Resources Module 3: Systems and Effect of Complexity on Patient Care

Topic 3

Systems and effect of complexity on patient care


“A patient with skin cancer noticed a swelling in their right groin. The referral letter described this to the surgeons and went on to say that an ultrasound scan had shown an enlarged external iliac chain lymph node which had been confirmed as metastatic melanoma by another test. The surgical consultant circled the words ‘right groin’ on the letter and this term was used thereafter. The wrong site was operated on but on the correct side."


The following failings were later identified:

  • The term groin was interpreted differently by the oncologists and the surgeons.
  • The patient didn’t have a detailed clinical assessment in the surgical clinic, the original referral letter and report of the ultrasound were not checked.
  • The ultrasound scan correctly identified the lymph node group but the cytology form incorrectly described it as being from the right groin.
  • The letter from the surgical team was sent to the patient’s GP and not copied to the referring oncology team.
  • The skin multi-disciplinary team never discussed imaging so the scan was not reviewed at the meeting.
  • The scan results were not displayed at the time of the operation and it was recorded on the WHO Surgical Safety Checklist that imaging was not applicable” (National Quality Board, 2013: 11)

The above scenario highlights the complexity of system that exist in healthcare sometimes leading to medical errors. All healthcare professionals need to have an understanding of the nature of complexity in healthcare, as it is important for preventing adverse events. Health care is complex due to the diversity of tasks involved in the delivery of patient care, the dependency of health-care providers on one another, the diversity of patients, clinicians and other staff; the huge number of relationships between patients, carers, health-care providers, support staff, administrators, family and community members, the vulnerability of patients, variations in the physical layout of clinical environments, variability or lack of regulations, implementation of new technology, the diversity of care pathways and organizations involved and increased specialization of health-care professionals.

A systems approach examines the organizational factors that underpin dysfunctional health care and accidents/errors (poor processes, poor designs, poor teamwork, financial constraints and institutional factors), rather than focus on the people who are blamed for an error. This type of approach helps to move away from blaming, towards understanding and improving the transparency of the processes of care. A systems approach emphasises the importance of understanding the underlying factors that caused an adverse event without diminishing the responsibilities or accountability of health professionals. J. Reason created the “Swiss cheese model” to explain how faults in different layers of a system lead to adverse events and medical errors.

Applying the lessons learned from High Reliability Organizations (HROs) to health care can improve patient safety. HRO refers to organizations that operate under hazardous conditions, but manage to function in a way that is almost completely “failure-free”. They have very few adverse events. Some examples of HROs include air traffic control systems, nuclear power plants and naval aircraft carriers.The key principles from HRO theory are: maintain a powerful and uniform culture of safety, use optimal structures and procedures, provide intensive and continuing training of individuals and teams and conduct thorough organizational learning and safety management (WHO, 2012)

Read more using the WHO handout, Systems and the effect of complexity on patient care (WHO, 2012)

Optional reading for this Topic includes: Human Error: Models and Management. BMJ (Reason, 2000)




National Quality Board (2013) Human Factors in Healthcare. A concordat from the National Quality Board [Online][Accessed on 1st October 2023][Available at]

Reason J (2000) Human Error: Models and Management. BMJ [Online]

[Accessed on 1st October 2023]

[Available at

World Health Organization (WHO) (2023). Systems and the effect of complexity on patient care [Online][[Accessed on 1st October 2023][Available at

Last modified: Wednesday, November 15, 2023, 7:00 AM