Table 12-1. Nonstress Test (NST)
| Criteria: >2 accelerations in 20 min: | ||
| Reactive NST | ↑ FHR >15 beats/min and lasting >15 seconds | |
| Assessment: reassuring of fetal well-being | ||
| Follow-up: repeat weekly/biweekly | ||
| Criteria: no FHR accelerations or did not meet criteria | ||
| Nonreactive NST | ||
| Assessment: sleeping, immature, or sedated fetus; acidotic, | ||
| compromised fetus? | ||
| Follow-up: VAS | ||
| If still NR: do CST or BPP | ||
Definition of abbreviations: BPP, biophysical profile; CST, contraction stress test; FHR, fetal heart rate; VAS, vibroacousticstimulation.
AMNIOTIC FLUID INDEX
The 4-quadrant amniotic fluid index test assesses in centimeters the deepest single vertical amniotic fluid pocket in each of the 4 quadrants of the uterus. The sum of the pockets is known as the amniotic fluid index, or AFI. Interpretation is as follows:
<5 cm—oligohydramnios 5–8 cm—borderline
9–25 cm—normal
>25 cm—polyhydramnios
BIOPHYSICAL PROFILE (BPP)
A complete BPP measures 5 components of fetal well-being: NST, amniotic fluid volume, fetal gross body movements, fetal extremity tone, and fetal breathing movements. The last 4 compo-nents are assessed using obstetric ultrasound. Scores given for each component are 0 or 2, with maximum possible score of 10 and minimum score of 0.
• Score of 8 or 10—highly reassuring of fetal well-being. Management is to repeat thetest weekly or as indicated. Fetal death rate is only 1 per 1,000 in the next week.
• Score of 4 or 6—worrisome. Management is delivery if the fetus is>36 weeks or repeatthe biophysical profile in 12–24 h if <36 weeks. An alternative is to perform a CST.
• Score of 0 or 2—highly predictive of fetal hypoxia with low probability of false posi-tive. Management is prompt delivery regardless of gestational age.
A modified BPP includes only the NST and amniotic fluid volume. Its predictive value is almost as high as a complete BPP.
|
|
|
104
| S2 OB-GYN.indb 104 | 7/8/13 6:35 PM | |||
GI
Chapter 12 l Overview of Antepartum Fetal Testing
| 200 | |||||||||||
| 180 | |||||||||||
| FHR | 150 | ||||||||||
| bpm | 120 | ||||||||||
| 90 | |||||||||||
| 00 | (A) Reactive NST | ||||||||||
| 100 | |||||||||||
| UC | 75 | ||||||||||
| 50 | |||||||||||
| mHg | |||||||||||
| 25 | |||||||||||
| 0 | |||||||||||
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | ||
| Minutes | |||||||||||
(A) Normal baseline range, and no UCs are present. Thus, only the NST component can be assessed.
Because 3 accelerations are present, the assessment is reactive NST. This is a reassuring tracing.
|
|
|
| 200 | |||||||||||
| FHR | 180 | ||||||||||
| 150 | |||||||||||
| bpm | 120 | ||||||||||
| 90 | |||||||||||
| 00 | (B) Nonreactive NST | ||||||||||
| 100 | |||||||||||
| UC | 75 | ||||||||||
| mHg | 50 | ||||||||||
| 25 | |||||||||||
| 0 | |||||||||||
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | ||
| Minutes | |||||||||||
| 200 | ||||||||||||
| 180 | ||||||||||||
| FHR | 150 | |||||||||||
| 120 | ||||||||||||
| bpm
| ||||||||||||
| 90 | ||||||||||||
| 00 | (C) Reactive (NST) Negative CST | |||||||||||
| 100 | ||||||||||||
| UC | 75 | |||||||||||
| 50 | ||||||||||||
| mHg | ||||||||||||
| 25 | ||||||||||||
| 0 | ||||||||||||
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | |||
| Minutes | ||||||||||||
(B) Normal baseline range and no UCs are present. Thus, only the NST component can be assessed.
Because no accelerations are present, the assessment is nonreactive NST. Because this is not a reassuring tracing, the next step should be a vibroacoustic fetal
stimulation.
(C) Normal baseline range and 4 UCs are present in 10 minutes. Thus, both the NST and CST components can be assessed. Because 3 accelerations are present,
and no late decelerations are present, the assessment is reactive NST, negative CST. This is a reassuring tracing.
| 200 | |||||||||||||
| FHR | 180 | ||||||||||||
| 150 | |||||||||||||
| bpm | 120 | ||||||||||||
| 90 | |||||||||||||
| 00 | (D) Nonreactive (NST) Negative CST
| ||||||||||||
| 100 | |||||||||||||
| UC | 75 | ||||||||||||
| mHg | 50 | ||||||||||||
| 25 | |||||||||||||
| 0 | 2 | 3 | 4 | 5 | 6 | ||||||||
| 1 | 7 | 8 | 9 | 10 | |||||||||
| Minutes | |||||||||||||
| 200 | |||||||||||
| 180 | |||||||||||
| FHR | 150 | ||||||||||
| 120 | |||||||||||
| bpm | |||||||||||
| 90 | |||||||||||
| 00 | (E) Nonreactive (NST) Positive CST | ||||||||||
| 100 | |||||||||||
| UC | 75 | ||||||||||
| 50 | |||||||||||
| mHg | |||||||||||
| 25 | |||||||||||
| 0 | |||||||||||
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | ||
| Minutes | |||||||||||
(D) Normal baseline range and 4 UCs are present in
10 minutes. Thus, both the NST and CST components can be assessed. Even though no accelerations can be seen,
no late decelerations are present. The assessment is nonreactive NST, negative CST. This suggests fetal sleep, sedation, or central nervous system (CNS) abnormality.
(E) Elevated baseline range and 4 UCs are present in 10 minutes. Thus, both the NST and CST components can be assessed. No accelerations can be seen, but
repetitive late decelerations are present. The assessment is nonreactive NST, positive CST. This is highly suggestive of fetal compromise.
Figure I-12-1. Antepartum Electronic Fetal Monitor (EFM) Tracings
All EFM tracings should be evaluated for the nonstress test (NST) and the contraction stress test (CST). If a technically adequate fetal heart rate (FHR) tracing is present, the NST component can be assessed as reactive or nonreactive. If 3 or more uterine contractions (UCs) are present in 10 minutes, the CST components can be assessed as negative or positive.
105
| S2 OB-GYN.indb 105 | 7/8/13 6:35 PM | |||
GI
USMLE Step 2 l Obstetrics
Дата добавления: 2018-11-24; просмотров: 292; Мы поможем в написании вашей работы! |
Мы поможем в написании ваших работ!