Quality Control & Assurance Flashcards

A newly prepared Alcian Blue pH 2.5 solution fails to stain acid mucins in the positive control. After checking pH, what is the next most likely variable to investigate?

Answer: Acetic acid concentration used to adjust pH

Alcian Blue pH 2.5 requires precise pH adjustment using acetic acid; incorrect concentration alters ionization of the dye and prevents mucin binding.

What is the purpose of including an 'external' control section mounted on the same slide as the patient tissue in IHC?

Answer: To confirm that all reagents and steps performed identically for the patient and control tissue

Mounting control and patient tissue on the same slide ensures they undergo identical processing, validating that any result difference is due to biology, not technique.

During tissue processor QC, a technician finds all paraffin-embedded tissues are soft and incomplete. Which processor station failure is most likely?

Answer: Incomplete dehydration in alcohol stations

Incomplete dehydration leaves residual water in tissue, which prevents paraffin infiltration and results in soft, incompletely embedded blocks.

Which element of a QC program specifically monitors whether patient results fall within medically appropriate ranges compared to prior specimens?

Answer: Delta check

A delta check compares a patient's current result to a previous result to detect unexpected changes that may indicate specimen or clerical errors.

A Grocott's Methenamine Silver (GMS) stain shows pale gray fungi instead of sharp black outlines. What is the most likely problem?

Answer: Silver solution under-reduced or developer time too short

GMS relies on reducing silver ions to metallic silver on fungal cell walls; insufficient reduction time produces pale gray instead of crisp black.

Under CLIA '88, which personnel role is responsible for overall laboratory quality management and ensuring QC policies are followed?

Answer: Laboratory director

CLIA '88 places ultimate responsibility for quality management, QC policy, and regulatory compliance on the laboratory director.

A tissue section floated onto a glass slide has multiple folds that could not be flattened in the water bath. Which sectioning variable most likely caused this?

Answer: Paraffin block too warm during cutting

A paraffin block that is too warm becomes soft and compresses during cutting, producing sections that fold and cannot be fully flattened on the water bath.