Surgery for obese patients: protect your patient and yourself from increased risks

Mar 21, 2017

In 2014-15, 63.4% of Australian adults were overweight or obese which has increased significantly from 56.3% in 1995. This means that surgeons and anaesthetists are treating more patients with a Body Mass Index (BMI) of 25 to 29.9 kg/m2 (Overweight), or ≥BMI 30 kg/m2 (Obese) and sometimes ≥BMI of 40 kg/m2 (Obesity Class 3).

Typically, obese patients face increased risks during surgery and require specific peri-operative care. Obese patients pose a unique set of challenges for doctors who need to be mindful of key issues in order to minimise these risks for their patients and to protect themselves from the increased medico-legal risks that can manifest from treating obese patients.

Risks to consider

In the case of obese patients, the risks may be confined to a higher risk of infection or thromboembolism. However, morbidly obese patients can face a multitude of risks including difficulties with airway maintenance, imaging, patient movement and positioning, pressure injuries, and surgical and intravenous access. In addition surgery on this cohort of patients can be impacted by the prevalence of pre-existing comorbidities including obstructive sleep apnoea (OSA), obesity hypoventilation syndrome (OHS), metabolic syndrome and impaired renal function. Surface landmarks may also be impossible to identify leading to difficulties with regional anaesthesia.

In patients undergoing bariatric surgery, surgeons and anaesthetists will need to consider these risks in many, if not all patients.

Case study

Dr Grey, an obstetrician, worked in a regional base hospital and shared care with several GPs in smaller towns. Ms Oh, 29, was in her first pregnancy and presented to Dr Grey at 32 weeks for an antenatal visit. Although her pregnancy had been uneventful, Ms Oh’s major risk factor was a BMI of 39. Dr Grey conducted a glucose tolerance test which was normal. Although Ms Oh was keen to have a vaginal delivery, she was concerned as an ultrasound she had at 31 weeks placed her baby on the 90th percentile for birth weight. Ms Oh indicated that she would have an elective caesarean section delivery if that’s what Dr Grey recommended.

Surgical risks discussed

Dr Grey discussed with Ms Oh the risk factors of having an elective caesarean section in comparison to a vaginal delivery. These included the increased risks associated with a caesarean section in a patient with obesity of anaesthesia, anaphylaxis, wound infection, scarring and placental implantation problems in any future pregnancies. He also discussed complications that can result from foetal macrosomia, including pelvic floor damage.

Dr Grey made a note in the medical record: ‘C.S v. vag delivery risks discussed.’ She handed Ms Oh the Royal Australian and New Zealand College of Obstetricians and Gynaecologists patient information pamphlet Caesarean Section – a Guide for Women and arranged a repeat ultrasound for 37 weeks.

Complaint to Medical Board of Australia

Dr Grey saw Ms Oh again at 38 weeks and discussed the ultrasound report, which predicted a foetal birth weight of 4300g. Ultimately, Ms Oh decided to have a caesarean section delivery. Following a failed attempt at a spinal anaesthetic, Ms Oh underwent a general anaesthetic for the delivery. The operation was uneventful and Ms Oh delivered a healthy girl weighing 3950g. However, two days after being discharged, Ms Oh developed a wound infection and then dehiscence. Her complications also culminated in a deep vein thrombosis (DVT) and an incisional hernia. The DVT was successfully managed and the hernia repaired.

Six months after delivering her baby, Ms Oh made a complaint to The Medical Board of Australia claiming that she had been traumatised by prolonged attempts by the anaesthetist to administer a spinal anaesthetic.

Failed to warn of increased risks of surgery with obesity

The complaint was dismissed based on expert evidence which demonstrated that the administration of spinal anaesthetic had been appropriate. However, three months later, a civil claim was brought against Dr Grey alleging that she failed to:

  • Warn of an increased risk of infection, wound breakdown, and the need for additional surgery related to an increased BMI.
  • Advise that an ultrasound undertaken at term cannot accurately identify foetal macrosomia.
  • Advise that in Ms Oh’s case, a vaginal birth was safer than an elective caesarean section.
  • Administer prophylactic antibiotics according to best practice guidelines.
  • Suture the wound effectively.

Ms Oh’s solicitors obtained an expert opinion from a subspecialist who was not currently involved in obstetric practice. Based on Ms Oh’s version of events, he was critical of the consent process and believed that Dr Grey had not sufficiently highlighted the increased risks associated with undergoing a caesarean section with obesity as a risk factor, to Ms Oh. The expert believed that this prevented Ms Oh from making an informed decision on the potential risks of surgery that resulted. He was also critical of the timing of administration of the prophylactic antibiotics and argued that Cephazolin 2g IV should have been given at least one hour before incision and not in the operating room.

Documentation of specific risks critical

Documentation of the discussion at the time of consent became the critical issue. While Dr Grey did make a note of the general nature of the discussion, she failed to document the specific risks involved with undergoing an elective caesarean section. A simple check list completed while she had the discussion would have mitigated any criticism.

A crucial issue in this case were the specific risks related to surgery in an obese patient that ultimately eventuated. Following the decision in Rogers v. Whitaker1992 HCA 58; 175 CLR 479, doctors have a duty to inform their patients of material risks which are :

  • Risks to which a reasonable person in the position of that particular patient would be expected to attach significance; or
  • Risks to which the doctor knows that particular patient would attach significance

The civil claim against Dr Grey was dismissed after Avant obtained an expert opinion which supported her consent process and performing the elective caesarean section.

Key lessons


  • Discuss any material risks and benefits of the proposed treatment or procedure with the patient. Watch our video, Gaining patient consent and material risk.
  • Document the discussion including any specific risks of the procedure at the time of consent and identify any written information provided to the patient. For more information, complete our eLearning courses: Consent: the key issues and Documentation: on the record.
  • Written notes can be supplemented by a letter to the referring doctor confirming the matters discussed with the patient.
  • The more elective the procedure, the more the patient requires advice about the possible risks.

For more information, read our factsheet – ‘Managing surgical risks in obese patients’ by Dr Lewis Macken, Senior Staff Specialist, Intensive Care Unit, Royal North Shore Hospital and Avant NSW Medical Experts Committee.

Learn more

Read our article on the inquest into the deaths of two high-risk surgical patients with morbid obesity who died following elective orthopaedic procedures.

If you require immediate advice on this issue, contact the Avant Medico-legal Advisory Service on 1800 128 268.

Share your view

We welcome your feedback on this article – email the Editor at: editor@avant.org.au