View
223
Download
1
Category
Tags:
Preview:
Citation preview
LaborLabor 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.
Labor - Mechanics Uterine contractions have two major goals:
1. To dilate cervix2. To push the fetus through the birth canal
Success will depend on the three P’s:1. Powers
2. Passenger3. Passage
PowerUterine contractionsPower 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.
Power
There is no specific criteria for adequate uterine activity
Generally 3-5 contractions in a 10 minute period is considered adequate labor
Passenger
Passenger =fetusFetal variables that can affect labor:Fetal sizeFetal Lie – longitudinal, transverse or obliqueFetal 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 fetusesPresence of fetal anomalies – hydrocephalus,
sacrococcygeal teratoma
Cervical effacement and dilation
StationStation – 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.
PassagePassage = PelvisConsists 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Bony pelvis can be measured by pelvimetry but it not accurate and thus has been replaced by a clinical trial of labor
Passage
www.uptodate.com
The Stages of Labor
First StageInterval 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, 1-1.2 cm /hour, regular uterine contractions
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.
LaborFreidman’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 0-30 min
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.
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:
1. Increased maternal show
2. Pelvic/rectal pressure3. Mother has active role
of pushing to aid in fetal descent.
Labor – Second StageMolding 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 – 0.5-3 h; mulitG 0-30min
Suctioning the nasopharynx
Clamp the umbilical cord
Cut between the clamps
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.
Labor – Third StagePlacenta 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
Inspect the placenta for completeness
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.
Labor – Fourth StageRefers to the time from delivery of the
placenta to 1 hour immediately postpartumBlood pressure, uterine blood loss and pulse
rate must be monitor closely ~ 15 minutesHigh 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!!!!!!
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
Seven distinct movements:
1.Engagement2.Descent3.Flexion4.Internal
rotation5.Extension6.External
rotation/restitution
7.Expulsion
Cardinal Movements of Labor
EngagementPassage of the widest diameter fetal presenting
part below the plane of the pelvic inletThe head is said to be engaged if the leading edge
is at the level of the ishial spines. DescentRefers to the downward passage of the presenting
part through the bony pelvisNot steady processGreatest at deceleration phase of first stage and
during 2nd stage of labor
Cardinal Movements of LaborFlexionOccurs 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 processComplete flexion places the fetal head in optimal
smallest diameter to fit through the pelvis
Internal RotationRotation of the fetal head from occiput transverse
to occiput either in anterior or posterior positionOccurs passively due to the shape of the bony
pelvis
Cardinal Movements of Labor
ExtensionOccurs when the fetus has descended to the level of
the vaginal introitusWhen occiput is just past the level of the symphysis,
the angle of the birth canal changes to upward position
External Rotation/RestitutionAs the head is delivered, it rotates back to its original
position prior to internal rotationIt aligns anatomically with the fetal torsoThe release of the passive forces on the fetal head
allows it to return to appropriate position
Expulsion
Delivery of the fetusAfter 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.
Analgesia in labor Discomfort during Labor and
BirthPain 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
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
Expression of painPain 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
Factors influencing pain response
Physiologic factorsCultureAnxietyPrevious experience
Childbirth preparation
Comfort and support
Environment
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-coloredshading indicates areas of intense discomfort.)
Nonpharmacologic Managementof 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
Nonpharmacologic Managementof Discomfort
Childbirth educationDick-Read methodLamaze methodBradley method
Relaxing and breathing techniquesRelaxationImagery and visualizationMusicTouch and massageBreathing techniquesEffleurage and counterpressureWater therapy (hydrotherapy)Transcutaneous electrical nerve stimulation
Pharmacologic Managementof Discomfort
Nerve block analgesia and anesthesiaLocal perineal infiltration
anesthesia
Prudendal nerve block
Spinal anesthesia (block) Disadvantages
Medication reactions (allergy)
Hypotension
Ineffective breathing
Headache Autologous epidural blood
patch
Sedatives
Analgesia and anesthesiaAnesthesia
Systemic analgesia Opioid agonist analgesics
Opioid (narcotic) agonist–antagonist analgesics
Co-drugs
Ataractics
Opioid (narcotic) antagonists
Pain Pathways and Sites of Pain Pathways and Sites of Pharmacologic Nerve BlocksPharmacologic Nerve BlocksA. A. Pudendal block; suitable Pudendal block; suitable
during second and third stages during second and third stages of labor and for repair of of labor and for repair of episiotomyepisiotomy
B.B. Epidural block; suitable Epidural block; suitable during all stages of labor and for during all stages of labor and for repair of episiotomyrepair of episiotomy
Pain Pathways and Sites Pain Pathways and Sites of Pharmacologic Nerve of Pharmacologic Nerve
BlocksBlocksNerve block analgesia and anesthesiaEpidural anesthesia/analgesia
Lumbar epidural anesthesia/analgesia
Walking epidural analgesiaEpidural and intrathecal opioids
Membranes and spaces of spinal Membranes and spaces of spinal cord and levels of sacral, cord and levels of sacral, lumbar, and thoracic nerveslumbar, and thoracic nerves
Cross section of vertebra and Cross section of vertebra and spinal cordspinal cord
Levels of Anesthesia Necessary for Levels of Anesthesia Necessary for Cesarean and Vaginal BirthsCesarean and Vaginal Births
Cesarean birth
Vaginal birth
Care ManagementPlan of care and interventions (cont’d)
Administration of medication Intravenous route Intramuscular route Spinal nerve block
Signs of potential problemsSafety and general careAnesthesia in the obese woman
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
In SummaryKnow the different stages of laborKnow the labor curveKnow the cardinal movements of laborKnow 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
Thank you for your attention!
Recommended