What is the primary feature of oligohydramnios?

Appeared in: BTSC Staff Nurse 31 July-2025

Explanation

Oligohydramnios is defined as an abnormally decreased volume of amniotic fluid.
The diagnosis is made via ultrasound when the Amniotic Fluid Index (AFI) is less than 5 cm.
Alternatively, it can be diagnosed if the Maximum Vertical Pocket (MVP) or single deepest pocket of fluid measures less than 2 cm.
This option accurately provides the quantitative criteria used to diagnose oligohydramnios.

Option B: This option describes the values for a normal amount of amniotic fluid, not oligohydramnios.
Option C: This statement is false. Ultrasound is the primary and standard method for assessing and quantifying amniotic fluid volume.
Option D: This option describes the criteria for polyhydramnios, which is an excessive amount of amniotic fluid, the opposite of oligohydramnios.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Definition and diagnostic criteria for oligohydramnios as background academic context rather than a clinical decision trigger.
Nurses play a key role in identifying risk factors for oligohydramnios, such as maternal dehydration, hypertension, or prelabor rupture of membranes, and in monitoring fetal well-being through non-stress tests and biophysical profiles.
A key nursing intervention is to educate the mother about signs of complications, such as decreased fetal movement, and to prepare for potential interventions like amnioinfusion or early delivery.
What if? If a patient presents with oligohydramnios and is also taking an ACE inhibitor for hypertension, the nurse should recognize this as a potential cause. The priority would be to notify the provider, as discontinuing the medication may resolve the low fluid.

How to Approach the Question

First, identify the key term in the question, which is 'oligohydramnios'.
Recall the definition of oligohydramnios. The prefix 'oligo-' means 'few' or 'scanty', and 'hydramnios' refers to amniotic fluid. Therefore, it means a decreased amount of amniotic fluid.
Next, review the options to find the one that matches this definition and includes the correct diagnostic criteria.
Evaluate each option's numerical values. Option A provides the correct thresholds for both the Amniotic Fluid Index (AFI < 5 cm) and the Maximum Vertical Pocket (MVP < 2 cm).
Eliminate the other options: Option B describes normal fluid, Option D describes polyhydramnios (excess fluid), and Option C is factually incorrect as ultrasound is the diagnostic tool.

Concept Tested & Keywords

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E6 Obstetrics Williams p. 54-72

Practise the full BTSC Staff Nurse 31 July-2025

Attempt every question from this paper in a timed mock, then review the full solution for each one.