Normal Labour

1. Normal Labour Professor Razia Mustafa Abbasi

2. Labour • It is the process by which regular pain full uterine contraction bring about effacement and dilatation of cervix and decent of presenting part leading to explosion of the fetus and placenta from the mother

3. Term Labour PTL prolonged 24 W 42W 40W 28 W 37 W 1 LNMP Labour can occur at:

4. Normal labour: • Spontaneous expulsion, through the natural passages (birth canal) of a single, mature (37-42 completed weeks of pregnancy) alive fetus, presenting by vertex, within a reasonable time, without fetal or maternal complications.

5. Physiology of labour Mechanical theories: - uterine distension Hormonal theories: • Maternal : • progesterone withdrawal • oxytocin stimulation • prostaglandins • serotonin • fetal: • fetal cortisol • fetal membranes • Neuronal factors: • sympathetic- alpha receptor stimulation

6. STAGE OF LABOUR. STAGES OF LABOUR: I-The First stage: stage of cervicaleffacement and dilatation Definition:the first stage of labour refers to the period from the onset of true uterine contractions to the fully dilation of the cervix, when the diameter of the cervical os measures 10cm.

7. Duration: • primigravida = 8-12 h • multigravida = 6-8 h Phases of the first stage: • Latent phase: started when the cervix dilatated slowly and reached to about 3cm. • in primigravida = 8h • in multigravida = 4h • - Active phase: rapid dilatation of the cervix to reach 10cm • in primigravda = 4h • in multigravida =2h

8. The active phase is divided into: • Accelerative phase • Slopping phase • Decelerative: • prolonged active phase • primary dysfunction: dilation in active phase of<1cm/hr • secondary arrest: active phase dilation stops or slow significantly. N.B – in primigravida the cervix dilates from above downwards, in multigravida dilatation of the internal os, taking up of the cervix and dilatation of the external os occurs simultaneously.

9. Factors affecting cervical dilatation: • Contraction and retraction of the uterus. • The bag of fore-water. • Absence of membranes. • Fitting of the presenting part to the lower segment and the cervix. • Pre-labour changes in the cervix (eg, softening)

10. II-The Second stage of labour: stage of delivery of the fetus. Definition:the second stage of labour refers to the period from complete cervical dilatation to the birth of the fetus. Duration: • in primigravida =1 h • in multigravida = ½ h however the timing of the second stage is very different to determine and controversial and can be extended as much as there is progress in descent and no harm to the mother or fetus

11. The second stage of labour had two phases: • Passive phase – stage of descent of the presenting part and dilatation of the vagina – due to contraction and retraction of the uterine muscle. • Expulsive phase – stage of bearing down – due to contraction and retraction of the uterine muscle and voluntary efforts by diaphragm and abdominal muscles.

12. A-Delivery of the fetal head: Enter the pelvis by flexion Engagement Increased flexion Internal rotation DESCENT Crowning Extension Restitution External rotation Delivery of the fetal head B-Delivery of the shoulder and body:

20. Mechanism of labour in vertex presentation: • Definition: The spontaneous adjustments of the fetal position and attitude to affect efficient passage of the fetus through the pelvis, marked by progressive descent until delivery of the fetus. • Delivery of the fetal head: • A- Descent: is a continuous movement throughout the process of delivery, however it becomes more rapid in the second stage of labour, it is caused by: • -Uterine contraction and retraction. • -bearing down effort – mainly in the second stage of labour

21. In normal pelvis, the fetal head enters with the sagittal suture in the transverse diameter (or occasionally oblique diameter of the brim). If the sagittal suture in between the symphysis pubis and sacral promontory – both parietal bones are felt vaginally at the same level – the head is said to be (synclitic). In such case the biparietal diameter (9.5cm) is the diameter of engagement. However some degree of lateral inclination of the head over the shoulder – (Asynclitism) is present normally as the head enters the pelvic inlet.

22. *If the sagittal suture lies close to the sacrum and the anterior patietal bone lies over the inlet (Anterior parietal bone presentation) - Anterior asynclitism. *If the sagittal suture lies close to the symphysis pubis and the posterior parietal bone lies over the inlet (posterior parietal bone presentation) – posterior asynclitism.

23. Increased flexion: As the head descends, it meets resistance from the pelvic walls and floor and this leads to increased flexion of the head. As the head flexed it brings the shortest longitudinal diameter of the head (sub-occipito-bregmatic – 9.5cm) to pass through the birth canal. Flexion is explained by the (two armed lever theory).

24. D-Internal rotation: The internal rotation occurs as the head descends through the pelvic cavity. As the head enters the pelvic inlet in transverse diameter will rotate 3/8 of the cycle to pass through the pelvic outlet in antero-posterior diameter. The rotation is favoured by the slopping shape of the pelvic floor, angling the leading point of the head (occiput) in downward and forward direction, by the effect of the contraction and retraction of the uterus.

26. E-Crowning, extension and delivery of the fetal head: The combined effect of descent and internal rotation bring the presenting diameter to the plane of the pelvic outlet, with the occiput lying under the pubic arch and the sinciput at the lower border of the sacrum or coccyx. When the widest diameter of the fetal head is embraced by the distended vulva, it is said to be crowned. The occiput remains under the pubic arch but the sinciput sweeps forwards as the neck extends.

