Normal labour-Causes and Physiology

Normal labour-Causes and Physiology

Q. 1 Which  of  the  following  statements  about prostaglandins is true?
 A They are precursors to arachidonic acid
 B They release  arachidonic acid  from  membranes through the action of phospholipase A
 C They   were   first   observed   to   cause   uterine contraction and lowering of blood pressure
 D Although   found   in   many   organs,   they   are synthesized only in the prostate and seminal vesicles
Q. 1 Which  of  the  following  statements  about prostaglandins is true?
 A They are precursors to arachidonic acid
 B They release  arachidonic acid  from  membranes through the action of phospholipase A
 C They   were   first   observed   to   cause   uterine contraction and lowering of blood pressure
 D Although   found   in   many   organs,   they   are synthesized only in the prostate and seminal vesicles
Ans. C

Explanation:

Although prostaglandins were originally isolated from prostate glands, seminal vesicles, and semen,

their synthesis in other organs has been amply documented; indeed, few organs have failed to demonstrate prostaglandin release. Prostaglandins cause platelet aggregation, smooth-muscle contraction, vasodilation, and uterine contraction. Prostaglandins are synthesized from arachidonic acid, a 20-carbon fatty acid with interspersed carbon double bonds. Signals such as angiotensin II, bradykinin, epinephrine, and thrombin can activate phospholipase A2 and release arachidonic acid from membrane lipids. The arachidonic acid is cyclized by cyclooxygenase to form prostaglandins. Arachidonic acid can also be oxidized to leukotrienes by the action of lipoxygenases.


Q. 2

Braxton — Hicks contractions :

 A

Is a positive feedback system

 B

Is another terms for labor contraction

 C

Occur during most of the months of pregnancy

 D

Result in hypoxia of the fetus

Q. 2

Braxton — Hicks contractions :

 A

Is a positive feedback system

 B

Is another terms for labor contraction

 C

Occur during most of the months of pregnancy

 D

Result in hypoxia of the fetus

Ans. C

Explanation:

Occur during most of the months of pregnancy


Q. 3

True labour pain includes all except:

 A

Painful uterine contraction

 B

Short vagina

 C

Formation of the bag of waters

 D

Progressive descent of presenting part

Q. 3

True labour pain includes all except:

 A

Painful uterine contraction

 B

Short vagina

 C

Formation of the bag of waters

 D

Progressive descent of presenting part

Ans. B

Explanation:

Ans. is b i.e. Short vagina.

Differences between true and false labour pains.

Mtures

Cervical changes (dilatation & effacement) Frequency & duration of contractions Pain

Bag of water

Show

Relief with enema / sedation


True labour pains Present

Regular & gradually T

Lower abdomen & back, radiating to thighs

Formed Present No


False labour pains Absent

Irregular

Lower abdomen only

Not formed Absent

Yes


Q. 4

Average pressure of uterine contractions during the first stage of labour is :

 A

100 mm Hg

 B

15 mm Hg

 C

20 mm Hg

 D

30 mm Hg

Q. 4

Average pressure of uterine contractions during the first stage of labour is :

 A

100 mm Hg

 B

15 mm Hg

 C

20 mm Hg

 D

30 mm Hg

Ans. D

Explanation:

30 mm Hg


Q. 5

Engagement in primigravida occurs at :

 A

Beginning of labour

 B

36 weeks

 C

34 weeks

 D

Second stage of labour

Q. 5

Engagement in primigravida occurs at :

 A

Beginning of labour

 B

36 weeks

 C

34 weeks

 D

Second stage of labour

Ans. A

Explanation:

Beginning of labour


Q. 6

During uterine contraction of labour, the uterine blood flow :

 A

Decreases

 B

Increases

 C

Does not change

 D

Temporarily cases

Q. 6

During uterine contraction of labour, the uterine blood flow :

 A

Decreases

 B

Increases

 C

Does not change

 D

Temporarily cases

Ans. A

Explanation:

Decreases


Q. 7

True labour differs from false labour by all except:

 A

Absence of ‘bag of water’

 B

Painful uterine contractions

 C

Progressive effacement and dilatation of the cer­vix

 D

Pain often felt in front of the abdomen or radiat­ing towards the thighs

Q. 7

True labour differs from false labour by all except:

 A

Absence of ‘bag of water’

 B

Painful uterine contractions

 C

Progressive effacement and dilatation of the cer­vix

 D

Pain often felt in front of the abdomen or radiat­ing towards the thighs

Ans. A

Explanation:

Absence of ‘bag of water’


Q. 8

Pressure of normal uterine contractions is between 190-300. Units in terms of which units.

