Obstetrics Flashcards
Labour definition
Regular painful uterine contractions causing progressive cervical dilatation and effacement
Most people don’t consider it to be true labour unless there is 4 cm of dilatation
Characteristics of true and false labour
True
- Regular uterine contractions
- Decreasing interval
- Increasing pain
- Cervical dilatation
- Sedation does not change contraction pattern
False
- Irregular uterine contractions
- Variable interval
- Unchanged intensity
- No cervical change
- Sedation decreases contraction pattern
Labour progress
Nullip
- Latent phase should be <24h
- Cervical dilatation should occur at 1.2 cm/h
- Second stage should be <2h, <3h with epidural
Multip
- Latent phase should be <8-12h
- Cervical dilatation should occur at 1.5 cm/h
- Second stage should be <0.5 h, <1.5 h with epidural
Cardinal Movements
- Engagement
- Descent
- Flex ion
- Internal rotation
- Extension
- External rotation (restitution)
- Expulsion (anterior and then posterior shoulder)
What are the 4Ps that determine the occurrence of dystocia
Power
Passenger
Passage
Psyche
How many eggs are females born with?
5 000 000 primordial follicles at 20 weeks
200 000 eggs at birth
1000 primordial follicles to make a mature one in one ovulatory cycle, which occurs 12-13 times per year with menstruation
Menopause definition
Permanent cessation of menstruation >12 months of amenorrhea
Mean age 51 yo
Menopause pathophysiology and presentation
Estrogen deficiency
Vast motor sx (hot flashes) Urogenital atrophy and dryness Sexual dysfunction Insomnia Weight gain
LH and FSH >40 IU/L
Most common malignancies in women
- Lung
- Breast
- Colorectal
- Endometrial
Normal duration labour stage 1
Latent phase Nulliparous: - Mean 6.5h - Longest normal 20h Multiparous - Mean 5h - Longest normal 13.5h
Active phase rate Nulliparous: - Mean 3 cm/h - Slowest normal 1.2 cm/h Multiparous: - Mean 6 cm/h - Slowest normal 1.5 cm/h
Normal duration labour stage 3
Usually within 30 minutes
Labour definition
Painful, regular uterine contractions with cervical dilation
Most people consider this dilation minimum to be 4 cm
Normal labour criteria
- Begins spontaneously
- Proceeds at normal rate (according to Friedman curve)
- Proceeds without intervention
- Results in spontaneous vaginal delivery of a healthy infant
Active management of 3rd stage of labour
- If failure to deliver placenta by 30-45 minutes
- prevents PPH
- Includes uterotonics (Oxytocin), controlled cord traction and uterine massage
- After delivery of placenta, clamp and cut cord
Delayed cord clamping benefits and contraindications
- If preterm delay cord clamping for at least 1 minute to infuse more iron and blood into fetus for improved outcome (less IVH, decreased need for transfusion)
- If thick meconium immediate clamping for prompt possible resuscitation
How to interpret fetal auscultation
Fetal heart tone audible starting at 20 weeks gestation
Listen with stethoscope, pinnard horn, fetoscope or Doppler on abdomen best at baby’s back for 1 minute while palpating maternal radial pulse before and after uterine contraction
Labour definition
Painful, regular uterine contractions with cervical dilation
Most people consider this dilation minimum to be 4 cm
Normal labour criteria
- Begins spontaneously
- Proceeds at normal rate (according to Friedman curve)
- Proceeds without intervention
- Results in spontaneous vaginal delivery of a healthy infant
7 cardinal movements
- Engagement - head at level of ischial spine
- Descent - downward passage through bony pelvic
- Flexion - partial flexion of head as baby descends through pelvis due to shape of bony pelvis
- Internal rotation - rotation of head from occiput transverse to anterior or posterior
- Extension - extension of head once past pubic symphysis
- Restitution (external rotation): when head is completely delivered, it rotates back to original position prior to internal rotation, realigning with fetal torso
- Expulsion - further descent brings shoulder to pubic symphysis followed by release of anterior then posterior shoulder and rest of fetus
