01_26: OB/GYN Fetal Monitoring
1. 20 minutes 2. >15 seconds 3. 15 bpm
A reactive test (R-NST) is a normal baseline heart rate (120-160 bpm), normal variability and at least two accelerations in __1__ minutes, each lasting __2__ seconds and peaking at __3__ bpm above baseline. Reactive = normal
38 weeks
After how many weeks gestation does amniotic fluid start to decrease?
500 mL
By 42 weeks, amniotic fluid is at about how many mL's?
Ripening
Cervical changes are called what?
short-term variability is absent, and there is less than two cyclic changes/minute of long term variability
Decreased beat to beat variability is diagnosed if if what is absent and there is less than home many cyclic changes/minute of long term variability?
Slowing of FHR, but never < 100 bpm
Define early deceleration
Bishop score
Degree of cervical ripeness is quantified by what?
o Shoulder dystocia o Clavicle fx o Erbs Palsy o C-section d/t CPD (cephalo-pelvic disproportion)
Dysmaturity Syndrome (Post-maturity syndrome) increases incidence of birth trauma. What 4 things is the fetus at risk for?
1. 15 bpm 2. 15-20 seconds
FHR accelerations: increase in FHR above baseline of at least __1__ bpm, usually __2__ seconds duration and associated with intact fetus, unstressed by hypoxia and academia. Reassuring and usually indicates fetal well being
1. <120 beats per minute 2. > 10-15 minutes
Fetal bradycardia is defined as a baseline fetal heart rate of __1__ for __2__ minutes
Hypoxia
Fetal distress definitions: decreased level of oxygen in tissue
Hypoxemia
Fetal distress definitions: decreased oxygen content in blood
Asphyxia
Fetal distress definitions: hypoxia with metabolic acidosis
Acidemia
Fetal distress definitions: increased concentration of hydrogen ions in the blood
Acidosis
Fetal distress definitions: increased concentration of hydrogen ions in tissue
Changes in fetal heart rate (FHR) and fetal blood pH
Fetal distress/hypoxia is detected through changes in what 2 things?
160 beats per minute
Fetal tachycardia is defined as what rate?
By placing woman in lateral recumbent position
How do you relieve supine hypotension?
minimum of 3 contractions in 10 minutes
How many contractions in 10 minutes are required to interpret the contraction stress test?
15-30 mins
How often should a low or low-normal scalp pH be repeated?
Cord around neck or under arm of fetus
If variable decelerations are recurrent what do you suspect?
uteroplacental vascular insufficiency
Late decelerations are usually found in association with acute or chronic..?
20 bpm
Mild FHR deceleration: change in heart rate of less than _____ beats/min-not bad
Baseline Fetal Heart Rate
Name that FHR pattern: Steady rate. A heart rate lasting greater than or equal to 10 minutes. Central "beat per minute". Beat-to-beat variability present.
Erb or Duchenne palsy
Name that brachial plexus injury: 1/500 --> paralysis of deltoid and infraspinatus and flexor muscles.
Klumpke's paralysis
Name that brachial plexus injury: 1/500 --> paralysis of hand from injury to lower nerves of brachial plexus
Peridural Anesthesia
Name that iatrogenic cause of fetal distress: Sympathetic block may cause decreased venous return and cardiac output, maternal hypotension, decreased uteroplacental perfusion and late decelerations. Avoid problems by hydrating well and lying in lateral position.
Dysmaturity Syndrome (Post-maturity syndrome)
Name that syndrome: Loss of subcutaneous fat; growth retarded "elderly appearance". Dry, wrinkled, and cracked skin. Meconium staining of the skin, membranes, and umbilical cord = respiratory distress from mechanical obstruction of small and large airways and chemical pneumonitis. Long nails. An unusual degree of alertness. Hypoglycemia due to placental dysfunction. hyperbilirubinemia.
Short-term Variability (STV) 3-8 bpm
Name that term and missing rate: Variation in amplitude seen on a beat-to-beat basis, normally _____ bpm. It is the roughness (STV present) or smoothness (STV absent) of the FHR tracing. May be decreased/absent due to alterations in the CNS or inadequate fetal oxygenation. Measured only by fetal scalp electrode.
