Normal labour and its physiology

This presentation contains :-
1.Introduction of normal labour
2. Definiation of normal labour
3.Criteria of normal labour
4. Physiology of normal labour
5. Pathophysiology of labor
6.Estrogen
7. Prostaglandin
8. Oxytocin
9. True labor and false labor difference
10. Uterine contraction in labor
11. Stages of labour
12. Management of 1 st stage
13. management of 2 nd stage
14. mamagement of 3 rd stage of labor
15. Cervix dilation
16. Friedman's curve
17. Fetal skull
18. Diameter of fetal skull
19. Sutures in fetal head
20. Moulding
21. Mechanism of labour

1. NORMAL LABOUR Presented By – Atul Yadav (RN,RM) For more info. – medicalexpertcare.blogspot.com

2. INTRODUCTION Labor is a physiologic process during which the products of conception (ie, the fetus, membranes, umbilical cord, and placenta) are expelled outside of the uterus.

3. DEFINITION OF NORMAL LABOUR Series of events that take place in the genital organ in an effort to expel the viable(alive) products of conception out of the womb/uterus through vagina into outer world is called Normal Labour.

4. DEFINITION OF NORMAL LABOUR Labour is defined as the presence of regular uterine contractions with progressive cervical dilatation and effacement.

5. CRITERIA/CHARACTERISTICS OF NORMAL LABOUR Spontaneous in onset and at term ( between 37 -40 weeks of gestation.) With Vertex presentation Without any undue prolongation. Without any complications. Naturally Terminated with minimal aid.

6. PHYSIOLOGY OF NORMAL LABOUR Phys io l o gy of n o rmal l a bou r c o mplet e i nt o two steps - UTERINE C O N T R A C T I O N RETRACTION

7. PHYSIOLOGY OF NORMAL LABOUR 1. Uterine contraction : During contraction, uterus becomes hard and somewhat pushed anteriorly to make the long axis of the uterus in the line with that of pelvic axis.

8. PHYSIOLOGY OF NORMAL LABOUR 1. Uterine contraction : Simultaneously, the patient experiences pain which i s s i tuated m o re on the hypogastric region, often radiating to the thighs.

9. PHYSIOLOGY OF NORMAL LABOUR 1. Uterine contraction : Probable cause of pain are – Myometrial hypoxia during contractions. Stretching of the peritoneum over the fundus. Stretching of the cervix during dilatation. Compression of the nerve ganglion. The pain of uterine contractions is distributed along the cutaneous nerve distribution of T10 to L1.

10. PHYSIOLOGY OF NORMAL LABOUR

11. PHYSIOLOGY OF NORMAL LABOUR

12. PHYSIOLOGY OF NORMAL LABOUR INTENSITY – The intensity of uterine contractions describes the degr e e o f uterine systole. The intensity gradually increases with advancement o f labour unti l it becomes maximum in the second stage during delivery of the baby. Intrauterine pressure is raised to 40-50 mm Hg during first stage and about 100-120 mm Hg in the second stage of labour during contractions .

13. PHYSIOLOGY OF NORMAL LABOUR

14. PHYSIOLOGY OF NORMAL LABOUR DURATION In the first stage, the contractions last for about 30 second initially but gradually increases in duration with the progress of labour. Thus in the second stage, the contractions last longer than in the first stag e .

15. PHYSIOLOGY OF NORMAL LABOUR FREQUENCY In the early stage of labour, the contractions come at intervals of ten to fifteen minutes. The intervals gradually shorten with advancement of labour until in the second stage, when it comes every t w o or t h r e e m i n u t e s .

16. PHYSIOLOGY OF NORMAL LABOUR

17. PHYSIOLOGY OF NORMAL LABOUR Retraction - Retract i on is a p h en o me n on of the uterus in labour in which the muscle fibers perm a nently are shortened.

