PROCESS OF NORMAL LABOR

PROCESS OF NORMAL LABOR
CHAPTER 7

Events Before Onset of Labor
nUnknown what actually starts labor
nLightening: “baby drops down”, baby settles in maternal pelvis
nVaginal discharge or bloody show: pink stained mucus
nEnergy spurt or nesting time
nFalse labor: no cervical dilatation
nSpontaneous rupture of membranes or SROM
nCervical changes – effacement & dilatation
nsee Figures 7-1,Table 7-1

Major Variables in the Birth Process: The 4 P’s

nPELVIS--size and shape of the pelvis

nPASSENGER- fetus size and position

nPOWERS-effectiveness of contractions

nPSYCHE-preparation, previous experience


PELVIS
nMust be adequate proportions in order for the fetal head to fit through
nAngles are downward, forward, & upward somewhat like the letter “J”

PASSENGER
nFetal Head – must be able to stand extreme pressure
nFetal Bony Skull – bones thin, very elastic, allows for molding

Fetopelvic Relationship

nTerminology:
•Attitude, fig 7-3
• Lie – relationship of the longitudinal axis of the fetus to the mother, should be parallel, not crosswise
•Presentation, body part lowest in mother’s pelvis, fig 7-4
•Position, more specific description of the relationship of the fetal presenting part to the maternal pelvis, fig 7-4
•Station – fig 7-5, -5 to +5, ischial spines used, hardest to determine during a vaginal exam


POWERS-UTERINE CONTRACTIONS

nInvoluntary
nIntermittent but regular
nExhibit a wavelike pattern in 3 phases:
ØIncrement, building up
ØAcme, peak
ØDecrement, decreasing intensity
nAffected by maternal position
Ø supine, more freq, lower intensity
Ø side lying, less freq, more effective

Assessment of Uterine Contractionsfig 7-6

nFrequency: amount of time between the beginning of one contraction to the beginning of the next
nDuration: time between the onset of the contraction & it’s end
nIntensity: strength of the contraction, rough estimate made by palpation;
Ø mild – easy to indent, like touching tip of nose
Ø moderate – harder to indent but still able to; touching the chin
Ø strong – fundus is very firm & difficult to indent, like touching the forehead
PSYCHE--Psychological and Cultural factors that affect labor
nAnxiety and fear can decrease ability to cope, previous poor experience can effect present experience negatively
nCulture, ethnic background may play a strong role in the way a woman perceives labor and her reaction to it
nMaternal/newborn bonding very important!

MECHANISMS OF LABOR (cardinal movements)

nFigure 7-7
nEngagement and decent
nFlexion
nInternal rotation
nExtension
nCrowning
nExternal rotation
nDelivery of anterior shoulder
nDelivery of posterior shoulder & expulsion

Placental expulsion

n5-30 min after delivery s/s: lengthening of cord--change in shape of uterus-trickle or gush of vaginal blood
nDull- maternal side --Duncan’s mechanism or Dirty Duncan—usually implanted low in uterus
nShiny- fetal side- Schultz’s mechanism or Shiny Schultz—usually implanted high in uterus

FOUR STAGES OF LABOR

n1ST STAGE – begins with the onset of regular contractions until the cervix is fully dilated to 10cm
n2nd STAGE – begins when cervix is fully dilated & ends with birth of the infant
n3rd STAGE – begins with birth of the baby & ends with expulsion of the placenta
n4th STAGE – from placental expulsion to the end of the recovery stage – usually 1-4 hours

Phases of 1st STAGE OF LABOR-

nLATENT PHASE-EARLY STAGE 0-4CM – EARLY, SLOW PART
nACTIVE PHASE-MID PHASE 4CM-7CM – STRONGER CONTRACTIONS
nTRANSITION PHASE-- LAST PART 8CM-10CM-CONTRACTIONS STRONGER, MORE FREQUENT LASTING 60-90 SECS & WOMAN BECOMES IRRITABLE, ANXIOUS, SELF FOCUSED !!!!!


Second Stage of Labor

nExpulsion stage cervix 10 cm
nCoach-- do not hold breath more than 5 secs when pushing
ncrowning of fetal head—seen in external opening of vagina—recedes after contractions
nSecond stage lasts from a few minutes to 2 hours
nepisiotomy- midline or mediolateral
nsupport fetal head and check position of umbilical cord= nuchal cord
nBirth= relief for laboring woman

Third and Fourth Stage

nThird stage-

nBegins with birth to expulsion of placenta lasts up to 30 minutes
nOxytocin (Pitocin) given to keep uterus firm and lessen blood loss after delivery of placenta

nFourth stage-

nRecovery phase after delivery of placenta through first 1-4 hours or until VS stable. 250-500 ml blood loss. CRITICAL--Observe for excessive bleeding! Teach fundal massage.

