MIS instruments and rigid endoscopes

If I am using sterile sheaths, can I dispense with immersing instruments and simply carry out wipe disinfection? Alternatively, what are the written sources describing the hygienic procedures to be adopted when using cameras as endoscopic accessories.

Our view is that camera heads should be cleaned and disinfected after use even if they are being used with a sterile covering. Unfortunately, there is no literature describing this procedure. This means it is extremely important to comply with manufacturers’ instructions. This process is also described in ISO17664.

Regarding the processing, how do you classify a conical amnioscope with a length of 20 cm and a diameter of about 14.5 cm at the wide end?

According to the Robert Koch Institute, an amnioscope is a lumened instrument and thus falls into Category B. The diameter is of secondary relevance. The classification as semi- critical or critical depends on its use. All instruments which come into contact with mucous membrane or pathologically mutated skin are considered semi-critical. Critical instruments are those which come into contact with blood or penetrate mucous membranes. As the amnioscope is used during the process of giving birth, there is definitely contact with blood. That is why this instrument should be classified as critical. As a lumened instrument, reprocessing in a class B steam steriliser according to DIN EN 13060 is recommended.

Is it OK to process laproscopic MIS instruments mechanically (washer- disinfector) 24 to 48 hours after manual pre-cleaning in the operating theatre? What are the official regulations and conditions?

The situation described should be an exception which may occur for example on a weekend. In this case, lumened instruments in particular should be thoroughly rinsed with fully demineralised water until clear water is discharged. If treated in such a way, laproscopic sets may be passed on to the CSSD for later processing in a washer-disinfector. This procedure must be previously discussed with the CSSD. If necessary, these instrument sets are additionally treated in CSSD, for example by means of ultrasound, before machine cleaning. Appropriate cleaning must be assured and should be verified randomly by means of a protein test. Providing such precautionary measures are taken, such a procedure could be tolerated in exceptional cases.

Is it possible to process MIS-instruments that cannot be disassembled?

There is no general answer to this question. Forceps and scissors equipped with a connection for washing cannot be disassembled but they can be sufficiently cleaned and sterilised. Make sure that the processing agent has access to all surfaces with direct or indirect patient contact.

How can you treat and autoclave irrigating cannulas (lumen<1mm)>

Cannulae with a diameter of less than 1 mm are difficult to reprocess. Cannulae with a diameter of less than 0.5 mm should not be reprocessed as perfect cleaning cannot be assured. However, the possibility to reprocess a cannula does not only depend on the diameter; its length is also important. To assure the safe processing of such narrow-lumened instruments, the following aspects must be taken into account: Lumens must be rinsed with sterile water immediately after use to prevent any blockage. If possible, use a non physiological salt solution. Check with a suitable guide wire that a lumen is not obstructed. Make sure that the interior is thoroughly dried after reprocessing; if necessary blow through it with a dry syringe until no more moisture emerges. Steam sterilise using a fractioned pre-vacuum according to EN285. Manufacturers have proved in a sterilisation study (Part 1 published in Zentralsterilisation 2001; 9(6) 425 - 437 and Part 2 published in Zentralsterilisation 2002; 10 (2) 100 - 109) that lumens with an inner diameter of 0.5 mm and a length of 500 mm can be sterilised with a fractioned pre-vacuum according to EN285.

What is the maximum length of narrow-lumened instruments sterilised in FO and steam sterilizers?

Until some time ago, sterilisation processes were tested according to DIN 58948 T 13/14 using a 1.5 m long (PTFE tube) test challenge device with an inner diameter of 2 mm and sealed at one end. This can currently be regarded as the limit for FO sterilisation, unless alternative proof is provided by "direct inoculation of the sterilised material". In the case of steam sterilisation (as will soon be the case with FO sterilisation), proof of validation of sterilisation processes must be provided. If goods cannot be tested using thermocouples, a "direct inoculation of the sterilised goods" must also be carried out (for more information, see DIN 58946 T6 or the appendix (draft).