Intrapartum Flashcards
Station
relationship of the leading edge of the fetal presenting part to the ischial spines (in cm)
0 = the presenting part is at the level of the spines
-3, -2, -1 = the presenting part is # cm above the ischial spines
+3, +2, +1 = number of centimeters the presenting part is below the ischial spines
Dilation
cervical os dilation from 0 - 10 cm (fully dilated)
Effacement
0-100% (fully effaced, like paper)
When to do a sterile speculum exam before the SVE?
ROM suspected, frank bleeding, inspection for herpes lesions
Presenting Part
the anatomic part of the fetus that first descends into the pelvis
- Cephalic
- Breech
- Shoulder
- Face
Position
relationship between the denominator of the presenting part and the maternal pelvis
What is the denominator for cephalic presentation?
Occiput
What is the denominator for breech presentation
sacrum
What is the denominator for shoulder presentation?
scapula
What is the denominator for face presentation
mentum (chin)
What is clinical pelvimetry?
manual examination of the pelvis to determine adequacy of the pelvis - this is not evidence based
What 4 bones compose the pelvis?
Two innominate (pubic) bones - the symphysis pubis joins these two pubic bones
Sacrum
Coccyx
What is the true pelvis?
Birth canal
What are the 3 parts of the true pelvis?
inlet, midplane, outlet
What are the boundaries of the inlet?
posteriorly: sacral prominatory
laterally: the linea terminalis
Anteriorly: the upper margins of the pubic bones
What are the boundaries of the midplane?
Posteriorly: sacrum at the junction of the 4th and 5th sacral vertebrae
Laterally: ischial spines
Anteriorly: the inferior border of the symphysis pubis
What are the boundaries of the outlet?
Posterior: sacrococcygeal joint
Laterally: inner surface of the ischial tuberosities
Anteriorly: lower border of the symphysis pubis
What are the 4 pelvis types?
Gynecoid
Android
Anthropoid
Platypelloid
What are the characteristics of a gynecoid pelvis?
- round shaped
- Transverse diameter is only slightly longer than AP diameter
- Incidence: 50% white women
- excellent prognosis for vaginal birth
What are the characteristics of an android pelvis?
- heart or triangular-shaped pelvis
- Posterior pelvis is wider than anterior pelvis
- Poor prognosis for vaginal birth, many times requiring operative VB or c/s
What are the characteristics of the anthropoid pelvis?
- Oval-shaped
- AP diameter is longer than transverse diameter
- Incidence: 40.5% of non-white women
- Good prognosis of vaginal birth, higher incidence of OP
What are the characteristics of a platypelloid pelvis?
- flattened gynecoid-shaped pelvis
- Wide transverse diameter with very short AP diameter
- Incidence: 3%
- Poor prognosis for vaginal birth
What are the types of FHR monitoring (3) during labor?
- Continuous by EFM
- Continuous by internal fetal monitoring
- Intermittent monitoring
What is continuous EFM and what are the risks/benefits?
FHR is monitored by External fetal monitor (u/s piece and toco)
Benefits: determines FHR, assesses variability, determines presence or absence of periodic changes such as decels, tachycardia, bradycardia
Risks: no risks really, but disadvantages can include: limiting mobility, not getting into tub, perhaps increases unnecessary intervention while not improving outcomes in low risk pregnancies
What is continuous INTERNAL fetal monitoring and what are the risks/benefits?
FHR is monitored by a fetal scalp electrode
Benefits: more accurate than EFM, especially if you can’t maintain a good reading with EFM
Risks: increased risk of infection
What is intermittent fetal monitoring and what are the risks/benefits?
Auscultation of FHR at prescribed intervals based on stage of labor to assess fetal tolerance of labor
Benefits: freedom of movement, be in water, can increase pt comfort; associated with decreased rates of intervention, equivalent to Cont EFM when performed at correct intervals
Risks: cannot determine variability or isolated decels, not used in high risk pregnancies, needs 1:1 ratio
What heart sounds are considered wnl in pregnancy?
