Proper surgical dissection of the structure to be ligated is paramount and is particularly important with larger arteries and veins. Entirely isolating the vascular structure from surrounding tissues (Fig. 5.1) ensures ligation only of the intended structure, allows for visualization of the tips of the clip during closure (Fig. 5.2), and allows the clip to maintain an occlusive position without slipping. A vascular stump below the most proximal clip should be maintained (Fig. 5.3) in case additional clips are needed in case of hemorrhage . The vessel should initially be partially cut rather than fully transected (Fig. 5.4) to confirm hemostasis. This allows better control of the vessel in case additional clips or other hemostatic measures are required. Clips placed over staple lines or other clips are likely to have problems closing and should be avoided. Similarly, calcified, atherosclerotic arteries are also more likely to prohibit proper closure and require a low threshold for the use of additional clips or the addition of a suture ligature.

Both locking and non-locking clips come in a variety of sizes, and an appropriately sized clip should be selected for ligation. If the tips of a locking clip are not completely around a vessel, whether by improper positioning or by using an undersized clip, it should be noted that the vessel will be pierced when the clip is locked into place. For this reason, a larger clip or a non-locking clip that is less likely to pierce the vessel wall should be selected.

For smaller vessels and less-defined structures such as the prostate vascular pedicles, it is helpful to create windows in the adventitial tissue so that the clips can properly lock and the connected tips can be directly visualized. Locking clips will still function if there is some tissue within the latching portion provided that it is not overly thick, and in this situation the tactile feedback from a proper clip closure is key.

Elliott et al. described how closures failed in laboratory studies at supraphysiologic pressures [10]. Non-locking clips tended to fail by leaking through the clip as though the intraluminal pressure was able to pry open the arms. Locking clips maintained a closed configuration; however with proximal ballooning of the vessel, the cut edge would retract behind the clip and result in a bursting failure. Although these failures were well above physiologic blood pressure (>900 mm Hg), this description of the mechanism of failure is helpful in considering prevention. Indeed, in clinical accounts of failures, locking clips were noted to be slipped off of the bleeding vessel but remained locked [11, 12].

In other laboratory studies, Jellison et al. showed that leaving a 1 mm cuff beyond the distal clip resulted in fewer failures than when the vessel was transected adjacent to the clip [13]. We and others advocate leaving at least a 1–2 mm cuff beyond the distal clip to prevent a slipped clip from catastrophically falling off the vessel [12, 14].

In both Elliott’s and Jellison’s studies, using more than one clip performed better than a single clip only at supraphysiologic pressures which suggests the effectiveness of using a single clip in clinical use. However, by weighing the very minimal benefits of using a single clip against the potential for catastrophic failure, we and others advocate for leaving at least two clips on the patient side of larger vessels such as the renal artery and vein [4, 6, 8, 13].