OB Exam 2

labor

function by which the products of conception (fetus, amniotic fluid, placenta, membranes) are separated and expelled from the uterus through the vagina into the outside world

true labor

• cervix softens, effaces and dilates and moves anteriorly

• contractions become “longer, stronger and closer together”

• regular contraction pattern

• intensity increases with walking or standing

• felt in lower back and radiate to lower abdomen

• continue to increase in intensity despite comfort measure or position changes

false labor

• usually little or no cervical change 

• cervix often stays in poster position 

• contractions have irregular pattern and intensity does not increase with time 

• contractions are easily interrupted with medications, walking or position change 

• felt in back or upper fundal area

labor initaition (patient) 

• uterine muscles stretch releasing prostagladins 

• pressure on cervix from fetus stimulates release of oxytocin (Ferguson reflex

• estrogen/progesterone ratio shifts so that estrogen stimulates contractile response of uterus and drop of progesterone increases oxytocin 

  • eestrogen= increased contractions

  • progesterone = relative decrease means oxytocin no longer inhibited meaning more contractions

• dramatic increase of oxytocin during labor

labor initiation (fetal)

• placental aging and deterioration

• cortisol production 

  • made in the fetal adrenal gland and stimulates labor onset by acting on placenta to reduce progesterone formation and increase prostaglandin

• prostaglandin produced by fetal membranes and uterine decidua stimulate contractions 

powers

uterine smooth muscle contractions with force generating capacity 

• frequency

• duration

passengers

fetus; affected by size, presentation, position, presenting part, degree of flexion (attitude) and placenta

passage and position

bony boundaries of the pelvis and position of the patient in labor

psyche

patients emotional state determines their response to labor and influences physiological functioning

• fear from past experiences

• hospital as point of no return

• unwanted pregnancy? high expectations?

• stress hormones can stall labor

LISTEN EDUCATE SUPPORT

strength of contraction (powers)

• pacemaker located in fundus because greater number of myometrial cells located there 

• normally 30-50mmHG/UC necessary for effective labor 

• adequate labor contractions= montevideo units (MVU’s) >200 mmHg total across contraction per 10 minutes (if IUPC)

• desire no more than 5 UCs in 10 minutes (MVU’s <280 mmHG)

measuring powers

• palpation

• external tocodynamometer (gives the frequency and duration but not the intensity)

  • affected by patient habitus and proper placement

• IUPC- measures MHG exerted by each contraction

  • associated with infection, uterine perforation, trauma

tachysystole

greater than 5 contractions in 10 minutes 

hypertonus

contractions lasting longer than 2 minutes in duration

cephalopelvic disproportion

mismatch between size and/or shape of the fetal head and size and/or shape of the pelvis, making it difficult for the baby to pass through the birth canal

gynecoid 

normal pelvis for individuals assigned female at birth with an incidence of 50%

round or transverse oval shape, all diameters are adequate 

most ideal for space

android

pelvis for individuals assigned male at birth with an incidence of 20%

heart of wedge shaped

reduced in all diameters

arrest of labor is common

anthropoid 

ape like pelvis with an incidence of 25%

long anteroposterior oval shape

OP presentation is common 

platypelloid

flat with an incidence of 5%

transverse oval shape

delay of descent at inlet is common and c/s is common

fetal lie

reference to maternal spine

• longitudinal

• transverse

• oblique

fetal presentation 

• cephalic: vertex, military, brow, face 

• breech: complete, frank, footling 

• shoulder 

fetal attitude

• flexion (vertex) - everything crossed in

• extension- neck and arms pushed back

fetal position

occiput, sacrum, mentum (chin)

anterior 

fontanelle that is closed by 18 months and is diamond 

posterior

fontanelle that is closed by 6-8 weeks and is triangle

engagement

when the widest diameter of the presenting part has passed the inlet, usually 0 station

floating

when presenting part is entirely out of the pelvis and freely movable in the inlet

cardinal movements 

• engagement and descent 

• flexion 

• internal rotation 

• extension 

• restitution 

• external rotation 

• expulsion 

5 P’s interventions 

• facilitate effective uterine contractions 

• minimize risk of infection/complication

• facilitate maximum pelvic capacity 

• facilitate fetal cardinal movements with position changes 

• minimize anxiety and fear associated with labor 

• maximize coping strategies and knowledge and understanding

initial labor admission

• review of systems

• urinary protein and glucose

• leopold’s maneuvers to determine fetal position

• fundal height

• signs of domestic abuse and support

• signs of preeclampsia

Risk factors:

