How do you ensure accuracy when processing a high volume of samples?

Accuracy under volume starts with preparation and systematic habits, not just care in the moment. I batch samples logically so I am working through one type of analysis at a time, which reduces context-switching errors. I label everything before I begin processing, not during, and I use double-check steps at critical points: before and after centrifugation, before analysis, and before reporting results. When I am working on an unusually high-volume run, I take short breaks at planned intervals rather than pushing through, because fatigue is one of the most common causes of transcription and pipetting errors. I also document every step in real time rather than reconstructing from memory at the end of the run. If I notice any result that falls outside expected reference ranges or seems inconsistent with the clinical context, I flag it immediately and repeat the test before releasing it.

Tell me about your experience with quality control in the laboratory.

Quality control has been central to every role I have worked in. My day typically starts with running QC samples before patient samples: I verify that the controls fall within the accepted ranges set by our laboratory's quality programme before I release any results. I maintain a QC log and I track trends, not just individual failures, because a series of results creeping toward the edge of the acceptable range is a warning sign worth acting on before a control fails. I have experience with both internal QC and external quality assurance schemes. When a control fails, I follow the defined Westgard rules to determine whether to repeat the run, recalibrate, or escalate. I document each QC failure and the corrective action taken, and I notify the senior biomedical scientist before releasing any patient results that were run in the same batch.

How do you handle a situation where two test results for the same patient are inconsistent?

I start by checking the most obvious sources of error before drawing any clinical conclusions. I verify that both samples are labelled correctly and belong to the same patient, check that the correct tubes were used for each test, and confirm that samples were stored and processed within the required timeframes. I review the patient's previous results if available to see whether either result is consistent with their history. If the inconsistency remains after those checks, I repeat the test on the original sample and, if possible, request a fresh sample. I document every step in the process and do not release either result until I have a clear explanation for the discrepancy or a confirmed result from the repeat. I also inform the requesting clinician that there is a delay and give them an estimated turnaround time so they can manage their clinical decision-making in the meantime.

How do you prioritise when you have urgent and routine requests arriving at the same time?

I prioritise by clinical urgency first, using the priority codes or turnaround time targets set by the laboratory's service level agreement. Urgent and STAT requests go to the front of the queue, and I communicate an estimated completion time to the ward or clinic as soon as I accept the sample. For routine work I batch efficiently so that similar tests are processed together rather than interrupting one workflow to start another. If I am managing multiple urgent requests simultaneously, I work through them in the order they arrived unless a clinical context makes one more time-critical than another. I keep the requesting team updated if there is any reason a turnaround time will not be met. I never cut corners on pre-analytical checks to save time on urgent samples: a faster wrong result is worse than a slightly delayed correct one.

Tell me about a time you identified an error before it reached the clinician.

I was processing a batch of coagulation samples late in a shift when I noticed that one result was significantly outside the expected range for a patient whose previous results had been consistently normal. Before releasing anything, I checked the sample integrity: the tube had slightly more than the acceptable fill level, which can affect PT and APTT results. I repeated the test on the same sample, got a similar abnormal result, and then requested a fresh sample from the ward. The repeat on the fresh sample came back within normal limits. I documented the entire sequence, flagged the original sample as rejected, and informed the requesting doctor of the delay and the reason. The clinician told me the patient was stable and the repeat result was reassuring. If I had released the original result without investigation, it might have triggered unnecessary anticoagulation treatment.

Describe a time you had to raise a concern about a safety issue in the lab.

In a previous role I noticed that a colleague was regularly disposing of sharps incorrectly: needles were going into the general waste bin rather than the sharps container. I did not escalate it immediately because I wanted to address it directly first. I spoke to the colleague privately and explained the risk clearly, assuming it was an oversight rather than a deliberate choice. They adjusted their practice straight away. I then checked the broader waste disposal area and found a labelling issue with the sharps bins that was making it easy to confuse them with general waste. I reported this to the lab manager, who arranged for clearer labelling and included waste segregation in the next team safety briefing. The situation reinforced for me that safety concerns are best addressed directly and promptly rather than left to accumulate.

Give an example of when you had to learn a new technique or piece of equipment quickly.

