1. INTRAPARTUM ASSESSMENT
Ch. 14.
INTRAPARTUM ASSESSMENT
부산백병원 산부인과
R1 손영실

2. INDEX 1. Periodic Fetal Heart Rate 2. Amnioinfusion
3. Second-stage Labor FHR Patterns
4. Fetal Scalp Blood Sampling
5. Complications From Electronic Fetal
Monitoring

3. PERIODIC FETAL HEART RATE
- Deviations from baseline that are related to uterine
contractions
① Acceleration
- increase in FHR above baseline
② Deceleration
- decrease below baseline rate
- early, late or variable type
- the waveform of these deceleration is also significant
for pattern recognition

4. PERIODIC FETAL HEART RATE
- slope of FHR change
early and late deceleration
⇒ gradual, resulting in a curvilinear and uniform
or symmetrical waveform
variable deceleration
⇒ abrupt and erratic, giving the waveform a jagged
appearance
◎ Another system (based on the pathophysiological cause)
• type Ⅰ : early type ⇒ head compression
• type Ⅱ : late type ⇒ uteroplacental insufficiency
• type Ⅲ : variable type ⇒ cord compression pattern

5. PERIODIC FETAL HEART RATE
1) Acceleration
- abrupt increase (defined as onset of acceleration to a
peak in <30 seconds) in FHR baseline
- occur most commonly antepartum, in early labor,
and in association with variable decelerations
- proposed mechanisms
• fetal movement
• stimulation by uterine contraction
• umbilical cord occlusion
• fetal stimulation during pelvic exam
• fetal scalp blood sampling & acoustic stimulation
- can occur during labor without any apparent stimulus

6. PERIODIC FETAL HEART RATE
2) Early deceleration
- gradual decrease and return to baseline associated with
a contraction
• drop in a heart rate with
uterine contractions
• related to cervical
dilatation
• physiological
- generally seen in active labor between 4~7 cm dilatation
Features of early fetal heart rate deceleration. Characteristics include gradual decrease in the heart rate with both onset and recovery coincident with the onset and recovery of the contraction. The nadir of the deceleration is 30 seconds or more after the onset of the deceleration.

7. PERIODIC FETAL HEART RATE
- not associated with fetal hypoxia, acidemia,
or low Apgar scores
- head compression probably cause vagal nerve activation
due to dural stimulation
⇒ mediate HR deceleration

8. PERIODIC FETAL HEART RATE
3) Late deceleration
- FHR response to uterine contractions
: an index of either uterine perfusion or placental
perfusion
- a smooth, gradual symmetrical decrease in FHR
beginning at or after the peak of the contraction and
returning to baseline only after the contraction has ended
- the magnitude is rarely more than 30~40 bpm below
baseline and typically not more than 10~20 bpm in
intensity
- usually not accompanied by acceleration
- maternal hypotension (m/c), excessive uterine activity,
or placental dysfunction
⇒ induce late deceleration

9. PERIODIC FETAL HEART RATE

10. PERIODIC FETAL HEART RATE
4) Variable deceleration
- most common deceleration pattern encountered during
labor (d/t umbilical cord occlusion)
• labor progressed to 5cm dilatation ⇒ 40%
• the end of 1st stage ⇒ 83%
Features of variable fetal heart rate decelerations. Characteristics include abrupt decrease in the heart rate with onset commonly varying with successive contractions. The decelerations measure ≥ 15 bpm for 15 seconds or longer with an onset to nadir phase of less than 30 seconds. Total duration is less than 2 minutes.

11. PERIODIC FETAL HEART RATE
◎ two type of variable deceleration
• A : seen with complete umbilical cord occlusion
• B : different configuration because of the “shoulders”
of acceleration before and after the deceleration
component
- the variation of variable decelerations was caused by
differing degrees of partial cord occlusion
Varying (variable) fetal heart rate decelerations. Deceleration B exhibits “shoulders” of acceleration compared with deceleration A.