Physiologic Changes in Laborsee table 7-2

nCardiovascular- increase in b/p, supine hypotension, increased pulse rate
nRespiratory- 02 demand equal to strenous exercise, hyperventilation—encourage to relax between contractions
nRenal--proteinuria, due to muscle breakdown; distended bladder, due to pressure
nGI--peristalsis and absorption decrease--NPO except ice chips, hydration by IV

Assessment of Fetal Health

Assessment of Fetal Health

Prenatal Fetal Assessment
•Why do antepartum testing?

To see if the fetus is okay.


Prenatal Fetal Assessment – table 6-1
• Diagnostic techniques and nursing considerations
§ Diagnostic (obstetric) ultrasound
§ Doppler ultrasound blood flow
§ Chorionic villi sampling
§ Amniocentesis
§ Percutaneous cord blood sampling
§ Nonstress test (NST)
§ Contraction stress test (CST)
§ Biophysical profile (BPP)
§ Vibroacoustic stimulation test
• Psychologic reactions to diagnostic testing – may produce fear & anxiety; allow time for questions & discussion

Fetal Assessment During Labor
• Fetal monitoring during labor is used to identify the healthy fetus vs the fetus showing signs of compromise; measures the response of the FHR to uterine contractions
• Intermittent FHR monitoring
Ø used for low risk pregnancies/labors see box 6-2
Ø uses a doppler or fetal monitor
Ø advantages: places fewer restrictions on maternal activity
Ø some health care providers feel legally vulnerable doing intermittent auscultation; there is a tendency to monitor FHR continuously

•Continuous electronic fetal monitoring
Ø can detect changes & problems immediately & intervene; there is a higher incidence of C-sections due to problems found
Ø data is transcribed on a continuous strip of graph paper or recorded in the computer-fig 6-5
•The nurse’s role
Ø reassuring heart rate pattern reflects adequate oxygenation
Ø nonreassuring heart rate pattern indicate presence of fetal distress,& appropriate nursing measures should be taken – fast focus 6-2
Ø documentation of interventions done on the strip as well as the medical record



Fetal Assessment During Labor
•Types of electronic monitoring
§External – skill 6-2, fast focus 6-3, fig 6-8
§Internal – fig 6-9, fast focus 6-4
•Relation of FHR to uterine contractions during labor: periodic changes – fig 6-10
Ø accelerations
Ø decelerations ( early & late)
Ø variable decelerations

Reassuring and Nonreassuring FHR Patterns – table 6-2

• Normal pattern /reassuring pattern– heart rate of 110-160 beats/min; beat to beat variability is between 6 – 25 beats/min, no decelerations
• Accelerations – brief, temporary increases in FHR of at least 15 beats/min above the baseline; sign of fetal well being
• Decelerations – transitory decreases in FHR from the baseline; labeled in relation to uterine contractions
§ Early
§ Late
§ Variable

EARLY DECELERATIONS
•Fig 6-10, A
•Slowing of FHR when contraction begins; returns to normal at the end of contraction
•Mirrors contraction
•Caused by head compression during contraction; vaginal exam; or fundal pressure
•No intervention required

Late Deceleration
•Fig 6-10, C
•Slowing of FHR after the contraction begins, when uterine blood flow is at a minimum; recover to normal is delayed, until uterine blood flow has resumed
•Causes: utero-placental insufficiency; inadequate fetal oxygenation; maternal HTN
•Interventions: change to side lying position, start O2 10L/min by MASK; correct hypotension if possible; discontinue oxytocin infusion; notify MD
Variable Decelerations
•Fig 6-10, B
•An abrupt, transient drop in FHR before, during, or after uterine contraction related to brief compression of the umbilical cord
•Causes: cord compression, short cord, prolapsed cord, cord around neck, oligohydramnios
•Intervention: Change maternal position, apply 02 if FHR does not respond, correct hypotension if possible, notify MD if measures do not work, amnioinfusioin

FETAL PULSE OXIMETRY
•A transcervical catheter placed against the fetal cheek; level should be between 40 – 70%
•Anything less than 30% may indicate fetal acidosis & require rapid delivery of fetus
•Amniotic membranes must be ruptured & cervix dilated to at least 2 cm

Amnioinfusion

• Intrauterine infusion of warm normal saline or Ringer’s lactate after ROM
• To decrease cord compression; increase fluid if oligohydramnios present; dilute intrauterine meconium; lessen risk of meconium aspiration
• Contraindicated with prolapsed cord, vaginal bleeding, severe fetal distress
• Must use an infusion pump for accurate administration
• Underpads used to absorb extra drainage