• prior OB history

• current pregnancy info

• prenatal

Labor Sx and Fetal Status:

• Oxygenation of patient and fetus

• assessment of labor tolerance - patient and fetus

labor continued assessment 

• vitals checked every hour while in active labor 

• I/O every 4 hrs 

• contraction pattern - assess by palpation, even with IUPC- confirm uterine relaxation 

• cervical exam- dilation, effacement, fetal station

• ROM- time,color, amount, odor 

• bleeding, discharge 

hyperventilation

• common with anxiety and occasionally occurs when utilizing relaxation breathing techniques 

• symptoms: lightheadedness, dizziness, tingling of fingers, spasms in hands or feet, circomoral numbness

Results: respiratory alkalosis 

interventions: 

• replacement of bicarbonate ion by rebreathing CO2

platelets (labor)

decreased thought to be due to hemodilution

WBCs(labor)

increase to 30,000 considered normal

same response as strenuous exercise

first stage of labor 

• assist with positioning 

• monitor maternal/fetal status 

• integrate support persons into plan of care doulas, friends, family, partners 

• implement pain management techniques/meds 

• monitor I/O

• assist with infection prevention- know your patient’s STI, GBS lab status  

second stage of labor

• encourage rest during latent phase

• optimize oxygenation (open glottis pushing, side-lying position, push every other UC)

third stage of labor

• facilitate bonding

• observe for signs of separating placenta

• monitor for and prevent increased bleeding

• expectant vs active management (pitocin, cord traction, fundal massage)

• inspect placenta for abnormalities

signs of placental separation

• lengthening of cord

• change in shape of fundus from discoid to globular

• gush of blood

shiny schultz 

fetal side of placenta 

dirty duncan

maternal side of placenta

fourth stage of labor

newborn:

• support trasition to extrauterine life

• APGAR, initial assessment, meds, etc.

maternal:

• monitor for signs of excessive bleeding

  • VS/fundal/lochia assessments- q15 ×4, q30×2 until stable

  • QBL- weigh pads (1gm=1ml)

  • oxytocin IV or IM

version

turning of fetus from one presentation to another (usually from breech/shoulder to vertex)

version prereqs

• confirm >=37 weeks

• ultrasound: placenta, cord, fluid, position, uterine anomalies

• reactive NST to confirm fetal well-being

• informed consent

• tocolysis (terbutaline) to relax uterus

version postprocedure 

• assess for abruption, rupture, PTL, AFE, fetal distress 

• monitor FHR, contractions for 1hr or until stable 

• RhoGam if mom is Rh- 

version contraindications

• uterine anomalies (ex: bicornuate uterus)

• labor contractions - can’t do with contracted uterus

• 3rd trimester bleeding (ex: previa)

• multiple gestation

  • internal version can be done for 2nd twin

• oligohydramnios

• evidence of uteroplacental insufficiency

• nuchal cord

• prior c/s of significnat uterine surgery

• obvious cephalopelvic disproprortion

1st stage pain

visceral

• cervical dilation and effacement

• ischemia of uterine muscles 

• stretching of LUS 

• pressure on pelvis, bowel, bladder 

2nd stage pain

somatic pain 

• distention of vagina 

• distention and stretching of perineal tissue 

• ischemia of uterine muscles 

• pressure on pelvis, bowel and bladder 

nonpharacologic pain management

• cognitive: relaxation, patterened breathing, imagery, hypnosis

• cutaneous: massage, warmth, hydrotherapy, positional assistance (birthing/peanut ball), rockinging/swaing

nitrous oxide

laughing gas

• 50% oxygen 50% nitrous oxide

• commonly used in midwives and homebirths

narcotics- fentanyl and butorphanol 

opioid agonist 

• increases pain threshold 

• may increase or decrease uterine contractions 

• may cause drowsiness 

• cross placental barrier—→ administer during contraction to minimize fetal effect 