All cardinal movements are accompanied by descent
Normal presentation and position
Cephalic vertex and occiput anterior
4 cardinal questions
- Fetal movement (normal >6 movements in 1 hour)
- Bleeding per vagina
- Rupture of membrane
- Contractions including regularity and pain
Differentiating false and true labour
In true labour contractions are regular, interval between decreases, worsening intensity/pain, back and abdomen location (vs lower abdomen for Braxton Hicks), dilating cervix, no change on contraction with sedation
Differentiating false and true labour
In true labour contractions are regular, interval between decreases, worsening intensity/pain, back and abdomen location (vs lower abdomen for Braxton Hicks), dilating cervix, no change on contraction with sedation
What is station
Vertical distance in cm from presenting part relative to maternal ischial spine
Negative = above
Positive = below
Indications to start pushing
- Exceeded 3rd hour of stage 2 labour
- Patient without epidural feels urge to push
- In patient with epidural urge to push or head is visible or station >+2 and OA, ROA, LOA
Maximum duration of pushing
Reassess after 2h of active pushing for operative vaginal delivery if nullparous or multiparous with epidural
Reassess after 1h of active pushing for multiparous patient without epidural
Earlier reassessment if maternal or fetal status is concerning
Dystocia
- Protracted descent <1 cm/h in nulliparous women
- <2 cm/h in multiparous women
- Arrest of descent >1h
Types of placentation with multiple pregnancy
Mono or dichorionic
Mono or diamniotic
Any combination of the above
Types of placentation with multiple pregnancy
Mono or dichorionic
Mono or diamniotic
Any combination of the above
Normal uterine contraction qualities
Frequency normally 0-5 in 10 minutes and not more than every 2 minutes
Duration normally <90 seconds
Resting time >30 seconds in between contractions
Timing regular singular
Indications for fetal scalp sampling
- Atypical or abnormal fetal tracings where delivery is not imminent
- Digital fetal scalp stimulation does not result in acceleration
Contraindications for fetal scalp sampling
- Gestation <34 weeks
- High risk of bleeding
- Face presentation
- Maternal infection (HIV, hepatitis, herpes simplex, intrauterine sepsis)
Sinusoidal variability
Variability following a sinusoidal pattern of regular peaks and troughs
Tachycardia and bradycardia
> 160 bpm or <110 bpm for 10+ minutes
Tachycardia and bradycardia
> 160 bpm or <110 bpm for 10+ minutes
Complicated variable deceleration
<70bpm lasting >1min
Biphasic deceleration
Prolonged secondary acceleration (overshoot >20 bpm and/or lasting >20 seconds)
Slow return to baseline
Continuation of baseline rate at lower rate than prior to deceleration
Presence of fetal tachy or bradycardia
Repetitive deceleration
> 3 episodes of deceleration
Late deceleration
Gradual decrease in fetal heart rate and return to baseline heart rate reaching nadir in 30+ seconds after contraction
Early deceleration
Gradual decrease in fetal heart rate and return to baseline heart rate reaching nadir in 30+ seconds before contraction
Usually a mirror image of contraction
Prolonged deceleration
deceleration >15 bpm below baseline lasting 2-10 minutes from beginning to return to baseline
Classification of fetal monitoring
Chart pg 38 Tony’s
Purpose of fetal scalp blood sampling
Determine if baby should be delivered immediately based on blood pH
Interpretation of fetal scalp blood
pH >7.25 - continue observation or repeat sampling within 30 minutes if persistent atypical or abnormal fetal monitor pattern
pH 7.21-7.24 - repeat within 30 mins or consider delivery if rapid fall since last sample
pH 0-7.2 - immediate delivery
see Tony’s for practice cardiotocography
pg 39
CSE definition
Combined spinal epidural analgesia
CSE indication
Provide instantaneous pain relief with spinal analgesia while waiting for onset of epidural analgesic effect, such as in early labour, late first stage labour or rapid progress of labour
What are the main differences between spinals and epidurals?
