Labor Flashcards
Physiologic process by which a fetus is expelled from the uterus
Labor
What is the purpose of uterine contractions during labor?
Effacement and dilatation of the cervix
What are components of a cervical exam to diagnose labor?
- Dilation
- Effacement
- Station
- Consistency
- Position
How open the internal os is
Dilation
What does dilation range from? What is complete dilation?
- 0-10 cm
- 10 cm = complete dilation
What is effacement?
Length of cervix (how thick it is)
Difference between the internal and external cervical os
What is station?
Degress of descent of the presenting part of the fetus- measured in centimeters from the ischial spines
* Can measure it in thirds
What is consistency? What consistency means not in labor?
- Soft, medium, or firm
- More firm means not in labor
What are positions? How does this progress during labor?
- Anterior, mid position or posterior
- Goes mid to anterior with labor progress
In order to diagnose labor, what must occur?
- Cervical change!
- Braxton Hicks contractions = contractions without cervical change
What is a Bishop score?
- Determines how favorable the cervix is for labor
- Score >8 indicates favorable cervix for labor
How is labor diagnosed with membranes?
- Ferning
- Nitrazine
- Presence of pooling
- AFI
What is spontaneous rupture of membranes? Premature rupture of membranes?
- Spontaneous rupture of membranes: rupture of membranes during labor
- Premature rupture of membranes: rupture of membranes before onset of labor
What does vaginal bleeding during labor mean?
- Can see small amount of blood called bloody show which is a good sign
- Excessive bleeding is not good sign
What is a major pathogen in neonatal sepsis that affects 2-3 per 1000 live births?
Group B streptococcus
What is screening for group B streptococcus?
- > 35 weeks all pregnant women have ano-vaginal swab
What do you do if a group B streptococcus swab is positive? Negative?
Positive: treat with penicillin during labor
If allergic, obtain sensitivities and use erythromycin or clindamycin. If don’t have sensitivities use vancomycin
Negative: no treatment in labor
What are general categories of pain management in labor?
- IV pain medication
- Regional anesthesia
- General anesthesia
What are considerations for IV pain medication in labor?
Try to avoid if possible because can cause nonreassuring fetal status and fetal respiratory depression
What are types of regional anesthesia used during labor?
- Epidural
- Spinal anesthesia
- Pudendal block
What is epidural anesthesia?
- Epidural catheter placed in L3-L4 interspace
- Initial bolus of anesthetic given then continuous infusion started
- Offered to patients having a vaginal delivery
What are complications of epidural anesthesia?
- Maternal hypotension
- Maternal respiratory depression
- Spinal headache
What are contraindications of epidural anesthesia?
- Maternal bleeding disorder or use of LMWH within 12 h
- Patient refusal
What is spinal anesthesia?
- One time dose placed directly into the spinal canal
- Used for cesarean delivery
- Complications and contraindications similar to epidural
What is pudendal block?
- Provides perineal anesthesia
- Used with operative vaginal deliveries or for extensive perineal repairs after delivery
When is general anesthesia used during labor?
- Cesarean delivery in emergent or urgent setting
What are complications of general anesthesia?
- Maternal aspiration
- Risk of hypoxia to mother and fetus
What is induction of labor?
Attempt to begin labor in a non-laboring patient
What are indications for induction of labor?
Maternal, fetal, or placental reasons
What indicates success of induction of labor?
Bishop score: <5 lead to failed induction 50% of time and need for cervical ripening
What are methods of induction of labor?
- Prostaglandins
- Pitocin
- Balloon catheter
- Laminaria
- Artificial rupture of membranes
What is the MOA of prostaglandins in induction of labor?
- Help ripen and dilate the cervix by dissolution of collagen bundles and increase water uptake by cells
Which prostaglandins are used in induction?
- Cervidil - PGE2, vaginal
- Cytotec- PGE1, vaginal or oral (but causes diarrhea orally)
What are side effects of prostaglandins?
- Tachysystole
- Fever
- Vomiting
- Diarrhea
- Uterine rupture
What are contraindications to prostaglandins?
- History of cesarean section
- Myomectomy (peeling tissue from uterus)
- Hysterotomy (incision into uterus)
How is pitocin given and what is its MOA?
