LABOR & DELIVERY

Lecture 6

Introduction

Uterus: pear-shaped muscle made of 3 layers: Endometrium – inner lining - shed during menses.

Myometrium - muscle layer – middle Perimetrium - outer layer -extra support to whole structure.

THEORIES of LABOR:

Combination of factors start labor: Oxytocin & prostaglandin - most important biochemical factors in stimulating uterine contractions. Estrogen ↑ uterus response & progesterone ↓ it.

THEORIES:

     Oxytocin Stimulation: Term uterus sensitive to oxytocin ↑ d/t pressure exerted on cervix by fetus.

Progesterone Withdrawl: ↓ progesterone by fetus & ↑ prostaglandins in chorioamnion results in ↑ uterine contxs. Estrogen Stimulation: ↓ progesterone allows estrogen to ↑ contractile response of uterus. Fetal Cortisol: Changes biochemistry of fetal membrane: ↓ progesterone & ↑ prostaglandin in placenta.

Distention: uterine muscles stretch causing ↑ prostaglandin.

Amniotic membranes (sac) makes arachidonic Acid → Prostaglandin - ^ uterine contractility.

Premonitory signs of labor: weeks before real labor AKA “ False Labor ”

      Lightening: Fetus settles into pelvic cavity. Braxton-Hicks: Irregular intermittent contractions; “ false labor ” ; DO NOT initiate true labor.

Cervical changes: cervix effaces [thins] & dilates slightly Baby's head in pelvis pushes against cervix causing relaxation and effacement.

Burst of Energy: Nesting instinct; cleans house, sets up nursery. ↑ epinephrine resulting from ↓ progesterone Cervix in posterior position.

Signs True Labor: closer to time of delivery

      Uterine Contractions: regular & frequent compared to Braxton-Hicks. Stronger w. time.

Bloody Show: pink tinged secretions d/t softening cervix.(aka mucous plug) Rupture of Membranes: (ROM) Labor in 24 hrs. Multiparas sooner. Big gush or slow trickle. Clear/odorless. Green/brown, danger sign Meconium aspiration > distress/infection.

Immediate medical attention. PROM or prolonged ROM – intrauterine infection [pathogens reach fetus]

Difference Between True & False Labor:

True Labor A. regular contx ’ s B. discomfort begins in back & spreads to abdomen. C. progressive cervical dilation/effacement D. Interval between contx.

’ s become shorter E. intensity of contx.

’ s ↑ with ambulation F. contx.

’ s ↑ in duration & intensity False Labor A. irregular contx.

C. no change D. No change F. No change ’ s B. discomfort localized in abdomen E. Ambulation has no effect

“

STAGES of LABOR

”

4 in All !

First Stage

Onset of true labor to complete dilation = 10 cm. ~ 6-18 hrs. primapara; 2-10 hrs. multipara. Cervix becomes more anterior.

3 phases

: Latent, Active, Transitional.

Latent

: Dilation 0-3 cms. Contx.

’ s mild/irregular.

Active

: 4-7 cms. Contx.

’ s 5-8 min. apart. Lasts 45-60 sec; moderate - strong intensity.

Transitional:

Dilation 8-10 cms. Contx.

’ s 1-2 min. apart; 60 – 90 sec.; strong intensity.

No pushing til fully dilated.

Second Stage: “Birthing of Baby”

Delivery of infant: up to 1 hr. or ~ 20 contx ’ s – primip. 20 min. or ~ 10 contx ’ s in multip. Can last up to 3 hrs.!

Cardinal movements occur here. Most difficult & uncomfortable part of labor.

Crowning occurs at +4 -+5 station.

Strong urge to push & bear down as infant passes through vagina & rectum – may have BM.

Positions: Sitting, Side Lying, Standing, Squatting, All Fours, Kneeling.

“Crowning” - External view “Cardinal Movements” - Internal motions

Third Stage

Delivery of placenta ~ 5 - 30 min.

