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Invasive, non-surgical procedures: What are the risks?

Originally published December 2015

Physicians from diverse, non-surgical disciplines will often need to perform various invasive procedures for purposes of screening, diagnosis, and treatment. These procedures can be inherently risky, and procedural complications can occur and lead to significant adverse outcomes including death.

To identify areas of medical-legal risk and enable targeted interventions to enhance the delivery of safe medical care, the CMPA reviewed medical-legal cases involving members from non-surgical disciplines who performed invasive procedures — those crossing the skin barrier (e.g. biopsy, percutaneous contrast administration) or entering into a body cavity (e.g. endoscopy).

In 40% of the 757 CMPA cases that closed between 2010 and 2014 involving a specialist performing an invasive procedure, peer experts supported the care provided. The care in these cases was sufficiently documented in the medical record, including the patient’s informed consent and acknowledgement of the recognized risks of the procedure.

In the other 60% of cases, a clinical issue associated with the care contributed to the patient safety incident. In 10% of these cases, patients suffered major or catastrophic disability and 21% succumbed to their injuries. Most incidents occurred in a hospital setting, though almost one-quarter occurred in a physician’s office. Nearly all non-surgical disciplines were represented, with gastroenterologists, radiologists, and general internists being the most frequently involved. Weaknesses in the areas of performance, communication, and diagnosis were the main areas of peer expert criticism of the care delivered.

A closer look at performance issues

In a subset of 146 cases where the performance of an invasive procedure was criticized by experts, more than half resulted in an unfavourable medical-legal outcome for the physician (i.e. criticism/disciplinary action from the medical regulatory authority [College]/hospital, or a loss at trial/settlement in a legal action). In 27% of these cases patients were left with a major or catastrophic disability or died.

Table 1: Patient outcomes from invasive procedures (n=93)

Body systems

% of cases

Types of interventions

Patient outcomes

Lower gastrointestinal


  • colonoscopy
  • polypectomy
  • biopsy
  • coagulation by laser/argon plasma
  • 4 deaths
  • 2 major disabilities
  • 30 minor or temporary disabilities

Upper gastrointestinal and hepatic


  • endoscopic retrograde cholangiopancreatography (ERCP)
  • excision of polyp(s)
  • gastrostomy tube insertion
  • gastroscopy
  • ablation of liver nodule
  • 5 deaths
  • 17 minor or temporary disabilities




  • angiography and/or angioplasty
  • cardiac ablation
  • pericardiocentesis
  • diagnostic cardiac catheterization
  • vascular access (e.g. venous catheter)
  • 5 deaths
  • 2 major disabilities
  • 15 minor or temporary disabilities



  • thoracentesis
  • intubation
  • 1 death
  • 2 major disabilities



  • bone marrow aspiration
  • punch biopsy of the hand
  • fine needle aspiration breast biopsy
  • circumcision
  • 1 death
  • 10 minor disabilities

Peer experts were critical of the care provided in the following areas:

  • Deficient informed consent process
    • Incomplete or absent discussion of risks (general and patient-specific) and alternatives
    • Delegation of consent discussion to untrained personnel
    • Consent discussion not concordant with the actual procedure(s) performed (e.g. (e.g. polypectomy or biopsy performed during a screening colonoscopy)
  • Breakdown in communication with the patient or family following the patient safety incident
    • Failure to disclose the injury, or that the injury may have been due to the procedure
    • Failure to provide fulsome explanations regarding complications and ongoing care
    • Failure to notify the family of a deterioration in the patient’s condition
  • Deficient documentation
    • Insufficient or absent documentation of the informed consent discussion
    • Inadequate assessment and documentation of the patient’s comorbid conditions before the procedure (e.g. steroid use)
    • Inadequate documentation of the care provided during the procedure (technique, monitoring, instruments, device, patient condition)
    • Inadequate recognition and management of the complication and inadequate documentation of the care provided

Experts noted that providing patients with handouts or other materials may be helpful in reinforcing the consent discussion.