18. PHYSIOLOGY OF NORMAL LABOUR

19. PHYSIOLOGY OF NORMAL LABOUR Unl i ke any other mus c le o f the bo d y , the uter i ne have th i s p r operty to mus c les becom e sh o rt e ne d o n ce and for a l l .

20. PHYSIOLOGY OF NORMAL LABOUR Contraction is a temporary reduction in length of the fibers, which attain their full length during relaxation. I n contrast, retraction results in permanent shortening and the fibers are shortened once and for all.

21. PHYSIOLOGY OF NORMAL LABOUR The net effect of retracton on normal l a b o u r a r e : - - Essential property in the formation of lower uterine segment and dilatation and effacement up of the cervix.

22. PHYSIOLOGY OF NORMAL LABOUR

23. PHYSIOLOGY OF NORMAL LABOUR To maintain the advancement of the presenting part made by the uterine contractions and to help in ultimate expulsion of the fetus. To reduce the surface area of the uterus favouring separation of placenta. Effective haemostasis after the separation of the placenta.

24. Exercise :- Define normal labor ? Character tics of normal labor ?

25. Pathophysiology of labor

26. NORMAL LABOR/ EUTOCIA  spontaneous in onset and at term with vertex presentation without undue prolongation Natural termination with minimal aids without having any complications affecting the health of the mother and/or the baby

27. ESTROGEN Increases release of oxytocin from maternal pituitary Promotes synthesis of myometrial receptors for oxytocin,PG  increase in gap junctions in myometrial cells Stimulates synthesis of myometrial contraction protein  actinomyosin through cAMP. Increases excitability of myometrial cell

28. PROS T AGLANDIN Initiates and maintain labor Major site of production: Amnion,chorion, decidual cells and myometrium Enhances gap junction formation Triggered by estrogen, glucocorticoids, separation or rupture of membrane

29. OXY T OCIN Peptide hormone Hypothalamus-posterior pituitary Fetal production: Maternal serum increase in second stage of labor Oxytocin receptors: Fundal location, increase during pregnancy Actions Stimulate uterine contractions Stimulate PG production from amnion/decidua

30. TRUE AND FALSE LABOR  True labor Painful contractions at regular intervals at term Contraction frequency, intensity, duration increases gradually Associated with Show Progressive effacement and dilatation of cervix Descent of presenting part Formation of “bags of water” Not relieved by enema/ sedatives (analgesics)  False labor Dull pain confined to groin and abdomen Pain interval doesn’t shorten Pain intensity remains same No cervical dilatation No hardening of uterus Relieved by enema or sedative

31. DURING PREGNANCY… Marked hypertrophy and hyperplasia of uterine muscles Length of uterus + cervix = 35 cm at term Uterus assumes pyriform/ ovoid shape Cervical canal occluded by thick, tenacious mucus plug

32. UTERINE CONTRACTION IN LABOR Irregular involuntary painless spasmodic uterine contraction (Braxton-Hicks) throughout pregnancy which changes during labor Pacemaker situated in : tubal ostia  contraction waves initiate Pain of contraction distributed along the cutaneous nerve distribution of T10 –L1

33. PATTERN OF CONTRACTION Good synchronization of contraction waves from both halves of the uterus Fundal dominance with gradual diminishing contraction wave through midzone down to lower segment in 10-20 sec Wave of contraction follow regular pattern Upper segment of uterus contracts longer and stronger than lower part Intra-amniotic pressure rises beyond 20mm Hg during uterine contraction Good relaxation occurs in between contraction(intra- amniotic pressure less than 8)

34. RETRACTION Phenomenon of uterus in labor in which muscle fibers are permanently shortened Effects of retraction: Formation of lower uterine segment + dilatation and effacement of cervix Decent of presenting part  expulsion of fetus Reduce surface area  separation of placenta Effective homeostasis after separation of placenta

35. STAGES OF LABOR First phase latent Active Second phase Propulsive Expulsive Third phase Fourth phase

36. FIRST STAGE Concerned with formation of birth canal Main events: Dilatation of cervix Effacement of cervix Lower uterine segment formation

