What does a B/C (Bowel-to-Contrast) kidney ratio of 26.7 indicate and how should it be managed?

From the Guidelines

A B/C (Bowel-to-Contrast) kidney ratio of 26.7 indicates significant renal obstruction requiring prompt urological intervention. This high ratio (normal is typically less than 10) suggests poor drainage of contrast from the kidney, with contrast accumulating in the bowel while remaining trapped in the obstructed kidney. Management should include immediate urological consultation for possible decompression of the urinary tract, typically via placement of a nephrostomy tube or ureteral stent. While awaiting intervention, the patient should receive appropriate pain management (such as ketorolac 30mg IV or morphine 4-6mg IV) and intravenous hydration with normal saline at 100-150 mL/hour to maintain renal perfusion. Antibiotics (such as ceftriaxone 1-2g IV daily) should be initiated if there are signs of infection or pyonephrosis. Laboratory evaluation including complete blood count, comprehensive metabolic panel, and urinalysis should be obtained to assess renal function and identify infection. The elevated B/C ratio occurs because contrast material normally filters through the kidneys and drains into the bladder, but with obstruction, contrast remains in the collecting system while continuing to accumulate in the bowel, creating this disproportionate ratio that serves as a quantitative marker of obstruction severity.

Key considerations in managing this condition include:

• Prompt urological consultation for possible decompression of the urinary tract
• Pain management and intravenous hydration to maintain renal perfusion
• Antibiotics if signs of infection or pyonephrosis are present
• Laboratory evaluation to assess renal function and identify infection

According to the most recent and highest quality study 1, referral to a nephrologist may also be necessary, especially if the patient's eGFR drops below 30 mL/min per 1.73 m2, or if there is consistent finding of significant albuminuria. However, the provided evidence does not directly address the B/C kidney ratio, and the management approach is based on general principles of renal obstruction management.

In terms of chronic kidney disease (CKD) management, the evidence suggests that CKD should be classified based on the cause, GFR, and albuminuria categories, as outlined in the study by 1. However, this classification system is not directly applicable to the B/C kidney ratio, and the management approach should prioritize prompt urological intervention and supportive care.

Overall, the management of a B/C kidney ratio of 26.7 should focus on relieving the obstruction, managing symptoms, and preventing complications, with referral to a nephrologist as needed based on individual patient factors.

From the Research

B/C Kidney Ratio Interpretation

• A B/C (Bowel-to-Contrast) kidney ratio of 26.7 is not directly addressed in the provided studies 2, 3, 4, 5, 6.
• The studies primarily focus on chronic kidney disease (CKD), proteinuria, and the use of angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs) in managing CKD and hypertension.

Management of CKD and Hypertension

• According to the study by 2, the combination of an ACEI or ARB and pentoxifylline has a protective effect in reducing proteinuria and ameliorating the decline in estimated glomerular filtration rate (eGFR) in patients with stages 3-5 CKD.
• However, the study by 3 suggests that ACEIs and ARBs may cause unrecognized significant worsening renal failure in CKD patients, especially in older hypertensive patients, and recommends withholding these medications for 2-4 days prior to or during certain clinical scenarios.

Renal Function and Blood Pressure Control

• The study by 4 found that CKD occurs more often in older patients and those with associated metabolic risk factors or clinical conditions, and emphasizes the need to improve awareness of the role of renal damage as a component of global risk.
• The study by 5 found that blood pressure control achieved among hypertensive CKD subjects was suboptimal, and patients with lower creatinine clearance were less likely to be prescribed ACE inhibitors.

Proteinuria Assessment

• The study by 6 found that spot urine protein/creatinine ratios are unreliable estimates of 24-h proteinuria in most systemic lupus erythematosus nephritis flares, highlighting the importance of accurate proteinuria assessment in managing CKD and related conditions.