Separation should be automatic [uterus contracts & mom bears down] Don’t palpate non-contracted uterus –possible eversion. Maternal vessels still open. MD/MW presses on contracted uterus. “

Crede’s

Maneuver”

Pitocin > placenta delivered to avoid retained placenta. If no spontaneous delivery of placenta, manually removed.

 Antibiotics

Fourth Stage

Placenta out; mother recovers in “LDR” “Labor, delivery, & recovery” Lasts ~ 1 hr. unless complications arise. Then pt. transferred to PP unit.

Nursing Interventions During Labor

    Triage - Admit client to birthing area

[MD determines true labor]

Emotional support & encourage rest Progress of labor Monitor/document contractions & FHR q 15 min.

 M onitor/document maternal VS q 1 - 4 hr  Assess pain & provide pain relief as prescribed .

Nursing Interventions Cont.

* Provide comfort measures [back rub, ice chips] * Explain equipment & procedures.

*

Observe & document time of ROM       Supine hypotension – Position on side - pressure off vena cava Role of coach during active/transitional stages Assist with pushing during 2 nd stage.

Record time of delivery, Apgar score, spontaneous cry, & resuscitative efforts to infant Monitor infant for extrauterine life adjustment Encourage family bonding > delivery

Breathing Techniques

   Slow chest: 6-12 “easy” breaths/min. Used in early labor. Combination: quicker, lighter breaths Used during active labor; one slow breath in beginning & quicker breaths to follow.

Pant-Blow: Used @ 3 - 4 quick breaths, with forceful exhalation.

end

of 1st stage when contx.’s strongest.

Elimination

Monitor UO q 2-4 hr. Pressure of fetal head reduces bladder tone. Full bladder > inhibits labor. Catheterize. Remove > delivery.

Hydration

IV to hydrate; pt. diaphoretic & NPO x ice chips.

Lactated ringers; good volume expander.

      

Assessing Progress of Labor

Dilation: 0 – 10 cm. [opening cervix] Effacement: 0 – 100 % [thinning cervix] Station: Relationship of presenting part to pelvic

ischial spines

-

midway

in pelvic cavity.

“

0

”

station aka

“

e

ngaged ” .

-1 to -5

above

“0” +1 to +5 (outlet)

below

“0” +4/+5: baby's head out.

Mechanism of Labor

: passage of fetus thru birth canal involves position changes called:

Cardinal Movements of Labor:

mechanical & spontaneous. “2 nd stage”

Engagement Descent:

thru pelvis. : presenting part enters midpoint of pelvis @ ischial spines. downward movement thru pelvic inlet, thru dilated cervix, reaches posterior vaginal floor. Mom feels like pushing. Widest part [head] passed “active forces of labor.”

Flexion:

pressure from pelvic floor causes head to flex towards chest; chin touches chest.

Internal Rotation

: occiput [back of head] in diagonal position & rotates towards face down

position. / to ↓

(occurs as body parts press on bony pelvic structures)

Extension

: top of head delivered & extends as face & chin are delivered.

External Rotation

delivered.

: head rotates back to previous lateral position. Rest of body is

Factors affecting labor process: 4 P’s [Powers of Labor]

– Passenger – Passageway – Powers – psyche

Passenger: [infant]

Fetal head

fontanelles.

: widest part of body; most difficult to pass thru vaginal canal; passage depends on bones, sutures, Cranium - 8 bones meet @ suture lines Cranial bones move & overlap, allows skull to pass thru birth canal. Fontanelles: soft spaces created by to aid in passage of fetus. “Molding” of infant head.

junctures of suture lines - covered by membranes; compress during delivery

Passenger cont

.

  Skull widest @ antero-posterior diameter [front to back] than @ transverse diameter [across]. Antero-posterior diameter @ different locations.

measures differently   Occipitomental diameter- widest - measured from chin to posterior fontanelle = 13.5 cm Smallest diameter - lower occiput to anterior fontanelle (suboccipitobregmatic) = 9.5 cm 

Complete flexion

allows smallest diameter of fetal skull to enter pelvis most easily .

