Safety of care

Improving patient safety and reducing risks

Specimen and report mix-ups

An article for physicians by physicians
Originally published December 2007


Pathological examination of a surgical specimen is the mid-point of a complex process involving many people. Mix-ups can occur at any point in the process, with adverse effects for patient and difficulties for health-care personnel


Of interest to all physicians

The handling, processing and reporting of pathology specimens is a complex, multi-step process that involves many members of the health-care team including physicians, nurses, medical laboratory technologists and administrative personnel. Mix-ups can occur at any stage during this process. When they do, they may result in serious clinical outcomes for the patients and medico-legal difficulties for the physicians and others involved.

The CMPA reviewed cases closed between 2002 and 2006 in which specimen mix-ups occurred. Most of these cases involved biopsies of the breast, of the female reproductive organs or of the prostate gland. Although the mix-ups occurred both with specimens from the same patient or from different patients, the majority of cases involved two patients. This resulted in an incorrect finding of malignancy for one patient who actually had benign disease, while the other patient with a malignancy was falsely reassured. Physicians played a direct role in some of these situations, whereas in other cases the actions or inactions of other health professionals contributed to the adverse patient outcomes.

Although not all-inclusive, the case review identified the following four primary categories of mix-ups and three key contributing factors:

Primary categories:

  1. Specimen delivery issues prior to arrival in the pathology department
    • Mislabelling of specimen containers
    • Incomplete or unclear clinical information on the pathology requisition
    • Loss of surgical specimens
  2. Mislabelling of tissue slides in the pathology department
  3. Mix-up of specimens or slides by the laboratory technologist or the pathologist
    • Also includes cross-contamination with extraneous tissue
  4. Reporting and management issues
    • Transposition or duplication of reports during dictation or transcription
    • Failure to recognize and question discrepancies between the pathology findings and the clinical facts

Key contributing factors:

  1. Multiple specimens from the same patient
  2. Similarities in patient characteristics, such as names, identification numbers, clinical information or biopsy sites
  3. Cross-contamination by tissue belonging to a different patient and/or anatomical site

The following cases illustrate situations in which mix-ups impeded the diagnostic process.

Case #1: Mix-up of specimens from the same patient at the time of biopsy

A gastroenterologist performed a routine colonoscopy on an elderly patient with a history of right colon resection and ileocolic anastomosis for cancer. Biopsies were taken from the anastomotic site of the previous resection and also from a polyp of the sigmoid colon. The specimen containers were labelled as "colonic anastomosis" and "colonic polyp" respectively. The requisition did not specify the sigmoid colon as the source of the polyp.

The pathologist reported the specimen labelled as "colonic anastomosis" as consistent with recurrent adenocarcinoma. The microscopic examination of the specimen in the container labelled "colonic polyp" identified benign small bowel mucosa with intestinal villi; no colonic polyp was noted.

Based on these pathology findings, the general surgeon performed a subtotal colectomy with ileosigmoid anastomosis. The surgical pathology on the resected segment of colon was negative for malignancy. A repeat biopsy of the sigmoid polyp confirmed adenocarcinoma, which necessitated further surgery. The patient commenced a legal action alleging the mix-up of biopsy specimens led to unnecessary surgery.

Expert medico-legal opinion

The pathology expert was of the opinion the biopsy specimens had been reversed prior to being received in the pathology department. The expert further noted that the microscopic presence of small bowel mucosa in the specimen labelled "colonic polyp" should have alerted all of the physicians that there was something unusual about the case; in particular, the gastroenterologist should have been aware that this specimen should have had findings consistent with the sigmoid colon. The expert also maintained that the surgeon and the pathologist should have considered the possibility of specimen reversal before any further surgical procedure was performed. Without expert support, the CMPA paid a settlement to the patient on behalf of all of the physician members involved for their failure to recognize the specimen reversal and take corrective action. The hospital shared the settlement equally with the CMPA for its role in the mix-up of the specimens.