RRR, but ALSO: rubs, gallops, may have split S1, grade 1 or 2 systolic murmur, audible S3
When to admit someone in labor?
Generally during ACTIVE labor
If admitted in latent phase, client incurs increased risk of interventions
Factors to consider:
- stage of labor
- nullipara vs multipara
- functional vs prodromal
- labor support at home
- need for increased fetal surveillance
What factors may necessitate IV access?
- hydration status - are they dehydrated? is there ketonuria?
- Need for oxytocin induction or augmentation
- Need for antibiotics
- Predisposing factors for PPH such as an overdistended uterus
- abnormal placentation
- grand multips
- need for pain medication or regional anesthesia
Moving around in labor?
Should be encouraged
Things that could limit movement include:
- HTN
- maternal exhaustion
- unstable lie or malpresentation
- need for increased surveillance/fetal monitoring
Nutrition and fluid status in labor?
Energy levels can be positively influenced by PO intake
Factors to consider in the decision making:
- GI motility and absorption
- potential need for anesthesia in labor
- birthing facility policy
What are non-pharm methods for pain management/increase coping in labor?
- ambulation, movement, position change, birthing ball
- hydrotherapy
- breathing and relaxation/hypnotherapy
- music
- acupuncture/acupressure
- sterile water injections for back labor
- touch and massage
- warm compress like heating pad or rice sock/cold compress
- aromatherapy
- tens unit
- Labor support - LIKE A DOULA!
What types of medications can be given for analgesia?
- opioids
- nitrous oxide
- Rarely: hypnotics/sedatives likes benzos b/c they don’t provide analgesia, may cause amnesia and disrupt thermal regulation of the newborn
When should opioids be used in labor?
In active and latent phases
Avoid within 1 hour of birth because of potential respiratory depressant effect on fetus
How is nitrous given?
self-administered inhaled gas in 50:50 mix with oxygen via face mask
- safe for mom and fetus
- administered before, during and after contraction
- Does not diminish uterine contractility
What types of anesthesia can be provided in labor?
Spinal/Intrathecal
Epidural
What are the risks/benefits of anesthesia in labor?
Benefits: provides complete neurologic block
Disadvantages/Risks:
- can interfere with muscular action
- possible slowing of labor progress, may cause an increase in need for intervention
- can have systemic effects like hypotension (most common) and fever
- Inadvertent dural puncture can cause spinal HA
What are local blocks and what types can be used in labor?
provide pain blockade at site of pain for a brief period of time
- paracervical
- pudendal
- local infiltration
What are the benefits of a doula?
dedicated labor support of a doula has been found to decrease use of obstetric interventions and promote physiologic birth
What are the 4 Ps of labor?
Power
Passenger
Passageway
Psyche
What does the power of labor encompass?
Power of contractile efforts
- assess adequacy of strength of contractions
- Assess need for augmentation of labor
What does the Passsenger of labor emcompass?
Fetus
Things to evaluate:
- lie
- presentation
- position
- size
- synclitism vs ascynclitism
What does synclitism and asynclitism describe?
The relationship of the sagittal suture line to the maternal sacrum and symphysis pubis
What is synclitism?
The sagittal suture is midway between the sacrum and the symphysis pubis; the biparietal diameter is parallel to the planes of the pelvis
What is asynclitism?
The saggital suture is not midway between the sacrum and the symphysis pubis, it is oriented towards one or the other
2 types: posterior and anterior
This can cause labor dystocia
Lax abdominal musculature can contribute to this
What is posterior asynclitism?
the saggital suture is closer to the symphysis pubis, so head is tilted towards the posterior
What is anterior ansynclitism?
the saggital suture is closer to the sacrum, so the head is tilted towards the anterior
What is the passageway?
The pelvis
- clinical pelvimetry, classification of pelvic structure
What is the psyche?
women’s view of labor/birth and her ability to handle it, things that can affect the psyche:
- appropriateness of emotional support
- education or preparation of labor
- meaning of the pregnancy
- ability to achieve birth plan
- hx of sexual abuse
What is the first stage of labor?
