Physiological changes during third stage of labor

1. Physiological Changes during Third Stage
of Labor
Prepared By:
Soni Shrestha
Roll no :26
B.Sc. Nursing 3rd year

2. General Objective
At the end of the session, B.Sc. Nursing 3rd year students will
be able to explain about the physiological changes during the
third stage of labor.

3. Specific Objectives
At the end of the session, B.Sc. Nursing 3rd year students will
be able to:
1. define third stage of labor.
2. state the length of third stage of labor.
3. describe the physiology of third stage of labor.

4. Definition
• The stage of labor which begins with the birth of baby and
ends with delivery of the placenta and membranes is known
as third stage of labor.
• It is also known as placental stage of labor.

5. Length of Third Stage of Labor

6. Physiology of Third Stage of Labor
• The physiology of third stage of labor consists of separation
and expulsion of placenta and membranes.
• The placental separation is facilitated by uterine contrations
which begins again after a brief pause at birth.
• After the placental expulsion, the amount of blood loss
depends upon how quickly the uterus contracts.

7. Physiology Continued......
• If the uterus doesnot contract normally then haemorrhage
may result.
• The estimated blood flow to the uterus is 500-800 ml per
minute.

8. Placental Separation
• Placental separation occurs as a result of the abrupt
decrease in size of the uterine cavity during and following
delivery of the baby.
• It is brought about by contraction and retraction of
myometrium which thickens the uterine wall and reduces
the size of placental area.
• Formation of retroplacental clot occurs which further
facilitates the placental separation.

9. Method of Placental Separation
1. Schultze Method
2. Matthew’s Duncan Method

10. Schultze Method
• Common method of placental separation.
• Separation of placenta begins centrally.
• Formation of central retroplacental clot.
• Fetal surface appears at the vulva with the membranes
trailing behind like an inverted umbrella.
• The majority of bleeding occurring with this mechanism is
not visualized until the placenta and membranes are
delivered.

12. Schultze Method

13. Matthew’s Duncan Method
• Separation takes place at margin or periphery of placenta.
• The placenta descends sideways and comes through the
vulva with the lateral border first like a button through
button hole.
• The maternal surface is seen and blood is visualized
externally.
• No formation of retroplacental clot.

14. Before Separation
Per Abdomen
 Uterus becomes discoid in shape, firm in feel and non
ballottable.
 Fundal height reaches slightly below the umbilicus.
Per Vaginum
 Length of the umbilical cord as visible from outside, remains
static.

15. After Separation
Per Abdomen
 The fundus feels hard and globular and rises abdominally to
the level of the umbilicus.It is mobile
 The fundal height is slightly raised as the separated placenta
comes down in the lower segment and the contracted
uterus rests on top of it.
 There may be slight bulging in the supra pubic region due to
distention of the lower segment by the separated placenta.

16. After Separation Continued…..
Per Vaginum
 The cord lengthens at the vulva.
 A trickle of blood appears when the placenta separates
(gush of the blood i.e 30-60 ml blood usually comes out
from vagina)

19. Separation of Membranes
• The membranes which are attached loosely in the active part
are thrown into multiple folds.
• Those attached to the lower segment are already separated
during its stretching.
• It’s separation is facilitated by partly uterine contraction and
mostly by weight of placenta.
.

20. Separation of Membranes Continued….
• The membranes so separated carry with them bits and
pieces of deciduas vera giving the outer surface of chorion its
characteristic roughness.
• Hence the placenta and membranes descend down into the
lower uterine segment or upper vaginal vault.

21. Expulsion of Placenta
• Placenta expels after the complete separation of placenta.
• It is expelled out by either voluntary contraction of
abdominal muscles (bearing down effort) or by manipulative
procedures.

22. Controlled Bleeding after Separation
Normal physiologic processes that control bleeding are as
follows:
1. Retraction of the oblique uterine muscle fibers in the upper
uterine segment through which the tortuous blood vessels
intertwine.
2. Presence of vigorous uterine contraction following
separation.
3. The achievement of hemostasis.

24. Any Queries??

25. Summary

26. Sample Questions
Objective Type Questions:
Write true or false for the following statements. (2*1 =2)
1. The third stage of labor begins with full dilatation of cervix
and ends with delivery of baby. ( )
2. Schultz method is the peripheral method of placental
separation. ( )

27. Subjective Type Questions:
Answer the following questions.
1.Define third stage of labor. 2
2.Explain briefly the physiology of third stage of labor. 6

28. Topic for the Next Class
Active management of third stage of labor

29. References
• Subedi, D.& Gautam, S. (2016).Midwifery Nursing Part II. (3rd ed.). Medhavi
Publication.(pp:104-106).
• Cooper, M.A. & Fraser, D.M. Myles Textbook for Midwives. (15th ed.). Churchill
Livingstone Elsevier. (pp: 531-534).
• Jacob, A. A Comprehensive Textbook of Midwifery. (3rd ed.). Jaypee Brothers
Medical Publishers. (pp: 205-207).
• Dutta, D.C.(2015).Textbook of Obstetrics. (8th ed.). Jaypee Brothers Medical
Publishers. (pp:143-145).
• Tuitui, R. (2007). Manual of Midwifery – B.(4th ed.). Vidyarthi Pustak Bhandar
• Daftary, N.S.& Chakravarti, S. Holland and Brews Mannual of Obstetrics (3rd ed.).
Elsevier limited.
• Cunningham G.F et.at.(2010).Williams Obstetrics .(22nd ed.) Medical Publishing
Division, New York