37. FACTORS RESPONSIBLE IN DIL AT A TION Uterine contraction and retraction Longitudinal fiber of upper segment attach to circular fiber of lower segment  if uterus contracts  canal opens + shortens  polarity of uterus Fetal axis pressure longitudinal lie of fetus  circular muscles contraction transmitted from podalic pole to head Not in transverse lie Bag of membrane Vis-a-tergo

38. EFFACEMENT OF CERVIX “processes by which muscular fibers of cervix pulled upward and merge with fibers of lower uterine segment” Primigravidae: effacement before dilation of cervix Multiparae : effacement and dilatation occur at same time

39. LOWER UTERINE SEGMENT  Formation of active upper segment and relatively passive lower segment forms during labor

40. Friedman’s Curve Friedman's Curve describes progress of two variables over time: dilation of cervix descent of baby Labor i s “ dysfuncti o nal ” when ce r vix st o ps dilating or fetal descent stops or both Possible diagnosis of "failure to progress" C-section indicated May be d ue t o CPD ( C e p halo Pel v i c D i s p rop o r t ion) or epidural anesthesia

41. Friedman’s Curve

42. SECOND STAGE OF LABOR “Begins when cervical dilatation is complete and ends with fetal delivery.” Median duration 50 minutes in primigravida 20 minutes in multiparous Uterine contractions and accompanying expulsive forces last: 60-90 seconds and recur every 60 seconds

43.  Propulsive phase:  Period of full dilation until head touches pelvic floor  Expulsive phase:  Sin c e the time mo t h e r has i r resistible d e sire t o ‘be a r down’ and push until the baby is delivered

44. DURATION OF LABOR Mean length of 1 st and 2 nd stage labor 12 hours in primigravida 6 hours in multipara

45. THIRD STAGE OF LABOR  Includes separation, descent and expulsion of placenta with its membrane. Signs of placental separation: Hardening of uterus Sudden gush of blood Rise of Uterus (because the placenta, having separated, passes down in the lower uterine segment and vagina) Lengthening of umbilical cord Signs of placental separation appear within 1-5 minutes within delivery of newborn.

46. FOURTH STAGE OF LABOR The placenta, membranes and umbilical cord should be examined for completeness and for anomalies observation: 1 hour after birth of baby Laceration of birth canal(vagina and perineum): first degree laceration Second degree laceration third degree laceration fourth degree laceration

47. Degree of Lacerations First degree laceration : Involved the perineal skin, vaginal mucus membrane but not underlying fascia and muscle 2 nd degree laceration : Involve in addition, the fascia and muscle of perineal body but not anal sphincter 3 rd degree laceration: Extent further to involve the anal sphincter 4 th degree laceration: Laceration extend through the rectum’s mucosa to exposed its lumen

48. MANAGEMENT OF FIRST STAGE Of LABOR Monitoring fetal well-being during labor Fetal heart should be monitored every 30 mins in 1 st stage and every 15 mins in 2 nd stage of labor Uterine contractions to evaluate the frequency, duration, and intensity of uterine contractions. Maternal vital signs Maternal temperature, pulse, and blood pressure are evaluated at least every 4 hours with prolonged membrane rupture(>18 hours) antimicrobial administration for prevention of group B streptococcal infections is recommended Subsequent vaginal examinations

49. CONTD.. Oral intake Food should be withheld during active labor and delivery Maternal position position that she finds most comfortable, which will be lateral recumbency most of the time Urinary bladder function Bladder distention-avoided, because it can hinder descent of the fetal presenting parts

50. MANAGEMENT OF SECOND STAGE LABOR 1. Preparation for delivery Put the patient in dorsal lithotomy position or lying flat on bed Clean the vulva, and perineum with antiseptic solution Encourage organized pushing down which she is feeling to do so 2. spontaneous delivery With each contraction, perineum bulges increasing Ritgen maneuv e r - w h e n he a d distends the vulva and perineum enough to open the vaginal introitus to 25 cm or more A towel-draped ,gloved hand –used to exert forward pressure on the chin of fetus through the perineum This ma n e u v e r allow d e live r y of he a d a n d also fav o rs the neck extension so that head is delivered with small diameter