Case #2: Mix-up of specimens from two patients during analysis

A middle-aged woman underwent a left breast biopsy for a palpable mass. The pathologist diagnosed infiltrating carcinoma. Based on this result, a left total mastectomy and axillary node dissection was performed. The surgical pathology revealed no residual tumour and negative axillary lymph nodes. In preparation for possible adjuvant therapy, a second pathologist reviewed the original biopsy slides. He interpreted the slides as fat necrosis with fibrosis and chronic inflammation; no carcinoma was identified.

A hospital investigation concluded the first pathologist most likely examined tissue slides from another patient twice. The other patient had an infiltrating carcinoma. The pathologist then included those findings on both patients' reports.

In addition to the loss of her breast, the unnecessary surgery unfortunately resulted in multiple postoperative complications including left arm lymphedema, postmastectomy pain syndrome, and persistent depression. These rendered her permanently disabled and unemployable. The patient commenced litigation alleging the pathologist failed to adequately evaluate her biopsy sample, which led to unnecessary surgery.

Expert medico-legal opinion

A review of the patient's original tissue slides by an expert pathologist confirmed the absence of carcinoma. The patient's initial specimen bag, requisition and slides were all properly labelled. The fact that the pathologist identified infiltrating carcinoma on another patient's slides the same day led the expert to believe the defendant pathologist had incorrectly examined and reported the malignant findings from the other patient's slides as the diagnosis for the patient-plaintiff. As there was no expert support, the CMPA paid a settlement on the member's behalf.

Case #3: Mix-up of specimen reports at dictation

A middle-aged man underwent a transrectal ultrasound and biopsy of the prostate to investigate an elevated prostate-specific antigen (PSA) level detected on routine screening. The pathology report indicated microscopic foci of adenocarcinoma in the left prostate tissue. A radical prostatectomy was performed on the basis of the biopsy report. However, the surgical pathology revealed glandular and fibromuscular hyperplasia with no evidence of malignancy. A review of the patient's original biopsy slides identified benign prostatic tissue with chronic prostatitis.

This prompted the pathologist to reassess all of the prostate biopsy cases she had processed the day of the biopsy. She discovered adenocarcinoma in another patient's tissue sample, yet the corresponding report was negative for malignancy. It became apparent that the microscopic descriptions and diagnoses had been directly transposed by the pathologist at the time of the dictation of these two patients' reports. Both patients had nearly identical clinical information recorded on the requisitions and the gross descriptions of the specimens were similar. These factors contributed to the mix-up.

The patient was left with urinary incontinence, sexual dysfunction and periods of depression following the surgery. He initiated a regulatory authority (College) complaint and a legal action.

College complaint outcome

As a result of this incident, this particular pathology department instituted a quality improvement process to prevent a similar occurrence. Although the College commended this change in practice, the pathologist was required to attend at the College to be cautioned.

Legal outcome

With respect to the legal action, a pathology expert expressed the view that the transposition of the two reports was most likely due to an oversight on the part of the pathologist rather than the result of a transcriptionist's error. Lacking expert support, a settlement was paid by the CMPA on behalf of the member.

Risk management considerations

As these cases demonstrate, the diagnostic interpretation of specimens may be compromised at any stage of the process.

Based on the cases presented and the expert opinions received, the following risk management considerations have been identified:

  • Are there clear policies and procedures in the workplace outlining the proper handling, labelling, processing and reporting of tissue specimens?
  • Does the completed requisition contain the pertinent clinical and specimen information as well as the correct patient identifiers?
  • Do the patient identifiers on the specimen being examined match the requisition and the final pathology report?
  • Do the microscopic and gross descriptions for the specimen match?
  • Do the pathology findings correspond with the clinical impression? If not, what steps have been taken to resolve the discrepancy, such as discussing your concerns with the other involved physicians prior to acting on the results?


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.