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Normal Labor and Delivery

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  1. Normal Labor and Delivery Obs&Gyn Department of 1st Clinical Hospital Wuhan University Associate Professor Ming lei (明蕾)

  2. Outline Definition 1 Four factors for labor 2 Mechanism of labor 3

  3. Outline 4 Diagnosis of threatened labor and labor Labor stages 5 Clinical course and management of 1st stages 6 Clinical course and management of 2nd stages 7 Clinical course and management of 3rd stages 8

  4. Definition 1 (定义) • Delivery is the process by which the mature or nearly mature (fetus ,umbilical cord,membranes and placenta) are expelled from the maternal body after 28 weeks

  5. Definition 1 (定义) • The last few hours of human pregnancy are characterized by uterine contraction that effect dilatation of the cervix and force the fetus through the birth canal. Much energy is expended during this time, hence the use of term labor to describe this process • Myometrium is unresponsive during pregnancy. After the prolonged period of quiescence, a transitional phase is requires during which myometrial unresponsiveness is suspend and cervix is softened and effaced

  6. Definition 1 (定义) • Cause of onset of labor: Precise mechanism in initiation of labor is not defined • Endocrine • Mechanical theory • Neurological factor

  7. Definition 1 1 Term delivery: 37-42 weeks Pre-term delivery: 28- 37 weeks 2 3 Post-term delivery:  42 weeks <28 weeks 4 Abortion: (定义) 5 LMP :last menstrual period 6 EDC :expected date of confinement

  8. Definition Four factors for labor 1 2 Psychical factors Birth canal Force Fetus Mechanism of labor 3 Outline 影响分娩的四大因素 Normal Labor and delivery

  9. Four factors for labor 2 This is created by contraction of the abdominal muscles simutaneously with forced respiratory efforts with the glottis close. this is referred to as pushing Force Intra abdominal pressure 影响分娩的四大因素 Ancillary Force Levator ani muscle is the most important part of pelvic floor Levator ani muscle Expulsive Force A rhythmic tightening in labor of the upper uterine musculature that contracts the size of the uterus and pushes the fetus toward the birth canal Major force uterine contraction

  10. Four factors for labor 2 Force 影响分娩的四大因素 uterine Contraction feature Four characteristics Rhythm Symmetry Polarity Retraction duration intermission duration

  11. retraction • Retraction is a phenomenon of the uterus in labor in which the muscle fibres are permanently shortened. Unlike any other muscles of the body • Contraction is a temporary reduction in length of the fibres, which attain their full length during relaxation

  12. retraction The effects of retraction in normal labor are: • Formation of lower uterine segment and dilatation and effacement of the cervix • Maintain the advancement of the presenting part made by the uterine contractions and help ultimate expulsion of the fetus • To reduce the surface area of the uterus favoring separation of placenta • Effective haemostasis after the separation of the placenta

  13. Normal Labor and delivery Four factors for labor 2 Birth canal Psychical factors Force Fetus 影响分娩的四大因素

  14. Four factors for labor 2 Birth canal 产道 Soft tissue canal Bony canal Birth canal 影响分娩的四大因素

  15. Pelvis anatomical marks • Sacral promontory • Ischial spine (L,R) • Symphysis pubis

  16. Four factors for labor 2 Bony canal 骨产道 Birth canal 影响分娩的四大因素 Pelvic inlet plane Superior strait Midpelvis outlet least pelvic dimension plane Pelvic outlet plane Inferior strait pelvic axis:A hypothetical line curving through the midpoint of the pelvic planes

  17. Pelvic inlet plane Posteriorly by the promontory and alae of the sacrum, laterally by the linea terminalis Anteriorly by the horizontal Rami of the pubic bones and symphysis pubis 4 diameters of the pelvic inlet Anteroposterior: 11cm Transverse: 13cm Two obliques: 12.75cm

  18. Pelvic Inlet • 4 types in shape – gynecoid (50%), anthropoid, android, platypelloid. Most are intermediate type. • 4 diameters – anteroposterior(AP), transverse, and 2 obliques • Obstetrical conjugate – the shortest distance between promontory and symphysis pubis. Estimated by substracting 1.5 to 2 cm from the diagonal conjugate. • True conjugate – the A-P diameter of the pelvic inlet

  19. DC:distance from the lower margin of symphysis to promontory of the sacrum OC:From result according to the height and inclination of the symphysis pubis,OC can be measured by substracting 1.5-2cm, it should be 10cm or more

  20. 中骨盆平面 mid plane of pelvis The midpelvis at the level of Ischial spines is of particular importance following engagement of the fetal head in obstructed labor Anteroposterior diameter through the level of the ischial spines>11.5cm Interspinous diameter is 10cm or somewhat more

  21. pelvic outlet plane Consists of two approximately triangular areas not in the same plane but having a common base, Which is a line drawn between the two ischial tuberosities

  22. Lower uterine segment Four factors for labor 2 Cervix, floor of pelvis, vagina Soft canal 软产道 Birth canal 影响分娩的四大因素 Soft tissue part canal

  23. Soft part of birth canal Formation of uterine lower segment Cervix effacement and dilatation

  24. Isthmus:between anatomical internal OS and histological internal OS Physiological retraction ring :develops at the junction of the upper and lower uterine segment. As labor progresses, a boundary ridge on the inner uterine surface is marked between the thinning of the lower segment and the concomitant thickening of the upper Pathological retraction ring: also called Bandl ring, develops from the physiological ring when the thinning of the lower uterine segment is extreme, as in obstructed labor, the ring is very prominent, forming it.

