1. Physiology of delivery. Analgesia in labor.
Korda I.

2. Labor
Labor is the physiologic process by which a fetus is expelled form the uterus to the outside world.
It involves the sequential integrated changes in the uterine decidua, and myometrium.
Changes in the uterine cervix tend to precede uterine contractions
Dilatation: the enlarging of the cervix to 10 centimeters.
Effacement: the thinning of the cervix. Your cervix starts out being two inches long, and 50% effaced would be a 1 inch cervix.

3. To push the fetus through the birth canal
Labor - Mechanics
Uterine contractions have two major goals:
To dilate cervix
To push the fetus through the birth canal
Success will depend on the three P’s:
Powers
Passenger
Passage

4. Power
Uterine contractions
Power refers to the force generated by the contraction of the uterine myometrium
Activity can be assessed by the simple observation by the mother, palpation of the fundus, or external tocodynamometry.
Contraction force can also be measured by direct measurement of intrauterine pressure using internal manometry or pressure transducers.

5. Power There is no specific criteria for adequate uterine activity
Generally 3-5 contractions in a 10 minute period is considered adequate labor

6. Passenger Passenger =fetus Fetal variables that can affect labor:
Fetal size
Fetal Lie – longitudinal, transverse or oblique
Fetal presentation – vertex, breech, shoulder, compound (vertex and hand), and funic (umbilical cord).
Attitude – degree of flexion or extension of the fetal head
Position
Number of fetuses
Presence of fetal anomalies – hydrocephalus, sacrococcygeal teratoma

7. Cervical effacement and dilation

8. Station -5 is a floating baby,
Station – degree of descent of the presenting part of the fetus, measured in centimeters from the ischial spines in negative and positive numbers.
-5 is a floating baby,
0 station is said to be engaged in the pelvis,
and +5 is crowning.

9. Passage
Passage = Pelvis
Consists of the bony pelvis and soft tissues of the birth canal (cervix, pelvic floor musculature)
Small pelvic outlet can result in cephalopelvic disproportion
Bony pelvis can be measured by pelvimetry but it not accurate and thus has been replaced by a clinical trial of labor

10. Passage

11. The Stages of Labor First Stage
Interval between the onset of labor and full cervical dilation
Two phases:
Latent phase – onset o f labor with slow cervical dilation to ~4 cm and variable duration
Active phase – faster rate of cervical change, cm /hour, regular uterine contractions

12. The Labor Curve
First stage - A: latent phase; B + C + D: active phase; B: acceleration; C: maximum slope of dilation; D: deceleration; E: second stage.

13. Labor
Freidman’s curve is a good guideline for expected progression in labor and therefore helpful to note abnormal labor patterns.
Labor
NulliG
MultiG
1st Stage
Active
phase
Duration
6-18 h
2-10 h
Dilation
~1 cm/h
~1.5 cm/h
Arrested
>2 h
>2h
2nd Stage
0.5-3 h
5-30 min
3rd Stage
0-30 min

14. Fig 1: An idealized labor pattern
Fig 1:  An idealized labor pattern.  The normal patterns of cervical dilation (solid line) and descent (broken line) as they are traced against elapsed time in labor. The distinctive phases of the first stage are shown. The active phase comprises the interval from the onset of the acceleration phase to the beginning of the second stage.

15. Labor – Second Stage
Interval between full cervical dilation to delivery of the infant.
Characterized by descent of the presenting part through the maternal pelvis and expulsion of the fetus.
Indications of second stage:
Increased maternal show
Pelvic/rectal pressure
Mother has active role of pushing to aid in fetal descent.

16. Labor – Second Stage
Molding is the alteration of the fetal cranial bones to each other as a result of compressive forces of the maternal bony pelvis.
Examining the fetal head during the second stage may become difficult due to molding
Caput is the localized edematous area on the fetal scalp caused by pressure on the scalp by the cervix.
PrimiG – h; mulitG 0-30min

17. Suctioning the nasopharynx
Cut between the clamps
Clamp the umbilical cord

18. Labor – Third Stage Placental separation and delivery.
The time from fetal delivery to delivery of the placenta
Signs of placental separation:
a. The uterus becomes globular in shape and firmer.
b. The uterus rises in the abdomen.
c. The umbilical cord descends three (3) inches or more further out of the vagina.
d. Sudden gush of blood.

