Surgical Site Surveillance in Ambulatory Settings

The following article was originally published in Preventing Infection in Ambulatory Care, the quarterly e-publication from the Association for Professionals in Infection Control and Epidemiology (APIC). To learn more about receiving this resource and joining APIC, visit To learn more about APIC, visit


Surveillance is the ongoing, system­atic collection, collation, and analysis of data and the ongoing dissemina­tion of information to those who need to know so action can be taken. Surgi­cal site surveillance is the identification of surgical site infections (SSIs) in patients under­going surgical proce­dures. CMS infection control measures require surveil­lance of SSIs as part of an overall quality improve­ment program in ambula­tory surgery centers.


Definitions of surgical site infections

Some states require SSI reporting through CDC's National Health­care Safety Network (NHSN). NHSN is a free, Internet-based reporting system that provides standardized definitions and reporting mechanisms for infections including SSIs, which allows comparison of infection rates among facilities.[1] Both inpatient and outpatient surgical facili­ties are included. Stan­dardized definitions are important in order to have consistent, compa­rable and reproducible data. A wound infection to one person might be a stitch abscess to another. Having specific criteria puts everyone on the same page for reporting.


NHSN definitions include time limita­tions; for most procedures, the infec­tion must occur within 30 days of the procedure to be counted. If any implants or hardware are left in, the surveillance period extends to one year. This includes intraocular lens implants.


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SSIs are placed in one of three categories: super­ficial, deep incisional, or organ space. See the definitions at (pdf).


It can be helpful to discuss these definitions with the surgeons so they will understand what informa­tion the infection preventionist is trying to collect. They can assist in classification of cases.


Identification of cases

One of the biggest challenges is identifying infected cases, as patients generally go home on the same day of the procedure. There are several approaches; generally more than one will be necessary.

  • Provide patients with a handout listing the signs and symptoms of infection when they discharged. Ask them to call in if they have signs and symptoms of infection within 30 days (one year if there was an implant) or are placed on an antibiotic related to the wound.
  • Call patients on or around post-op day 30 to inquire about any wound problems. It is also a good idea to create a standardized question list to be consistent and save time.
  • Send each surgeon a list of their surgical patients from the past month or quarter and ask them to indicate if any became infected.
  • Establish relationships with the nurses and medical assistants in the surgeons' offices and ask them to call if a patient returns with an infection. Mid-level providers are another great source; physicians assistants and advanced registered nurse practi­tioners can be very helpful as they often are the first to see these patients in the office.
  • Establish relationships with the infection preven­tionists at your local hospitals. Ask them to call if they see any patients with SSIs from your facility. Or, if you are aware of a patient that was admit­ted to the hospital for infection, give the infection preventionist a call. Often they can provide infor­mation on the infection — the infecting organism, date of onset, the depth of the infection, the anti­biotic and more.

Data collection

Forms can make data collection faster and more systematic. For each SSI, include space for the patient's name, phone number, medical record number, date of surgery, surgeon, procedure, wound classification and skin-to-skin time, date of onset of infection, level of infection (superficial, deep incisional or organ space), and the infecting organism. Also include a space to indicate whether the patient required reoperation or opening of the wound and antibiotics. This helps to ensure that critical elements won't be missed. It's helpful to include the NHSN criteria in a checklist format so you can check the appropriate boxes and have all the information at your fingertips. Do not collect any more data than you will use. It's a waste of time. This information can also be entered into an Excel spreadsheet to automatically populate the line list.

Data analysis

Once the SSI forms for any given period of time (month or quarter) are complete, the data should be transferred to a line list. Just as it sounds, a line list should include the names of all the patients identified with SSIs over a specified period of time. Each line contains data on one patient and include the same information as above – only all on one line. Once the line list is completed, an analysis should be done to identify trends and patterns. Are there infections from just one surgeon? Are the organisms mostly skin bugs like Staphylococcus epidermidis or coagulase-negative staphylococci? This may indicate a problem with skin prepping or skin shedding by OR personnel. Rates for a particular type of infection (e.g., inguinal hernia repairs) can be calculated by dividing the number of SSIs by the number of inguinal hernias done during the month or quarter and multiplied by 100 to obtain a simple percentage.

Sharing the results

Analysis of the line list can help pinpoint areas for further study — observing the skin prep and observ­ing basic operating room (OR) discipline. The results should be shared with the OR staff, as they are the ones who can make changes to improve care. Get staff involved by presenting the data, including your inter­pretation and asking them to come up with reasons the infections may have occurred and how best to prevent these in the future.


Test your knowledge (answers available below references):

1. True or False: Infection surveillance is part of the overall facility quality improvement program.

2. True or False: Standardized infection definitions allow comparisons among different facilities.

3. True or False: The National Healthcare Safety Network is only for hospitals.

4. True or False: A line list is a form that includes data only on an individual infected patient.

5. True or False: It is important to collect ONLY the data you will use.

6. True or False: Data analysis includes looking for trends and patterns in the data and possible causes

7. True or False: Don't share infection data with staff, as they might report it to the news media.

8. True or False: Infection data must be shared with the people who can impact change.


[1] National Healthcare Safety Network, Centers for Disease Control and Prevention. Accessed August 2011. Avail­able at:


Answers: 1.) True 2.) True 3.) False 4.) False 5.) True 6.)True 7.) False 8.) True


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