51. CON T .. Clearing the nasopharynx: Once the thorax –delivered and the newborn can inspire Face quickly wiped and the nares and mouth cleared Nuchal cord : Found in 25% of deliveries and ordinarily no harm If coil of umbilical cord felt-it should be slipped over the head if loose enough If too tight, the loop should be cut between two clamps

52. CON T ... Clamping the cord : Umbilical cord is cut between two clamps placed 4 to 5 cm from the foetal abdomen and later an umbilical cord clamp-applied 2 to 3 cm from the fetal abdomen Plastic clamp –safe Timing of cord clamping:  If after delivery of the newborn –placed below the level of the vaginal introitus for 3 min and Fetoplacental circulation – not immediately occluded by cord clamping, then approx. 80 ml of blood shift from placenta to neonate  this reduces the frequency of iron deficiency anemia later in infancy

53. MANAGEMENT OF THIRD STAGE LABOR  Delivery of the placenta : -Traction on the umbilical cord must not be used to pull the placenta out of uterus. -uterine inversion is one of the complication associated with delivery  Manual removal of placenta: - Adequate analgesia is mandatory and aseptic surgical technique should be used -occasionally, placenta will not separate especially common in case of preterm delivery -if there is brisk bleeding and the placenta can not be delivered- indicated

54. CON T ... 1.Oxytocin Given before delivery of placenta will decrease blood loss(they may entrap an undiagnosed, undelivered 2 nd twins) The spontaneously labouring uterus is typically sensitive to oxytocin and dosing should be titered to achieved adequate contraction After delivery of the foetus, dosing should be fixed It should be given as a dilute solution by continuous iv. Infusion or im 10 USP unit i.m. (oral not effective) T1/2 3-4 minutes- iv. Infusion (large bolus should not be given)

55. CON T .. CVS effect: IV bolus of 10 unit of oxytocin caused marked fall in BP with an abrupt increase in CO . These hemodynamic changes could be dangerous for women hypovolemic from haemorrhage or those with cardiac disease. Water intoxication: Has antidiuretic action With high dose of oxytocin- produce water intoxication if the oxytocin administered with large volume of electrolyte free aqueous dextrose solution Oxytocin given with NS or ringer solution

56. 2. Ergonovine and methylergonovine : Ergot alkaloids Stimulation of myometrium contraction Given IV (0.1mg),IM or orally(0.25mg) They are dangerous for mother and foetus prior to delivery- tendency of relaxation IV administration sometimes initiation of transient hypotension- severe in gestational hypertension 3. prostaglandins: Analogs not used routinely for management of 3 rd stage labour

57. MANAGEMENT OF FOURTH STAGE LABOR Examine the placenta for their completeness, anomalies , ( single umbilical artery  Multiple births) length , and number of vessels in the cord and record the placental weight Suture the episiotomy or any laceration Est i m a t e blo o d loss, c o unt sw a bs, and take cord blo o d for Hb, blood group, Rh, bilirubin, and Coomb’s test for Rh negative mother Check BP, P, T and firmness of the uterus before transferring the patient Allow no food during the first hour, sips of water may be taken

58. Diameter of skull and the way it moves through pelvis

59. FETAL SKULL o Mad e of th i n pli a ble t a b u lar (fl a t) b o n e s forming the vault o Compressible to some extent o Areas of skull: Vertex Brow Face

60. Vertex : quadrangular area bounded anteriorly by bregma and coronal sutures Posteriorly by lambda and lambdoid suture Laterally by lines passing through parietal eminences Brow: One side anterior fontanels and coronal sutures Other side root of nose and supra-orbital ridges of either side Face: One side root of nose and supra-orbital ridges On other side junction of floor of mouth with neck