B. Fetal Attitude

: degree of flexion of fetal head; chin touches sternum. Complete flexion : allows smallest diameter of skull to pass thru pelvic cavity. Best position!

Moderate flexion : head less flexed making diameter wider (aka military or neutral) Poor flexion: brow or face presentation; presents skull diameter too wide making delivery difficult.

Friedman’s Curve

 Friedman's Curve describes progress of two variables over time: dilation of cervix and descent of baby.  Labor is “dysfunctional” when cervix stops dilating or fetal descent stops or both.

   Possible diagnosis of "failure to progress" C-section indicated. Maybe due to CPD (cephalo pelvic disproportion or epidural anesthesia (can slow labor).

C. Fetal lie

: [position of fetus in utero] relationship of long axis of fetus [spine] to long axis of mother:

1. Longitudinal

– vertex/breech; vertical in relation to mom; ~ 99%.

2. Transverse

– horizontal in relation to mom; < 1 %.

C/S; ^ in grand multip – stretched uterine muscles; try version.

3. Oblique - diagonal

D. Fetal presentation

: part of fetal head enters pelvis; 1. Cephalic 95.5% 2. Breech 3.5% 3. Face 0.3% 4. Shoulder 0.4% [transverse lie]

E. Fetal position

: “occiput is landmark”

Described in 3 letters : 1 st

: presenting part in relation to mother ’ s R or L. Middle: presenting part [occiput, mentum, sacrum ] Last: landmark is anterior, posterior, transverse to mother ’ s spine. Anterior (A) back of head against symphysis pubis & face towards spine. Posterior (P) Back of head = mother = fetus sideways.

’ in relation s spine; painful contxs. Transverse (T) Common positions in vertex presentations: *LOA, ROT, ROP, ROA, LOT, LOP.

Passageway:

Refers to fetus passing thru uterus, cervix, vaginal

canal.

Single most important determinant to mechanism of labor.

A. 4 Types of pelvis :



1. Gynecoid – 50% of women; rounded, oval shape; easy vaginal delivery; considered “ normal female pelvis ”

 2. Android – 20 % of women; vaginal delivery difficult; prob. C/S; “ true male pelvis ”  3. Anthropoid – forceps; 20-25% oval; assisted vaginal birth usually with

 4. Platypelloid – < 5 % of women; flattened pelvis; vag. del. difficult

B. Structure of Pelvis :

bones held together by ligaments. Supports/protects organs inside. False Pelvis: Outer - broader. Hip bones.

True Pelvis: Internal – narrower. Holds bladder, rectum, & reprod. Organs.

True pelvis - 3 parts - inlet, midpelvis, outlet.

[Most important in childbirth]   If pelvis too small, home birth not done. CPD - cephalopelvic disproportion > C/S.

PELVIC INLET

: Antero-posterior diameter - front to back ~ 12.5 cm. (diagonal conjugate) True conjugate - actual opening of outlet. Subtract width of symphysis pubis [1.5 cm] from diagonal conjugate. 12.5 – 1.5 = 11.0 cm.

(complete flexion = 9.5cm diameter) Transverse diameter [across] ~ 13.5 cm

MIDPELVIS

: narrowest part of pelvis that fetus must pass through - “ischial spines”

PELVIC OUTLET

: Trouble passing through pelvic opening, pelvis too small or poor fetal attitude.

Soft Tissue

: Ligaments, Uterus, cervix, vaginal

canal

Powers:

 Uterine contx ’ s: primary force moving fetus thru maternal pelvis during 1st stage of labor.

 Maternal Efforts: woman adds voluntary pushing force to force of contx.

’ s during 2nd stage of labor to propel fetus thru pelvis.

Psyche:

Psychologic Response to birth process:       Prepared for childbirth - Childbirth classes-Prenatal care.

Previous childbirth experience - Complicated?

Support from significant other - Separated? Marital strain? FOB involved? Abuse?