• can cause sinusoidal appearing FHR pattern 

IV fentanyl

advantages:

• strong narcotic

  • decreases severe pain

• short acting

  • effect worn off in less than 1 hr

• cardiovascular stability

  • BP usually does NOT drop

• moderate sedation

• minimal nausea

• minimal newborn effects

• can be given right up to time of delivery (epidural form only not IV)

• inexpensive

disadvantages:

• strong narcotic

  • can cause respiratory depression narcan

• short acting

  • needs to be repeated frequently

• itching is common

agonist-antagonists 

• butorphanol tartrate (stadol) or nalbuphine hydrocholride (nubain) 

• good analgesia with less respiratory depression and N/V

agonists

• promethazine (phenergan)

• decrease anxiety and apprehension, increase sedation and reduce nausea and vomiting

• may potentiate narcotic- help them work more effectively (morphine)

sedatives

• zolpidem (ambien) or secobarbitol (seconal)

• provide sedation or sleep and reduce tension and fear

• cross placenta and may affect newborn up to 12-24 hours

pudendal block

• perineal body is injected with local anesthesia (into nerve)

• performed just before delivery at site of episiotomy

• no fetal effect

mechanism of action

• drugs: lidocaine, bupivicaine, chloroprocaine, tetracaine

• inactivates voltage dependent sodium channels

epidural advantages

• superior pain relief and position changes are less uncomfortable

• provides sufficient relief for episiotomy repair

• emergency c/s can occur more quickly

• beneficial to women for whom general anesthesisa is a risk

epidural contraindications 

• coagulation disorders 

• maternal hypotension

• allergy to local anesthetics 

• infection at injection site 

• increased ICP 

vaginal epidural

T10 to S5 placement

c/s epidural

T8 to S1 placement

epidural

• placed in epidural space

• increased vascularity and sensitivity to local anesthetics present during in pregnancy

• observe for signs of toxicity within 60 seconds after injection- indicates meds injected into vein

  • tingling, tinnitus, shivering

• goal is pain relief, not numbness, want sensation of lower extremities to facilitate movement

epidural disadvantages

• Sympathectomy-induced vasodilation 

  • venous pooling resulting in decreased blood pressure

• lower extremity weakness and numbness

• may prolong the second stage of labor

• potential for post-dural puncture headache

• technically challenging with great potential for harm

  • needs to be done by an anesthesiologist

BP drop (epidural)

sympathetic blockade with resulting BP drop is a common side effect of regional anesthesia 

• fetal hypoxia can occur if maternal systolic blood pressure drops below 100 mmHG in healthy pregnant woman 

concurrent infusion of 500-1000ml of crystalloid fluid may be used to prevent hypotension 

Ephedrine: drug used to treat BP drop- increases BP by increasing cardiac output without causing general vasoconstriction 

• preserves uterine/placental blood flow 

ephedrine

drug used to treat BP drop- increases BP by increasing cardiac output without causing general vasoconstriction 

• preserves uterine/placental blood flow 

spinal anesthesia

anesthetic deposited inside the dural sheath and has direct contact with the nerves

• stops or decreases impulses at spinal cord

• variable numbness and weakness

combined spinal epidural advantages

• complete pain relief established after only a few minutes

• ambulation is possible during the early part of labor

• epidural provides route for very effective pain relief that can be used throughout labor and c/s if necessary

general anesthesia 

use:

• more for emergency 

• may be used if a contraindiciton to spinal or epidural block 

maternal risk: 

• mortality associated with aspiration 

• stomach displaced upward 

• slow GI emptying 

• uterine relaxation may cause hemorrhage 

fetal risk:

• at risk for receiving anesthetic if procedure takes longer 

maternal pain management complications

effects last up to 6hrs post medication:

• respiratory depression

• BP drop

• limits mobility

• itching

fetal pain management complications

• decrease in FHR variability

• neonatal respiratory depression

med admin care 

monitor: 

• vitals, mobility, LOC, perception of pain 

• bladder status (distended bladder, decreased sensation or inability to void may indicate catheter

• fetal response to medications 

• change patients position every hour—→ encourage lateral rather than supine 

vaginal assisted indications

maternal

• progress of 2nd stage stops due to inadequate contraction strength, poor pushing efforts, excessive fetal size, non-vertex position

