Stages of labour

Stages Of Labor

1. Stages of Normal Labor

2. Criteria for Normal labour Spontaneous expulsion, Of a single, Mature fetus (37-42 weeks), Presented by vertex, Through the birth canal (vaginal delivery), Within a reasonable time, Without complications to the mother, Without complications to the fetus .

3. Stages of Labour

4. First Stage of Labour It starts with regular and rhythmic uterine contractions till completion of full cervical dilatation (10cm). Aims at :- Dilatation and effacement of the cervix Full formation of lower uterine segment DURATION : For primi gravida 16hrs to 18hrs. For multi gravida 6hrs to 10hrs.

5. Latent phase Onset –regular contractions Ends –3 cm of dilatation Prolonged latent phase->20 hours in the nullipara , >14 hours in the multipara

6. Active phase Onset –cervical dilatation of 3 cm Protraction –slow rate of cervical dilatation Arrest –complete cessation of dilatation or descent

7. MATERNAL PROGRESS IN I STAGE OF LABOR Criteria Latent phase Active phase Transition phase Duration Primi gravida Multi gravida 8 – 10 hrs 5 hrs 3 – 6 hrs 4 hrs 2 hrs 1 hr Contraction Strength Rhythm Frequency Duration Mild – Moderate Irregular 5 – 30 mts 30 – 45 seconds Moderate – Strong More regular 3 – 5 mts 40 – 70 seconds Strong – Very strong Regular 2 – 3 mts 45 - 90 seconds Cervical dilatation 0 – 3 cm 4 – 7 cm 1.2 cm / hr in Primi 1.5 cm / hr in Multi 8 – 10 cm 1 cm / hr in Primi 2 cm / hr in Multi Station of the head Primi gravida Multi gravida -2 to 0 cm +2 cm +1 to +2 cm +3 and above Show Brownish Pale pink discharge Pink to bloody mucus Bloody mucus

8. Events in 1 st Stage of Labour

9. Factors responsible :- Uterine Contraction :- While the upper segment contracts , retracts and pushes the fetus the lower segment dilate in response to forces of contraction of upper segment. Retraction:- the quality of uterine muscle fiber remains shortened after contracting during the labour . This results in a gradual progression of the fetus downward through pelvis. Fetal axis pressure :- With longitudinal lie and well fitted fetal head on cervix the upper segment contraction force is transmitted to the lower pole causing mechanical stretching of lower segment and dilation.

10. Bag of Membranes As the lower uterine segment forms and stretches , the chorion becomes detached from it and the increased intrauterine pressure causes its loosened part of the sac of fluid to bulge downward into the internal os , to the depth of 6-12 mm. The well flexed head fits into the cervix and cuts off the fluid in front of the head from that which surrounds the body. The former is known as ‘ forewaters ’ and the latter the ‘ hindwaters ’.

11. Formation of Physiological Retraction Ring A distinct ridge is produced at the junction of upper and lower uterine segment due to progressive thickening of upper segment and thinning of lower uterine segment. Pronounced in late first stage A Pathological retraction ring is formed in obstructed labor.

12. Phases of 2 nd Stage of Labour LATENT PHASES / PROPULSIVE PHASE : Descend of the fetus 2 cm below from the os to the pelvic floor . ACTIVE PHASES / EXPULSIVE PHASE : Descend of the fetus from the os 2cm below to the vaginal outlet ( Crowning ) Ferguson reflux : Pressure exerted by the presenting part over the cervix causing involuntary uterine contraction TRANSITION PHASES / COMPULSIVE PHASE : Birth of the baby from the vaginal outlet till extension .

13. Rupture of Membranes The optimal physiological time for the membranes to ruptures spontaneously is at the end of the first stage of labour after the cervix becomes fully dilated and no longer supports the bag of forewaters .

14. Second Stage of Labour It begins with full cervical dilatation (10cm) till the birth of the baby. DURATION : Primi gravida - 2 hours. Multi gravida - 30 minutes.

15. RECOGNITION OF COMMENCEMENT OF II STAGE OF LABOUR Expulsive uterine contraction Rupture of the fore waters Dilatation and gaping of anus Appearance of present part Congestion of the vulva

16. PHYSIOLOGY OF II STAGE OF LABOUR I Uterine action Contraction becomes stronger, longer but less frequent. Membranes rupture spontaneously. Consequent drainage of liquor allows the hard, round fetal head to be directly applied to the vaginal tissues and aid distension. Fetal axis pressure increasing the flexion of the head which results in smaller presenting diameter ,more rapid progress and less trauma to both mother and fetus . Expulsive contraction:- irresistible desire to ‘bear down’ and push until baby is delivered , added by voluntary contraction of abdomen (bearing down efforts) . Propulsive contraction :- from full dilation until head touches the pelvic floor Involuntary uterine contraction.

17. II Soft tissue displacement : As the hard fetal head descend, the soft tissue of the pelvis become displace. Anteriorly the bladder is pushed upwards into the abdomen which cause stretching and thinning of the urethra. Posterioly the rectum becomes flattened into the sacral curve and the pressure of the advancing head expels any residual faecal matter. Laterally the Levator ani Muscles dilate and thins out and perineal body is flattened ,displaced ,stretched and thinned.

18. Third Stage of Labour Begins after delivery of the baby and ends with the delivery of the placenta and membranes It contains two phases A. Separation B. Expulsion

19. BEFORE SEPARATION Per abdomen: Uterus become discoid in shape, firm in feel and ballottable . Fundal height reaches slightly below the umbilicus. Per vaginum : There may be slight trickling of blood. Length of the umbilical cord as visible from outside remains static.

20. AFTER SEPARATION Per abdomen: Uterus become globular, firm and ballottable . fundal height is slightly raised. supra pubic bulging Per vaginum : Slight gush of vagina bleeding. Permanent lengthening of the cord.

21. Mechanism of Separation Marked retraction in the size of uterus causes buckling of inelastic placenta which brings about its separation. The plane of separation runs through deep spongy layer of decidua basalis . Central Seperation ( Schultze ) :- Detachment of placenta from it’s uterine attachment starts at centre resulting in opening of sinuses and accumulation of blood , this weight also facilitates placental separation. Marginal Separation (Mathews- Duncan) :-Separation starts from margin and is unsupported , more frequently observed.

22. DESCEND OF THE PLACENTA Sudden trickle or gush of blood. Lengthening of the umbilical cord. Change in the shape of the uterus, globular. Change in the position of the uterus.

23. Expulsion of Placenta :- After complete separation of placenta, it is forced down into the flabby lower uterine segment or upper part of vagina by effective contraction and retraction of uterus. It is expelled out by either voluntary contraction of abdominal muscles (bearing down efforts) or by manual procedures.

24. HEMOSTASIS After placental separation , innumerable torn sinuses having free circulation have to be obliterated. Retraction of the oblique uterine muscle fibres leading to clamping of arterioles. vigorous uterine contraction following placental separation. transitory activation of the coagulation and fibrino-lytic systems.