Labor and Delivery Flashcards
Theories about what causes labor
- Progesterone withdrawal (estrogen-progesterone ratio changes)
- Increased release of prostaglandins
- Increased oxytocin sensitivity
Premonitory Signs of Labor
- Lightening
- Braxton-Hicks contractions
- Cervical ripening
- Bloody show
- Sudden burst of energy
- 1-3 pound weight loss
- Diarrhea, indigestion, or nausea and vomiting
- Rupture of membranes
Describe True Labor Contractions
- At regular intervals
- Intervals between contractions gradually shorten
- Increase in duration and intensity
- Discomfort begins in back and radiates around to abdomen
- Intensity increases with walking
- Do not decrease with rest
Factors Affecting Labor
- Birth passage
- Fetus
- Relationship between the passage and the fetus
- Physiological forces of labor
- Psychological considerations
Factors Affecting the Birth Passage
- Size of the maternal pelvis
- Type of maternal pelvis
- Ability of the cervix to dilate and efface
- Ability of the vaginal canal and the external opening of the vagina (introitus) to distend
What is the best and most common type of pelvis?
Gynecoid
What is presentation?
The body part of the fetus that enters the pelvic passage first (referred to as the presenting part)
What are the different types of presentation?
- Cephalic (also called vertex)
- Breech (buttocks and/or feet)
- Shoulder (transverse lie)
What is position?
Refers to the relationship between a designated landmark on the presenting part and the front, sides, or back of the maternal pelvis
What are the position landmarks?
- Occipital bone (vertex)
- Breech (sacrum)
- Shoulder (scapula)
Positions of fetal occiput in relation to Mom’s pelvis
- Anterior
- Posterior
- Transverse
What is station?
Refers to the relationship of the presenting part to an imaginary line drawn between the ischial spines of the maternal pelvis
-Measures the degree of descent of the presenting part of the fetus (in cm) through the birth canal
Degrees of station
- (-) above spines
- (0) station = engaged; at level of spines
- (+) below spines
What is engagement?
Occurs when the largest diameter of the presenting part reaches or passes through the pelvic inlet
- When engagement occurs, the presenting part is at the level of the ischial spines
What are primary physiologic forces of labor?
Uterine muscular contractions which cause CERVICAL CHANGES during the firs stage of labor
What are secondary physiologic forces of labor?
Use of abdominal muscles to push during the second stage of labor (helps the baby come out)
What are the cervical changes in the first stage of labor?
- Effacement
2. Dilation
What is effacement?
The shortening and thinning of the cervix
- Described in percentages
What is dilation?
- Opening of the cervix
- Described in cm
- When the cervix widens to a diameter of 10 cm, it is considered completely dilated
Physiologic Responses to Labor (Maternal)
- WBC increases
- Temp increases
- HR, CO, RR, BMR increase
- GI motility decreases
- Glucose decreases
Physiologic Responses to Labor (Fetal)
- Periodic HR changes
- Decreased fetal movement
- Decreased circulation and perfusion
First Stage of Labor
- Begins with the onset of true labor (regular contractions)
- Ends when the cervix is completely dilated at 10 cm
- Divided into 3 phases
What are the three phases in the first stage of labor?
