The fetal kidneys start producing urine at:

Appeared in: AIIMS Rishikesh & Jodhpur NO - 2017

Explanation

At 12 weeks of gestation, the fetal kidneys (metanephros) are sufficiently developed to begin producing and excreting urine.
This is a critical developmental milestone, as fetal urine becomes the primary source of amniotic fluid for the remainder of the pregnancy.
The ability to produce urine indicates that the glomeruli and basic tubular structures are functional.
Ultrasound visualization of the fetal bladder, typically possible between 10-14 weeks, confirms that urine is being produced and collected.

Option A: At 8 weeks, the permanent kidney (metanephros) is still in the early stages of development and is not yet functional enough to produce urine.
Option B: While initial glomerular filtration may start around 9-10 weeks, this is not considered the point of established, consistent urine production. 12 weeks is the clinically accepted milestone.
Option D: By 14 weeks, urine production is already well-established. This timeframe is more significant for the maturation of tubular function, specifically the functionality of the Loop of Henle, which allows for reabsorption.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Fetal renal development and the onset of urine production as background academic context rather than a clinical decision trigger.
Fetal urine production is the main source of amniotic fluid from the second trimester onward. Assessing amniotic fluid volume is a key part of fetal well-being assessment.
Oligohydramnios (low amniotic fluid) can be a sign of fetal renal anomalies, such as renal agenesis (failure of kidneys to develop) or urinary tract obstruction, which can lead to poor lung development (pulmonary hypoplasia).
What if? An ultrasound at 20 weeks shows no visible fetal bladder and severe oligohydramnios? This would raise strong suspicion for a major fetal renal anomaly like bilateral renal agenesis or a severe blockage. The prognosis would be poor due to the high likelihood of lethal pulmonary hypoplasia.

How to Approach the Question

This is a factual recall question testing knowledge of fetal embryology.
Identify the key concepts in the question: 'fetal kidneys' and 'start producing urine'.
Recall the major milestones of fetal organ development.
Differentiate between the start of kidney development (around 5 weeks), the start of initial filtration (around 9 weeks), and the start of established urine production (12 weeks).
Evaluate the given options against this timeline. 12 weeks is the correct milestone for the onset of urine production.
Eliminate other options: 8 weeks is too early, and by 14 weeks, production is already underway and other functions are maturing.

Concept Tested & Keywords

Qf_Kjzw7bWkxekP125aEal

E6 Obstetrics Williams p. 28-47

E6 Ghai Essential Pediatrics(pp 26-904 of 913) p. 488-490

Practise the full AIIMS Rishikesh & Jodhpur NO - 2017

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