10. Normal Labour and Delivery Flashcards
Define: True labour (3)
- regular, painful contractions of increasing intensity associated
- with progressive dilatation and effacement of cervix
- and descent of presenting part, or progression of station
Differentiate preterm, term and post-term (3)
- preterm (≥20 to ≤36+6 wk GA)
- term (37-41+6 wk GA)
- postterm (≥42 wk GA)
Describe: False labour (6)
- (Braxton-Hicks contractions)
- irregular contractions
- with unchanged intensity and long intervals
- occur throughout pregnancy
- and not associated with any cervical dilatation, effacement, or descent
- often relieved by rest or sedation
Define: Fetal lie (1)
orientation of the long axis of the fetus with respect to the long axis of the uterus (longitudinal, transverse, and oblique)
Define: Fetal presentation (1)
- Fetal body part closest to the birth canal
Name different fatal presentations (5)
- breech (complete, frank, and incomplete)
- cephalic (vertex/occiput, face, or brow)
- transverse (shoulder)
- compound (fetal extremity prolapses along with presenting part)
- all except vertex are considered malpresentations
Describe: Fetal position (1)
position of presenting part of the fetus relative to the maternal pelvis
Name: Fetal positions (3)
- OA: most common presentation (“normal”) – left OA most common
- OP: most rotate spontaneously to OA; may cause prolonged second stage of labour
-
OT: leads to arrest of dilatation
- normally, fetal head enters maternal pelvis and engages in OT position
- subsequently rotates to OA position (or OP in a small percentage of cases)
Define: Attitude (2)
flexion/extension of fetal head relative to shoulders
- brow presentation: head partially extended (requires C/S)
- face presentation: head fully extended
- mentum posterior always requires C/S, mentum anterior can deliver vaginally
Define: Station (3)
position of presenting bony part relative to ischial spines – determined by vaginal exam
- at ischial spines = station 0 = engaged
- –5 to –1 cm above ischial spines
- +1 to +5 cm below ischial spines
Define: Asynclitism (2)
- alignment of the sagittal suture relative to the axis of the birth canal
- lateral tilt seen with either anterior or posterior asynclitism and may impact descent
Name the stages of labour (4)
- First Stage of Labour (0 – 10 cm cervical dilation)
- Second Stage of Labour (10 cm dilation – delivery of the baby)
- Third Stage of Labour (delivery of the baby – delivery of the placenta)
- Fourth Stage of Labour (First hour post-partum)
Name phases of first stage of labour (2)
- Latent phase
- Active phase
Describe latent phase of first stage of labour (2)
- uterine contractions typically infrequent and irregular
- slow cervical dilatation (usually to 4 cm) and effacement
Describe active phase of first stage of labour (4)
- rapid cervical dilatation to full dilatation (nulliparous ≥1.0 cm/h, multiparous ≥1.2 cm/h)
- phase of maximum slope on cervical dilatation curve
- painful, regular contractions q2-3min, lasting 45-60 s
- contractions strongest at fundus
Describe: Second stage of labour (4)
- from full dilatation to delivery of the baby; duration varies based on parity, contraction quality, and type of analgesia
- mother feels a desire to bear down and push with each contraction
- women may choose a comfortable position that enhances pushing efforts and delivery
- upright (semi-sitting, squatting) and left lateral decubitus position LLDP are supported in the literature
- progress measured by descent
Describe: Third Stage of Labour (5)
- from baby’s birth to separation and expulsion of the placenta
- can last up to 30 min before intervention is indicated
- demonstrated by gush of fresh blood, umbilical cord lengthening, uterine fundus changing shape (firm and globular), and rising upward
- active management: start oxytocin IV drip, or give 10 IU IM or 5 mg IV push, after delivery of anterior shoulder in anticipation of placental delivery, otherwise give after delivery of placenta
- routine oxytocin administration in third stage of labour can reduce the risk of postpartum hemorrhage PPH by >40%
Describe: Fourth Stage of Labour (5)
- first postpartum hour
- monitor vital signs and bleeding, repair lacerations
- ensure uterus is contracted (palpate uterus and monitor uterine bleeding)
- inspect placenta for completeness and umbilical cord for presence of 2 arteries and 1 vein
- 3rd and 4th stages of labour most dangerous to the mother (i.e. hemorrhage)
Describe time of course of normal labour (Nulliparous vs Multiparous)
- First
- Second
- Third
- First: 6-18 h vs 2-10 h
- Second: 30 min-3 h vs 5-30 min
- Third: 5-30 min vs 5-30 min
*without epidural
Name: Signs of Placental Separation (4)