- Latent (early) 0-3 cm dilated
- Active 4-7 cm dilated
- Transition 8-10 cm dilated
Describe the contractions in the latent phase
- Frequency - widely spaced
- Duration - short
- Intensity - begin as mild and progress to moderate
Appearance/Behavior of the mother during the latent phase
- Relieved that the labor has started
- Excited
- Anxious
- Eager to talk about herself and answer questions
- Feels able to cope with discomfort
Describe the contractions during the active phase of labor
- Frequency - regular pattern
- Duration - increasing
- Intensity - begin as moderate and progress to strong
Appearance/Behavior of the mother during the active phase of labor
- Anxiety tends to increase as contractions and pain increase
- Begins to fear a loss of control
- May use a variety of coping mechanisms or exhibit decreased ability to cope and a sense of helplessness
Describe the contractions during the transition phase
- Frequency - definite pattern (2-3)
- Duration - (60-90 seconds)
- Intensity - strong by palpation
Appearance/Behavior of mother during the transition phase of labor
- Severe pain
- Increased apprehension and irritability
- Sense of powerlessness or loss of control
- Intense physical sensations: increasing rectal pressure and feeling the urge to bear down, nausea/vomiting, shaking
Second Stage of Labor
- Begins when the cervix is completely dilated and effaced
- Ends with the birth of the baby
- Length:
- Primigravida: up to 3 hours
- Multiparas: less than 1 hour; averages 15 minutes - Early in this stage the fetus descends passively through the birth canal as the uterus contracts
- Have patient rest and begin pushing only after she feels the urge to push
- Use gravity to help with fetal descent
Mechanisms of Labor
- Engagement
- Descent
- Flexion
- Internal rotation
- Extension
- External rotation
- Expulsion
Third Stage of Labor
- Begins with birth of baby
- Ends with delivery of the placenta
- Stage 3 should last a maximum of 30 minutes
Signs of placental separation
- Globular-shaped uterus
- Fundus rises in the abdomen
- Sudden gush or trickle of blood
- Further protrusion of the umbilical cord out of the vagina
Fourth Stage of Labor
- First 1-4 hours after birth
- Physiologic recovery
- Family formation
Causes of pain during first stage of labor
- Dilation of the cervix
- Stretching of the lower uterine segment
- Pressure on adjacent structures
- Hypoxia of the uterine muscle cells during contractions
Causes of pain during the second stage of labor
- Hypoxia of the contracting uterine muscle cells
- Distention of the vagina and perineum
- Pressure on adjacent structures
Causes of pain during the third stage of labor
- Uterine contractions and cervical dilation as the placenta is expelled
Factors affecting responses to pain
- Preparation for childbirth
- Culture
- Fatigue/sleep deprivation
- Previous experiences with pain
- Anxiety level
What is the goal for pain relief during labor?
To provide maximum analgesia with minimal risk for the mother and fetus
Opioids that can be given during labor
- Butorphanol
- Nalbuphine
- Meperidine
- Fentanyl
Antiemetics that can be given during labor
- Hydroxyzine
2. Promethazine
Benzodiazepines that can be given during labor
- Diazepam
2. Midazolam
Butorphanol
- Is both a narcotic agonist and antagonist
- May cause withdrawal in narcotic-dependent patients
- May be reversed with Narcan (Nalaxone)
Maternal side effects of butorphanol
- “Floating” feeling
- Sedation
- Respiratory depression
- Hallucinations
- Urinary retention
Butorphanol dosage, onset, peak, and duration
- Usual dose is 1-2 mg slow IVP q 3-4 hours
- Onset of action occurs in 1-2 minutes
- Peak analgesia occurs in 30-60 minutes
- Duration is 3-4 hours
What are analgesic potentiators?
- Potentiate the effects of narcotic analgesics without increasing unwanted side effects (smaller doses of narcotics are more effective)
- Also treat other unpleasant side effects of narcotic analgesics such as nausea/vomiting
What is the main side effect of analgesic potentiators?
Sedation
Commonly prescribed analgesic potentiators
- Promethazine
- Hydroxyzine
- Metoclopramide
What is regional anesthesia?
- The temporary loss of sensation produced by injecting an anesthetic agent into direct contact with nervous tissue
- May be achieved through injecting either a local anesthetic agent or a combination of a local anesthetic and a narcotic
Types of regional analgesia/anesthesia
- Epidural
- Intrathecal (spinal)
- Combination spinal/epidural (CSE)
What is an epidural?
- Usually placed between the 4th and 5th vertebrae
2. Most effective method available for pain relief in labor
What is intrathecal analgesia?