Case examples

The following cases illustrate two similar situations which resulted in two different legal outcomes.

Case 1: Duodenal perforation following cholecystectomy

Following a cholecystectomy, a patient is referred to a gastroenterologist for a transient increase in liver enzymes and recurrent episodes of biliary colic. The gastroenterologist’s differential diagnosis includes choledocholithiasis, and an endoscopic retrograde cholangiopancreatography (ERCP) is arranged. During the procedure, the gastroenterologist is unsuccessful in cannulating the common bile duct despite performing a sphincterotomy. After the procedure, the patient complains of severe abdominal pain, and investigations reveal a duodenal perforation. The patient subsequently develops life-threatening complications, including necrotizing pancreatitis, requiring several surgeries and lengthy hospitalization.

A legal action ensues. Experts are of the opinion that the gastroenterologist should have included a sphincter of Oddi dysfunction in the differential diagnosis, and should have performed other non-invasive diagnostic tests before the ERCP, such as a magnetic resonance cholangiopancreatography (MRCP) to confirm the presence of stones. At trial, the judge rules in favour of the patient, finding that the gastroenterologist failed to obtain informed consent by not outlining the risks of ERCP and not advising the patient of the availability of less invasive alternatives that may have assisted in arriving at a diagnosis.

Case 2: Sigmoid perforation following colonoscopy

A 58-year-old patient is referred for a screening colonoscopy. The gastroenterologist discusses various options for screening, including fecal occult blood testing, barium enema, and colonoscopy, specifically discussing the risk of bowel perforation during colonoscopy. The patient agrees to a colonoscopy, which reveals diverticulosis and internal hemorrhoids. Approximately one hour following the procedure, the patient complains of abdominal pain. The gastroenterologist assesses the patient and although the abdominal exam is benign, keeps the patient for observation. Abdominal X-rays done for persistent pain demonstrate free air in the abdomen. The patient undergoes a laparotomy and repair of a sigmoid perforation.

A College complaint ensues, which is subsequently dismissed with no criticism of the gastroenterologist’s care. The College concludes that the patient was appropriately advised of the risk of perforation and that informed consent was obtained and well documented. Bowel perforation is an inherent risk of colonoscopy and is usually not indicative of substandard care. The College also determines that the gastroenterologist appropriately assessed the patient in a reasonable and timely manner after the procedure and ordered appropriate investigations for ongoing symptoms.

Risk management considerations

Invasive procedures carry inherent risks that may occur despite diligent care. Physicians should undertake, and carefully document, informed consent discussions with their patients in advance of a procedure. These should include a personalized assessment of the material risks1 and special risks2 and benefits of the procedure for that patient and information about any available less invasive alternatives, and should be tailored to the patient’s level of health literacy. Use of decision aids and other written, verbal, or visual information, particularly where there is a comprehension barrier (e.g. language, education, age), should be considered as a supplement to the informed consent discussion.

Physicians should appropriately monitor and assess the patient following the procedure and carefully document the condition of the patient, discharge instructions, and follow-up plan.

Any procedural complications should be disclosed to patients as soon as reasonably possible. The implications, including the need for further care, should be discussed and follow-up care provided or arranged. These discussions and the steps taken to address the complications should be carefully documented in the medical record.

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  1. Material risks: Generally considered by the courts as those that a reasonable person, in the same circumstances as the patient, would want to know before consenting to an investigation or treatment. This would include complications that occur commonly, and also those complications that occur rarely but have significant consequences for that patient.
  2. Special risks: Generally considered by the courts as those that a patient’s physical or psychological makeup will make even an uncommon risk of a medical investigation or treatment special or more important for that patient.

DISCLAIMER: The information contained in this learning material is for general educational purposes only and is not intended to provide specific professional medical or legal advice, nor to constitute a "standard of care" for Canadian healthcare professionals. The use of CMPA learning resources is subject to the foregoing as well as the CMPA's Terms of Use.