19. Labor – Third Stage
Placenta is delivered using one hand on umbilical cord with gentle downward traction. Other hand on abdomen supporting the uterine fundus.
Risk factor for aggressive traction is uterine inversion.
Obstetrical emergency!!
Normal duration between 0-30 min for both PrimiG and MultiG

20. Inspect the placenta for completeness

22. AMTSL = Active management of third stage of labour
AMTSL = Active management of third stage of labour. RP = retained placenta. CCT = controlled cord traction. Hb = Haemoglobin. BP = Blood pressure. MRP = Manual removal of placenta. Hb = haemoglobine.

23. Labor – Fourth Stage
Refers to the time from delivery of the placenta to 1 hour immediately postpartum
Blood pressure, uterine blood loss and pulse rate must be monitor closely ~ 15 minutes
High risk for postpartum hemorrhage from:
Uterine atony, retained placental fragments, unrepaired lacerations of vagina, cervix or perineum.
Occult bleeding may occur – vaginal hematoma
Be suspicious with increased heart rate, pelvic pain or decreased BP!!!!!!

24. Cardinal Movements of Labor
This refers to the movements made by the fetus during the first and second stage of labor. As the force of the uterine contractions stimulates effacement and dilatation of the cervix, the fetus moves toward the cervix.
When the presenting part reaches the pelvic bones, it must make adjustments to pass through the pelvis and down the birth canal

25. Seven distinct movements:
Engagement
Descent
Flexion
Internal rotation
Extension
External rotation/restitution
Expulsion

26. Cardinal Movements of Labor
Engagement
Passage of the widest diameter fetal presenting part below the plane of the pelvic inlet
The head is said to be engaged if the leading edge is at the level of the ishial spines.
Descent
Refers to the downward passage of the presenting part through the bony pelvis
Not steady process
Greatest at deceleration phase of first stage and during 2nd stage of labor

27. Cardinal Movements of Labor
Flexion
Occurs passively as the head descends due to the shape of the bony pelvis.
Partial flexion occurs naturally but complete flexion usually occurs only in the labor process
Complete flexion places the fetal head in optimal smallest diameter to fit through the pelvis
Internal Rotation
Rotation of the fetal head from occiput transverse to occiput either in anterior or posterior position
Occurs passively due to the shape of the bony pelvis

28. Cardinal Movements of Labor
Extension
Occurs when the fetus has descended to the level of the vaginal introitus
When occiput is just past the level of the symphysis, the angle of the birth canal changes to upward position
External Rotation/Restitution
As the head is delivered, it rotates back to its original position prior to internal rotation
It aligns anatomically with the fetal torso
The release of the passive forces on the fetal head allows it to return to appropriate position

29. Expulsion Delivery of the fetus
After delivery of the fetal head, descent and intraabdominal pressure by mother brings shoulder to the level of the symphysis
Downward traction allows release of the shoulder and the fetus is delivered.

30. Analgesia in labor Discomfort during Labor and Birth
Pain and discomfort experienced during labor have
two neurologic origins: visceral and somatic
Neurologic origins
Visceral pain: from cervical changes, distention of lower uterine segment, and uterine ischemia
Located over the lower portion of abdomen
Referred pain: originates in uterus, radiates to abdominal wall, lumbosacral area of back, iliac crests, gluteal area, and down the thighs
Somatic pain: pain described as intense, sharp, burning, and well localized
Stretching and distention of perineal tissues and pelvic floor to allow passage of fetus, from distention and traction on peritoneum and uterocervical supports during contractions, and from lacerations of soft tissue

31. Perception of pain
Threshold remarkably similar in all, regardless of gender, social, ethnic, or cultural differences
Differences play definite role in person’s perception of and behavioral responses to pain