- Gush of blood
- Lengthening of cord
- Uterus becomes globular
- Fundus rises
Name: The Cardinal Movements of the Fetus During (8)
Name: Non-Pharmacologic Pain Relief Techniques (11)
- reduction of painful stimuli
- maternal movement, position change, counter-pressure, and abdominal compression
- activation of peripheral sensory receptors
- superficial heat and cold
- immersion in water during labour
- touch and massage, acupuncture, and acupressure
- transcutaneous electrical nerve stimulation TENS
- intradermal injection of sterile water
- aromatherapy
- enhancement of descending inhibitory pathways
- attention focusing and distraction
- hypnosis
- music and audio analgesia
- biofeedback
Name Pharmacologic Methods for pain relief (5)
- nitrous oxide (e.g. self-administered Entonox®)
- narcotics (usually combined with anti-emetic)
- pudendal nerve block
- perineal infiltration with local anesthetic
- regional anesthesia (epidural block, combined spinal-epidural, and spinal)
Name techniques for Fetal Monitoring in Labour (5)
- Vaginal Exam
- Intrapartum Fetal Monitoring
- Electronic FHR Monitoring
- Baseline FHR
- Variability
- Periodicity
- Fetal Scalp Blood Sampling
- Fetal Oxygenation
In Fetal Monitoring in Labour, describe: Vaginal Exam (5)
- membrane status, as indicated by amniotic fluid (clear, pink, bloody, and meconium)
- cervical effacement (thinning), dilatation, consistency, position, and application
- fetal presenting part, position, and station
- bony pelvis size and shape
- monitor progress of labour at regular intervals and document in a partogram
In Fetal Monitoring in Labour, describe: Intrapartum Fetal Monitoring (2)
- intermittent fetal auscultation with Doppler device q15-30min for 1 min in first stage active phase following a contraction, q5min during second stage when pushing has begun
- fetal scalp sampling should be used in conjunction with electronic FHR monitoring and contraction monitoring (CTG) to resolve the interpretation of abnormal or atypical partterns
Continuous electronic FHR monitoring reserved for when? (6)
- abnormal auscultation
- prolonged labour
- labour which is induced or augmented
- meconium present
- multiple gestation/fetal complication
- and concerns about the fetus tolerating labour
Use of continuous electronic monitoring when used routinely in all patients (i.e. no risk factors) shown to lead to what? (1)
higher intervention rates and no improvement in outcome for the neonate
Name techniques for continuous monitoring (2)
- external (Doppler)
- internal (fetal scalp electrode) monitoring
Describe: Electronic FHR Monitoring (2)
- FHR measured by Doppler; contractions measured by tocometer
- described in terms of baseline FHR, variability (short-term, long-term), and periodicity (accelerations, decelerations)
What’s the normal range of baseline FHR? (1)
is 110-160 bpm
Describe variability in Electronic FHR monitoring (5)
- physiologic variability is a normal characteristic of FHR
- variability is measured over a 15 min period and is described as:
- absent
- minimal (<6 bpm)
- moderate (6-25 bpm)
- or marked (>25 bpm)
- normal variability indicates fetal acid-base status is acceptable
- can only be assessed by electronic contraction monitoring (CTG)
- variability decreases intermittently even in healthy fetus
Describe: Accelerations in FHR monitoring (2)
- increase of ≥15 bpm for ≥15 s
- or ≥10 bpm for ≥10 s if <32 wk GA
Describe: Decelerations in FHR monitoring (2)
- 3 types
- described in terms of shape, onset, depth, duration recovery, occurrence, and impact on baseline FHR and variability
Describe: Approach to the Management of Abnormal FHR (11)
POISON – ER
- Position (LLDP)
- O2 (100% by mask)
- IV fluids (corrects maternal hypotension)
- Fetal scalp stimulation
- Fetal scalp electrode
- Fetal scalp pH
- Stop oxytocin
- Notify MD
- Vaginal exam to rule out cord prolapse
- Rule out fever, dehydration, drug effects, prematurity
- If above fails, consider C/S
Name Factors Affecting Fetal Heart Rate: Fetal Tachycardia (FHR >160 bpm) (13)
- Maternal Factors
- Fever
- Hyperthyroidism
- Anemia
- Dhydration
- Fetal factors:
- Arrhythmia
- Anemia
- Infection
- Prolonged activity
- Chronic hypoxemia
- Congenital anomalies
- Drugs: Sympathomimetics
- Uteroplacental:
- Early hypoxia (abruption, HTN)
- Chorioamnionitis
Name Factors Affecting Fetal Heart Rate: Fetal Bradycardia (FHR <110 bpm) (17)
- Maternal factors
- Hypothermia
- Hypotension
- Hypoglycemia
- Position
- Umbilical cord occlusion
- Fetal factors
- Rapid descent
- Dysrhythmia
- Heart block
- Hyopoxia
- Vagal stimulation (head compression)
- Hypothermia
- Acidosis
- Drugs
- B-Blockers
- Anesthetics
- Uteroplacental
- Late hypoxia (abruption, HTN)