From the onset of REGULAR contractions through full dilation (10 cm), includes latent and active phases
What is latent labor?
During the first stage of labor: from onset to 4-6 cm
What is the contraction pattern in latent labor typically?
From every 10-20 minutes lasting 15-20 seconds to every 5-7 munutes lasting 30-40 seconds
mild to moderate intensity
How long is latent labor for nulliparas?
20 hours or less per Friedman
How long is latent labor for multiparas?
14 hours or less per Friedman
What is active labor?
During the first stage of labor, from 6 cm to 10 cm (full dilation)
What are contractions like in active labor?
Become more frequent, regular and intense
typically every 2-3 minutes and moderate to strong by palpation
How are contractions measured?
Externally by palpation
Internally: by IUPC
What is considered adequate contraction strength by intrauterine pressure catheter (IUPC)?
Adequacy in the active phase is considered 200-250 Montevideo units (mVu) in 10 minutes, averaged over 30 minutes
What is the second stage of labor?
from full dilation until the birth of the baby - this is the pushing or expulsive phase
What is abnormal latent phase in a nullipara?
more than 20 hours (friedman)
What is abnormal latent phase in multipara?
more than 14 hours (friedman)
What is considered abnormal labor progress in the active phase for nullipara?
less than 1.2 cm per hour (friedman)
Mean time to dilate from 4-10 cm is 3.7 hrs, 95th percentile 16.7 hrs (Zhang)
What is considered abnormal labor progress in the active phase for a multipara?
less than 1.5 cm/hr (friedman)
Mean time to dilate from 4-10 cm: 2.4 hrs for parity 1, 2.2 hrs for parity 2+, 95th percentile 14.2 hrs
What is considered abnormal progress of second stage/descent in nullipara?
Less than 1 cm/hr (friedman)
more than 3 hours without an epidural or more than 4 hours with an epidural
What is considered abnormal progress of second stage/descent in multipara?
Less than 2.1 cm/hr (Friedman)
More than 2 hours without an epidural, more than 3 hours with an epidural
Vital signs in first stage: Temp
slightly elevated, but less than 100 during labor, highest in time preceding and immediately after birth
epidural anesthesia can artificially elevate temperature
Vital signs in the first stage: BP
systolic BP increases by 10-20 during contractions, diastolic BP increases 5-10 during contractions
BP should return to prelabor levels between contractions
pain and fear can contribute to elevations in BP
Vital signs in the first stage: Pulse
Because of increased metabolic rate during labor, pulse rate is slightly elevated
Inversely proportional to action of the contraction - increases during increment (buildup/rise) and decreases at acme (peak) –> therefore if fetus is having recurrent accelerations during contractions, it is important to place plase ox on mom to distinguish baby from mom
Vital signs in the first stage: Respirations:
slightly increased rate during labor
Hyperventilation is common (But not normal) and r/t pain response, can lead to alkalosis
When should labor be augmented in the first stage?
Not until active labor!
Individualized approach per Zhang
One article states that aggressive intervention (like oxytocin) should not be administered unless dilation averages are < 0.56-0.64 cm/hr in active labor
Stress in labor:
increases cortisol - can cause decreased placental perfusion, decreased contractions
What opioids can be used in labor?
- morphine sulfate for prodromal labor 10-15 mg IM
OR - fentanyl 50-100 mcg IV or IM
OR - Meperidine 50-75 mg IM or 25-50 mgIV - rarely used b/c its metabolite accumulates in fetus and potentiates depressant effects on newborn
Mixed agonist-antagonist:
- Butorphanol 1-2 mg IV or 2 mg IM
- Nalbuphine 10-20 mg IM or 5 mg IV
avoid all with active labor
What is responsible for the variability of FHR?
parasympathetic/sympathetic nervous system:
Baroreceptors in carotid arteries - increased pressure can cause a vagal response
Chemoreceptors in aortic arch and carotid sinus - sensitive to changes in fetal pH, O2 level, CO2 level- respond by increasing fetal BP and HR
ACTIVATION OF SYMPATHETIC nervous system: increases baseline HR
ACTIVATION of PARASYMPATHETIC nervous system: decreases baseline HR
What is normal range HR for fetus at term?