27. The head is acted upon by: • The downward and forward force of the uterine contraction and retraction. • The upward and forward force offered by pelvic floor resistance so the head passes forwards i.e. extends vertex, forehead, and face come out successively. Frequently, especially in primigravida, the soft tissues are not able to distend equally so that tearing of the perineum and adjacent tissues may occur unless steps are taken to avoid it by making a formal incision (episiotomy).

28. F-Restitution and external rotation: Following delivery of the head the occiput rotates to the lateral position, in the opposite direction of internal rotation to correct the twist of the head on the shoulders produced by internal rotation. The internal rotation of the shoulders inside the pelvis transmitted to the delivered head which in turn move one eight of a circle outside the pelvis, in the same direction as that of the restitution, so at the end the occiput is towards one thigh and the face is towards the other thigh.

29. Delivery of the shoulder and body: The widest diameter of the shoulders,( the bi-acromial diameter), pass the pelvic brim at the time when the anterior rotation of the head is occurring. Thus the anterior rotation of the occiput is favourable for both the head and the shoulders. Similarly external rotation of the head is associated with rotation of the shoulders to bring them into the antero-posterior diameter of the outlet. With further descent, the anterior shoulder delivered first from under the pubic arch, followed by posterior shoulder, during which time lateral flexion of the trunk is occurring. The trunk and buttocks follow with the same or the next contraction.

30. Even in the course of normal delivery, there are many variations of the mechanisms, dependent on the variation in the size and shape of the pelvis and of the fetal head. III-The Third stage of labour:the stage of expulsion of the placenta and membranes.

31. Duration: up to 30 minutes, however the average length of the third stage of labour is 10 minutes. • Mechanism: the third stage is made of two phases: • The first phase: phase of placental separation occurs through the spongiosa layer of the decidua at the time of expulsion of the baby or very soon afterwards. The shearing force responsible for the separation is the contraction and retraction of the uterus, reducing the uterine volume and the area of the placental site, as the fetus is expelled.

32. The second phase: phase of placental expulsion – The separated placenta descends from the upper (active) segment into lower (passive) uterine segment, cervix, and vagina by two mechanisms: • -Schultze mechanism:(80%) • The placenta delivered as an inverted umbrella with it’s fetal surface presenting first followed by the membranes with retro-placental haematoma. • Mattews – Duncan mechanism: (20%) • The placenta delivered side way and it presents with it’s inferior surface first.

34. Issues in the management of labour • Review of antenatal record if available • Diagnosis of labour • Non engagement of presenting part • Problems of first stage • Problems of second stage • Problem of third stage • Contraception • Breast feeding

35. High risk pregnancy • Age:<20 or >35 • Parity: Primigravida or Grand multipara • Previous obstetric out come and mode of delivery • Any medical disorder: hypertension/ diabetes /epilepsy/autoimmune disorder • Any obstetric problem in previous pregnancy: difficult delivery/ instrument delivery /PPH/Perineal tears

36. Diagnosis • symptoms: • True labour pains – colicky pain in the abdomen and back are characterized by:

37. Causes of non-engagement: • Erroneous dates (primigravida) • Extra-uterine: • full bladder or loaded rectum • Pelvic tumours • Pendulous abdomen and marked lumbar lordosis. • High angle of inclination of the pelvis. • Contracted pelvis. • -Uterine: • Poor uterine tone. • Congenital deformities. • Fibromyomata. • Placenta previa.

38. -Fetal: • polyhydramnios. • Short umbilical cord(acutal or relative, due to entanglement) • Large baby. • Deflexion attitude, and malposition. • Multiple pregnancy. • Hydrocephalus. Engagement – can be assessed by abdominal station in fifths during antenatal period, and by abdominal and vaginal stations during labour.

39. Partogram - Maternal Name / DOA /Gestation Medical / Obstetrical issues HR / BP/ Temp Urinanalysis

40. Partogram - Fetal • Fetal heart rate Colour of liquor • Moulding

41. Moulding of the skull: • means obliteration of the suture line between the bones and overlapping of the un-united bones of the fetal skull, and is measured by degree. As the degree of moulding increase- means there is CPD

42. Partogram - Progress Uterine contractions Cervical dilatation Descent of presenting part Caput / Moulding Fetal position

43. FRIEDMAN’S CURVE

44. Problem of first stage

45. Problem of first stage

46. Problem of second stage

47. What can go wrong? Powers Poor contractions/Maternal effort Passages Small pelvis/Pelvic shape Passenger Big baby/Presentation/Malposition

48. Abnormal powers • Artificial rupture of membranes • Oxytocin infusion • Change position • Encouragement • Review after four hours if no improvement refer for operative delivery.

49. Problem in passenger/pelvis Refer for operative delivery if there is problem with passenger/ passage Passenger • Good size baby • Malpresentation • Malposition • Congenital abnormalities • Multiple pregnancies

50. Problem in passenger/pelvis • Contracted pelvis • CPD • Congenital abnormalities of pelvis