANISM:

Full dilatation of the cervix          Stronger uterine contraction and retraction
            ↓                                                       ↓
Membranes ruptures                       Contractions of the circular muscle fibers  
            ↓                                                       ↓
↓volume of uterine cavity                 Uterus elongate during contraction
                                                                     ↓
                                                     ↓anteroposterior and transverse diameters

FORCES:

  • Downward:By uterine contractions supplemented by voluntary contraction of abdominal muscles
  • Upward:Elastic recoil of the tissue of the vagina ,pelvic floor, bony and soft tissues of birth canal.
  • Counterbalanced by the power of retraction.
  • Increasing contraction and retraction, the upper segment becomes more  thicker with thinning of lower segment.
  • The expulsive force of uterine contractions is added by voluntary contraction of the abdominal muscles  called “bearing down” efforts.

EVENTS IN THIRD STAGE OF LABOR:

  • Birth of infant to delivery of placenta is 3rd stage of labour.
  • Placental separation
  • Placental Descent to the lower segment
  • Placental Expulsion with the membranes

PLACENTAL SEPERATION:

  • Retraction→ ↓surface area at placental site to its half→ buckling
  • Shearing force between placenta and the placental site which brings ultimate separation

  • Two ways of separation
  • Central separation (Schultz):Detachment starts at center leads to retroplacental hematoma
  • Marginal separation (Mathews-Duncan):starts at the margin & more frequently.

SEPARATION OF THE MEMBRANES:

  • Loosely attached  membranes(to active part) thrown into multiple folds
  • Attached to the lower segment are already separated during its stretching.
  • separation is by uterine contraction and weight of the placenta

EXPULSION OF PLACENTA:

  • Contraction and retraction of uterus→ forced down placenta to flabby lower uterine segment or upper part of the vagina
  • Voluntary contraction of abdominal muscles (bearing down efforts) or by manual procedure expelles placenta out.
  • CCF is most likely in pregnancy at 3rd stage of labour
  • Pressure inside uterus in 3rd stage is  100-120 mm Hg.
Exam Question
 
  • Latent phase of labour is followed by Accelerated phase
  • CCF is most likely in pregnancy at 3rd stage of labour
  • Second stage of labor starts from Full dilatation of cervix
  • Expulsion of the fetus, Increase in contraction & Cervical dilatation are  seen in 2nd stage of labor
  • From full dilatation of cervix to complete birth of baby is 2nd stage
  • Birth of infant to delivery of placenta is 3rd stage of labour.
  • Pressure inside uterus in 3rd stage is  100-120 mm Hg.
Don’t Forget to Solve all the previous Year Question asked on Stages of Normal Labour

Stages of Normal Labour

Stages of Normal Labour

Q. 1

Latent phase of labour is followed by :

 A

Accelerated phase

 B

Phase of maximum slope

 C

Deceleration phase

 D

2nd stage of labour

Q. 1

Latent phase of labour is followed by :

 A

Accelerated phase

 B

Phase of maximum slope

 C

Deceleration phase

 D

2nd stage of labour

Ans. A

Explanation:

Accelerated phase


Q. 2

CCF is most likely in pregnancy at :

 A

32 weeks

 B

1st stage of labour

 C

2nd stage of labour

 D

3rd stage of labour

Q. 2

CCF is most likely in pregnancy at :

 A

32 weeks

 B

1st stage of labour

 C

2nd stage of labour

 D

3rd stage of labour

Ans. D

Explanation:

3rd stage of labour


Q. 3

Second stage of labor starts from:

March 2013

 A

Rupture of membranes

 B

3/5 dilatation of cervix

 C

Full dilatation of cervix

 D

Crowning of head

Q. 3

Second stage of labor starts from:

March 2013

 A

Rupture of membranes

 B

3/5 dilatation of cervix

 C

Full dilatation of cervix

 D

Crowning of head

Ans. C

Explanation:

Ans. C i.e. Full dilatation of cervix

Stages of labor

  • 1st stage: Onset of labor to dilatation of cervix

– 6-20 hours in primigravida

– 2-10 hours in multigravida

  • 2nd stage: From full dilatation of cervix to complete birth of baby
  • 3rd stage: Birth of infant to delivery of placenta

Q. 4

Which of the following is seen in 2nd stage of labor:

September 2005

 A

Expulsion of the fetus

 B

Increase in contraction

 C

Cervical dilatation

 D

All of the above

Q. 4

Which of the following is seen in 2nd stage of labor:

September 2005

 A

Expulsion of the fetus

 B

Increase in contraction

 C

Cervical dilatation

 D

All of the above

Ans. D

Explanation:

Ans. D: All of the above

Second stage (expulsion) begins when the cervix is fully dilated, and ends when the baby is finally born.

At the beginning of the normal second stage, the head is fully engaged in the pelvis; the widest diameter of the head has successfully passed through the pelvic brim. Ideally it has successfully also passed below the interspinous diameter. This is the narrowest part of the pelvis.

The volume of the uterine cavity is reduced and uterine contractions and retraction becomes stronger.


Q. 5

From full dilatation of cervix to complete birth of baby is?

 A

1st stage

 B

2nd stage

 C

3rd stage

 D

4th stage

Q. 5

From full dilatation of cervix to complete birth of baby is?

 A

1st stage

 B

2nd stage

 C

3rd stage

 D

4th stage

Ans. B

Explanation:

2nd stage.


Q. 6

Birth of infant to delivery of placenta is?

 A

1st stage

 B

2nd stage

 C

3rd stage

 D

4th stage

Q. 6

Birth of infant to delivery of placenta is?

 A

1st stage

 B

2nd stage

 C

3rd stage

 D

4th stage

Ans. C

Explanation:

3rd stage of labour.


Q. 7

Stage of labor lasting from full dilatation of cervix to complete birth of baby is?

 A

1st stage

 B

2nd stage

 C

3rd stage

 D

4th stage

Q. 7

Stage of labor lasting from full dilatation of cervix to complete birth of baby is?

 A

1st stage

 B

2nd stage

 C

3rd stage

 D

4th stage

Ans. B

Explanation:

2nd stage.


Q. 8

Pressure inside the organ as “marked by a box” shown in the picture below in 3rd stage of labor is ? 

 A

30-40 mm Hg.

 B

40-60 mm Hg.

 C

80-100 mm Hg.

 D

100-120 mm Hg.

Q. 8

Pressure inside the organ as “marked by a box” shown in the picture below in 3rd stage of labor is ? 

 A

30-40 mm Hg.

 B

40-60 mm Hg.

 C

80-100 mm Hg.

 D

100-120 mm Hg.

Ans. D

Explanation:

The organ shown in the picture above represents uterus.

Pressure inside the uterus in 3rd stage of labor is about 100-120 mm Hg.


Q. 9

 Stage of labour process shown in the Photograph is 

 A

First stage Latent phase

 B

 First stage Active phase 

 C

Second stage 

 D

Third stage

Q. 9

 Stage of labour process shown in the Photograph is 

 A

First stage Latent phase

 B

 First stage Active phase 

 C

Second stage 

 D

Third stage

Ans. D

Explanation:

After expulsion of baby TILL complete expulsion of placenta & membranes

The period from just after the fetus is expelled until just after the placenta is expelled is called the third stage of labour or the involution stage. Placental expulsion begins as a physiological separation from the wall of the uterus



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