Long-term Variability (LTV) 1. 3 to 6 cycles 2. 5 to 15 BPM
Name that term and missing rates: Irregular, crude wave-like(oscillatory) pattern with a cycle of __1__ cycles per minute and an amplitude of __2__ bpm. Results in waviness of baseline. Can be measured by Doppler or FSE (fetal scalp electrode).
Late decelerations
Name that term: b. Slowing of FHR that occurs after peak of and extends past the length of the uterine contraction. Often a slow return to baseline. c. Brought on by hypoxemia (slows FHR as result of CNS asphyxia), direct myocardial depression or both. d. May be associated with mixed resp and metab acidosis e. Increased incidence in patients w/ preeclampsia, HTN, DM, IUGR, or other disorders associated with chronic placental insufficiency. f. Seen with abruptio placentae, maternal hypotension from anesthesia, or excessive uterine activity (hyperstimulation during oxytocin infusion)
Amniotic fluid index (AFI)
Name that term: A calculation of the volume of amniotic fluid. Maternal abdomen divided into quadrants. Using US the maximum vertical pocket of each quadrant is measured in centimeters and added.
Variable Decelerations
Name that term: Abnormal FHR pattern; can be mild, moderate or severe. Slowing of FHR inconsistent in configuration. May start before, during or after contraction starts. No uniform relationship to onset of contraction. Variable in location, pattern, and cause. Characterized by rapid fall in FHR, often < 100 bpm, then rapid return to baseline. Usually result of transient compression of umbilical cord between fetal parts or between fetus and maternal tissues. Often associated with oligohydramnios, +/- ruptured membranes. Causes short-term resp acidosis if mild. May be associated with profound combined acidosis if prolonged and recurrent
Polyhydramnios
Name that term: Greater than 20 amniotic fluid index, or 2 liters.
Amnioinfusion
Name that term: Infusion of fluid into the amniotic cavity through dilated cervix; relieves pressure on a compressed umbilical cord.
Prolonged Decelerations
Name that term: Isolated decelerations lasting 90 to 120 seconds or more Causes: prolonged umbilical cord compression, profound placental insufficiency, sustained head compression
Oligohydramnios
Name that term: Leads to increased fetal stress and distress. Amniotic fluid approximately 1 liter at 36-38 weeks, then decreases to 500 ml at 42 weeks --> decreased protection of cord--> cord impingement.
Reactivity
Name that term: Response of a healthy fetus when stimulated. Usually results in a transient increase in variability or baseline acceleration (10-15 bpm). Stimulation may be external (sound or scalp stimulation) or internal (spontaneous fetal movement)
Meconium Aspiration
Name that term: Severe resp distress from mechanical obstruction of large and small airways --> pneumonitis. *Seen in 13-15% of all term pregnancies
Early decelerations
Name that term: The timing of onset, peak and end coincides with the timing of the contraction. The degree of deceleration is proportional to the contraction strength. "mirror image" of uterine contraction. No intervention necessary
Postdates Pregnancy
Name that term: a pregnancy that continues for more than 42 weeks
Vibroacoustic stimulation
Name that test: Response of the FHR to a vibroacoustic stimulus. An acceleration on NST (> 15 bpm for > 15 sec) is a positive result. Useful adjunct to decrease the time to achieve a "reactive" NST (R-NST) and to decrease the proportion of non-reactive NST at term, precluding the need for further testing.
External (indirect) Electronic FHR monitoring
Name that type of fetal monitoring: detected through abdominal wall with a transducer (CTG-cardiograph) that emits ultrasound. Uterine contractions are also detected
Internal Electronic FHR monitoring
Name that type of fetal monitoring: uses bipolar spiral electrode attached to fetal scalp (FSE or FSC) which detects peak R-wave voltage of fetal ECG
acidosis and the fetus must be delivered immediately
No beat-to-beat variability = ?
Non-stress Test (NST)
Non-invasive test of fetal activity. Correlates with fetal well-being. Watch fetal heart acceleration during fetal movement, recorded by external monitor.
