In the second stage of labor, how is the duration of a uterine contraction measured?

NORCET 10 Prelims-2026

Obstetrics & Gynaecology

Easy

Appeared in: NORCET 10 Prelims-2026

Explanation

The duration of a uterine contraction is correctly measured from the beginning (onset of tightening) to the very end (complete relaxation) of a single contraction.
This measurement quantifies how long each individual contraction lasts, which is a key indicator of effective labor.
In the active phase of labor, contractions typically last between 45 and 80 seconds.
Monitoring duration is vital because contractions lasting longer than 90 seconds (tetanic contractions) can compromise fetal oxygenation by reducing blood flow to the placenta.

Option A: This option describes the measurement of contraction frequency, not duration. It measures how often contractions occur.
Option B: This option describes the measurement of the interval between contractions, which is the resting period for the uterus.
Option D: Measuring from the peak (acme) of one contraction to the peak of the next is another way to determine the frequency of contractions.

Visual 1: Diagram - A cardiotocography (CTG) tracing illustrating a uterine contraction. The diagram should have clear labels pointing to the start and end of one contraction to show 'Duration', the time from the start of one to the start of the next for 'Frequency', the time between two contractions for 'Interval', and the highest point for 'Intensity (Acme)'.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Measurement of Uterine Contraction Parameters as background academic context rather than a clinical decision trigger.
Accurate assessment of uterine contractions is a fundamental nursing skill in labor and delivery. It allows the nurse to evaluate the progress of labor and identify patterns that could be harmful to the mother or fetus.
Abnormal contraction patterns, such as tachysystole (more than five contractions in 10 minutes) or prolonged durations (greater than 90 seconds), require prompt nursing intervention. This may include repositioning the mother, administering oxygen, or stopping oxytocin infusion to prevent fetal distress.
What if? - If the interval between contractions is consistently less than 60 seconds, the fetus may not have enough time to recover and re-oxygenate between contractions. This is a sign of uterine hyperstimulation, which can lead to fetal hypoxia and acidosis, requiring immediate intervention.

How to Approach the Question

This is a factual recall question that tests your knowledge of fundamental obstetric terminology.
First, identify the key term in the question: 'duration'. Understand that duration refers to how long an event lasts.
Next, analyze each option to see which one describes the length of a single contraction.
Option A ('start to start') and Option D ('peak to peak') both measure how often contractions occur, which is frequency.
Option B ('end to start') measures the time between contractions, which is the interval.
Option C ('start to end') correctly describes the measurement of how long one contraction lasts. This matches the definition of duration.

Concept Tested & Keywords

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