61. SUT U RES Frontal : between the two frontal bones Sagittal: between the two parietal bones Two coronal : between the frontal and parietal bones Two lambdoid : between the posterior margins of the parietal bones and upper margin of the occipital bone

62. Diameter Measurement(cm) Attitude of head Pr e s e ntatio n Suboccipito-bregmatic (nape of neck to center of bregma) 9.5 cm C o mp l ete flexion Vertex Suboccipito-frontal (nape of neck to ant. end of ant. fontanelle ) 10.5 cm Inc o mp l ete flexion Vertex Occipito-frontal(occipital eminence to glabella) 11.5 cm Marked d e fle x i o n Vertex Mento-verticle (mid point of chin to highest point on sagittal suture) 14 cm (13cm in oxford hand book) Partial e x te n si o n Brow Submento-verticle (junction of floor of mouth and neck to highest point on sagittal suture) 11.5 cm Inc o mp l ete extension Face Submento-bregmatic (junction of floor of mouth and neck to center of bregma) 9.5 cm C o mp l ete e x te n si o n Face ANTERO-POSTERIOR DIAMETER OF HEAD THAT MAY ENGAGE

63. 9.5 cm Extends between two parietal eminences Super-subparietal diameter: 8.5 cm Extends from a point placed below one parietal eminence to a point placed above other parietal eminence of opposite side Bitemporal diameter: 8 cm Distance between antero-inferior ends of coronal suture Bimastoid diameter: 7.5 cm Distance between tips of mastoid processes TRANSVERSE DIAMETER Bipari tal dia m eter :

64. Attitude of head Plane of engagement Circumference Complete flexion Biparietal-suboccipito-bregmatic Shape - almost round 27.5 cm Deflexed Biparietal-occipito-frontal Shape – oval 34 cm Incomplete extension Biparietal-mento-vertical Shape - bigger oval 37.5 cm Complete extension Biparietal-submento-bregmatic Shape - almost round 27.5 cm CIRCUMFERENCE Circumference of the plane of diameter of engagement differs according to attitude of head Circumference of head in different attitude :

65. MOU L DING “The alteration of the shape of the fore coming head while passing through the resistant birth passage during labor” There is little alteration in size of head as the volume of content inside skull is incompressible An alternation of 4mm in skull diameter commonly occur during normal delivery Disappears within few hours after birth

66.  MECHANISM: Compression of engaging diameter of head with corresponding elongation of the diameter at right angle to it GRADING OF MOULDING Grade 1: Bones touching but not overlapping Grade 2: Bones overlapping but easily separated Grade 3: Fixed overlapping of bones

67. IMPORTANCE OF MOULDING Slight moulding is inevitable and beneficial Enables head to pass more easily through the birth canal Extreme moulding may produce  Severe intracranial disturbance in the form of tearing of tentorium cerebelli or subdural haemorrhage Shape of moulding gives information about position of head occupied in pelvis

68. CARDINAL MOVEMENTS OF LABOR

69. the passage of the widest diameter of the presenting part to a level below the plane of the pelvic inlet In the cephalic presentation with a well-flexed head, the largest transverse diameter of the fetal head is the biparietal diameter (9.5 cm) ENGAGEMENT

70. Engagement can be confirmed clinically by palpation of the presenting part abdominally and/or vaginally The head is assumed to be engaged if the leading edge has reached the ischial spines and there is no significant molding or scalp edema

71. Head in Synclitism : the sagittal suture corresponds to the diameter of engagement with the head enters the brim Anterior asynclitism: Anterior parietal presentation Posterior asynclitism: Posterior parietal presentation Mild degree of asynclitism are common but severe degrees indicate cephalopelvic disproportion PRESEN TA TION

72. downward passage of the presenting part through the pelvis The greatest rate of descent occurs during the deceleration phase of the first stage and during the second stage of labor Forces involved:- Pressure of amniotic fluid Pressure of fundus upon breech with contraction Maternal abdominal muscles Extension and straightening of fetal body DESCE N T