  25. Four factors for labor Soft canal 软产道 2 Birth canal 影响分娩的四大因素 cervical effacement and dilatation 宫颈管

  26. Normal Labor and delivery Fetus Fetus 胎儿 Psychical factors Birth canal Force 产 力 产 道 胎 儿 精神因素 Four factors for labor 2 影响分娩的四大因素 Fetal lie胎产式 Fetal size胎儿大小 Fetal attitude 胎姿势 Fetal position 胎方位 Fetal presentation 胎先露 Fetal station 胎先露高低

  27. Four factors for labor 2 Fetus 影响分娩的四大因素 • Fetal lie • Relation of long axis of fetus to that of the mother. Longitudinal (99%), transverseor oblique

  28. Four factors for labor 2 Fetus 影响分娩的四大因素 • Fetal presentation • Fetal part that directly overlies pelvic inlet • Cephalic , breech , or shoulder

  29. Four factors for labor 2 Fetus 影响分娩的四大因素 Fetal position The relation of a chosen portion of the presenting part of the fetus to the right or left side of the maternal birth canal. For more accurately – anterior, transverse, posterior

  30. Four factors for labor 2 Fetus 影响分娩的四大因素 LOA (left occipito-anterior) ROA (right occipito-anterior) Denominator:bony fixed point on presenting part occiput

  31. Four factors for labor 2 Fetus 影响分娩的四大因素 LOT(left occipito-transverse) ROT(right occipito-transverse)

  32. Four factors for labor 2 Fetus 影响分娩的四大因素 LOP(left occipito-posterior) ROP(right occipito-posterior)

  33. Four factors for labor 2 Fetus 影响分娩的四大因素

  34. Four factors for labor 2 Fetus 影响分娩的四大因素 The fetus is in the occiput or vertex presentation in approximately 95% of all labor In majority of cases, the vertex enters the pelvis with the sagittal suture in the transverse pelvic diameter or the oblique lines The fetus enters the pelvis in the left occiput transverse(LOT) or LOA position in 40%;in the ROT or ROA in 20%; in OP position in 20%

  35. 4 step Leopold’s maneuvers • Gently palpate the fundus with the tip of the fingers of both hand in order to define which fetal pole is present in the fundus and appropriate size. 1 step • Run hands down maternal abdomen on either side of fetus to determine fetal lie, identifying small parts and fetal spine 2 step • Using the thumb and fingers of one hand, the lower portion of the maternal abdomen is grasped just above the symphysis pubis to determine the presentation 3 step • With the tips of the fingers of each hand, exerts deep pressure in the direction of the axis of the pelvic inlet to determine if the head or breech descended into the pelvis

  36. The mother should be supine • and comfortable position with • her abdomen bared • 2.During the first three maneuvers • the examiner stands at the side • of the bed that is most convenient • and faces the patient • 3.The examiner reverses this • position and face the feet for the • last maneuver

  37. Gently palpate the fundus with the tip of the fingers of both hand in order to define which fetal pole is present in the fundus and appropriate size. 1 step

  38. Run hands down maternal abdomen on either side of fetus to determine fetal lie, identifying small parts and fetal spine 2 step

  39. Using the thumb and fingers of one hand, the lower portion of the maternal abdomen is grasped just above the symphysis pubis to determine the presentation 3 step

  40. 4 step • With the tips of the fingers of each hand, exerts deep pressure in the direction of the axis of the pelvic inlet to determine if the head or breech descended into the pelvis

  41. fetus Adult bregma Suture: it permits gliding movement of one bone over the other during moulding of the head while the head passes through the pelvis; During Internal examination in labor, palpation of sagittal suture give an idea of the manner of engagement of the head

  42. post fontanelle(lambda) Occipital bone BPD(parietal bones diameter) Sagittal suture Bregma(Ant fontanelle) frontal bones fontanelle:wide gap in suture line The bones of the vault are not joined thus changes in the shape of the fetal head during labor can occur due to molding

  43. Four factors for labor Mechanism of labor 2 3 Outline Occiput presentation (枕先露的分娩机转) 1. The ability of the fetus to successfully negotiate the pelvis during labor involves changes in position of its head during its passage in labor 2. The mechanisms of labor, also known as the cardinal movements, are described in relation to a vertex presentation, as is the case in 95% of all pregnancies 3. In reality, the mechanism of labor consists of a combination movements that are ongoing simultaneously 4. For purposes of instruction, the various movements often are described as though they occurred separately and independently the cardinal movements are described as 7 discrete sequences, as discussed below Definition 1

  44. 6 3 2 5 4 1 Four factors for labor Mechanism of labor 2 3 internal rotation external rotation extension engagement descent flexion Outline Occiput presentation (枕先露的分娩机转) Definition 1 7. expulsion

  45. 1. Engagement Occiput presentation Mechanism of labor 3 (枕先露的分娩机转) • Passage of widest diameter of presenting part to level below the plane of the pelvic inlet • Occurs earlier in primigravidae, usually before the onset of labor while in multiparae, the same may occur in late 1st stage with rupture of the membrane ischial spines