• condition requiring short 2nd stage (cardiac/pulmonary disease)

• extreme fatigue

fetal

• distress that warrants shortened 2nd stage

forceps/vacuum prereqs

• no cpd 

• head is engaged 

• membranes ruptured 

• cervix is 10 cm dilated 

• empty bladder 

forceps/vacuum complications

• bruising

• cephalhematoma

• facial nerve damage

• maternal lacerations, hematoma

• maternal abx indicated after operative vaginal birth to prevent infection

bishop score

• rating system to measure the physiologic readiness of cervix

  • decide if can go directly to pitocin or start with cervical ripening approaches

• labor induction more likely to be successful with a higher score (13 points possible)

  • 9 or more for nulliparous patients

  • 5 or more for multiparous patients

risk of macrosomia

not a ACOG approved medical indication for induction

induction (augmentation) indications

• maternal conditions (DM, HTN)

• chorioamnionitits/ prolonged ROM

• IUGR

• postdates

• fetal death

• Rh sensitization

induction (augementation) relative contraindications

• unfavorable cervix

• presenting part not engaged

• abnormal presentation

• polyhydramnios

• hypertonic uterus

induction (augementation) absolute contraindications 

• cephalopelvic disproportion 

• fetal distress 

• complete previa or vasoprevia 

• prior uterine surgery (not including c/s) 

• active genital herpes

induction risks

• hyperstimulation of uterus (tachysytole)

• fetal distress

• increased incidence of c/s

• uterine rupture

• increased postpartum

cervical ripening

makes cervix more favorable for dilation and effacement - physically softer

• mechanical

  • catheters, laminaria

• chemical

  • cervidil(dinoprostone) alpha prostaglandin

  • misoprostil (cytotec) alpha prostaglandin

• stripping of membranes

• amniotimy (breaking the water)

fetal indications for cervical ripening

• gestational age established by early ultrasound test or measurement of appropriate parameters

• acceptable lecithin/sphingomyelin (L/S) ratio (usually 2:1 or higher)

• prescence of phosphatidylglycerol in amniotic fluid

laminaria

seaweed or synthetic dilators

ballon dilators (cooks)

soften cervix

change bishop score and facilitate amniotomy

*usually come out around 3-4 cm

tachysystole occurs less often than with use of pharmacologic methods

misoprostil (cytotec) 

prostaglandin E1

• ripens cervix, making it soften and causing it to begin to dilate and efface and stimulate uterine contractions 

• used for preinduction cervical ripening (bishop score <4) and to induce labor or abortion) 

Not FDA approved for use in cervical ripening or labor induction (off labor use) 

considerations

• caution with asthma, glaucoma, renal, hepatic or cardiovascular disorders

• pt. void prior to insertion

• supine position w/tilt or side lying 30-40 min after insertion (don’t want it to fall out)

• Initate Oxytocin NO SOONER than 4 hrs after last dose d/t onset 20-6hrs d/t risk of uterine hyperstimulation

adverse effects 

• tachysystole 

• N/V/D

• fever 

• risk lower at lower doses 

amniotomy 

artifically rupturing amniotic sac 

• used to induce labor when cervix is ripe or augment labor if progress begins to slow 

considerations 

• performed by provider 

• fetal head engaged (no prolapse) —→ Check FHR immediately after AROM 

• avoid if vaginal infection (genital herpes, HIV) 

• note: time, color, consistency, amount, odor

• assess temperature every 2 hrs 

• assess for s/sx of infection- tender abdomen, chills fetal tachycardia 

• labor usually beings within 12 hrs 

• can decrease duration of labor by 2hrs without oxytocin 

adverse effects 

• increased risk of intra-amniotic infection 

• variable decelerations as result of cord compression 

• cord prolapse or low AFI 

pitocin

• synthetic version of the hormone oxytocin

• produced by the posterior pituitary gland

• stimulates the uterus to contract

• hormone responsible for milk ejection reflex

• only pharmacologic agent FDA approved for induction of labor

• stimulation UC by increasing myometrial cell membrane permeability to sodium ion

dosing 

• 0.5-1 mU/min 

• increased no more than 1-2 mU/min every 30-60 mins 

  • steady state reached after 40 minutes 

• increased only until active labor is established and may be turned off 

• titrated as needed to eliminate tachysytole 

  • >5 contractions in a 10-minute strip averaged over 30 minutes 

high alert medication

uterine effects (pitocin)

