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Flashcards in Antenatal Testing Deck (71)
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1
Q

True or false: in most populations, antepartum fetal surveillance has been shown to improve perinatal outcomes

A

False–only a few populations have shown benefit

2
Q

True or false: randomized trials have NOT been performed to determine the best antenatal test

A

True

3
Q

How reliable are abnormal results with antenatal testing?

A

Often not

4
Q

What is the best way to yield the most reliable results?

A

Using multiple modalities

5
Q

What should be asked at every visit?

A

Fetal movement

6
Q

What is the contraction stress test?

A

Looks at contractions, and what happens to FHT

–not used and not really reliable

7
Q

Is there an optimal protocol to assess fetal movement?

A

No–relies on kick counts and maternal assessment of fetal movement

8
Q

When do mothers feel movement? When do kick counts begin?

A

20 weeks

28 weeks

9
Q

What is the non-stress test based on?

A

Based on the premise that the HR of a fetus is that is not acidotic or neurologically depressed, will temporarily accelerate with fetal movement

10
Q

True or false: fetal heart reactivity is a good indicator of normal fetal autonomic function

A

True

11
Q

What, generally, is the nonstress test? What are the two outcomes?

A

Check for acceleration above baseline before and after movement

Reactive (2x rxn within 20 mins)

Nonreactive (above not met w/in 40 mins)

12
Q

What is the biophysical profile?

A

NST with 4 observations of the fetus made by real-time US

13
Q

What is the umbilical artery doppler? What is this used to assess? How are results reported?

A

Doppler US used to assess hemodynamic components of vascular impedance, used to screen for IUGR.

Reported as a systolic /diastolic ratio

14
Q

How, besides US, do you screen for IUGR? (2)

A
  • Fundal height

- Biochemical profile (MSAFP)

15
Q

Increased MSAFP increases the risk for IUGR how much?

A

10x

16
Q

What indicates IUGR with umbilical artery doppler?

A

Decrease in umbilical artery diastolic flow

17
Q

Who, specifically, needs antenatal screening? (4)

A
  • IDDM
  • h/o fetal demise
  • Post-date pregnancies (more than 41 weeks)
  • Chronic HTN
18
Q

What is intrapartum fetal monitoring primarily used for? Is this done continuously or intermittently? Internally or externally

A

Evaluate intrapartum fetal oxygenation

Can be done either continuously or intermittently, and internally/externally

19
Q

What are the two factors that are measured intrapartum?

A

FHT and contractions

20
Q

Is intrapartum fetal monitoring a diagnostic test?

A

No–screening tool

21
Q

Has intrapartum fetal monitoring impacted the incidence of cerebral palsy?

A

No

22
Q

When is external monitoring used? (3)

A
  • When clinically undesirable or impossible to rupture membranes
  • NST
  • Obese women
23
Q

What does internal monitoring require? (2)

A
  • Requires membranes/amnion to be ruptured

- Cervix has to be dilated 1-2 cm

24
Q

What is used to assess FHR? (2)

A
  • Electrode attached to the fetal scalp to monitor R-R intervals
  • US thru abdo
25
Q

What part of the head it the FSE attached to?

A

Anywhere, but not face or fontanelle

26
Q

If the fetus is dead, but there are still electrical signals from the internal electrical FHR monitor, what does this probably represent?

A

Maternal electrical activity

27
Q

What is the risk of infection with internal FHR?

A

Low

28
Q

How do you monitor uterine contractions externally?

A

Tocodynamometer placed on the maternal abdomen, to detect alterations in the curvature of the abdomen

29
Q

What are the factors that the Tocodynamometer measures?

A

Frequency and duration, but not amp

30
Q

What is the internal device that can be used to assess contraction?

A

Intrauterine pressure catheter (IUPC) that is inserted after ROM

31
Q

What are the risks associated with Intrauterine pressure catheter (IUPC) placement?

A

Small risk of perforation of the myometrium or placenta

32
Q

Is there an increased risk of chorioamnionitis or postpartum endometritis with IUPC placement? If so, how much?

A

No

33
Q

What is the normal amount of uterine contractions during labor?

A

5 ctx or less in 10 min avg over 30 mins

34
Q

What is tachysystole? how can you tell if this is problematic?

A

More than 5 ctx in 10- min

qualified by presence or absence of FHR decelerations

35
Q

What is the regular fetal heart rate?