Anesthetic “caines” with or without opioids injected into the subarachnoid space. Works for several hours to block pain without compromising motor ability
Epidural advantages
- Alert and able to participate in birth
- Good relaxation is achieved
- Airway reflexes remain intact
- Gastric emptying is not delayed
- Only partial motor paralysis develops
Epidural disadvantages
- Limited movement of the lower extremities
- Hypotension
- Slowed labor progress and fetal descent
- Increased second stage labor
- Less effective pushing efforts in second stage labor
- Delayed return of bladder sensation
How can hypotension be prevented if the mom has an epidural?
Preloading with IV fluid for blood volume expansion
Epidural Potential Problems
- Breakthrough pain (hot spots)
- Sedation
- Nausea/vomiting
- Pruritis (itching)
- Hypotension
Local Infiltration Anesthetics
- Produces rapid anesthesia
- Used in stages 2 and 3 of labor
- Used for episiotomy and/or repair of episiotomy/lacerations
Pudendal Anesthetics
“Saddle-Block”
- Blocks pudendal nerves at level of the ischial spines
- Does not help with pain from contractions
- Only used in stages 2 and 3 of labor
- Must be administered 10-20 minutes before anesthesia is needed
- Just pelvis is numb, not the limbs
When is general anesthesia indicated for a laboring mother?
In emergent cases
General anesthesia drugs
- Sodium pentothal (unconsciousness, amnesia)
- Anectine (muscle relaxant, paralytic)
- Nitrous oxide, analgesic (pain relief)
Complications of general anesthesia
- Fetal depression
- Nausea/vomiting (aspiration pneumonia)
- Uterine relaxation
Contraindications of Epidural Administration
Women with a previous history of …
- Spinal surgery
- Spinal abnormalities
- Coagulation defects
- Cardiac disease
- Obesity
- Infections
- Hypovolemia
- Or if the woman is receiving coagulation therapy
Types of Fetal Heart Rate Monitoring
- Intermittent auscultation
2. Continuous electronic
Types of Intermittent Auscultation
- Fetoscope
2. Doppler
External Continuous Electronic Fetal Monitoring
- Ultrasound transducer
2. Tocotransducer
Internal Continuous Electronic Fetal Monitoring
- Spiral electrode
2. Intrauterine pressure catheter
Normal range of fetal HR
110-160
Normal baseline fetal HR equation
CO = HR x SV
What is considered fetal tachycardia?
FHR baseline > 160 bpm for 10 minutes or longer
What is considered fetal bradycardia?
FHR baseline > 110 bpm for 10 minutes or longer
Causes of fetal tachycardia (maternal and fetal causes)
- Infection
- Medications
- Illegal drugs
- Fetal hypoxia
- Fetal tachyarrhythmias
- Cardiac abnormalities or heart failure
- Prematurity
Causes of fetal bradycardia (maternal and fetal causes)
- Supine position
- Hypotension
- Medications
- Prolonged hypoglycemia
- Anesthetics
- Conditions that cause acute maternal cardiopulmonary compromise
- Structural defect or heart block
- Umbilical cord occlusion
What is variability?
The variations or fluctuation in the FHR baseline caused by the interplay of the sympathetic and parasympathetic branches of the autonomic nervous system
*The presence of variability is reassuring
Presence of variability implies what?
Both the sympathetic and parasympathetic branches are working and are oxygenated and that the medulla is intact
Types of variability
- Absent
- Minimal
- Moderate
- Marked
Absent variability
Undetectable from baseline
Minimal variability
> undetectable from baseline but = 5 bpm
Moderate variability
6-25 bpm
Marked variability
> 25 bpm
Causes of absent or minimal variability
- Preterm gestation (< 28-32 weeks)
- Alteration of fetal nervous system function
- Inadequate oxygenation
FHR Episodic Patterns
Changes that are NOT associated with uterine contractions (such as variables and accelerations)
FHR Periodic Patterns
Changes that ARE associated with uterine contractions
Types of Periodic FHR Patterns
- Early Decelerations
- Late Decelerations
- Variable Decelerations
- Accelerations
FHR Accelerations
- Increase above the baseline FHR
- Abrupt increase (onset to peak in < 30 sec)
- Meet the “15 x 15” rule
- Last no longer than 2 minutes
- No intervention required
Early Deceleration
- Decrease in FHR that occurs concurrently with a uterine contraction
- > 30 seconds form onset to nadir
- Uniform shape
- Begins and ends with the contraction
- “Mirror image” of the contraction
What causes early deceleration?