Above 170 beats per minute
Pathological pattern fetal tachycardia is defined as what rate?
1. 60 bpm 2. 1 minute 3. 90 bpm
Severe FHR deceleration: change of heart rate greater than __1__ beats/min, lasting at least __2__ minute duration OR a heart rate of less than __3__ bpm-BAD sign
Fetal compromise
Sinusoidal pattern (rate 120-160 bpm) that is smooth and undulating pattern of 5-10 bpm in amplitude and shortened short term variability is a probable sign of what?
Fetal hypoxia
Stressed fetus: When perfusion is decreased because of impaired uterine or umbilical blood flow, transfer of O2 to fetus is decreased. This leads to accumulation of CO 2 in fetus.
161-170 beats per minute
Suspicious fetal tachycardia is defined as what rate?
1. 35mmHg 2. 50 mmHg 3. 3 to 5 4. 80 to 100 5. 5 to 6
Uterine contractions increase in the first stage of labor progressively and in intensity from __1__ to __2__ mm Hg. The frequency increases from ____3___ contractions per 10 minutes. In the second stage of labor contractions increase even more to __4__ mmHg and in frequency to __5__ per 10 minutes
Cord compression and/or head compression
What 2 things can cause variable decelerations?
1. Continuous fetal heart rate monitoring 2. Fetal scalp capillary blood sampling→ fetal blood pH
What 2 ways will you monitor a fetus in distress?
1. Sodium bicarbonate (counteract acidosis) 2. Epinephrine-stimulate heart 3. Naloxone-d/t narcotic effect from mom
What 3 medications are/can be used during neonatal resuscitation?
System of rapid assessment of fetal condition at 1 minute and 5 minutes after birth. *Evaluates five signs of fetal status, assigning a maximum of 2 points for each. ● Heart rate ● Respiratory effort ● Muscle tone ● Reflex ● Color
What 5 things does the APGAR evaluate?
1. Change maternal position to the lateral recumbent position 2. Give oxygen by face mask 3. Stop oxytocin infusion 4. Provide IV fluid bolus 5. Give IV tocolytic drug (MgSO 4 ) 6. Monitor maternal blood pressure 7. If decelerations persist longer than 30 minutes, get fetal scalp blood pH and consider C-section
What 7 possible things could you do when you intervene for late decelerations?
1. Reactivity (non-stress test) 2. Fetal breathing movements (chest wall movements) 3. Fetal tone (flexion and extension of an extremity) 4. Fetal activity (gross trunk or limb movements) 5. Amniotic fluid index
What are the 5 components of a biophysical profile?
1. Asphyxia (sudden/profound) 2. Drugs 3. Reflex (ex: pressure on fetal head) 4. Arrhythmias 5. Hypothermia 6. Idiopathic (unknown)
What are the 6 cause of fetal bradycardia?
1. Fetal asphyxia and/or acidemia 2. Drugs (atropine, scopolamine, tranquilizers, narcotics, barbiturates, anesthetics, MgSO 4 ) 3. Prematurity 4. Fetal tachycardia 5. Physiologic fetal "sleep states" 6. Fetal cardiac and CNS abnormalities 7. Arrhythmias 8. Prolonged uterine contractions (uterine hypertonus) 9. Maternal academia
What are the 9 causes of decrease beat-to-beat variability?
Maternal Urinary Estriol
What biochemical evaluation can be used to indicate fetal compromise? Less than 12 mg/24 hr indicates fetal jeopardy.
Fetal Death
What can result from severe intrapartum asphyxia?
Internal uterine pressure catheter (IUPC)
What device is used to measure uterine contractions internally?
suspect for asphyxia and the BPP should be repeated in 4-6 hours or consider delivery.
What does a biophysical profile score of 6 or less mean?
baseline FHR unchanged and NO FHR decels in response to contractions. Considered reassuring.
What does a negative contraction stress test (CST) indicate?
Placental Dysfunction
What fetal complication of post-dates causes intrauterine nutritional and resp. deprivation?
