Physiological changes during third stage of labor

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 3 rd year

2. General Objective At the end of the session, B.Sc. Nursing 3 rd 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 3 rd year students will be able to: d efine third stage of labor. s tate the length of third stage of labor. d escribe 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. I t 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 Schultze Method 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.

11. Schultze Method

12. 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.

13. 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.

14. 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.

15. 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)

16. 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. .

17. 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.

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

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

20. Any Queries??

21. Summary

22. 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 . ( )  

23. 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  

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

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