Suture needs to be of sufficient size to withstand the tensile forces placed on the loop and shear forces at the knot. Regardless of the knotting technique used, the use of monofilament suture is recommended because it appears to be stronger and provides more efficient hemostasis then multifilament suture [30]. Monofilament suture is also advised for laparoscopic ligating loops because the shape of the loop is usually maintained reasonably well by the increased stiffness [28, 29]. Ligature loops should be tied table‐side rather than pre‐tied and sterilized because sterilization can weaken the suture material and predispose to ligation failure [28]. A 4‐S modified Roeder knot using monofilament suture is recommended for maximal ligature loop strength [28].
The performance of the single knot loop has been shown to be biomechanically superior to a double knot loop in tensile breaking strength because with the single knot loop the forces are equally divided over the whole ligature, whereas with a double knot loop the two loops of the ligature will have different tensions after every knot [27]. A transfixation ligature can be performed to prevent slippage of the ligature; however, postoperative bleeding may still occur due to ligature failure of one of the double knot loops [27]. Sliding knots have been shown to be quicker and behave similar to or better than a surgeon’s knot in establishing hemostasis of arteries [30].
Tissue bulk can be overcome by dividing it into smaller sections (“divide and conquer method”) or multiple ligatures can be placed around a bulky structure to improve the hemostasis [26]. Clamping to crush the tissue and reduce its bulk, as well as “flashing” the clamp adjacent to the ligature being placed, are additional techniques for improving vessel occlusion and ligature security [26].
Diagnosis
Ligature loop failure can be observed intraoperatively under direct visualization or via laparoscopy. Postoperatively, incisional swelling or hemorrhage from the incision line can develop. Ultrasound and/or aspirate of the swelling are the most common diagnostics used to differentiate a hematoma from seroma or edema formation. Diagnosis of hemorrhage into a body cavity, such as pedicle ligation failure and development of a hemoperitoneum, are discussed in their respective chapters.
Treatment
When ligation failure occurs intraoperatively, the cause of the failure should be determined as to whether it is ineffective occlusion (knot slippage), loop slippage, or suture breakage and measures used to correct the failure. The use of ligating clips, staples, electrocautery and other electrosurgical instrumentation can be used in appropriate situations to provide hemostasis after ligature failure [28, 29]. If there is hematoma formation then treatment options differ depending on the degree and location. With mild hemorrhage and hematoma formation no treatment may be needed. For more significant hemorrhaging and hematoma formation there are multiple treatment options. If there is active hemorrhaging then the incision may need to be opened and hemostasis achieved via intraoperative methods discussed. Alternatively, compression or a compression bandage can be an effective means of hemostasis and prevention of hematoma formation.
Expected outcome
The prognosis is dependent on the degree of hemorrhage but incisional vessel ligation failure usually has a good outcome once time has been allowed for the hematoma to resolve. However, hematoma formation can increase morbidity to the patient, prolong wound healing time, and can increase treatment costs. Also, even mild hemorrhages can have an impact on the safety and efficiency of a given procedure, as well as effect outcome, depending on the situation [28].
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