# A nurse is caring for a 38-year-old client with a history of calcium oxalate kidney stones who is experiencing severe flank pain and hematuria. The client's urine output has decreased to 20 mL/hour over the past 4 hours. Which nursing intervention should be the priority?

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## 문제

A nurse is caring for a 38-year-old client with a history of calcium oxalate kidney stones who is experiencing severe flank pain and hematuria. The client's urine output has decreased to 20 mL/hour over the past 4 hours. Which nursing intervention should be the priority?

## 보기

1. Notify the healthcare provider immediately about the decreased urine output **✔ 정답**
2. Administer prescribed analgesics for pain management
3. Encourage increased fluid intake to promote stone passage
4. Apply heat to the flank area to reduce muscle spasm

**정답: 1**

## 해설

Decreased urine output (oliguria) in this context suggests possible urinary obstruction or renal impairment, requiring immediate provider notification to prevent complications like hydronephrosis or acute kidney injury. Other interventions (analgesics, fluids, heat) are important but secondary to addressing the potential emergency.

## 심화 해설

Understanding the Clinical Picture

A 38-year-old client with a known history of calcium oxalate stones presents with severe flank pain, hematuria, and critically, a urine output that has dropped to 20 mL/hour over the past 4 hours. This oliguric state is a hallmark sign of acute kidney injury (AKI), which is defined by a sudden decrease in kidney function characterized by a rise in serum creatinine and/or a decrease in urine output [3]. In the context of a stone former with unilateral flank pain, the most likely etiology is a postrenal AKI caused by an obstruction, even if the stone is small. While distal ureteral calculi measuring ≤5 mm are generally expected to pass spontaneously, persistent obstruction can occur and directly result in renal impairment [1].

Prioritizing the Intervention

The priority intervention is to notify the healthcare provider immediately. The clinical reasoning is rooted in the pathophysiology of obstructive uropathy. An acute severe obstruction of the urinary tract is a potentially threatening situation for the kidneys and requires prompt identification and management to relieve the obstruction [2]. The decrease in urine output is not merely a symptom to be observed; it is a direct indicator that the functional interruption of urinary outflow is now compromising kidney function. Delaying notification to administer analgesics or apply heat addresses comfort but does not resolve the life-threatening obstruction that is actively causing an AKI. Similarly, encouraging increased fluid intake is contraindicated in a setting of obstruction because it will increase hydrostatic pressure behind the blockage, worsening hydronephrosis and renal parenchymal damage without promoting stone passage.

The Pathophysiology of the Priority

Obstructive uropathy is regarded as one of the most prevalent causes of AKI, accounting for 5%-10% of cases [2]. The mechanism involves a structural or functional interruption of urinary outflow at any level in the urinary tract [2]. When a calculus lodges at the ureterovesical junction, as is common with distal stones, it creates a physical barrier [1]. The backup of urine increases intraluminal pressure, which is transmitted retrograde to the nephrons, reducing the glomerular filtration rate (GFR). This is a time-sensitive emergency because prolonged obstruction leads to irreversible nephron loss. The definitive management consists of the correction of the underlying cause, which requires urgent urological intervention such as stent placement or lithotripsy [3]. The nurse’s role is to recognize that the oliguria signifies a transition from a simple renal colic episode to a complicated postrenal AKI, making immediate provider notification the only action that facilitates definitive, kidney-saving treatment [1][3].References (research sources)

- [1]A Rare but Critical Presentation in Primary Care: A Case Report on Unilateral Ureterolithiasis Leading to Postrenal Acute Kidney Injury.Case reportDorter M, Eid A, Darwish Saad N. (2026) · DOI: 10.7759/cureus.104362

- [2]Obstructive uropathy: Overview of the pathogenesis, etiology and management of a prevalent cause of acute kidney injury.Research articlePérez-Aizpurua X, Cabello Benavente R, Bueno Serrano G, Alcázar Peral JM, Gómez-Jordana Mañas B, Tufet I Jaumot J, Ruiz de Castroviejo Blanco J, Osorio Ospina F, Gonzalez-Enguita C. (2024) · DOI: 10.5527/wjn.v13.i2.93322

- [3]Acute kidney injury in urological conditions.Research articleWeerapolchai K, Lumlertgul N, Srisawat N, Ostermann M. (2026) · DOI: 10.2478/abm-2026-0002

## 임상 시나리오

Clinical Practice Guide: Recognizing Postrenal AKI in the Stone Former

1. Pathophysiology of the Emergency

In a patient with a history of calcium oxalate stones, the sudden drop in urine output to 20 mL/hour (oliguria) signals a transition from simple renal colic to **postrenal acute kidney injury (AKI)**. A stone causing complete or near-complete obstruction increases intraluminal pressure, which is transmitted back to Bowman's capsule, drastically reducing the glomerular filtration rate (GFR). This is a time-sensitive, reversible cause of kidney failure if the obstruction is relieved promptly.

2. Priority Nursing Actions

- **Immediate Provider Notification:** Report the precise hourly urine output, current pain level, and any new onset of nausea or confusion (signs of uremia). The provider must decide on urgent decompression via stenting or nephrostomy.

- **Strict Intake and Output (I&O) Monitoring:** Insert an indwelling urinary catheter if not already in place to ensure accurate measurement and rule out bladder outlet obstruction.

- **Hold Fluids and Medications:** Do not encourage oral or IV fluids until the obstruction is ruled out or relieved, as this can exacerbate hydronephrosis. Hold nephrotoxic medications (NSAIDs, certain antibiotics) as they can compound the intrinsic kidney injury.

- **Diagnostic Preparation:** Anticipate the need for a non-contrast CT scan or renal ultrasound to confirm the location and degree of obstruction.

3. Rationale for Withholding Other Comfort Measures

While severe flank pain requires treatment, administering analgesics before notifying the provider can mask a worsening clinical picture. Applying heat or repositioning does not address the mechanical blockage. The priority is always to reverse the cause of the AKI to prevent permanent loss of nephron function.

## 핵심 개념

- **Postrenal Acute Kidney Injury** — A sudden decline in kidney function caused by an obstruction in the urinary tract below the level of the kidneys, leading to increased back-pressure and reduced glomerular filtration.
- **Oliguria** — A urine output of less than 400 mL per day or less than 0.5 mL/kg/hour, often a key indicator of acute kidney injury or severe dehydration.
- **Calcium Oxalate Stones** — The most common type of kidney stone, formed from calcium and oxalate in the urine, often associated with dehydration and certain dietary factors.
- **Obstructive Uropathy** — A structural or functional blockage of the normal flow of urine, causing distension of the renal pelvis and calyces (hydronephrosis) and potential renal impairment.
- **Nursing Prioritization** — The process of ranking patient problems and interventions based on urgency, using frameworks like Maslow's hierarchy or the ABCs to address life-threatening issues first.

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