32. Expression of pain
Pain results in physiologic effects and sensory and emotional (affective) responses
Emotional expressions of suffering often seen
Increasing anxiety
Writhing, crying, groaning, gesturing (hand clenching and wringing), and excessive muscular excitability
Cultural expression of pain varies

33. Factors influencing pain response
Physiologic factors
Culture
Anxiety
Previous experience
Childbirth preparation
Comfort and support
Environment

34. Distribution of labor pain
A. Distribution of labor pain during first stage
B. Distribution of labor pain during later phase of first stage and early phase of second stage
C. Distribution of labor pain during later phase of second stage and during birth
(Gray shading indicates areas of mild discomfort; light-colored shading indicates areas of moderate discomfort; dark-colored shading indicates areas of intense discomfort.)

35. Nonpharmacologic Management of Discomfort
Nonpharmacologic measures often simple, safe, and inexpensive
Provide sense of control over childbirth and measures best for woman
Methods require practice for best results
Try variety of methods and seek alternatives, including pharmacologic methods, if measure used is not effective

36. Nonpharmacologic Management of Discomfort
Childbirth education
Dick-Read method
Lamaze method
Bradley method
Relaxing and breathing techniques
Relaxation
Imagery and visualization
Music
Touch and massage
Breathing techniques
Effleurage and counterpressure
Water therapy (hydrotherapy)
Transcutaneous electrical nerve stimulation

37. Pharmacologic Management of Discomfort
Sedatives
Analgesia and anesthesia
Anesthesia
Systemic analgesia
Opioid agonist analgesics
Opioid (narcotic) agonist–antagonist analgesics
Co-drugs
Ataractics
Opioid (narcotic) antagonists
Nerve block analgesia and anesthesia
Local perineal infiltration anesthesia
Prudendal nerve block
Spinal anesthesia (block)
Disadvantages
Medication reactions (allergy)
Hypotension
Ineffective breathing
Headache
Autologous epidural blood patch

38. Pain Pathways and Sites of Pharmacologic Nerve Blocks
A. Pudendal block; suitable during second and third stages of labor and for repair of episiotomy
B. Epidural block; suitable during all stages of labor and for repair of episiotomy

39. Pain Pathways and Sites of Pharmacologic Nerve Blocks
Nerve block analgesia and anesthesia
Epidural anesthesia/analgesia
Lumbar epidural anesthesia/analgesia
Walking epidural analgesia
Epidural and intrathecal opioids

40. Membranes and spaces of spinal cord and levels of sacral, lumbar, and thoracic nerves
Cross section of vertebra and spinal cord

41. Levels of Anesthesia Necessary for Cesarean and Vaginal Births
Cesarean birth
Vaginal birth

42. Care Management Plan of care and interventions (cont’d)
Administration of medication
Intravenous route
Intramuscular route
Spinal nerve block
Signs of potential problems
Safety and general care
Anesthesia in the obese woman

43. Key Points
Expected outcome of preparation for childbirth and parenting is “education for choice”
Nonpharmacologic pain and stress management strategies are valuable for managing labor discomfort alone or in combination with pharmacologic methods
Gate-control theory of pain and stress response are bases for many of the nonpharmacologic methods of pain relief
Type of analgesic or anesthetic used is determined in part by stage of labor and method of birth
Opioid effects can be potentiated with ataractics

44. In Summary Know the different stages of labor Know the labor curve
Know the cardinal movements of labor
Know the causes of postpartum hemorrhage
MD must understand medications, expected effects, potential adverse reactions, and methods of administration
Maternal fluid balance is essential during spinal and epidural nerve blocks
Maternal analgesia or anesthesia potentially affects neonatal neurobehavioral response
Use of opioid agonist-antagonist analgesics in women with preexisting opioid dependence may cause symptoms of abstinence syndrome (opioid withdrawal)
General anesthesia rarely used for vaginal birth
May be used for cesarean birth or when needed in emergency childbirth situation

45. Thank you for your attention!