Emotional status - anxious/depressed, drug use, psych hx Culture - background may influence response to pain. Some moan, some stoic, some verbally expressive. Fear/anxiety exacerbate pain → uterine dysfunction & ineffectual labor & posttraumatic stress disorder

Maternal/Fetal Evaluation During Labor With Electronic External/Internal Monitoring

EFM “electronic fetal monitoring” Measures: Fetal Heart Rate (FHR) and Uterine Contractions (UC) • • External – Toco (UC) and Cardio (FHR) Toco transducer uses graph paper [60 sec intervals] UC assessed for intensity, length, frequency.

Abdominal palpation. Uterus hard then soft.

3 Phases of UC: a. increment ↑ b. acme [peak] c. decrement As contractions intensify, labor progresses.

Vaginal Exam -

dilation, effacement, station, & presentation

.

Assessment:

Intermittent

- 20 minute tracing standard.

Continuous -

for active labor or with complications.

Duration: beg. of contx. to end of same contx. Lasts ~ 30 sec. [early] to ~ 60 sec. [active].

Frequency: beg. of one contx. to beg. of next.

~ q 5 -30 min.

early

labor; q 2-3 min.

active

labor.

Resting Tone: period of uterine rest bet. contx.

’ s. Measure by palpation; internally measures ~10 mmHg.

   

Be Careful Not To

….

Rely on verbal clues from mother regarding contractions & labor progress.

Misleading, giving false impression of good labor pattern. Contractions may be more or less intense than what pt. reports. RN may miss forceful contractions d/t excellent coping skills or high pain tolerance

External Fetal Monitoring

Also Records: Fetal Heart Rate (cardio transducer) FHR Advantages: Evaluates contractions & FHR Provides written record of both Disadvantages: May be inaccurate due to maternal/fetal movements.

Need experienced clinician to read otherwise info can be misinterpreted.

Internal Monitoring

More Accurate !

Fetal scalp electrode: wire electrode attached to scalp of fetus -monitors FHR accurately & continuously. Advantages: precise assessment of FHR; not affected by fetal movement.

Disadvantages: lacerations of fetal scalp, mom can ’ t ambulate.

IUPC -intrauterine pressure catheter inserted into uterine cavity to monitor contx.’s precisely/continuously.

Advantages: precise assessment of maternal contractions. Mom can turn side to side.

Measures Intensity: “strength” of UC internally [30-50mmHg during peak of contx] Disadvantages: ↑ risk of maternal infection, mom can’t ambulate.

Fetal Heart Rate



“

Baseline

”

average fetal heart rate that occurs between contx.

’ s during 10 min. period.

Normal 110/120 - 160 [accels/decels not counted]  

Bradycardia

– FHR < 110 for 10 minutes; <100bpm sign of fetal hypoxia; danger sign.

Seen with prolapsed cord 

Tachycardia

– FHR > 160 for 10 minutes.

assoc. with maternal temp. and infection such as chorioamnionitis.

Variability [FHR] aka “Baseline Variability”

 “Fluctuations” in FHR. Normal & expected finding. Should always be present; appears as “jitters”.     Clinical Significance fetal well-being .

Caused by natural pacemaker ability effects of sympathetic & parasympathetic nervous system.

of FH d/t Nursing Interventions- cont. monitoring & assess tracing q 15 min. Should show 6-25 bpm fluctuations within one min. period. 120 → 135 “reassuring”

Main Causes of decreased variability include: Hypoxemia/acidosis (due to fetal distress) Fetal sleep cycles Drugs (Analgesics, barbiturates, tranquilizers, anesthetics) Prematurity Arrhythmias Fetal tachycardia Preexisting neurological abnormality Congenital anomalies

Decreased variability of FHR   Nursing Interventions: * accoustic stimulation to “wake” fetus * Narcan * Amnioinfusion - decreases cord comp; dilutes mec. * Left/right lateral position or knee-chest; notify MD; fetal scalp pH, possible emergency C/S; IVF, O2 “Flat tracing” or “minimal” aka non-reactive tracing [pencil mark pattern] indicates fetal distress; must be corrected or delivered ASAP. Experienced RN usually able to determine reason for non-reactive tracing.

