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OB/ Maternity
Fetal Assessment during Labor
Question | Answer |
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Causes of decrease in fetal oxygen supply | Reduction of blood flow through the maternal vessels, reduction of oxygen content in maternal blood, alterations in the fetal circulation with compression of cord, reduction of blood flow to the intervillous space in placenta due to uterine hypotonus |
Uterine Activity | A normal uterine activity pattern in labor is contractions occuring every two to five minutes and lasting less than 90 seconds. |
Fetal Heart Monitoring | Reassuring FHR includes normal baseline rate of 110-160 bpm, moderate variability, presence of accelerations, absence of deaccelerations. |
Nonreassuring FHR | Baseline of FHR less than 110 or more than 160, absent or persistantly minimal variability, recurrent late or variable decelerations, bradycardia. |
FHR Monitoring | Is used to assess fetal oxygenation. Low risk women should be monitored every 30 minutes during the first stage of labor and every 15 during the second. High risk should be evaluated every 15 minutes during the first stage of labor and every 5 the second. |
Modes of EFM | 1. The external mode which uses external transducers placed on the maternal abdomen to assess FHR and UA. 2. The internal mode, uses a spiral electrode applied to the fetal presenting part to assess FHR,pressure, and UA/ |
External Monitoring | Works by high-frequency waves off a moving interface, the fetal heart and valves. Records the frequency, regularity, and approximate duration of uterine contraction. Not intensity. Semi sitting or lateral position, confines women to bed or chair. |
Internal Monitoring | Not interrupted by fetal or maternal movement like EFM. The membranes must be ruptured and cervix dilated 2-3cm. |
Fetal Heart Rate Factors | An increase in sympathetic response results in acceleration of the FHR, an augmentation in the parasympathetic response produces a slowing of the FHR. |
Variability | Absent or undetectable variability, minimal variability less than or equal to 5 bpm, moderate variability 6 to 25 bpm, marked variability greater than or equal to 25 bpm. |
Diminished Variability | Can result from fetal hypoxemia and acidosis from certain drugs that depress the CNS. |
VEAL CHOP | Variable-Cord, Early decel-Head, Accel-Ok, Late decel-Placenta |
Contraction | Beginning of one to the beginning of another |
Fetal Tachycardia | Can result from a fetal or maternal infection such as prolonged rupture of membranes with amnionitis, maternal hyperthyroidism, fetal anemia, or in response to drugs. |
Fetal Bradycardia | Fetal cardiac problem, viral infections, maternal hypoglycemia, maternal hypothermia. |
Accelerations | Defined as visually apparent, abrupt increase in the FHR about the baseline rate. Abrupt is onset to peak in less than 30 seconds. Prolonged is 2 minutes or more but less than 10 minutes. |
Early Decelerations | Visually apparent gradual decrease and return to the baseline FHR associated with uterine contraction. Often referred to as "mirror image" of a contraction. Thought to be caused by transient fetal head compression and are considered a benign finding. |
Late Decelerations | The deceleration begins after the contraction has started and the lowest point of the decel occurs after the peak of the contraction. Usually does not return to baseline until after contraction is over |
Accelerations Cause | Spontaneous fetal movement, vaginal examination, electrode application, scalp stimulation, reaction to external sounds , breech presentation, uterine contractions, fundal pressure, abdominal palpation. |
Early Decelerations Cause | Head Compression resulting from Uterine contractions,vaginal examination, fundal pressure , placement of internal monitoring. |
Variable Decelerations | Visual abrupt decrease in the FHR below the baseline. Caused by compression of the cord. Most commonly found during the transition phase of the first stage and second stage as a result of umbilical cord compression and stretching during fetal descent. |
Prolonged Decelerations | Visually apparent decrease in FHR below the baseline 15beats/min or more and lasting more than 2 but less than 10 min. When the deceleration lasts longer than 1 to 2 minutes a loss of variability with rebound tachycardia usually occurs. |
Prolonged Deceleration Causes | Benign causes are generally pelvic exam, application of electrode, rapid fetal descent, maternal valsalva maneuver. Other causes sudden umbilical cord prolapse, hypotension, paracervical anesthesia, placental hemorrhage, uterine rupture, maternal hypoxia. |
Components of FHR | Baseline rate, baseline variability, accelerations, decelerations, and changes or trends in the FHR pattern over time. |
Fetal Monitoring Assessment | Maternal temp, pulse, RR, Bp, position, comfort, voiding pattern, status of membranes, uterine contraction pattern, cervical effacement and dilation, and emotional status. Fetal assessment includes fetal presentation,position, FHR. |
Intrauterube resuscitation | Used to refer to the interventions initiated when a nonreassuring FHR pattern is noted. Basic interventions include supplemental oxygen, maternal position changes, and increase IV fluid administration. |
Priority Interventions | The first priority is to open the maternal and fetal vascular systems, the second is to increase blood volume and the third is to optimize oxygentation of the circulating blood volume. |
FHR Response to stimulation | Scalp stimulation (using digital pressure during vaginal examination)and vibroacoustic stimulations (using artificial device over fetal head for 1-2 seconds). ONLY be performed when FHR is at baseline. |
Fetal Scalp Blood Sampling | A sample of fetal scalp blood is obtained through the dilated cervix after the membranes have ruptured. Seldom done in US |
Amnioinfusion | Infusion of room temperature isotonic fluid into the uterine cavity through a double lumen IUPC when the volume of amniotic fluid is low. |
Purpose of amnioinfusion | To relieve intermittent umbilical cord compression by restoring the amniotic fluid volume to a normal or near normal level. |
Tocolytic Therapy | Tocolysis (the relaxation of the uterus) can be achieved through the administration of drugs that inhibit UC. Improve blood flows through the placenta. Often administered when women are having excessive UC spontaneously or after decision for C-section. |
Umbilical Cord Acid-Base Determination | In assessing the immediate condition of the newborn after birth, a sample of cord blood is useful in determining APGAR. Tested for PH,PCo2, Po2. |
Maternal positioning | Avoid the supine position. Encouraged to maintain a side lying position or semi-fowler with lateral tilt to the uterus. |
Valsalva Maneuver | Discouraged because it results in decrease of maternal heart rate and BP and as a result can decrease placental blood flow, alter maternal and fetus blood flow, decrease fetal Ph and Po2, increase fetal PCo2 and increase chances of fetal hypoxemia. |
Stages of Labor- 1st stage | 1st stage- onset of regular uterine contractions to full dilation of the cervix. Latent- more progress of effacement and little in descent. Active and Transition phase- More rapid dilation of the cervix and increased rate of descent. |
Stages of Labor- 2nd stage | Second stage- The time the cervix is fully dilated to the birth. 1st phase begins when complete dilation has occurred and contractions are weak or unnoticeable. 2nd phase is when contractions resume and woman begins to push. 3rd-crowning until birth. |
Stages of Labor- 3rd Stage | Birth of the fetus until the placenta is delivered. |
Stages of Labor- 4th Stage | Lasts 2 hours after the delivery of the placenta. |