- Location of injection
- Spinals last for a shorter period of time
- Spinals provide stronger analgesia effect
- Spinal has larger risk of PDPH, pruritus, fetal bradycardia, limited analgesia duration in single shot spinal analgesia
Regional pudendal nerve block procedure
Insertion of local anesthesia using needle through vagina to pudendal nerve (S2-4)
Regional pudendal nerve block role
Only provide pain relief for perineum
Regional pudendal nerve block indication
Spontaneous use of outlet forceps or spontaneous vaginal delivery
Regional pudendal nerve block disadvantages
- High risk of local anesthesia toxicity, laceration, hematoma, fetal injury
- Often inadequate pain relief for delivery, repair of vagina and cervix and manual exploration of uterine cavity
Para-cervical block indication
1st stage of labour
Para-cervical block procedure
Needle inserting local anesthesia into vaginal fornices
Para-cervical block disadvantages
Risk of fetal bradycardia, fetal injury
Perineal infiltration indication, procedure and advantages
- Indication - commonly used for vaginal delivery
- Procedure - needle injecting local into posterior fouchette (posterior to vagina) to freeze perineum
- Advantage - rapid onset
Pre-term labour diagnosis, signs and symptoms
Pre term labour is a clinical diagnosis based on active labour of painful regular uterine contractions (2 in 10 minutes) with signs of cervical changes (dilation and effacement)
- Menstrual like cramps
- Low, dull backache
- Abdominal pressure, cramping, +/- diarrhea
- Pelvic pressure
- Uterine contraction, often painless
- Increase or change in vaginal discharge (mucous, watery, light bloody)
- Pelvic exam (cervical effacement >80%) or dilatation >2cm or change in cervix
- Speculum exam ROM
Pre-term labour definition
labour occurring at 20-37 weeks GA
Processes proposed in the pathogenesis of pre-term labour
Remains unknown. Proposed:
- Irritation of chorion and decidua by stress, infection, abruption, uterine distention
- Irritation triggers uterine contractions and cervical changes (release of proteases cause cervical change and ROM, release of uterotonins cause uterine contraction)
- Uterine contractions and cervical changes result in pre-term labour and delivery
Management plan for pre-term labour
- Initial - hydration, bed rest
- U/S assessment of fetus
- Abx therapy (may decrease maternal infection risk if intact membranes, definitely indicated if ROM)
- Suppression of labour
- tocolysis, usually <48h
- 1st line Indomethacin or Nifedipine
- 2nd line MgSO4 - Enhance fetal pulmonary maturity with corticosteroids
- Cervical cerclage
Pre-term labour definition
labour occurring at 20-37 weeks GA
Tocolytic in pre term labour goal and risks
- prolongs latent phase labour and delay delivery by goal of 3 days, which allows administration of 2 doses corticosteroids for maturation of lungs, thereby improving outcomes of premature babies once delivered
- Risks - narrow therapeutic index with many side effects
NSAID in pre term labour contraindication, MOA, maternal SE, fetal SE, newborn SE
a) NSAID Indomethacin
- Most commonly used tocolytic
- Contraindication: maternal platelet dysfunction, bleeding idsorder, hepatic dysfunction, GI bleed, renal failure, asthma
- MOA: inhibition of conversion of free arachidonic acid to prostaglandin –> decreased prostaglandin –> decreased uterine contraction
- Maternal SE: nausea, esophageal reflux, emesis, gastritis, platelet dysfunction
- Fetal SE: in utero constriction of ductus arteriosus, oligohydramnios
- Newborn SE: NEC, PDA
MgSO4 in pre term labour indication, maternal contraindication, MOA, maternal SE, newborn SE
b) MgSO4
- Indication: fetus 24-28 weeks due to neuroprotective effects
- Maternal contraindication: myasthenia gravis
- MOA: compete with calcium for entry into muscle cells –> decreased uterine contraction
- Maternal SE: flushing, diaphoresis, nausea, loss of deep tendon reflexes, respiratory depression, cardiac arrest especially combined with CCB
- Newborn SE: neonatal depression
Nifedipine in pre term labour maternal contraindication, MOA, maternal SE
c) CCB Nifedipine
- Maternal contraindication: hypotension, AR
- MOA: block Ca entry into muscle cells –> decreased uterine contraction
- Maternal SE: dizziness, flushing, hypotension, bradycardia, decreased cardiac output
Beta adrenergic receptor in pre term labour agonist maternal contraindication, moa, maternal se, fetal se
