Specialist & Consultant Clinical Pathology oral assessment prep

Knowledge: This is an acute haemolytic transfusion reaction, and the grouping discrepancy means the pre-transfusion sample almost certainly came from another patient. Anti-A in a group O recipient causes intravascular haemolysis, leading to shock, disseminated intravascular coagulation and acute kidney injury, with severity related to the volume given. Bacterial contamination, anaphylaxis and TRALI must also be considered. Investigations include repeat grouping and antibody screen, direct antiglobulin test, haemolysis markers, coagulation, renal function and cultures of the patient and the bag. A second patient is at risk, because whoever was bled into her tube may now have a wrong group on record.

Management: I would confirm the transfusion is stopped and the team is resuscitating, monitoring urine output and treating DIC and hyperkalaemia with critical care input. I would ask for the bag and giving set to be returned sealed and cultured. I would quarantine units crossmatched on the suspect sample and identify every patient bled by the same staff member on that round, so their groups are rechecked urgently. Until her group is confirmed on two independent samples, I would issue only group O red cells and AB plasma. I would report the event through the incident system and the facility's haemovigilance route. I would lead a root cause analysis of patient identification and labelling and press for bedside electronic identification and a two-sample rule.

Ethics and communication: She and her family should be told promptly and honestly that she received incompatible blood because of a sampling error, with an apology and a plan. The other patient whose record may be wrong also needs to be informed. Federal Decree-Law No. 4 of 2016 on Medical Liability may apply, but my priority is safety and learning, not defending the department. The nurse deserves a fair, system-focused review rather than blame.

Reference: AABB Technical Manual (21st ed, 2023); ISBT Proposed Standard Definitions for Surveillance of Non-infectious Adverse Transfusion Reactions (2011)

Knowledge: The high control breaches the 1-3s rule and both controls together breach the 2-2s rule, which signals systematic rather than random error. The timing points to the new reagent lot, but calibration drift, electrode faults, control material problems and temperature faults must be excluded. QC rules and frequency should be designed from each assay's sigma metric, and potassium has tight allowable error, so multirule QC and more frequent runs are justified. Patient-based moving averages can detect a shift between QC runs. ISO 15189 requires nonconforming work to be identified, its clinical impact assessed and corrective action recorded.

Management: I would stop potassium reporting on analyser B, divert work to another analyser and confirm its QC is in control. The scientists would troubleshoot, recalibrate, rerun QC and revert to the previous lot if needed. I would retest stored samples from before and after 02:15 to measure the bias and define the affected window. If the bias is clinically significant, I would retest all affected stable samples and issue amended reports. Results that crossed a decision threshold would be phoned to clinicians, starting with emergency and intensive care. I would log a nonconformity, complete root cause analysis and require lot-to-lot verification before new reagents go live. I would review QC frequency and add patient moving averages for key analytes.

Ethics and communication: Clinicians rely on released results, so I have a duty to correct them openly even when this exposes a laboratory failure. Amended reports must show the original value, the corrected value and the reason, never a silent overwrite. If a patient was treated for hyperkalaemia or had potassium withheld on a falsely high value, the treating team must be told so they can review and disclose. The incident is documented to accreditation standards.

Reference: Westgard JO, Basic QC Practices (4th ed); CLSI C24 Statistical Quality Control for Quantitative Measurement Procedures (4th ed); ISO 15189:2022 Medical Laboratories: Requirements for Quality and Competence

Knowledge: Persistent low serum hCG with a negative urine test and no detectable disease strongly suggests false-positive or phantom hCG from interfering antibodies, such as heterophile or human anti-animal antibodies, which bridge the capture and detection antibodies of a sandwich assay. These large antibodies do not pass into urine, so a negative urine test supports interference when the serum value exceeds the urine detection limit. The differential includes pituitary hCG, true quiescent trophoblastic disease and rarely a non-trophoblastic tumour. Assays differ in the hCG forms they detect, so one platform should not be trusted alone. Unnecessary chemotherapy and hysterectomy for phantom hCG are well documented.

Management: I would ask the clinician to hold methotrexate for a few days while interference is investigated. In the laboratory I would measure quantitative urine hCG, repeat the serum on a different manufacturer's platform, perform serial dilutions to look for non-linearity, and retest after heterophile blocking reagent. If the value falls after blocking, differs widely between platforms and is non-linear, I would report that the result is likely due to interference. I would recommend sending samples to a trophoblastic disease reference centre for confirmation. If interference is confirmed, I would add a permanent alert to her record so that future immunoassays are interpreted with caution. If hCG proves genuine and pituitary hCG is suspected, a short suppression test with combined oral contraception can help.

Ethics and communication: My duty is to prevent harm from a test result, including telling the clinician clearly that our own result may be false. The patient should hear about the uncertainty and the reason for delay from her clinician, with my support. I would document the advice and investigations, and if treatment had already been given on a false result, it should be disclosed and reported as an incident.