- Given IV
- Identical to oxytocin released from posterior pituitary leading to uterine contractions
What are side effects of pitocin?
- Tachysystole >5 contractions in 10 mins
- Uterine rupture (but not as likely as prostaglandins)
- Hyponatremia
- Hypotension
- Amniotic fluid embolism
What are contraindications to pitocin?
- Fetal distress
- Hypersensitivity
What is a laminaria?
Rolled up seaweed that pulls out water and in turn dilates the cervix
What is augmentation and how is it done?
- Intervening to increase already present contractions
- Typically use pitocin
What are types of operative vaginal delivery?
- Forceps and vacuum (used more often now)
What are indications for operative vaginal delivery?
- Prolonged second stage of labor
- Maternal exhaustion
- Hasten delivery for fetal compromise
What is cesarean deivery?
Abdominal delivery of fetus
What are the stages of labor?
- First stage: onset of labor to complete cervical dilation
- Second stage: complete cervical dilation to expulsion of fetus
- Third stage: delivery of infant to delivery of placenta
- Fourth stage: delivery of placenta to one hour postpartum
What is Freidman’s curve?
- Good guideline for expected progression in labor
- Helps determine abnormal labor patterns
What is Zhang labor curve?
Revaluated labor curves
What is spontaneous labor progression?
- Labor similar for multips and primips until 6 cm
- Defined active phase at 6 cm
- After 6 cm, multips progress much quicker
What is induced labor progression?
- Latent phase of labor significantly longer in induced labor
- Active phase similar
What is the average duration of the first stage of labor?
- Nulliparous patient: 10-12 hours
- Multiparous patient: 6-8 hours
What are the two phases of the first stage of labor?
- Latent phase: onset of labor with slow cervical dilation to 6 cm. This is slower phase
- Active phase: 6 cm to complete dilation with faster rate of cervical change–> nulliparous patient: 1.2 cm/h; multiparous patient: 1.5 cm/h
What are factors that affect the active stage of labor?
- Power-uterus
- Passenger-fetus
- Pelvis- baby has to fit out of
What does power refer to?
- Force generated by contractions of uterine myometrium
- Activity can be assessed by observation of the mother, palpation of the fundus, or external tocodynamometry
- Contraction force can be measured by direct measurement of intrauterine pressure using internal pressure monitor (IUPC)
What is considered adequate labor power?
3-5 contractions in a 10 minute period
>200 montevideo units in 10 min (measured by IUPC)
If IUPC measures less than 200 Montevideo units in 10 minutes, what should you do?
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- Start pitocin to augment labor
What are fetal variables that affect labor?
- Fetal size- macrosomia
- Fetal lie- longitudinal, transverse, or oblique
- Fetal presentation- vertex, breech, shoulder, compound, and funic
- Attitude: degree of flexion or extension of fetal head
- Position: relationship between fetal presenting part to the right or left of the birth canal
- Station
- Number of fetuses
- Presence of fetal abnormalities: hydrocephalus, sacrococcygeal teratoma
How is fetal presentation and position diagnosed?
- Leopolds maneuver (abdominal palpation): can determine fetal lie, fetal weight, fetal position, fetal presentation
- Vaginal examination: palpation of fetal sutures and fontanels
- Ultrasound
What could make Leopolds maneuver difficult?
Obese mother, polyhydramnios, multifetal gestation
What passenger factor usually results in cesarean delivery?
- Any position other than vertex
- Fetus greater than 5000 grams (macrosomia), 4500 grams in diabetics
What does passage consist of?
- Bony pelvis and soft tissues of birth canal (cervix, pelvic floor musculature
- Small pelvic outlet can result in cephalopelvic disproportion –> cesarean delivery
- Bony pelvis can be measured by pelvimetry but is not accurate
What pelvis type is ideal for the baby?
Gynecoid
What are passage abnormalities?
- Cephalopelvic disproportion
- Passenger too large for pelvis
How do you manage cephalopelvic disproportion?
- Cesarean delivery
What are abnormalities in the first stage of labor?
- Active phase arrest of labor
- Prolonged second phase of labor
- Umbilical cord prolapse
What is active phase arrest of labor?