- Acute cord prolapse
- Hypercontractility
Name Factors Affecting Fetal Heart Rate: Decreased Variability (10)
- Maternal Factors:
- Infection
- Dehydration
- Fetal factors:
- CNS anomalies
- Dysrhythmia
- Inactivity/sleep cycle
- Preterm fetus
- Drugs:
- Narcotics, sedatives
- Magnesium sulphate,
- β-blockers
- Uteroplacental: Hypoxia
Describe: Early Decelerations (4)
- Uniform shape with onset early in contraction, returns to baseline by end of contraction, mirrors contraction (nadir occurs at peak of contraction)
- Gradual deceleration and return to baseline
- Often repetitive; no effect on baseline FHR or variability
- Benign, due to vagal response to head compression
Describe: Variable Decelerations (4)
- Variable in shape, onset, and duration
- Most common type of periodicity seen during labour
- Often with abrupt drop in FHR >15 bpm below baseline (>15 s, <2 min); usually no effect on baseline FHR or variability 120
- Due to cord compression or, in second stage, forceful pushing with contractions
Describe: Complicated Variable Decelerations (6)
- FHR drop <70 bpm for >60 s
- Loss of variability or decrease in baseline after deceleration
- Biphasic deceleration
- Slow return to baseline
- Baseline tachycardia or bradycardia
- May be associated with fetal acidemia
Describe: Late Decelerations (4)
- Uniform shape with onset, nadir, and recovery occurring after peak of contraction, slow return to baseline 120
- May cause decreased variability and change in baseline FHR
- Due to fetal hypoxia and acidemia, maternal hypotension, or uterine hypertonus
- Usually a sign of uteroplacental insufficiency (an ominous sign)
Describe: Classification of Intrapartum EFM Tracings (3)
- Normal Tracing (Category 1)
- Atypical Tracing* (Category 2)
- Abnormal Tracing* (Category 3)
Describe: Normal EFM Tracing (Category 1)
- Baseline
- Variability
- Decelerations
- Accelrations
- Action
- Baseline: 110-160 bpm
- Variability:
- 6-25 bpm
- ≤5 bpm for <40 min
- Decelerations:
- None
- Early decelerations
- Occasional uncomplicated variable decelerations
- Acceleration:
- Accelerations spontaneous or during scalp stimulation
- Action: EFM may be interrupted for ≤30 min if mother/fetus stable
Describe: Atypical Tracing* (Category 2)
- Baseline
- Variability
- Decelerations
- Accelrations
- Action
- Baseline:
- Bradycardia 100-110 bpm
- Tachycardia >160 for 30-80 min
- Rising baseline
- Variability:
- ≤5 bpm for 40-80 min
- Decelerations:
- Repetitive (≥3) uncomplicated variable decelerations
- Occasional late decelerations
- Any prolonged deceleration (2-3 min)
- Acceleration: Absent with scalp stimulation
- Action: Further assessment required
Describe: Abnormal Tracing* (Category 3)
- Baseline
- Variability
- Decelerations
- Accelrations
- Action
- Baseline:
- Bradycardia <100 bpm
- Tachycardia >160 bpm for >80 min
- Erratic baseline
- Variability:
- <5 bpm for >80 min
- ≥25 bpm for >10 min
- Decelerations:
- Repetitive (≥3) complicated variable decelerations
- Repetitive late decelerations
- Any prolonged deceleration (≥3 min)
- Acceleration: Nearly absent
- Action:
- review clinical
situation
* obtain scalp pH * prepare for possible delivery
Describe: Fetal Scalp Blood Sampling (3)
- cervix must be adequately dilated
- indicated when atypical or abnormal fetal heart rate is suggested by clinical parameters including
- heavy meconium
- moderately to severely abnormal FHR patterns (including unexplained low variability, repetitive late decelerations, complex variable decelerations, and fetal cardiac arrhythmias)
- done by measuring pH or more recently fetal lactate
Describe results: Fetal Scalp Blood Sampling (pH and lactate) (3)
- pH ≥7.25, lactate <4.2 mmol/L: normal, repeat if abnormal FHR persists
- pH 7.21-7.24, lactate 4.2-4.8 mmol/L: repeat assessment in 30 min or consider delivery if rapid fall since last sample
- pH ≤7.20, lactate >4.8 mmol/L indicates fetal acidosis, delivery is indicated
Name contraindications: Fetal Scalp Blood Sampling (2)
- known or suspected fetal blood dyscrasia (hemophilia, vWD)
- active maternal infection (HIV, genital herpes)
Describe: Fetal Oxygenation (3)
- uterine contractions during labour decrease uteroplacental blood flow, which results in reduced oxygen delivery to the fetus
- most fetuses tolerate this reduction in flow and have no adverse effects
- distribution of oxygen to the fetus depends on maternal, uteroplacental, and fetal factors
Describe fetal response to hypoxia/asphyxia (4)
- decreased movement, tone, and breathing activities
- anaerobic metabolism (decreased pH)
- transient fetal bradycardia followed by fetal tachycardia
- redistribution of fetal blood flow
Name: Factors Affecting Fetal Oxygenation (7)