12. PERIODIC FETAL HEART RATE
◎ physiological scheme
① only vein occlusion
⇒ reduce fetal blood return
⇒ triggering a baroreceptor
-mediated acceleration
② subsequent complete
occlusion
⇒ umbilical artery flow
obstruction
⇒ result in fetal systemic
hypertension
⇒ baroreceptor-mediated
deceleration

13. PERIODIC FETAL HEART RATE
◎ significant variable deceleration
decreasing to less than 70 bpm
lasting more than 60 seconds
⇒ pathological
◎ saltatory baseline HR
- rapidly recurring couplets of
acceleration and deceleration
causing relatively large
oscillations of baseline FHR
- related to cord occlusion
- in the absence of other FHR
finding, these do not signal
fetal compromise

14. PERIODIC FETAL HEART RATE
5) Prolonged deceleration
- isolated decelerations lasting 2 minutes or longer
- but less than 10 minutes from onset to return
- difficult to interpret (d/t many different clinical situations)
- more common cause
① cervical exam
② uterine hyperactivity
③ cord entrapment
④ maternal supine hypotension
- others
: epidural, spinal analgesia, maternal hypoperfusion or
hypoxia, placental abruption, umbilical knots or
prolapse, maternal seizure, impending birth, maternal
valsalva maneuver

15. PERIODIC FETAL HEART RATE
- fetus may die during prolonged deceleration
- thus, management can be extremely tenuous

16. AMNIOINFUSION
◎ infused saline through the intrauterine pressure catheter in
laboring women who had either variable decelerations or
prolonged deceleration attributed to cord entrapment
⇒ such therapy improved the heart rate pattern in half
◎ clinical areas of transvaginal amnioinfusion
① treatment of variable or prolonged decelerations
② prophylactically in cases of known oligohydramnios, as
with prolonged rupture of membranes
③ in an attempt to dilute or wash out thick meconium
◎ protocol
- 500~800 ml bolus warmed normal saline followed by a
continuous infusion of approximately 3 ml/hr

17. AMNIOINFUSION Complication Centers Reporting No. (%)
Uterine hypertonus
27 (14)
Abnormal fetal heart rate tracing
17 (9)
Amnionitis
7 (4)
Cord prolapse
5 (2)
Uterine rupture
4 (2)
Maternal cardiac or respiratory compromise
3 (2)
Placental abruption
2 (1)
Maternal death
[ Complications Associated with Amnioinfusion from a Survey of 186 Obstetrical Centers ]

18. SECOND-STAGE LABOR FHR PATTERNS
◎ only 1.4% of over 7,000 deliveries did not have FHR
deceleration during 2nd stage labor
(by Melchior & Bernard, 1985)
◎ both cord compression and fetal head compression have
been implicated to cause decelerations and bradycardia
during 2nd stage labor
◎ loss of beat-to-beat variability and baseline FHR less than
90 bpm were predictive of fetal acidemia

19. FETAL SCALP BLOOD SAMPLING
◎ measurement of the pH in capillary scalp blood
⇒ help to identify the fetus in serious distress
◎ procedure
① an illuminated endoscope is inserted through the dilated
cervix after ruptured membranes so as to press firmly
against the fetal scalp
② skin is wiped clean with a cotton swab and coated with
a silicon gel
③ an incision is made through the skin to a 2mm depth with
a special blade on a long handle
④ as a drop of blood forms on the surface, it is
immediately collected into a heparinized glass capillary
tube, and the pH of the blood is promptly measured

20. FETAL SCALP BLOOD SAMPLING
◎ protocol to try to confirm fetal distress
① pH > 7.25
⇒ labor is observed
② 7.20 < pH < 7.25
⇒ the pH measurement is repeated within 30 minutes
③ pH < 7.20
⇒ another scalp blood sample is collected
immediately
mother is taken to an operating room and prepared
for surgery
delivery is performed promptly if the low pH is
confirmed

21. FETAL SCALP BLOOD SAMPLING

22. ELECTRONIC FETAL MONITORING
COMPLICATIONS FROM
ELECTRONIC FETAL MONITORING
① injury to the fetal scalp or breech by the electrode
- rarely a major problem
- the eye in case of face presentation ⇒ serious
② fetal vessel in placenta may be ruptured by catheter
③ penetration of the placenta
④ uterine perforation
⑤ infection

23. 감사합니다.