Polyhydramnios is seen in all of the following conditions, except?

RUHS, Jaipur, PB B.Sc Nursing Entrance-2018

Obstetrics & Gynaecology

Hard

Appeared in: RUHS, Jaipur, PB B.Sc Nursing Entrance-2018

Explanation

Congenital abnormalities of the fetal kidney, such as bilateral renal agenesis (Potter syndrome) or severe obstructive uropathy, lead to a failure of fetal urine production.
In the second half of pregnancy, fetal urine is the primary source of amniotic fluid.
A significant decrease or absence of fetal urine output results in oligohydramnios (abnormally low amniotic fluid) or anhydramnios (absence of amniotic fluid), not polyhydramnios.
Therefore, this condition is the exception among the choices provided.

Option A: Duodenal atresia is a congenital blockage of the duodenum. This obstruction prevents the fetus from swallowing and absorbing amniotic fluid, leading to its accumulation and causing polyhydramnios.
Option B: Tracheoesophageal fistula, often occurring with esophageal atresia, is an abnormal connection between the trachea and esophagus. This defect impairs the normal passage of swallowed fluid to the stomach for absorption, resulting in polyhydramnios.
Option C: Anencephaly is a severe neural tube defect where parts of the brain and skull are missing. This condition often impairs or eliminates the fetal swallowing reflex, leading to an inability to clear amniotic fluid and causing polyhydramnios.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Pathophysiology of amniotic fluid volume regulation, specifically the causes of polyhydramnios and oligohydramnios as background academic context rather than a clinical decision trigger.
Amniotic fluid volume is a key indicator of fetal well-being. An abnormal volume prompts further investigation to identify the underlying cause.
Polyhydramnios (Amniotic Fluid Index [AFI] greater than or equal to 24 cm) increases the risk of preterm labor, premature rupture of membranes (PROM), fetal malpresentation, and umbilical cord prolapse.
Oligohydramnios (AFI less than or equal to 5 cm) is associated with risks like pulmonary hypoplasia (underdeveloped lungs), fetal growth restriction, skeletal deformities, and umbilical cord compression during labor.

How to Approach the Question

First, identify the keyword 'except'. This indicates you need to find the option that does not fit with the others.
The question is about polyhydramnios (excess amniotic fluid). Recall the basic physiology of amniotic fluid: it's produced by fetal urination and cleared by fetal swallowing.
Evaluate each option based on this physiology.
Analyze 'Duodenal atresia', 'Tracheoesophageal fistula', and 'Anencephaly'. All these conditions interfere with the fetus's ability to swallow or process fluid, which would lead to an excess (polyhydramnios).
Analyze 'Congenital abnormalities of fetal kidney'. Kidney problems would affect urine production, the source of the fluid. A lack of production would lead to too little fluid (oligohydramnios).
Conclude that the kidney abnormality is the exception because it causes the opposite condition (oligohydramnios) compared to the others.

Concept Tested & Keywords

Concept Tested: Pathophysiology of amniotic fluid volume regulation, specifically the causes of polyhydramnios and oligohydramnios.
Stem keywords: Polyhydramnios, Duodenal atresia, Tracheoesophageal fistula, Anencephaly, Congenital abnormalities of fetal kidney
Lead-in keywords: except
Negative lead-in flag: The question asks for the exception, meaning the condition that does NOT cause polyhydramnios.

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E6 Obstetrics Williams p. 69-95

E6 Midwifery Obstetrics and Gynecology Nursing Sandeep Kaur p. 30-38