In a 55-year-old female intensive care unit patient two days after a Hartmann procedure who develops oliguria (urine output ~20 mL/hr), a borderline‑high central venous pressure (~10 cm H₂O) and new lower‑leg edema with otherwise stable vital signs, what is the appropriate next step in management?

Management of Post-Hartmann Oliguria with Elevated CVP

The appropriate next step is abdomen ultrasound (Option C) to assess for intra-abdominal complications including fluid collections, urinoma, or early signs of abdominal compartment syndrome that could explain the oliguria despite borderline-high CVP. 1

Clinical Reasoning

This patient presents with a paradoxical picture: oliguria (20 mL/hr, which is <0.5 mL/kg/hr) alongside a CVP of 10 cm H₂O and lower extremity edema, suggesting adequate or even excessive intravascular volume rather than hypovolemia. 1, 2 This constellation of findings in a post-Hartmann patient raises concern for venous congestion impairing renal perfusion or intra-abdominal pathology affecting renal function. 3

Why CVP of 10 cm H₂O Matters

• A CVP of 10 cm H₂O (approximately 7-8 mmHg) is at the upper limit of normal and, when combined with lower extremity edema, suggests the patient is euvolemic or hypervolemic rather than hypovolemic. 4, 5
• Elevated CVP is independently associated with impaired renal function through venous congestion and reduced renal perfusion pressure, even when cardiac output appears adequate. 3
• In post-abdominal surgery patients, elevated intra-abdominal pressure can increase venous outflow pressure, further compromising renal perfusion despite seemingly adequate CVP. 4

Why Ultrasound is the Correct First Step

Abdominal ultrasound is non-invasive, rapidly available, and can identify multiple post-operative complications that would explain oliguria in this clinical context: 1

• Urinoma or urinary leak from the rectal stump or inadvertent ureteral injury during Hartmann procedure 4
• Intra-abdominal fluid collections (abscess, hematoma) causing mass effect on ureters or bladder 4
• Bladder outlet obstruction from catheter malposition or clot 1
• Hydronephrosis suggesting ureteral obstruction 4
• Ascites and signs of abdominal compartment syndrome which would explain both oliguria and elevated CVP 4

Why Other Options Are Less Appropriate

Option A (Re-exploration) is premature without imaging evidence of a surgical complication requiring intervention. The patient is hemodynamically stable with normal vital signs, making emergent re-exploration unnecessarily invasive. 4

Option B (Renal duplex US) focuses only on renal vasculature and parenchyma but would miss intra-abdominal complications like urinoma, abscess, or ureteral obstruction that are more likely in this post-operative context. 4

Option D (CT abdomen with contrast) would provide excellent anatomic detail but exposes the patient to nephrotoxic contrast when renal function is already compromised (oliguria suggests developing acute kidney injury). Ultrasound should be performed first as it is non-nephrotoxic and can guide whether CT is truly necessary. 4, 1

Management Algorithm After Ultrasound

If Ultrasound Shows Obstruction or Collection:

• Hydronephrosis/ureteral obstruction: Proceed to percutaneous nephrostomy or ureteral stenting 4
• Urinoma: Place percutaneous drain and consider ureteral stenting 4
• Abscess/infected collection: Percutaneous drainage and antibiotics 4
• Bladder outlet obstruction: Replace or reposition urinary catheter 1

If Ultrasound is Normal:

• Verify true oliguria by confirming catheter patency 1, 2
• Assess for venous congestion as cause of renal dysfunction: Given the elevated CVP and edema, this patient may have cardiogenic oliguria or venous congestion-mediated acute kidney injury 3
• Avoid additional fluid administration, as the patient already shows signs of fluid overload (CVP 10, lower extremity edema). Further fluids would worsen venous congestion and renal function. 1, 6
• Consider diuretic trial if volume overload is confirmed, targeting improved renal perfusion pressure by reducing venous congestion 1
• Ensure adequate mean arterial pressure (≥60-65 mmHg) with vasopressors if needed, as organ perfusion pressure = MAP - CVP 4, 7

Critical Pitfalls to Avoid

• Do not assume oliguria always requires fluid resuscitation. In this patient with elevated CVP and edema, additional fluids would worsen outcomes by increasing venous congestion and impairing renal perfusion. 1, 3
• Do not proceed directly to CT with IV contrast without first performing ultrasound, as contrast nephrotoxicity could worsen already compromised renal function. 4, 1
• Do not ignore the significance of elevated CVP. A CVP of 10 cm H₂O with oliguria suggests venous congestion-mediated renal dysfunction rather than hypovolemia. 6, 3
• Do not delay imaging. Post-operative day 2 oliguria with these findings requires prompt evaluation for surgical complications like urinoma or abscess. 4