How Do Uterine Contractions Affect Fetal Heart Rate?

Uterine contractions can affect fetal heart rate by increasing or decreasing that rate in association with any given contraction.

The three primary mechanisms by which uterine contractions can cause a decrease in fetal heart rate are compression of:

  

Fetal head compression Umbilical cord compression Uterine myometrial vessel compression

Decelerations: decreases in FHR. Early deceleration of FHR- periodic ↓ in FHR

    Cause = head compression during contx.

’ s  Shape= onset of decel to peak > than 30 sec.

Nadir of decel (lowest point) & peak of contx. (highest point) coincide. Mirror image of contx.

Range= lasts as long as contx.; resolves with end of contx. Occurs late in labor when head has descended.

Clinical Significance= normal; if it occurs early in labor before head fully descends, may be indication for cephalo-pelvic disproportion [CPD].

Late deceleration of FHR:

    Cause= uteroplacental insufficiency or ↓ blood flow thru uterus during contx.

’ s Shape – nadir of decel. occurs > end of contx.

range - occur 30-40 seconds > contx. starts & continue > contx. ends clinical significance time for recovery] – needs immediate attention; possible fetal distress. Could be d/t pitocin that is causing hypertonic uterus.[ too many contx.- no

Nursing Interventions: -Left lateral position –takes pressure off aorta & vena cava; ↑circulation to uterus.

-↑ IV flow rate – ↑ Circulation –oxygen - face mask [5liters/min].

–D/C pitocin & document –assist with fetal blood sampling –[measures acidosis in fetus which signifies hypoxia] –Prepare for emergency C/S if decels. persist

Variable deceleration of FHR

Cause: compressed umbilical cord Shape – U or V shaped waves in FHR Range – no pattern; occur in relation to contx.

’ s Clinical Significance – dangerous if persist. fetus lying on cord; could be Occurs more > ROM [less fluid as cushion] V = C variable decels = cord compression E = H early decels = head compression A = O accelerations = OK L = P late decels = Placental insufficiency Bradycardia = R/O prolapsed cord [emergency]!

 

Nursing Interventions

– oxygen via face mask; IV fluids – change maternal position; take pressure off cord – continue monitoring w.EFM

– follow hospital protocol: MD will do amnioinfusion > ROM to supplement amniotic fluid that ’ s left; provides fluid barrier to prevent further cord compression.

Sterile, warm 500 ml NS/RL inserted into uterus EFM observed for improved FHR pattern.

 4. Accelerations of FHR: temporary abrupt increase in FHR above normal baseline.

cause- fetal movement; contractions *   shape-FHR rises w. return to baseline; can occur @ same time as contx. or independently.

Premie < 32 wks.; 10 bpm rise lasting 10 sec. ok    32 wks. or >, 15 bpm rise baseline lasting 15 sec. ok ex. 135 ↑ to 150’s for 30 seconds.

clinical significance: normal; signifies fetal well-being. FHR meeting demands of labor process well.

Fetal Blood Sampling- assesses fetal hypoxia; from fetal scalp [cervix dilated 3-4 cm]. Clean scalp w. iodine. Results: 7.25ph > normal 7.20 -7.24 preacidotic < 7.2 + acidosis; indicates hypoxia [↓ O2]

Role of Coach in Labor & Delivery

– emotional support – physical support – touch, massage – reduce anxiety – bonding with newborn as a couple

Obstetrical Procedures

Episiotomy: incision on perineum to

enlarge vaginal outlet. New trend: not done routinely. (in 2 nd stage)

Types:

Median to heal.

– vertical incision. Medio-lateral – slanted to R/L of perineum; done if tear anticipated.

Advantages: median or midline epis.

medio-lateral prevents tearing towards rectum. Less chance of laceration.

Disadvantages: medio-lateral -longer

Forceps: double bladed instrument to assist passage of fetus. Not routinely done today.   When 2nd stage labor has stopped d/t epidural Infant in abnormal position; posterior position in birth canal; macrosomia.