• stimulates contractions by increasing frequency strength and duration

• enhances cervical ripening indirectly by stimulating the active synthesis of prostaglandins in the decidua

cardiac effects (pitocin)

• initially a slight increase in maternal blood pressure

• increased cardiac output and stroke volume (use caution in preeclamptic patients)

maternal adverse effect of pitocin

• uterine hyperstimulation

  • placental abruption

  • uterine rupture

  • anaphylactoid syndrome of pregnancy

• soft tissue damage

  • cervical lacerations

  • perinaeal hematoms

  • rectal tears

• increased incidence of c/s

• increased PPH

• water intoxication- leading to seizure and coma

  • s/sx H/A, N/V, decreased urinary output, confusion, hypotension and arrhythmias

fetal adverse effects of pitocin  

hypoxemia and acidosis resulting from uterine tachysytole 

• late decelerations and minimal/absent baseline variability 

pitocin nursing

• vaginal exam PRIOR to beginning infusion (document cervical status and presentation of fetus)

• prepare IV solution

• infuse through closest port to patient

• perform ongoing maternal and fetal assessments

• interventions for tachysystole:

  • stop med

  • reposition

  • IV fluids

  • O2

  • terbutaline

  • may take up to 1hr to wear off

c/s indications 

• medical (ex: previa) 

• complications of labor (dystocia or malpositon) 

• maternal request 

• non-reassuring fetal status (cord prolapse) 

• active HSV/HIV +

c/s contraindiciations

• thrombocytopenia severe enough to prohibit clotting at time of delivery

• respiratory or cardiac instability

c/s maternal complications

• increased mortality from anesthesia

• surgical wound infections

• thromboembolism

• increased blood loss

• previa, accreta, scar dehiscence and uterine rupture in future pregnancies

c/s fetal complications

• increased respiratory complications and NICU admissions 

• skin lacerations and clavicular fractures 

low transverse

• most commonly used c/s

• associated with lowest risk of fetal injury

• less blood loss

• causes fewer intra-abdominal adhesions

• vaginal birth is possible in subsequent pregnancies

classical

• faster method c/s

• uterine wall weaker in subsequent pregnancies

• requires future pregnancies be delivered by c/s

VBAC 

• increased to 14.2% (2% in 2021) 

contraindications 

• classical incision 

• more than 2 prior uterine scars and no vaginal births 

complications 

• uterine rupture incidence (0.7-0.13%)

• hemorrhage

• hysterectomy 

• neonatal hypoxemia 

• cerebral palsy 

predictors of success

• history of SVD

• history of successful VBAC

• cervical dilation >4 at admission 

• SROM at admission 

Uterine rupture

nonsurgical disruption of uterine cavity

• complete- endometrium, myometrium, serosa separated

• incomplete- not all layers disrupted

risk factors:

• preserve uterine incision

• operative vaginal delivery

• abdominal trauma

• uterine manipulation

• postpartum fever during previous c/s

nursing assessment/ symptoms

• Cat II or III EFM tracing

• maternal abd. pain

• unterine tenderness

• change in uterine shape

• cessation of contraction

• hematuria

• signs of shock \

Prepare for emergency C/S

gynecoid, anthropoid

pelvic anatomy types that are favorable for a vaginal birth

fetal monitoring low risk (no oxytocin) 

latent phase (<4cm)

• at least hourly 

latent phase (4-5cm)

• 30 minutes 

Active phase (>6cm)

• 30 minutes 

2nd stage (passive fetal descent) 

• 15 minutes  

2nd stage (active pushing) 

• 15 minutes 

fetal monitoring with oxytocin or risk factors 

latent phase (<4cm)

• 15 minutes with oxytocin, 30 without 

latent phase (4-5cm)

• 15 minutes 

Active phase (>6cm)

• 15 minutes 

2nd stage (passive fetal descent) 

• 15 minutes  

2nd stage (active pushing) 

• 5 minutes