When our laboratory upgraded to a new automated haematology analyser, I was one of the first staff members trained on the system before the wider team was trained. I had about a week before we went live. I read the operator manual thoroughly and attended the vendor's training session, but I knew that theoretical knowledge was not enough for a high-volume clinical environment. I ran parallel testing with the old and new analyser for several days, comparing results on the same patient samples to understand where the two platforms diverged and why. When the go-live day arrived I felt confident with the equipment, and I was able to support colleagues who were less familiar with it. I documented the key differences between the two analysers in a short reference guide for the team, which reduced the volume of questions during the first few weeks.

Walk me through how you would process a blood sample from receipt to result.

When a sample arrives in the laboratory I check three things before anything else: the patient's details on the request form match those on the sample tube, the tube type is correct for the requested test, and the sample meets minimum volume requirements. I inspect the sample for haemolysis, lipaemia, or icterus if those are likely to affect the assay. I log the sample into the laboratory information system and assign it the correct priority. For tests requiring centrifugation I ensure the correct time and speed, then transfer the separated specimen appropriately. I load the sample onto the analyser according to the instrument's workflow, confirm the correct assay is selected, and monitor the run. When results are generated I check them against the reference range, flag any critical or panic values for immediate communication to the requesting clinician, and review the QC status for that batch before releasing. I document everything in the LIS and attach any comments relevant to sample quality.

How do you maintain and troubleshoot analytical equipment?

Routine maintenance is the foundation of reliable results. I follow the manufacturer's maintenance schedule for each instrument: daily, weekly, and monthly tasks. Daily maintenance typically includes cleaning the sampling probe, running system checks, and verifying QC before patient testing begins. I keep a maintenance log for each instrument and record any unusual behaviour, even minor things like intermittent flags, because patterns often predict larger failures. When an instrument gives unexpected results or error codes, I start with the simplest explanation: reagent levels, QC status, and whether recent maintenance steps were completed on schedule. I work through the troubleshooting guide systematically before escalating to the biomedical scientist or the instrument engineer. I never reset an error code without documenting what the error was and what caused it, because that information matters for identifying recurring faults.

How do you approach working with hazardous materials safely?

Safe working with hazardous materials starts with the COSHH assessment for each reagent and waste stream I work with. I read the safety data sheet before using any new reagent, paying particular attention to the exposure limits, required PPE, storage conditions, and disposal requirements. In practice, I follow standard precautions for all patient samples regardless of known status, wear appropriate PPE, work inside the biosafety cabinet for any aerosolising procedures, and never pipette by mouth. I dispose of chemical waste and biological waste through the correct labelled containers and never mix them. If I have a spillage, I follow the written spill procedure: contain, absorb, decontaminate, and report. I report every incident regardless of scale, because near-misses are as important to log as actual incidents. Regular training keeps me current on any changes to waste handling regulations or new hazards introduced into the lab.

Lab Technician

Lab technician interviews assess your technical accuracy, attention to detail, and ability to follow strict protocols in high-stakes environments. Interviewers want to see that you handle equipment and samples correctly, flag discrepancies when you spot them, and maintain quality standards consistently under pressure. This guide covers the questions asked most often and the answers that show hiring managers you can be trusted with critical results.

For general interview preparation tips, read our guide to common interview questions.

Prepare further

How to answer competency-based interview questions How to answer "What are your greatest strengths?"

Common Lab Technician Interview Questions

Behavioural Interview Questions for Lab Technician Roles

Technical Questions for Lab Technician Candidates

What Hiring Managers Look for in Lab Technician Interviews

The single quality that separates exceptional lab technicians from adequate ones is how they respond when something looks wrong. Candidates who can describe a specific time they caught an error, explain their systematic approach to investigating it, and articulate the clinical consequence of releasing that result are the ones who stand out. Technical skills can be trained over time. The discipline to pause, investigate, and escalate before releasing a result you're uncertain about is much harder to develop from scratch. Interviewers also listen for whether a candidate understands pre-analytical variables: sample integrity, tube type, and timing issues cause the majority of erroneous results in any clinical laboratory, and a technician who doesn't know this is missing a significant part of the picture.

Questions to Ask Your Interviewer

→What quality assurance schemes does the laboratory participate in, and how are external quality assessment results reviewed with the team?
→What does the training and competency sign-off process look like for new staff?
→How is out-of-hours or on-call cover managed in this department?
→Are there opportunities to get involved in method validation or new analyser evaluations?

Practise These Questions Before Your Interview

The mock interview tool builds a practice session around a specific job posting and your background, so you rehearse the questions most likely to come up.

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