Chicken leg model anastomosis - 120 degrees, 12 stitches

Anastomosis – 120 degrees, 12 stitches

Remember to alternate the magnification, switching it higher for placing stitches and lower for tying knots.
The first two stitches are some of the most challenging to perform, as they need to accurately match the still movable vessel stumps.
To place the first stitch, simply enter the vessel lumen with a vessel dilator to provide contra-pressure. Then rotate the needle through the vessel wall, at a steep enough angle to penetrate all vascular layers.
Once you have placed the needle in the vessel wall, reassure yourself that it is positioned in the correct distance to the cut edge. If you have placed it too close to the edge, appreciating symmetry will be difficult.
If you have approximated the vessel ends well and are holding the needle correctly, you can pass it directly through the opposed vessel stump, grasping the adventitia to immobilize the vessel.
You can now tie a knot. Make sure that you exchange the suture ends accurately to keep them from reaching into the lumen after they are cut short. Keep the short suture end long for self-evaluation, as will be explained shortly.
The second stitch is placed at exactly 120 degrees from the first, on both vessel stumps. If this distance is not symmetric on both vessel stumps, the vessel circumference will not be distributed evenly across the three 120-degree thirds, leading to a mismatch of the vessel ends commonly referred to as a “dog-ear.”
Once you have tied the knot, leave the short suture end long as for the first stitch.
The third stitch is placed exactly in the middle between the first and second stitch.
To verify whether the needle was placed parallel to the vessel’s long axis, the suture ends of the first and second knot, which were left long, can now be pulled perpendicular to the vessel’s long axis. Here is a correct stitch. If the needle is not parallel to the vessel’s long axis it is best taken out and the stitch repeated.
Beware of both false positive and false negative results. The test yields the clearest results for stitches three, seven and ten. For all other stitches correct appreciation is more difficult, since the distance between the knots that are being pulled on is significantly shorter. The curvature and lateral tilt of the needle stuck in the vessel wall and the internal structure of the knots further limit precise appreciation.

Correct mistakes as soon as they become apparent

If you realize you have made a mistake in your work, stop! First take time to correct the mistake, only then continue. Each uncorrected mistake carries the
potential of making subsequent steps more difficult than they need to be. Speed will come in time by mere repetition, but accuracy is best learned through continuous self-evaluation and correction. Place the fourth stitch and tie its knot. Place the fifth stitch. Here is the finished front wall. You can now flip over the approximator and start working on the back wall.
Before you continue, check whether you have stitched the back wall along with the front wall.
Place the sixth stitch in the middle of the back wall.
You can perform a needle test here, but be aware that it may not be accurate, since the back wall, having twice the circumference of the front wall, cannot be fully stretched out.
Tie the knot and cut only the long end, as for stitches one and two. Place the seventh stitch and perform a needle test. Place stitches eight and nine to finish the second 120-degree segment. Place stitch ten and perform a needle test. Lastly, place stitches eleven and twelve. Here is the finished anastomosis.