Three anastomosis configurations are established to unite lumina in the gastrointestinal tract:
- The end-to-end anastomosis is appropriate when both lumina have a comparable, sufficiently large diameter and the probability of anastomosis stenosis is minimal.
- An end-to-side anastomosis is chosen for different lumen diameters.
- A side-to-side anastomosis enables a large-lumen anastomosis with small-lumen ends and thus prevents later anastomosis stenoses.
Retrospective studies could not demonstrate any advantage of the single-knot vs. the
continuous suture technique in a single-layer suture. Advantages of the continuous technique are the small amount of foreign material introduced, cost-effectiveness of the procedure, shorter operating times, and uniform adjustment of the suture tension over the entire circumference of the anastomosis. This prevents the escape of contaminated material into the surroundings and reduces abscess formation. Disadvantages of the continuous suture: In case of thread breakage, the risk of complete dehiscence increases, the stitching is less clear.
The continuous suture technique is only suitable for invertible bowel segments.
In butt-to-butt anastomoses, earlier and increased vascularization occurs.
In the exudative phase, tissue edema of the wound edges occurs. When knotting and pulling the thread, this tendency to swell must be taken into account. Knots and thread pulls that are too tight lead to secondary ischemia. Connections that are too loose do not provide tightness.
The use of absorbable suture material is appropriate to avoid stenosis induction by a permanent foreign body reaction to the anastomosis.
Regarding the stitch technique, a distance of 5mm is recommended both to the wound edge and to the neighboring thread.
Coating the threads with doxycycline can increase the strength of the suture.
Requirements for the thread material: low tissue trauma, high flexibility of the thread, gliding ability with high knot security, good tissue compatibility, no tendency to swell, no capillarity (wicking effect), high tensile strength with low thread thickness, defined resorption time, cost-effective. The optimal thread that meets the mentioned requirements does not exist.
For anastomoses in the gastrointestinal tract, monofilament absorbable threads of size 4/0 or 3/0 are generally used, for single-knot sutures alternatively also braided (coated) absorbable threads.
Of the 4 layers of the intestinal wall, the submucosa is the most important layer for the suture. The submucosa contains the most collagen fibers and is the vascular layer. Sutures that do not include this important tissue only have an adapting character and no significant tensile strength.
In extramucosal stitching, the excess mucosa presses against each other and a slight inversion of the intestinal walls occurs.