To fully understand the concept and the discussion it is preferred to know the standard procedure used when dealing with tumors in the large intestine.
The large intestine (colon) frames the abdominal cavity. It starts in the lower right corner and then progresses straight up towards the liver (right colon). It then crosses the abdominal cavity to the spleen (transverse) and then down along the left side (left colon). Thereafter the colon makes an S-shaped bend (sigmoid). When the colon passes downward into the pelvis it is renamed the rectum. The rectum ends up in the anal canal when it passes through the pelvic floor.
When tumors located in the colon are resected the intestinal ends may be joined together in different ways. The most common way is hand-sewn connections (anastomosis) but staplers of various sizes and types can also be used. If staplers are chosen it will take at least two (infrequently four) staplers (i.e. magazines of staplers) to achieve an anastomosis. Intestinal ends of the rectum can only be joined together with staplers since there is too little space to perform a hand-sewn anastomosis in this area. It usually takes three steps to perform an anastomosis. First you cut and staple the intestine above the tumor than you cut and staple the intestine below the tumor and after that you rejoin the intestinal ends with a circular stapler. After that the surgeon often creates a relieving stoma to reduce the risk for leakage in the rectal anastomosis.
CREX (Colorectal anastomosis; Rejoin the intestine and validate the anastomosis; Extract samples for analysis; X-ray through connected catheters) is a method to anastomose the large intestine or rectum after resection of a segment due to tumor, injury, or other disease. The CREX FixAid comprises of surgically invasive devices, RapAn, intended for short-term use and a transient surgical instrument FixAid. RapAn and FixAid are assembled when delivered and as such the device is named CREX FixAid. CREX FixAid can be ordered in three different sizes.
RapAn – Two ring-shaped, surgically invasive devices intended for short-term use are placed in the intestine on the proximal and distal ends of the resection line. Two elastic O-rings lock the intestinal ends to the RapAn male and female sections. Male and female part of RapAn is connected together with a simple click function. The rings then form a single unit, named assembled or intact RapAn. This makes up the complete anastomosis and it can be monitored both during and after surgery, through a catheter system connected to RapAn male. Corresponding rings for Lapaid is named LapAn and for RectoAid the corresponding rings is named RectoAn.
FixAid – This device is used to place the RapAn (the rings that belongs to FixAid) into the intestine. It is preferably used on the left colon (descending colon and sigmoid colon) and the upper rectum (15 cm above the anal rim). CREX FixAid is indicated for single colonic (large intestinal) anastomoses but not for small intestinal, gastric and esophageal anastomoses. The device may be used in any disease process for which large intestinal resection and anastomosis is indicated, e.g., carcinoma, colostomy closure, injuries etc. Use of the RapAn in the distal portion of the rectum (<15cm above anal rim) is not within the intended use.
LapAid – This device is used to place the LapAn (the rings that belongs to LapAid) into the intestine. It is preferably used on the upper rectum (15 cm above the anal rim) when it´s tough to put the ring in place with CREX FixAid. CREX LapAid is indicated for single colonic (large intestinal) anastomoses but not for small intestinal, gastric and esophageal anastomoses. The device should only be used, at the moment, for clinical studies.
RectoAid – This device is used to anastomose rectum to colon after resection of tumours located in lower rectum. RectoAn (the rings that belongs to RectoAid) is put in place by a transanal approach. The device is preferably used on the lower rectum (5 – 15 cm above the anal rim). CREX RectoAid is indicated from low rectal anastomoses up to the very distal part of Sigmoid (upper rectum). The device should only be used, at the moment, for clinical studies.