d) Beta-Adrenergic Receptor Agonist
- Maternal contraindication: Tachycardia sensitive maternal cardiac disease, poorly controlled maternal diabetes
- MOA: increase cAMP concentration –> decreased Ca in muscle cell –> decreased uterine contraction
- Maternal SE: tachycardia, hypotension, tremor, SOB, angina, pulmonary edema, hypokalemia, hyperglycemia
- Fetal side effects: fetal tachycardia
Corticosteroid in pre term labour examples, MOA, maternal contraindications
Betamethasone (Celestone), Dexamethasone
MOA: unknown, promotes lung maturation and increases surfactant production, thereby reducing severity of RDS, rate of IVH and mortality of premature newborn
Maternal contraindications: active TB, viral keratosis, DM
Tocolytics in pre term labour management indications and contraindications
Indications If all of the following are satisfied: - Live immature fetus - Intact membrane - Cervical dilatation <4cm - Absence of maternal or fetal contraindications
Contraindications
- Maternal bleeding from placental previa or abruption
- Maternal disease: hypertension, DM, heart disease, pre-eclampsia, eclampsia, chorioamnionitis
- Fetus: erythroblastosis fetalis, severe congenital anomalies, fetal distress/demise, IUGR, multiple gestation
Cervical cerclage definition
Placement of cervical sutures, wires or synthetic tape at internal os to close cervix
Cervical cerclage indications
Primary structural abnormality of cervical incompetence (cervical dilatation and effacement in absence of uterine contractility)
Premature rupture of membranes signs and symptoms
- fluid gush or continued leakage per vagina
- Speculum exam
a) pooling of fluid in posterior fornix
b) fluid leaking out of cervix on cough or Valsalva (“cascade”)
PROM diagnostic investigations
- Positive nitrazine test: basic amniotic fluid turns nitrazine paper blue, which can be positive with blood, urine or semen
- Fluid ferning on microscopic slide
- Ultrasound - decreased amniotic fluid volume suggests ROM
- If PPROM amniocentesis for lecitin/spingomyeline (L/S) ratio to assess lung maturity
Factors predisposing to PROM
- Maternal
- Multi-parity
- Cervical incompetence
- Infection
- Family history of premature rupture of membrane
- Poor nutrition, low SES - Current pregnancy
- Congenital anomaly
- Multiple gestation
Risks and benefits of expectant management vs immediate delivery of patient with PROM
Expectant management
- may buy time for fetus to mature
- prolongs elapse from ROM to delivery thereby increasing risk of chorioamniotis and sepsis
Immediate delivery
- Shortense elapse from ROM to delivery (decrease risk chorioamniotis and sepsis)
- Shortens time for fetus to mature in case of premature, increasing risk of complications especially RDS
Pre-term premature ROM (PPROM)
ROM before 37 weeks gestation and prior to onset of labour
Prolonged rupture of membrane
Elapse of >24h from ROM to onset of labour
PPROM risk factors
- Maternal
- Smoking
- Prior PPROM or pre-term delivery
- Short cervical length - Current pregnancy
- Polyhydramnios
- Multiple gestations
- Bleeding in early pregnancy (threatened abortion)
PROM complications
- Chorioamniotic –> maternal or fetal sepsis, cord prolapse, limb contracture
Management of PROM
1
b) . If intra-uterine environment safer than NICU –> expectant management and wait for spontaneous delivery
2. Monitoring and investigations
- admit
- daily CBC and BPP (biophysical profile) by ultrasound
- avoid bimanual to avoid introducing infection
- culture urine and genital tract (lower vagina for GBS and cervix for Gonorrhea and Chlamydia)
3. a) 34+ weeks: delivery by induction of labour or CS, GBS prophylaxis unless negative swab within 5 weeks
b) 32-33 weeks: expectant management, GBS prophylaxis, IV abx prophylaxis to prolong latency if no contraindication
c) 24-31 weeks: above + corticosteroid for lung maturation, tocolytics may be considered if ROM trigger pre-term labour
d) <24 weeks: consider termination, expectant management or induction, GBS prophylaxis, IV antibiotic prophylaxis not indicated
GBS prophylaxis
Single dose Penicillin G or Ampicillin at ROM
Indications for GBS pophylaxis
- GA<37 weeks
- Positive swab GA 35-37 weeks
- Prior history of GBS infected infant
- GBS bacteriuria
Antibiotic prophylaxis in PROM
Ampicillin and Erythromycin x 48h
Followed by Amoxicillin and Erythromycin x 5 days