During this time period, 137 patients underwent colorectal surgery. Only basic measures for preventing SSI were performed:

1. Hair was removed in the operating field with a clipper instead of shaving hair.
2. Blood glucose was monitored only during the operation.
3. Antibiotic prophylaxis was applied 60 minutes before the operation.
4. The application of an antibiotic prophylaxis was repeated if the operation lasted longer than 4 hours.
5. Measures of warming were only applied during the operation and in the recovery room.
6. Instruments and gloves were changed after finishing the anastomosis.

During this phase, additional measures have been introduced:

1. Implementation of wound protectors during colorectal surgery.
2. Colorectal operations were only performed with the support of an experienced consultant surgeon.

During this phase, additional measures are implemented.

1. Close monitoring of blood glucose. During the stay in the recovery room and for 48 hours post-operative, blood glucose is monitored closely. Moreover, if blood glucose is higher than 9 mmol/l, the patient will be treated with insulin. This measure is applied to diabetic as well as to non-diabetic-patients.
2. The measures of warming will be intensified. First of all, during the operation and during the stay in the recovery room patients will be placed on warming mattresses. Moreover, a warming towel will be placed on the operating field directly after the operation.
3. The patients will be asked to take a shower the night before surgery. In case of an emergency operation, patients will be asked to wash the axilla, trunk, genitalia, groins and umbilicus

Hair removal with Clipper Glucose Control Preoperative antibiotics Repeat antibiotics after 4 Hours Optimize Body temperature Instrument change for colorectal anastomosis Use of wound protectors Experienced surgeon Preoperative showering

rate of SSIs and classification of SSIs (superficial SSI, deep SSI or organ space SSI)

Determination of the risk factors for SSI (Obesity, age, diabetes, alcoholism, immune-deficit illnesses (such as HIV and Hepatitis), smoking, immunosuppressive drugs, chemotherapy, radiotherapy, COPD, pAVK, renal insufficiency and poor Nutrition)