73. Occurs passively as the head descends due to resistance related to the shape of bony pelvis & by the soft tissues of the pelvic floor Although flexion of the fetal head onto the chest is present to some degree in most fetuses antepartum, complete flexion usually only occurs during the course of labor A deflexed head presents a larger diameter, which may be too large to negotiate the pelvic bone FLEXION

74. o Rotation of the presenting part from its original position (usually transverse with regard to the birth canal) to the anteroposterior position as it passes through the pelvis o As with flexion, internal rotation is a passive movement resulting from the shape of the pelvis and the resistance of the pelvic floor musculature INTERNAL ROTATION

75. Occurs once the fetus has descended to the level of the introitus This descent brings the base of the occiput into contact with the inferior margin of the symphysis pubis At this point, the birth canal curves upwards The fetal head is delivered by extension and rotates around the symphysis pubis EXT E NSION

76. After the fetal head deflexes (extends), it rotates to the correct anatomic position in relation to the fetal torso; left or right rotation depends on the orientation of the fetus Passive movement resulting from a release of the forces exerted on the fetal head by the maternal bony pelvis and its musculature and mediated by the basal tone of the fetal musculature EXTERNAL ROTATION

77. Exercise :- Define management of 3 rd stage of labor? Write I st stage of labor? Define Fetal head movement in normal delivery? Define moulding ? Define fetal skull ? Difference between true and false labor ?

78. MECHANISM OF LABOUR

79. DEFINITION Series of events that takes place on genital organ in an effort to expel the viable product of conception out of the womb through vagina into the outer world.

80. P R I N C I P L E S :- There are three principles of mechanism of labour. Descent takes place throughout labour. Whichever part leads and first meets the pelvic floor will rotate forward until it comes under symphysis pubis. Whatever part emerges from the pelvis will pivot around pubic bone. Nemonics DSP (descent, symphysis pubis and pubic bone) to remember principles of mechanism of labour.

81. CRITERIA FOR NORMAL MECHANISM OF LABOUR Lie is longitudinal Presentation cephalic Position ROA or LOA Attitude is good flexion Denominator is occiput Pr e s e nti n g par t i s post e r i o r p a rt o f anteri o r parietal bone

82. PRINCIPLE MOVEMENTS IN NORMAL MECHANISM OF LABOUR E ngagement D escent F lexion I nternal rotation of head C rowning E xtension of head R estitution

83. PRINCIPLE MOVEMENTS IN NORMAL MECHANISM OF LABOUR I nternal rotation of shoulders E xternal rotation of head D elivery of body by lateral flexion Nemonics to remember mechanism of labour E N D F L ICER I C ED (flicer means very bright ) so flicer company ke end hone se uska manaager iced ho gya.

84. PRINCIPLE MOVEMENTS IN NORMAL MECHANISM OF LABOUR Engagement En g ages w ith sag i t t al sutures i n r i g h t o b li q u e and biparietal diameter in left oblique Occiput points to left ileo pectineal eminence Descent Fetu s descent due t o con t raction and ret r action of uterine muscle Flexion Engaging diameter is sub occipito frontal (10cm) Changes to sub occipito bragmatic (9.5cm)

85. Engagement

86. Internal rotation of head Occiput is the leading part Rotates one by eighth of the circle Sagittal suture comes in APD Slight twist in the neck of the fetus Crowning Biparietal diameter stretches at vulval outlet Extension of head Releases Sinciput face and chin Head is born by flexion Restitution Twist in the neck of the fetus is corrected by slight untwisting movement Occiput turns one by eighth of the circle towards the maternal side

87. Crowning

88. Internal rotation of shoulders Shoulders rotate one by eighth of a circle to lie under symphysis pubis External rotation of head O c ciput rotates f u rth e r one b y eighth to the mothers left side Delivery of body by lateral flexion Anterior shoulder escapes under symphysis pubis Posterior shoulder sweeps the perineum Body is born by lateral flexion