A patient who has increased blood urea nitrogen (BUN) and serum creatinine levels is scheduled for a renal arteriogram. Which bowel preparation order would the nurse question for this patient?

A. Fleet enema: Fleet enemas contain phosphate, which can be absorbed systemically and worsen hyperphosphatemia in patients with impaired kidney function. For a patient with elevated BUN and creatinine, indicating possible renal impairment, phosphate-based enemas increase the risk of electrolyte imbalance and should be questioned. B. Sennandocusate (Senokot-S): This stool softener and stimulant combination works by drawing water into the bowel and softening stools. It does not contain phosphate or other nephrotoxic substances, making it generally safe for patients with renal impairment. C. Tap-water enema: Tap-water enemas are non-phosphate-based and generally safe for patients with impaired kidney function. They help evacuate the bowel without introducing substances that could exacerbate electrolyte disturbances. D. Bisacodyl (Dulcolax) tablets: Bisacodyl is a stimulant laxative taken orally, which acts locally on the colon. It does not contain phosphate and does not pose significant risk to patients with elevated BUN or creatinine, making it an acceptable bowel preparation.