 A

Montevideo units

 B

Mm of Hg

 C

Cm of water

 D

Joulesikg

Q. 8

Pressure of normal uterine contractions is between 190-300. Units in terms of which units.

 A

Montevideo units

 B

Mm of Hg

 C

Cm of water

 D

Joulesikg

Ans. A

Explanation:

Ans. is a i.e. Montevideo units

Montevideo unit is to define uterine activity.

According to it, uterine performance is the product of the intensity – (increased uterine pressure above baseline tone of a contraction) in mm of Hg multiplied by contraction frequency per 10 minutes. For example 3 contrac­tions in 10 minutes, each of 50 mm of Hg intensity would be equal to 150 Montevideo units.

As per this:

Clinical labour usually commences when uterine activity reaches values between 80-120 Montevideo units. (This translates into approximate 3 contractions of 40 mm of Hg every 10 minutes)

During labour – Normal uterine contractions are between 190 – 300 Montevideo units (At the time of delivery it is 300 Montevideo units)

Extra Edge

  • Uerine contractions are clinically palpable only after their intensity exceeds > 10 mm of Hg

Uterine contractions are not associated with pain unless their intensity is > 15 mm of Hg.


Q. 9

A primigravida female at term presents to the clinic with labor pains. Which of the following is a sure sign of labour?

 A

Show

 B

Bag of waters

 C

Cervical effacement

 D

Progressive dilatation of cervix

Q. 9

A primigravida female at term presents to the clinic with labor pains. Which of the following is a sure sign of labour?

 A

Show

 B

Bag of waters

 C

Cervical effacement

 D

Progressive dilatation of cervix

Ans. B

Explanation:

Formation of bag of waters is almost a certain sign of onset of labour. During dilatation of the cervical membrane the unsupported lower pole of the fetal membranes tends to bulge into the cervical canal. It is called bag of waters when this bulging membrane contains amniotic fluid. When uterine contractions occur this bag becomes tense and convex, and it disappears when the contraction passes off.

Features of true labour pains:

  • Occurrence of painful uterine contractions at regular intervals
  • Contraction with increasing intensity and duration
  • Show
  • Progressive effacement and dilatation of cervix
  • Formation of bag of waters

Ref: Textbook of Obstetrics By D.C Dutta, 6th edn, page 117.


Q. 10

Cervical ripening is mainly due to the action of :

 A

PGE2

 B

PGF2

 C

PGI2

 D

PGG7

Q. 10

Cervical ripening is mainly due to the action of :

 A

PGE2

 B

PGF2

 C

PGI2

 D

PGG7

Ans. A

Explanation:

PGE2


Q. 11

Maximum cervical dilatation during labor is:

March 2013

 A

6 cm

 B

8 cm

 C

10 cm

 D

12 cm

Q. 11

Maximum cervical dilatation during labor is:

March 2013

 A

6 cm

 B

8 cm

 C

10 cm

 D

12 cm

Ans. C

Explanation:

Ans. C i.e. 10 cm


Q. 12

True labour pains is represented by:         

September 2006

 A

Pain and discomfort in the abdomen

 B

Show

 C

Relieved by enema ans administration of sedative

 D

Dull in nature

Q. 12

True labour pains is represented by:         

September 2006

 A

Pain and discomfort in the abdomen

 B

Show

 C

Relieved by enema ans administration of sedative

 D

Dull in nature

Ans. B

Explanation:

Ans. B: Show

Features of true pain:

  • Painful uterine contractions at regular intervals
  • Contraction with increasing intensity and duration
  • Expulsion of cervical mucus plug, mixed with blood (show)
  • Progressive effacement and dilatation of cervix
  • Formation of bag of waters

Q. 13

Pressure inside the organ as “marked by a box” shown in the picture below in early part of labor is ? 

 A

50 mm Hg.

 B

100 mm Hg.

 C

150 mm Hg.

 D

200 mm Hg.

Q. 13

Pressure inside the organ as “marked by a box” shown in the picture below in early part of labor is ? 

 A

50 mm Hg.

 B

100 mm Hg.

 C

150 mm Hg.

 D

200 mm Hg.

Ans. A

Explanation:

The organ shown in the picture above represents uterus.

Pressure inside the uterus in early stage of labor is about 50  mm Hg.



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