- No progression in cervical dilation in patients who are at least 6 cm dilated with rupture of membranes
- Despite 4 hours of adequate uterine activity or 6 hours of inadequate uterine activity with oxytocin augmentation
How is active phase arrest of labor managed?
Cesarean delivery
What is prolonged second stage of labor? How is it managed?
- More than 3 hours of pushing in nulliparous individuals and 2 hours of pushing in multiparous individuals
- Indication for cesarean delivery
What is umbilical cord prolapse and how do you manage it?
- Prolapse of umbilical cord in front of head
- Obstetrical emergency
- Indication for cesarean delivery
What are risk factors for umbilical cord prolapse?
- Artificial rupture of membranes
- Unengaged fetal head
What is the second stage of labor?
- Interval between full cervical dilation to delivery of infant
- Descent of presenting part through pelvis and expulsion of fetus
What are indications of second stage?
- Pelvic/rectal pressure
- Mother has active role in pushing to aid in fetal descent
What can make examining the fetal head difficult during the second stage of labor?
Molding
What is molding?
Alteration of the fetal cranial bones to each other as a result of compressive forces of the maternal bony pelvis
What is caput?
Localized edematous area on the fetal scalp caused by pressure on the scalp by the cervix
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What are the degrees of perineal lacerations?
- First degree: injury to perineal skin and vaginal mucosa only
- Second degree: injury to the perineal body
- Third degree: injury through the external anal sphincter
- Fourth degree: injury through the rectal mucosa
What is an episiotomy?
- Surgical incision of female perineum
- Increases diameter of soft tissue pelvic outlet to allow delivery of a fetus
What are guidelines regarding episiotomy?
- ACOG restricts use because
- Reduction of third or fourth degree lacerations
- Ease of repair
- Reduction in neonatal trauma
- Reduction in should dystocia
What are indications to episiotomy?
Fetal distress
What are complications of episiotomy?
- Increase vaginal bleeding
- Increase postpartum pain
- Unsatisfactory anatomic results
- Sexual dysfunction
- Increase risk of infection
What are types of episiotomy?
Midline and mediolateral
What is shoulder dystocia?
Difficulty in delivery of anterior shoulder due to impaction of the anterior shoulder on the pubic symphysis
What are risk factors for shoulder dystocia?
- Fetal macrosomia
- Diabetes-overt and gestational
- Previous shoulder dystocia
- Maternal obesity
- Postterm pregnancy
- Prolonged second stage of labor
- Operative vaginal devliery
Causes increased morbidity and mortality to mother and fetus
What are fetal complications of shoulder dystocia?
- Fracture of humerus and clavicle
- Brachial plexus injuries
- Phrenic nerve palsy
- Hypoxic brain injury
- Death
How is the diagnosis of shoulder dystocia made?
When routine delivery maneuvers fail to deliver the anterior shoulder
How is shoulder dystocia managed?
- Call for help
- Episiotomy
- McRoberts maneuver- sharp flexion of maternal hips
- Suprapubic pressure
- Delivery of posterior shoulder
- Other maneuvers- Rubin, Wood’s corkscrew
- Symphisiotomy
- Zavanella- replace infants head back into the pelvis and do a c-section
What is the third stage of labor?
Time from fetal delivery to delivery of the placenta, about 30 mins usually
What are 3 signs of placental separation?
- Lengthening of umbilical cord
- Gush of blood
- Fundus becomes globular and more anteverted against abdominal hand
How is the placenta delivered?
- One hand on umbilical cord with gentle downward traction
- Other hand on abdomen supporting uterine fundus
What can happen with aggressive traction on the umbilical cord during the third stage of labor?
- Uterine eversion
- Obstetrical emergency!!
- Immediate replacement of fundus required either mechanically or surgically
What is the fourth stage of labor?
- Time from delivery of placenta to 1 hour immediately postpartum
What must be monitored closely during fourth stage of labor?
- Blood pressure
- Uterine blood loss
- Pulse rate
What are causes of high risk of postpartum hemorrhage?
- Uterine atony- MCC (uterine muscle doesn’t tighten to stop bleeding)
- Retained placental fragments
- Unrepaired lacerations of vagina, cervix, or perineum
What is diagnosed as postpartum hemorrhage?
