What portion of the nephron extends into the medulla?

Correct Answer: A

Rationale: Nephron loop (loop of Henle) extends into medulla, not PCT, DCT (cortex), or papillary duct (collecting). This locates medullary segment, critical for concentration, contrasting with cortical parts.

Correct Answer: A

Rationale: Dipstick nitrite sensitivity isn't 96% it's ~50-60%, missing many UTIs (e.g., non-nitrate reducers like Enterococcus), incorrect. Leucocyte esterase specificity isn't 96% lower, ~80%, false positives occur (e.g., contamination). Culture >10⁵ CFU/mL is standard 95% infection probability holds. Blood cultures rarely alter UTI management urine suffices, true. Nitrite's low sensitivity distinguishes the error, key to diagnostic limits, unlike specificity, culture, or blood utility statements.

Correct Answer: B

Rationale: Staph aureus isn't the most common CAPD peritonitis organism Staph epidermidis (skin flora) leads, incorrect. Gram stain positivity (10-40%) aligns low yield, true. Parenteral antibiotics are rare intraperitoneal suffices, correct. Cell count >100 with >50% neutrophils defines it accurate. Epidermidis's dominance distinguishes the error, key to CAPD infection patterns, unlike stain, route, or diagnostic truths.

Correct Answer: B

Rationale: 100-1000 WBC/mm³ (0.1-1/µL) is below UTI threshold (<10,000) dysuria alone without pyuria suggests non-bacterial cause (e.g., urethritis), no antibiotics. 'Yes' risks overtreatment lacks evidence. Repeat culture delays unnecessary here. Two specimens overcomplicates low counts persist. Negative treatment need distinguishes it, key to avoiding misuse, unlike proactive or delayed options.

Correct Answer: A

Rationale: IV fluids in renal colic aim for 200 mL/hr urine output hydrates, aids stone passage (e.g., <5 mm), standard. 2 L/2 hr risks overload excessive. Maintenance is too slow insufficient push. 1 L/1 hr lacks precision cardiac caveat vague. Output goal distinguishes it, key to flushing strategy, unlike volume or rate errors.