Oligohydramnios is related with which of the following condition?

Appeared in: AIIMS Nagpur NO- 2020

Explanation

Oligohydramnios is a condition of abnormally low amniotic fluid, diagnosed when the Amniotic Fluid Index (AFI) is less than 5 cm or the single deepest pocket (SDP) is less than 2 cm.
The primary source of amniotic fluid from the second trimester onwards is fetal urine.
Renal agenesis is the failure of one or both fetal kidneys to develop.
In bilateral renal agenesis, the absence of fetal urine production leads directly to severe oligohydramnios.
This lack of amniotic fluid can cause pulmonary hypoplasia (underdeveloped lungs) and Potter's sequence, which is often fatal.

Option A: Esophageal atresia prevents the fetus from swallowing amniotic fluid, which is the primary mechanism for its removal from the amniotic sac.
Option C: Anencephaly, a severe neural tube defect, often impairs the fetal swallowing reflex.
Option D: Down's syndrome (Trisomy 21) is not directly associated with oligohydramnios.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Pathophysiology of Oligohydramnios as background academic context rather than a clinical decision trigger.
Assessing amniotic fluid volume via ultrasound (AFI or SDP) is a routine part of antenatal surveillance. It provides crucial information about fetal health.
Oligohydramnios can lead to severe complications, including fetal growth restriction, umbilical cord compression, and pulmonary hypoplasia. It requires close monitoring and may necessitate early delivery.
Conversely, polyhydramnios can cause maternal respiratory distress, preterm labor, and postpartum hemorrhage due to uterine overdistention.

How to Approach the Question

First, understand the term 'oligohydramnios', which means 'too little amniotic fluid'.
Recall the basic physiology of amniotic fluid circulation: it is primarily produced by the fetal kidneys (as urine) and removed by fetal swallowing.
Analyze each option based on this physiological principle.
Consider 'Renal Agenesis'. If the kidneys are absent, no urine can be produced. This would directly cause a lack of amniotic fluid. This is a strong candidate.
Consider 'Esophageal atresia'. This condition prevents swallowing. If the fetus can't swallow the fluid, it will accumulate, leading to too much fluid (polyhydramnios). This is incorrect.
Consider 'Anencephaly'. This condition often impairs the swallowing reflex, also leading to polyhydramnios. This is incorrect.

Concept Tested & Keywords

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E6 Obstetrics Williams p. 53-72

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