- > 500 cc blood loss in vaginal delivery or 1000 cc in a cesarean delivery
What is treatment of postpartum hemorrhage?
- Removal of placental fragments or repair of lacerations
- Additional IV access
- Type and cross match for blood
- Medications for uterine atony: pitocin, methergine, cytotec, hemabate
What are the 7 cardinal movements of labor?
Changes in fetal head position during passage through canal
- Engagement
- Descent
- Flexion
- Internal rotation
- Extension
- External rotation/restitution
- Expulsion
Engaged Dads Feel Internally Extended Extra in the Evening
What is engagement?
- Passage of the widest fetal diameter fetal presenting part below the plane of the pelvic inlet
- Head is engaged if leading edge at level of ischial spines
What is descent?
Downward passage of presenting part through the bony pelvis
What is flexion?
- Passive flexion as head descends through bony pelvis
- Complete flexion allows fetal head’s smallest diameter, subocciptobregmatic diameter, to fit
What is internal rotation?
Rotation of fetal head from occiput transverse to occiput anterior or posterior position
Occurs passively due to shape of bony pelvis
What happens during extension?
- Fetus descends to level of vaginal introitus
- Occiput just past level of symphysis and angle of birth canal changes to upward position
What happens during external rotation/restitution?
- Head is delivered and rotates back to original position prior to internal rotation
- head aligns anatomically with fetal torso
- Release of passive forces on head allows to return to appropriate position
What happens during expulsion?
- Delivery of the fetus
- Downward traction allows release of the shoulder and the fetus is delivered
What is a normal fetal heart rate?
110-160 bpm
What is considered fetal bradycardia?
FHR <110
What are common causes of fetal bradycardia?
- Congenital heart block
- Infants whose mothers suffer from SLE
- Maternal hypotension
What is considered fetal tachycardia?
FHR >160 bpm
What are common causes of fetal tachycardia?
- Infection
- Terbutaline
What is baseline? Variability?
- Baseline: mean bpm over 10 minute window
- Variability: moment to moment variation from baseline
If a fetal heart rate has no variability (0 bpm), is that good or bad? What about minimal (1-5 bpm)?
- No variability: concerning!
- Minimal: common when fetus asleep or inactive, or certain medications
What variability is considered normal?
5-25 bpm of variation
If you see >25 bpm of variation, what should you be thinking?
Worrisome!
What are normal accelerations?
- > 32 weeks: at least 15 bpm and lasting 15 s
- <32 weeks: at least 10 bpm and lasting 10 s
What are the 3 types of decelerations?
- Early deceleration: begin and end approx at same time as contraction and result from head compression (can be normal)
- Late deceleration: begin at peak of contraction and slowly return to baseline after finished due to uteroplacental insufficiency (not enough O2 reserve)
- Variable decelerations: can occur at anytime, drop more precipitously, and result of cord compression
What are interventions for late decelerations?
- Position
- Oxygen
- Stop pitocin
- Check cervix
- Fluid bolus
- Consider assisted delivery or cesarean delivery with more than 50% of the contractions
What intervention may be necessary with variable declerations?
- Amnioinfusion- infusion of saline into amniotic sac
What does a sinusoidal waveform in fetal heart rate mean?
Often due to fetal anemia
What is happening in a category I fetal heart rate tracing?
Normal heart rate tracing
* Baseline FHR 110-160
* Moderate FHR variability
* Absence of late or variable decelerations
* Acclerations may be present or absent
What is happening in a category III fetal heart rate tracing?
- Absent FHR variability with: recurrent late decelerations, recurrent variable decelerations, bradycardia
- Sinusoidal pattern
Not good!! Delivery now!
Category II is anything not I or III
What is a contraction stress test?
- Evaluates fetal response to transient reduction in fetal oxygen delivery during uterine contractions
- Use pitocin to achieve 3 contractions in 10 minutes
- Indicated to evaluate fetal status before induction of labor
If a contraction stress test is positive, what does that mean?
- BAD! Do a c-section, non-reassuring fetal heart tracing
What does an equivocal or negative contraction stress test mean?
- Equivocal- wait and see –> nonpersistent late declerations
- Negative - good to go –> reassuring fetal heart tracing