Human Chorionic Somatomammotropin (hCS)/HPL
What hormone is secreted by the placenta? Level is proportional to weight of fetus and the placenta. Should follow serial measurements. ↑ tissue and liver resistance to insulin → ↑ hyperglycemia → glucose → facilitated diffusion → fetus → ↓ FBS in mom (and ↑ BS after carbo load).
Oxytocin stimulation
What iatrogenic cause of fetal distress is associated with increased incidence of late decelerations and decreased placental perfusion?
Amnioinfusion-infuse normal saline into the uterus through the IUPC to alleviate cord compression. Change maternal position to side/Trendelenburg position. Deliver fetus by C-section.
What interventions are typically done during variable decelerations?
Uses US and cardiotocography to ascertain fetal well-being.
What is a Biophysical Profile (BPP)?
Indirect measure of placental function (test for uteroplacental dysfunction)
What is a contraction stress test used to measure/test for?
Good Variability
What is a predictor of good fetal outcome and the presence of this is highly suggestive of adequate fetal CNS oxygenation?
severe variable or late decelerations with > 50% of contractions)
What is considered a positive CST?
Mild feta hypoxemia
What is going on with the fetus if there is an increase in beat-to-beat variability?
ABC's-airway, breathing, circulation
What is most important to check during neonatal resuscitation?
Asphyxia
What is often responsible for perinatal morbidity and morality of a post-dates pregnancy?
Scored by 0 to 3 points assigned for each parameter. *Score based on: ● fetal station ● degree of dilation ● effacement ● consistency of cervix ● position of cervix
What is the bishop score based on? (5 things)
three uterine contractions over 10 minutes with no evidence in the FHR of late decels, severe variable decels or loss of beat-to-beat variability.
What is the criteria for a negative CST?
25%
What is the false-positive rate of CSTs?
Fetal scalp pH
What is the gold standard in determining well-being of fetus?
fetal compromise secondary to placental insufficiency from placental aging.
What is the major concern in postdates pregnancy?
800-1000 mL
What is the maximum amount amniotic fluid that is reached at about 34-38 weeks?
Each test given from 0 to 2 points for maximum of 10 points. (normal = 8 to 10 points)
What is the maximum amount of points (minus placenta grading) that one can get during a biophysical profile?
Ultrasound exam
What is the most accurate diagnostic measurement available in determining gestational age?
Maternal fever
What is the most common cause of fetal tachycardia?
Rupture of membranes
What is the most common cause of oligohydramnios?
Variable decelerations
What is the most common periodic FHR patter?
Amniotic fluid volume/index
What is the most important variable for scoring a biophysical profile?
Tocodynamometer
What is the name of the device that measures uttering contraction externally?
Contraction stress test (CST)
What is the name of the test of FHR in response to artificially induced uterine contractions? How many contractions in 10 minutes are required to interpret the test?
120-160 beats per minute
What is the normal baseline fetal heart rate?
7.25 to 7.35
What is the normal fetal capillary pH in the first stage of labor?
7.20-7.24
What is the pH range that is considered pre-acidotic?
Beat-to-Beat Variability (BTBV)
What is the single most important characteristic of the baseline FHR and indicator of fetal status/fetal well being?
prolonged diminished beat-to-beat variability (BTBV)
What is the single most reliable sign of fetal compromise?
Decreased Variability
What may be a sign of loss of fine autonomic control of FHR?
prostaglandin gel: Only dinoprostone (PGE 2 ) approved for ripening Mistoprostol (Cytotec)-PGE 1 synthetic (or luminaria tents = seaweed)
What medications can you use to help ripen a cervix?
less than 7.20
What pH is indicative of significant asphyxia?
Associated with extreme fetal jeopardy (Rh isoimmunization and fetal anemia from fetomaternal transfusion). Also seen after giving narcotics to mother.
What scenarios can cause a sinusoidal pattern on the fetal monitor?
Biophysical profile and/or contractions tress test (CST)
What should you do if the stress test is a non-reactive NST (NR-NST)?
if there is evidence of deteriorating fetal well-being or if pregnancy is over 42 weeks.
When is delivery indicated?