[Outlet] Low forcep delivery: fetal head @ + 2, +3 station. Some anesthesia used. Midforceps & High forceps: not done ^ birth trauma. Cervical lacerations; Newborns > facial palsy or subdural hematoma; forcep marks on face.

Vacuum Assisted Delivery:

disk shaped cup placed on scalp & vacuum pressure applied; Used in C/S.

“ pull ” will deliver infant. No anesthesia - fewer cervical lacerations. Not done in preterm infants d/t soft skull.

  Not used > scalp pH done; risk for hematoma [vacuum pressure].

Can cause caput for ~ 1 wk. Used w.macrosomia.

VBAC [vaginal birth after cesarean]

OK after low abd. incision; Not after classical incision - risk for uterine rupture. New Trend: not routinely done anymore. ** Pros & cons  

1st baby: breech, fetal distress, pre-eclampsia

Should space deliveries ~18 mos. apart. to prevent rupture

Types of Uterine Incisions:

Low transverse = Pfannenstiel = cases; “ crash ” “ bikini cut C/S. Quick access to baby. ” . Most desired & less visible. Right above pubic bone.

Vertical=classical incision. Visible scar; emergency

Cesarean Delivery ( C-section) Major Indications for C/S:           Active genital herpes or overgrowth of genital warts HIV infection CPD (cephalopelvic disproportion) Severe HTN (toxemia) Failure to progress with labor Previous C/S with classical incision (vertical) Placenta previa Placental abruption –separation of placenta from uterus Cord Prolapse; Macrosomia = large fetus Breech positions; Fetal Distress & Transverse fetal lie

Induction of Labor: start labor. Goal: NSVD

Without Meds.- Natural

Amniotomy: Artificial ROM; amnio hook; break sac.

Monitor for poss.prolapsed cord. Continue EFM. Usu.starts contx.

’ s & labor progresses [@ 3 cm dilation]

With Meds

. Pitocin drug of choice. 1/3 rd deliveries @ term in US done by induction. Reason: Life in uterus no longer beneficial *Fetal maturity 39 wks, post dates 41-42 wks.

*Cervical Readiness- ripe; ≥3 cm. dilated.

*Longitudinal lie; presenting part engaged *Fetal Demise, Arrest of Labor Induction - give Pitocin IVPB, ^ slowly as labor progresses; shut off if contx ’ s too strong. Need MD order.

Augmentation: assisting labor that ’ s in progress. Pitocin used. Contraindications: Maternal: placenta previa; active herpes; structural abnormalities; previous vertical uterine scar Fetal: transverse or breech; fetal distress; premie.

Nursing Interventions:

           IVF 10 units Pitocin in 1000 ml. RL Start rate @ 1 milliunit/min - pump Gradually ↑ to establish effective contx. pattern Monitor UC for frequency, rate, intensity Monitor FHR for signs of fetal distress Maternal BP, pulse, temp I&O Notify MD of progress Chart q 15 min on graph Prepare for delivery: radiant warmer, O2, suctioning, Hyper-stimulation of uterus; shut off pitocin as per MD.

Bishop’s score: determines cervical readiness for induction; looks at 5 factors. Score ≥ 8 favorable.

  Multip can be induced @ 5 Primip can be induced @ 7 Uterus/cervix should respond to induction. Score < 5 low probability of success. Ripen cervix 1st.

Bishop Scoring System - evaluates cervical readiness for induction. 5 elements measured: Score Cervical Cervical Station Cervical Position dilation effacement consistency _______cm.________%_______________________________ 0 closed 0-30 -3 firm posterior 1 1-2 40-50 -2 medium mid 2 3-4 60-70 -1, 0 soft anterior 3 >5 >80 +1, +2

Cervical Ripening: Artificial softening of cervix before labor. Prostaglandin gel 0.5mg.or dinoprostone 10mg.=[cervidil] 2-3 times q 12 for max. of 24 hrs. * Done if cervix “unripe” or thick & undilated.