A

110-160

36
Q

Why is there a slowing HR with increased gestational age?

A

Fetal increased parasympathetic tone

37
Q

The mean FHR is rounded to increments of what in what timeframe?

A

Increments of 5 bpm in a 10 min segment

38
Q

When, relative to contractions, does FHR monitoring occur?

A

Between contractions

39
Q

What defines fetal tachycardia? How long?

A

-10 minutes or longer of HR more than 160 bpm

40
Q

What defines fetal bradycardia?

A

Prolonged HR less than 110

41
Q

How do you quantitate fluctuations in the FHR?

A

As the amplitude of peak-to-peak trough in BPM

42
Q

What is FHR a good indicator of, in terms of fetal physiology?

A

Indicator of intact integration between CNS and the fetal heart

43
Q

By the time a fetus reaches (__) weeks gestation, the fetal CNS should be mature enough to produce normal variability?

A

28

44
Q

Loss of FHR variability suggests what?

A
  • Hypoxia
  • Fetal sleep state
  • CNS depressant drugs
45
Q

What are the three primary mechanisms by which uterine contractions can cause a decrease in FHR?

A

Compression of:

  • Fetal head
  • Umbilical cord
  • Uterine myometrial vessels
46
Q

What are the two major classifications of periodic/non-periodic FHR?

A

Accelerations and decelerations

47
Q

What are periodic changes in FHR? Non=periodic?

A

Periodic = FHR changes associated with contractions

Non = When fetal HR changes are not associated with contractions

48
Q

What is acceleration of FHR? Deceleration?

A

Transient increase/decreased

49
Q

What are the only 2 mechanisms that alter FHR?

A
  • Reflex of ANS

- fetal myocardial hypoxia

50
Q

What is the usual morphology of early deceleration, in relation to contractions? Is this concerning?

A
  • Mirror image of the contractions

- not concerning-normal vagal response from compression

51
Q

What causes early deceleration?

A

Compression by vagal stimulation from head compression

52
Q

FHR never falls before what rate with early deceleration?

A

100 bpm

53
Q

Is FHR deceleration a reassuring finding?

A

yes

54
Q

What are late decelerations? What causes these?

A

Transitory decreases in FHR caused by uteroplacental insufficiency

55
Q

What is the most common FHR develeration noted during labor? How do you correct these?

A

Variable deceleration

Move the patient to relive cord compression

56
Q

How do you calculate variable decelerations?

A

From the onset to the nadir of the deceleration

57
Q

Onset, depth, and duration of decelerations vary with what?

A

Successive contractions

58
Q

What causes variable deceleration? When is this commonly seen?

A

Reflex change mediated by the vagus nerve, generally caused by umbilical cord compression.

Commonly seen with oligohydramnios

59
Q

How can you relieve variable deceleration?

A

Changing maternal position to alleviate cord compression

60
Q

What is category I classification of FHR tracings? What is this predictive of?

A

Normal–strongly predictive of normal acid-base status

61
Q

What is category II classification of FHR tracings? What is this predictive of?

A
  • Indeterminate

- Not predictive of abnormal fetal-acid-base status

62
Q

What is category III classification of FHR tracings? What is this predictive of?

A

Abnormal–associated with fetal acid-base status at the time of observation

63
Q

In a patient without complications, how often should FHR tracing be reviewed (first and second stages of labor)?

A

First stage = q 30 mins

Second stage = q 15 mins

64
Q
A
65
Q

What is the position of the mother that can help relieve cord compression?

A

Left lateral

66
Q

What are the three major steps if intrauterine resuscitation if there is abnormal FHR?

A
  • Stop oxytocin and startTocolysis (decrease uterine activity)
  • Increase IVF to mother and fetus
  • Oxygen
67
Q

True or false: moderate FHR variability reliably predicts the absence of metabolic acidemia at the time of observation

A

True

68
Q

When does intrapartum interruption of fetal oxygenation result in neurological injury?

A

Will not unless it progresses to metabolic acidemia

69
Q

True or false: minimal absent variablity alone can reliably preduct the presece of fetal metabolic acidemia

A

False-does not predict

70
Q

What are the four observations for the NST + biophysical profile?

A
  • Fetal breathing
  • Fetal movement
  • Fetal tone
  • Amniotic fluid volume
71
Q

What is the crown-to-rump length used for?

A

Gestational age