Identify the following rhythm of cardiotocograph?

NORCET-7 Mains-2024

Obstetrics & Gynaecology

Medium

Appeared in: NORCET-7 Mains-2024

Explanation

The CTG tracing shows abrupt, sharp decelerations in the fetal heart rate (FHR).
The shape of these decelerations is characteristic of a 'V' or 'U', with a rapid drop from baseline and a rapid return.
The timing of the decelerations is inconsistent and varies in relation to the uterine contractions shown in the lower panel.
This combination of an abrupt onset, V-shape, and variable timing is the classic presentation of variable decelerations.
Variable decelerations are caused by transient compression of the umbilical cord.

Option A: Early decelerations are gradual, not abrupt. Their shape mirrors the uterine contraction, with the lowest point of the FHR (nadir) coinciding with the peak of the contraction.
Option B: Late decelerations are also gradual, and their onset is delayed. The nadir of the deceleration occurs after the peak of the uterine contraction, indicating uteroplacental insufficiency.
Option D: An acceleration is an abrupt increase in the FHR from the baseline, not a decrease. Accelerations are generally a sign of fetal well-being.

Visual 1: Diagram - A comparative chart showing the waveforms of early, late, and variable decelerations alongside uterine contractions to highlight differences in timing, shape, and cause (Head compression, Placental insufficiency, Cord compression).

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Interpretation of Cardiotocograph (CTG) Tracings as background academic context rather than a clinical decision trigger.
Recognizing variable decelerations is a critical nursing skill, as they indicate umbilical cord compression. While often benign and transient, recurrent or severe variable decelerations can lead to fetal hypoxia and acidosis.
Initial nursing interventions, such as changing the mother's position, are crucial first steps to alleviate cord compression and improve fetal blood flow.
Persistent variable decelerations, especially with loss of FHR variability or tachycardia, are non-reassuring and require prompt escalation to the healthcare provider for further evaluation and potential intervention, including amnioinfusion or expedited delivery.

How to Approach the Question

First, analyze the two tracings on the cardiotocograph: the top line is the Fetal Heart Rate (FHR) and the bottom line is Uterine Contractions (UC).
Determine the baseline FHR, which is the average rate between contractions. In this image, it's around 150 bpm.
Look for any periodic or episodic changes from the baseline. The image clearly shows several drops, or decelerations.
Assess the shape and timing of these decelerations. Note that they are sharp, deep, and V-shaped, with a rapid drop and recovery.
Compare the onset of the decelerations to the uterine contractions. Observe that their timing is inconsistent; they don't have a uniform relationship with the contractions.
Recall the characteristics of different decelerations: Early (mirror contractions), Late (delayed after contractions), and Variable (abrupt, V-shaped, inconsistent timing). The pattern in the image matches the description of variable decelerations.

Concept Tested & Keywords

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