Reference: Tietz Textbook of Laboratory Medicine (7th ed, 2022); CLSI EP07 Interference Testing in Clinical Chemistry (3rd ed, 2018)

Knowledge: Very high potassium with very low calcium, magnesium and alkaline phosphatase is the classic pattern of K2EDTA contamination, often from incorrect order of draw or decanting between tubes. EDTA chelates calcium and magnesium, and alkaline phosphatase activity falls because it needs these metal cofactors. These values are hardly compatible with a man who walked into a clinic, which supports artefact. However, an ACE inhibitor with spironolactone can cause genuine hyperkalaemia, and contamination hides his true potassium. Delayed separation, refrigeration, thrombocytosis and fist clenching are other causes of spurious hyperkalaemia.

Management: I would not release the potassium and calcium as valid; I would report them as unsuitable due to suspected EDTA contamination with a clear comment. Because genuine hyperkalaemia cannot be excluded, I would treat this as urgent and try to reach the requesting doctor or the clinic's out-of-hours contact. If nobody can be reached within the time set in our critical result policy, I would contact the patient, confirm his identity, explain that he needs an urgent repeat test tonight and advise an emergency department visit if he has weakness or palpitations. I would document each call attempt with times and names. I would send the clinic written feedback on order of draw. I would log a pre-analytical nonconformity and track repeat events from that clinic.

Ethics and communication: Contacting the patient directly is justified when his doctor cannot be reached, but I would share only what he needs to act. Releasing an artefactual potassium could trigger harmful treatment, while silently cancelling it could leave real hyperkalaemia untreated, so honesty about uncertainty is essential. Clear records protect the patient and the laboratory.

Reference: Tietz Textbook of Laboratory Medicine (7th ed, 2022)

Knowledge: Isolated APTT prolongation with new major bleeding in an older person, and loss of correction after incubation, is typical of an acquired factor VIII inhibitor. A factor deficiency corrects fully, lupus anticoagulant usually causes thrombosis rather than bleeding, and heparin should be excluded with a thrombin time. Factor VIII, IX, XI and XII assays, a Bethesda titre and lupus anticoagulant testing follow, remembering that a strong inhibitor can falsely lower other intrinsic factor assays. Factor VIII level and titre do not predict bleeding reliably, so bleeding is treated on clinical grounds. International recommendations advise bypassing agents or recombinant porcine factor VIII for bleeding, and prompt immunosuppression.

Management: I would phone the team at once to say this is probable acquired haemophilia A and that surgery should be avoided unless essential and then done only with haemostatic cover agreed with a haemophilia specialist. I would advise avoiding intramuscular injections, arterial punctures and antiplatelet drugs. I would request factor assays and Bethesda titre urgently. For active bleeding I would support recombinant activated factor VII, activated prothrombin complex concentrate or recombinant porcine factor VIII, dosed according to the product and the recommendations. I would advise starting corticosteroids promptly, with cyclophosphamide or rituximab as the haematologists decide. I would suggest screening for underlying malignancy or autoimmune disease, and monitoring for thrombosis during bypassing therapy.

Ethics and communication: He needs a clear explanation of the immune cause, the risks of procedures and the risks of immunosuppression, so that his consent is informed. If the surgeons proceed, I would document my advice and the agreed plan. Bypassing agents are expensive, and I would escalate rather than let cost delay life-saving treatment.

Reference: Tiede A et al, International Recommendations on the Diagnosis and Treatment of Acquired Hemophilia A, Haematologica (2020); Hoffbrand's Postgraduate Haematology (7th ed)

Knowledge: A reactive fourth-generation screen confirmed by a differentiation assay establishes HIV-1 infection, and a second sample is good practice to exclude a mix-up. Baseline HIV-1 RNA viral load, CD4 count and resistance testing are needed. Antiretroviral therapy started early in pregnancy, aiming for an undetectable viral load by delivery, reduces mother-to-child transmission to very low levels. Results are released to the requesting clinician through secure channels, never by phone to a relative, even one who knows identifying details. HIV is a notifiable disease under Federal Law No. 14 of 2014, and her husband's risk makes partner notification important.

Management: I would decline politely to give the husband any result, tell him results go through the treating doctor, and log the call. I would phone the obstetrician directly with the confirmed result and arrange a repeat sample, viral load, CD4 count and resistance testing. I would advise urgent referral to the HIV service so treatment can start without delay, with planning for delivery and infant prophylaxis. I would complete the statutory notification through the approved route. I would support the clinicians in counselling her about telling her husband, offering help with disclosure and explaining that public health staff can assist with partner notification. I would check that access to her result in the electronic record is restricted to staff involved in her care.

Ethics and communication: Identifying details do not authorise disclosure to a spouse. The laboratory respects her request, while the clinical team works with her and public health staff on partner notification because he faces a serious, preventable risk. Notification is made to the authority, not to family, and the electronic record is protected under Federal Law No. 2 of 2019. I would avoid judgement so that she stays engaged with antenatal care.

Reference: WHO Consolidated Guidelines on HIV Testing Services (2019); CDC Laboratory Testing for the Diagnosis of HIV Infection: Updated Recommendations (2014); Federal Law No. 14 of 2014 on the Prevention of Communicable Diseases (UAE)