MLPAO Urinalysis and Body Fluids Advanced Practice 2

Question 1

What are the different types of peritoneal fluid analysis performed in suspected spontaneous bacterial peritonitis (SBP)?

Accepted Answer

Cell count with differential (WBC >250 neutrophils/µL diagnostic), protein, albumin, glucose, LDH, Gram stain, and culture (in blood culture bottles)

Answer

SBP diagnosis is based on ascitic fluid polymorphonuclear (PMN) count >250 cells/µL. Additional analysis includes total protein, albumin (SAAG = serum albumin - ascitic albumin; >11 g/L suggests portal hypertension), glucose, LDH, Gram stain, and culture. Inoculating ascitic fluid into blood culture bottles at the bedside increases culture sensitivity from ~50% to ~80%.

Question 2

What is the significance of xanthochromia in cerebrospinal fluid?

Accepted Answer

A yellow discolouration of CSF supernatant indicating the presence of hemoglobin degradation products (bilirubin, oxyhemoglobin), suggesting subarachnoid hemorrhage at least 2-4 hours old

Answer

Xanthochromia (yellow discolouration of CSF supernatant after centrifugation) indicates in vivo hemoglobin degradation, distinguishing subarachnoid hemorrhage (SAH) from traumatic tap. It develops 2-4 hours after SAH as RBCs lyse and hemoglobin is converted to oxyhemoglobin and then bilirubin. Spectrophotometric analysis provides objective xanthochromia assessment.

Question 3

What is the serum-ascites albumin gradient (SAAG) and how is it used?

Accepted Answer

SAAG = serum albumin - ascitic fluid albumin; ≥11 g/L indicates portal hypertension; <11 g/L indicates non-portal hypertensive causes

Answer

SAAG is calculated by subtracting the ascitic fluid albumin from the serum albumin. A SAAG ≥11 g/L (1.1 g/dL) indicates portal hypertension with 97% accuracy (cirrhosis, heart failure, Budd-Chiari). SAAG <11 g/L suggests non-portal hypertensive causes (malignancy, TB peritonitis, nephrotic syndrome, pancreatitis). SAAG has replaced the traditional transudate/exudate classification for ascites.

Question 4

How should a CSF specimen be prioritized if the volume is limited?

Accepted Answer

Cell count and differential first (tube 1), then chemistry/serology (tube 2), then microbiology (tube 3 — least likely contaminated)

Answer

When CSF volume is limited, prioritization depends on clinical suspicion. Generally: Tube 1 (cell count — most affected by traumatic tap, so use first tube), Tube 2 (chemistry/protein/glucose), Tube 3 (Gram stain and culture — last tube is least contaminated by blood from traumatic tap). However, if meningitis is strongly suspected, microbiology may take priority.

Question 5

What is the significance of finding eosinophils in a pleural fluid?

Accepted Answer

Pleural eosinophilia (>10% eosinophils) suggests parasitic infection, drug reaction, malignancy, or prior pneumothorax/hemothorax

Answer

Pleural eosinophilia (>10% eosinophils in pleural fluid) has a specific differential diagnosis including parasitic infection, drug-induced pleuritis, malignancy (especially lymphoma), and prior air or blood in the pleural space. It notably makes tuberculosis very unlikely (<1% of TB effusions have eosinophilia), which can be diagnostically useful.

MLPAO - Medical Laboratory Professionals Association of Ontario Practice Test

MLPAO - Medical Laboratory Professionals Association of Ontario Practice Test

MLPAO Urinalysis and Body Fluids Advanced Practice 2