Patient safety incidents are rarely caused by a single person's mistake. They are almost always the result of system-level gaps — in protocols, training, technology, or communication. The 5 Whys method helps clinical teams trace each incident back to its true systemic root cause. Below are five complete case studies from healthcare settings, each with five levels of analysis and a concrete corrective action.
1. Wrong Medication Dosage Administered
Case Study: Overdose of anticoagulant on cardiac step-down unit
A patient on a cardiac step-down unit received twice the prescribed dose of a high-alert anticoagulant. The error was caught during the next shift's medication reconciliation, but the patient required reversal therapy and extended monitoring.
ProblemPatient received 2x the prescribed anticoagulant dose, requiring reversal therapy and 48 hours of additional monitoring.
Why #1The administering nurse drew up the wrong concentration from a multi-dose vial that contained a higher-concentration formulation.
Why #2Two different concentrations of the same anticoagulant were stored side-by-side in the same medication drawer of the automated dispensing cabinet.
Why #3The pharmacy's restocking protocol does not separate look-alike/sound-alike (LASA) medications by concentration within the same cabinet drawer.
Why #4No independent double-check was performed before administration because the unit does not require a second nurse to verify high-alert medication draws.
Why #5 (Root Cause)There is no independent double-check protocol for high-alert medications on this unit. The hospital's high-alert medication policy exists in the formulary manual but was never operationalized into a mandatory bedside verification step.
Corrective Action: Implemented a mandatory independent double-check protocol for all high-alert medications, requiring two licensed nurses to verify drug, dose, concentration, and patient identity before administration. Separated LASA medications into distinct drawers in all automated dispensing cabinets. Added barcode scanning at the point of administration to verify medication against the electronic MAR.
2. Patient Fall Post-Surgery
Case Study: Post-operative hip replacement patient falls during transfer
A 72-year-old patient fell during an assisted transfer from bed to wheelchair 14 hours after hip replacement surgery. The fall resulted in a hip dislocation, requiring a return to the operating room and extending the hospital stay by 5 days.
ProblemPost-surgical patient fell during assisted transfer, causing hip dislocation and requiring reoperation.
Why #1The patient became dizzy and lost balance during the transfer because of residual effects from general anesthesia and post-operative pain medication.
Why #2The transfer was attempted with only one staff member assisting, despite the patient's sedation level warranting two-person assist.
Why #3The patient's fall risk score in the chart was rated "moderate" instead of "high," so the care plan specified single-person assist.
Why #4The fall risk assessment was completed pre-operatively and was not reassessed after anesthesia and narcotic pain medication were administered.
Why #5 (Root Cause)The fall risk assessment protocol does not require reassessment after anesthesia status changes. There is no trigger in the system to automatically escalate a patient's fall risk score when post-operative sedation or narcotic orders are active.
Corrective Action: Updated the fall risk assessment protocol to require automatic reassessment within 2 hours of any anesthesia event or narcotic medication order. Built an EMR alert that auto-escalates fall risk to "high" when post-operative sedation orders are active. Mandated two-person assist for all transfers within 24 hours of general anesthesia, regardless of current fall risk score.
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3. Surgical Site Infection Cluster
Case Study: Cluster of 4 SSIs after elective orthopedic procedures
Four patients developed surgical site infections within a 3-week period following elective orthopedic procedures performed in the same operating room. Environmental cultures and instrument tracing were initiated as part of the infection control investigation.
Problem4 surgical site infections in 3 weeks from the same OR, exceeding the baseline rate by 400%.
Why #1Instrument cultures revealed bacterial contamination on reprocessed surgical trays that should have been sterile.
Why #2The sterile processing department (SPD) was running shortened wash cycles to keep up with surgical volume, reducing contact time below the validated minimum.
Why #3The SPD was processing 40% more instrument trays per day than its staffed capacity allows, due to a recent increase in surgical case volume.
Why #4SPD staffing levels have not been adjusted since surgical volume increased, because staffing is tied to an annual budget cycle rather than to case volume.
Why #5 (Root Cause)The sterile processing department is understaffed relative to current surgical volume, and the reprocessing turnaround time exceeds the safe window. There is no dynamic staffing model that ties SPD resources to actual surgical case volume.