110-160 bpm
on FHR strip, judge baseline based on 10 minute strip and round to nearest 5
What is fetal bradycardia?
< 110 bpm for 10 or more minutes
What is marked fetal bradycardia?
< 100 bpm for 10 or more minutes
What are causes of bradycardia?
- cord compression
- rapid descent
- vagal stimulation
- medications
- anesthesia
- placental insufficiency
- fetal cardiac anomalies
- Terminal condition of fetus
What is fetal tachycardia?
> 160 bpm for more than 10 min
What are the causes of fetal tachycardia?
- maternal fever
- infection
- medications, esp beta sympathomimetics
- chronic fetal hypoxia
- can be compensatory after temporary fetal hypoxia event
- undiagnosed prematurity
- excessive fetal movement
What is FHR variability and what are the categories?
Baseline variability: fluctuations in the baseline of the HR
Absent
Minimal
Moderate
Marked
Absent FHR variability
undetectable amplitude
Minimal FHR variability
amplitude range of </= 5 bpm
Moderate FHR variability
amplitude range of 5-25 bpm
Marked FHR variability
amplitude >/= 25 bpm
What are accelerations a sign of?
fetal well-being, cannot be produced by acidotic fetus (indicates fetal pH of more than 7.20)
What is the definition of an acceleration for a fetus greater than 32 weeks?
a peak of >/= 15 bpm above baseline lasting 15 seconds or more, but less than 2 minutes from beginning to end of acceleration
What is the definition of an acceleration for a fetus 32 weeks or less?
a peak of >/= 10 bpm above baseline lasting 10 seconds or more, but less than 2 minutes from beginning to end of the acceleration
What is the definition of a variable decel?
Abrupt (onset to nadir < 30 seconds) periodic or non-periodic decrease in the FHR that differs in shape from one deceleration to another. The decrease in FHR from the baseline is >/= 15 bpm lasting >/= 15 seconds but less than 2 minutes
- it DOES note reflect the shape of the contraction
- can occur at any time in relation to the contractions
- Inconsistent shape: U, V, W
- Generally occurs as an abrupt from below the FHR baseline and a rapid return to baseline
What causes variable decels?
CORD COMPRESSION
What are the implications of variable decels?
- with rapid recovery to baseline and good variability, generally considered an uncompromised fetus
- suspect fetal compromise with slow recovery to baseline, increasing length or depth of decelerations, absent variability or increasing frequency of decels
Management of variable decels?
- position change
- IV fluid bolus
- O2 at 10 LPM via face mask
- pelvic exam to r/out cord prolapse
- contact consulting MD if warranted
- consider amnioinfusion
What is an early decel?
- Uniformly shaped slowing of the FHR that mirrors the contractions
- Gradual descent to the nadir (>/= 30 seconds) with gradual return
- FHR usually remains within the normal range and deceleration is usually , 90 seconds
- Deceleration begins, peaks and ends with contraction
What causes early decel?
Head compression/vagal stimulation
Implications of early decels?
generally benign
Management of early decels?
Surveillance
What is a late deceleration?
- Uniformly shaped gradual (>/= 30 seconds) slowing of the FHR that begins with the peak of the contraction and does not return to baseline until after the completion of the contraction
- FHR may not remain within the normal fetal heart range
What are implications of late decels?
- can occur in an isolated fashion; more ominous when occurs repetitively
What are the causes of late decels?
Uteroplacental insufficiency
fetal hypoxia
uterine tachysystole
decreased placental blood flow
maternal hypotension
abruptio placenta
medication effect
Management of late decels:
- left lateral position
- fluid bolus
- O2 at 10 LPM
- attempt to correct underlying cause
- consult with MD
What is intermittent fetal monitoring?
Intermittent FHR auscultation by fetoscope or doppler