Fetal head compression (stimulates a reflex vagal response)
Treatment for early deceleration
No treatment
Late Deceleration
- Gradual decrease in FHR below the baseline
- > 30 seconds from onset to nadir
- Uniform shape
- Begins late in the contraction (after the peak) and returns to baseline after contraction ends
What causes late deceleration?
Uteroplacental insufficiency (decreased O2 availability)
Interventions for late deceleration
- Maternal lateral positioning
- Discontinue oxytocin
- Consider tocolytic drug (stops labor)
- IV fluid bolus
- Correct maternal hypotension
- Administer oxygen (non-rebreather)
What is Variable Deceleration?
Abrupt decrease in FHR that is variable in shape, duration, intensity, and timing related to onset of contractions
Characteristics of variable deceleration
- Usually abrupt; onset to nadir occurs in < 30 seconds
- Shaped like the letters U, V, or W
- VERY common; occur in 50% of all labors
Cause of variable deceleration
Umbilical cord compression
Interventions for variable deceleration
- Vaginal exam to check for prolapsed cord or imminent birth
- Maternal position change to take pressure off the cord
- Administer oxygen
- Discontinue oxytocin
- Amnioinfusion if ordered
Characteristics of contractions
- Frequency
- Duration
- Intensity
- Resting tone
Frequency
Determine by counting the time from the beginning of one contraction to the beginning of the next contraction
- Should be approximately every 2-3 minutes
Duration
Determine by counting from the beginning to the end of the contraction
- Range should be approximately 40-70 seconds
Intensity (external monitor)
- Palpate fundus at the peak of a contraction to determine
- Chart subjectively as “mild”, “moderate”, or “strong”
Intensity (internal monitor)
Chart objectively, as mm Hg using graph on monitor paper or screen
Uterine Resting Tone
Degree of uterine muscle relaxation between contractions
- How soft is the uterus?
Resting Tone (external monitor)
- Palpate fundus between contractions to determine
- Chart subjectively; often as “good” or “poor” to palpation, or as “soft” or “firm”
Resting Tone (internal monitor)
Chart objectively, as mm Hg using graph on monitor paper or screen
Antepartum Assessment to Determine Fetal Well-Being
- Non-stress test
- Daily kick counts
- Biophysical profile
What is a non-stress test?
2 or more “15 x 15” accelerations in 20 minutes is considered a reactive (reassuring) result
Biophysical Profile
- Combines the non-stress test with fetal assessment done by ultrasound
- Maximum possible score is 10
- Desired score is 8-10 (indicates a healthy fetus)
- Includes 5 separate components
5 Components of Biophysical Profile
- Tone
- Breathing
- NST (non-stress test)
- Fluid
- Movement
Two methods used to evaluate fetal response to stimulation
- Scalp stimulation
2. Vibroacoustic stimulation
Cardinal Movements (engagement)
Largest diameter of head passes through pelvic inlet
Cardinal Movements (descent)
Downward movement
Cardinal Movements (flexion)
Meets resistance and chin flexes down to chest to in effect change to be the smallest fetal skull diameter presenting into the maternal pelvic dimension
Cardinal Movements (internal rotation)
Further descending and again meets resistance from the pelvic floor, causes rotation to where the AP diameter of the head in line with the AP diameter of the pelvis
Cardinal Movements (extension)
Head extends so it can pass usder the symphysis
Cardinal Movements (external rotation)
Head rotates that allows for shoulders to rotate internally to fit the pelvis
Cardinal Movements (expulsion)
Remainder of body delivered