Corrective Action: Implemented a dynamic staffing model linking SPD technician hours to weekly surgical case volume. Added biological indicator verification on every sterilization load (not just daily). Installed cycle-lock controls on washers and sterilizers that prevent manual shortening of validated cycles. Hired two additional SPD technicians immediately to cover the current volume gap.
4. Delayed Lab Results Causing Treatment Delay
Case Study: Critical potassium result delayed 4 hours in ICU
An ICU patient's critically elevated potassium level (6.8 mEq/L) sat unreported for 4 hours because the result was filed in the EMR but no one was actively alerted. Treatment was delayed, and the patient developed a cardiac arrhythmia that required emergency intervention.
ProblemCritical lab result (potassium 6.8 mEq/L) went unreported for 4 hours, leading to preventable cardiac arrhythmia in an ICU patient.
Why #1The attending physician did not see the result because they were in surgery and did not check the EMR during that time.
Why #2No phone call was made to the ordering physician or covering provider because the lab technician marked the result as "reported" after filing it in the EMR.
Why #3The lab's critical value notification SOP considers EMR filing as equivalent to verbal notification, which does not guarantee a provider sees the result in real time.
Why #4The EMR does not have an automated critical value alert that pushes a notification to the ordering provider's mobile device or pager.
Why #5 (Root Cause)There is no automated critical value alert system integrated with the EMR. The hospital relies on manual verbal notification for critical results, and the SOP incorrectly treats passive EMR filing as active notification.
Corrective Action: Deployed an automated critical value alert system that sends push notifications to the ordering provider's pager and mobile device for any result exceeding critical thresholds. Updated the critical value SOP to require verbal read-back confirmation (not just EMR filing) for all critical results. Added an escalation pathway: if the ordering provider does not acknowledge within 15 minutes, the alert escalates to the covering provider and charge nurse.
5. Patient Misidentification During Handoff
Case Study: Wrong patient received post-op medications after shift handoff
During a night shift handoff in a post-anesthesia care unit (PACU), a nurse administered post-operative pain medication intended for Patient A to Patient B. The error occurred because both patients had similar-sounding last names and were in adjacent bays.
ProblemWrong patient received post-operative medications after a shift handoff, resulting in an adverse drug event.
Why #1The oncoming nurse confused Patient A and Patient B because their last names sound similar and the handoff identified patients by name only.
Why #2No wristband or ID verification was performed before administering the medication because the nurse relied on the verbal handoff information.
Why #3The PACU handoff process is verbal-only, conducted at the nursing station rather than at the bedside, with no standardized format.
Why #4There is no requirement in the PACU handoff policy for bedside ID verification or use of a standardized communication tool like SBAR.
Why #5 (Root Cause)The PACU uses a verbal-only handoff protocol without a standardized SBAR checklist or mandatory two-identifier verification at the bedside. The handoff policy was never updated to incorporate Joint Commission patient identification requirements.
Corrective Action: Implemented a mandatory bedside handoff protocol using SBAR format that includes two-identifier verification (name + date of birth + wristband scan) for every patient. Created a printed SBAR handoff checklist for PACU nurses. Added a hard stop in the medication administration workflow requiring wristband barcode scan before any medication can be documented as given.
Frequently Asked Questions
Why is the 5 Whys method effective for patient safety investigations?
The 5 Whys forces investigators to move past proximate causes ("a nurse made an error") to systemic failures ("the system allowed the error to happen"). This aligns with Just Culture principles and helps organizations build safer systems rather than simply retraining individuals after every incident.
How does 5 Whys relate to Joint Commission sentinel event requirements?
The Joint Commission requires a thorough root cause analysis for every sentinel event. The 5 Whys is one of the simplest tools that meets this requirement. It helps investigation teams identify systemic failures behind sentinel events, which is exactly what the policy demands. Many hospitals use it as a starting point before more detailed methods like FMEA for complex cases.
Can you combine 5 Whys with other healthcare quality methods?
Yes, and most quality teams do. Use 5 Whys as the initial reactive investigation tool after an incident. Then use FMEA proactively to identify potential failure modes in the processes you discovered. Apply PDSA cycles to test and implement the corrective actions. This combination covers reactive analysis, proactive prevention, and structured improvement.
For more on applying root cause analysis in clinical settings, read our 5 Whys healthcare guide. Browse all industry examples.