Fetal surveillance - IPM abnormalities

Question 1

Examples of abnormalities

Answer 1

• Decelerations
• Sinusoidal pattern
• Tachysytole

Question 2

General types of decelerations

Answer 2

• Gradual
  
  • Early
  • Late
• Abrupt
  
  • Variable

Question 3

Gradual versus abrupt deceleration

Answer 3

• Gradual
  
  • Onset to nadir ≥ 30 secondsm(calculated from the onset of the nadir to the return
• Abrupt
  
  • Onset to nadir < 30 secondsm(calculated from the onset of the nadir to the return
• Both
  
  • Transient episode of slowing of FHR below the baseline more than 15 bpm

Question 4

Early deceleration

• Definition
• Cause
• Mechanism of cause

Answer 4

• Definition
  
  • Gradual onset
  • Onset of deceleration occurs at the onset of contraction
• Cause
  
  • Fetal head compression
• Mechanism of cause
  
  • Head compression → increased ICP → vagal nerve innervation

Question 5

Late deceleration

• Definition
• Cause
• Mechanism of cause

Answer 5

• Definition
  
  • Gradual onset
  • Deceleration occurs after the peak of contraction (time delay of more than 15 seconds after contraction)
• Cause
  
  • Uteroplacental insufficiency
• Mechanism of cause
  
  • Uteroplacental insufficiency → decrease U-P O₂ transfer → chemoreceptor stimulus → vagal nerve stimulation → deceleration

Question 6

Variable deceleration

• Definition
• Cause
• Mechanism of cause

Answer 6

• Definition
  
  • Abrupt onset
  • Occurs anytime in the contraction
• Cause
  
  • Cord compression
• Mechanism of cause
  
  • Occlussion of vein → reduced fetal blood return → deceleration

Question 7

What is prolonged deceleration?

Answer 7

Decrease in FHR from the baseline is ≥ 15 bpm, lasting ≥ 2 minutes but < 10 minutes in duration

Question 8

At what cervical dilation does early deceleration usually occur?

Answer 8

4–7 cm

Question 9

Sinusoidal pattern

• Definition
• Causes

Answer 9

• Definition
  
  • Visually apparent, smooth, sine wave-like undulating pattern in FHR baseline with a cycle frequency of 3-5 bpm which persists for ≥ minutes
• Causes
  
  • Severe fetal anemia or tissue hypoxia in fetal brain stem
    
    • Fetal intracranial hemorrhage
    • Severe fetal asphyxia
    • Rh alloimmunization
    • Fetomaternal hemorrhage
    • Twin-twin transfusion
    • Vasa previa with bleeding

Question 10

Causes of pseudosinusoidal heart rate

Answer 10

Nubain, Mepiridine, Morphine, Alphaprodine, Butorphanol (Stadol)

Question 11

What is tachysystole?

Answer 11

> 5 contractions in 10 minutes (averaged over 30 minutes window)

Question 12

Categories according to the three tier system

Answer 12

• Category I
  
  • Normal tracing
• Category II
  
  • Intermediate tracing
• Category III
  
  • Abnormal tracing

Question 13

Category I tracing criteria

Answer 13

• Baseline
  
  • 110-160
• Variability
  
  • Moderate
• Decelerations
  
  • Absence of late or variable decelerations
  • Early decelerations may or may not be present
• Accelerations
  
  • May or may not be present

Question 14

Category II tracing criteria

Answer 14

• Baseline
  
  • Tachycardia
  • Bradycardia (not accompanied by absent baseline variability)
• Variability
  
  • Minimal baseline variability
  • Absent baseline variablity not accompanied by recurrent deceleration
  • Marked baseline variability
• Deceleration
  
  • Periodic or episodic deceleration
    
    • Recurrent variable decelerations accompanied by minimal or moderate baseline variability
    • Prolonged deceleration ≥ 2 minutes but < 10 minutes
    • Recurrent late decelerations with moderate baseline variability
    • Variab;e decelerations with other characteristics, such as slow return to baseline, ‘overshoots,’ or ‘shoulders’
• Acceleration
  
  • Absence of acceleration after fetal stimulation
    *

Question 15

Category III tracing criteria

Answer 15

• Absent baseline FHR variability along with any of the following:
  
  • Recurrent late deceleration
  • Recurrent variable deceleration
  • Bradycardia
• Sinusoidal pattern

Question 16

Resuscitative measures

Answer 16

• Put the patient on a left lateral decubitus position
• Oxygen support
• Discontinue oxytocin
• IVF bolus (200cc)