Management of Bowel Surgery Complications

Splenic Flexure

Splenic injury has been associated with many procedures including omentectomy for tumor debulking and staging, and whereas historical reports reveal a 9% incidence, injury is now a rare event. Iatrogenic injury occurs most frequently during colorectal procedures (0.42%–3%) and is largely due to splenic flexure mobilization. Injury has also been reported during left nephrectomy (1.3%–24%), gastric operations (2%), reflux procedures (4%), and exposure and reconstruction of the proximal abdominal aorta or its branches (1%). Splenic capsular injury is initially managed conservatively with electrocautery or topical agents with success rates up to 17%, but a majority (76%) of patients ultimately require splenectomy for definitive hemorrhage control.

Although splenic capsular tears (95%) comprise the majority of injuries, additional locations have been reported. A report by Merchea and colleagues revealed that of 13,897 colectomies, the locations of 71 splenic injuries were 24 (34%) inferior, 14 (20%) hilar, 3 (4%) posterior, 2 (3%) lateral, and 1 (1%) superior, with the location of 24 (34%) injuries not described. A frequent maneuver to increase exposure to the pelvis and retroperitoneal structures includes packing small bowel and omentum into the upper abdomen by first reflecting the omentum anterior to the liver in the right hemi-abdomen and left upper quadrant anterior to the stomach, in combination with nasogastric (NG) decompression. The bowel can then be compartmentalized with a radiopaque towel for protection. Owing to variable omental adhesions to the spleen and the splenocolic ligament, care must be taken during this maneuver not to tear the splenic capsule. Simple capsular injuries are initially managed conservatively with use of an electrocautery device on high settings and/or use of oxidized cellulose (Fibrillar or Surgicel), which can be removed at the end of the operation.

A self-retaining abdominal wall retractor is often necessary to provide adequate exposure to the left upper quadrant during splenic flexure mobilization for colon resection, or a left-to-right medial visceral rotation for exposure to the left retroperitoneal viscera and vascular structures. Medial and inferior traction on the descending colon during its mobilization off the white line of Toldt is necessary to adequately dissect the colonic mesentery free from the retroperitoneum. Use of right-angled instruments or even blunt finger manipulation may still produce enough tension to induce splenic injury during flexure mobilization. Attempts to immediately stop the resultant hemorrhage may not be easy with limited exposure and may cause inadvertent injury to the colon, stomach, small bowel, pancreas, or splenic artery and vein. Completing the splenic flexure mobilization facilitates adequate exposure and identifies the splenic injury, allowing appropriate control.

Ureteric Injury

Identification of the left ureter is typically required during rectal or colonic mobilization distal to the splenic flexure. The four most common locations of left ureter injury during colon and rectal mobilization include (1) the origin of the inferior mesenteric artery (IMA) off the aorta, (2) the left pelvis where the sigmoid mesentery is intimately associated with the retroperitoneum and the ureter courses over the left internal iliac artery, (3) the deep anterior pelvis as the ureter courses from lateral to medial heading toward the base of the bladder, (4) and under the bladder neck during the most proximal anterior dissection of the distal rectum and anal canal during an abdominal perineal resection (APR). The ureter is equally close to the uterocervical junction, and care must be taken during a hysterectomy to identify and protect it. Although ureteric stents have long been used to identify the ureters, the best and most predictive means is direct observation of the Kelly sign, peristalsis of the ureter with application of gentle pressure.

Although the anatomic path of the left ureter can be fairly well predicted, paired with the left gonadal vein in the retroperitoneum, its location can be largely unpredictable after any previous pelvic operation, pelvic radiation, or history of sigmoid diverticulitis with resultant inflammatory phlegmon. Injury remains low, around 0.2% to 7.8% of all pelvic surgical procedures, with elective colon and rectal operations accounting for 1% to 15% and gynecologic procedures up to 50% of all ureteral injuries in some series. During abdominal hysterectomy, injury incidence is low at 2.2% and 7.3% during hysterectomy with concurrent prolapse surgery and as high as 5% during radical hysterectomy alone. Use of ureteric stents with the intent of preventing ureteral injury has been controversial, with limited literature addressing the issue. To date, there has not been a randomized controlled trial to prove efficacy at preventing injury, although they have been useful in identification of injuries. Stents (lighted or nonlighted) can be readily seen at the time of a tangential or transection injury that may occur during a pelvic dissection. Immediate ureteral injury identification and repair are crucial to obtaining best outcomes and decreasing perioperative morbidity when compared with delayed identification and management.

Repair of a ureteric injury is dependent on two important factors: location and mechanism of injury. Thermal injury is a frequent cause owing to electrocautery and occurs often during normal dissection or as an attempt at coagulation of adjacent tissue bleeding. Injury caused by sharp dissection is typically managed by primary repair with an absorbable, nonbraided suture placed over an indwelling stent, spatulated and anastomosed end to end if greater than 50% transection; simple repair can be performed primarily in transverse fashion if the injury is minimal. A spatulated end-to-end anastomosis is the repair of choice for injuries that occur in the proximal two-thirds of the ureter, because the injury is frequently a transection due to incomplete mobility of the ureter off the colon mesentery bringing it into the vascular bundle with the IMA. If the injury occurs deeper into the pelvis, on the distal one-third of the ureter, then reimplantation into the bladder as a ureteroneocystostomy is preferred and is completed with use of bladder mobilization and a Boari flap or psoas hitch repair.

Vascular Anatomy

Although it is anticipated that most individuals have the same general vascular anatomy, important variants exist, and knowledge of these helps provide a road map to safe operations and improved outcomes. Blood supply within the small bowel distribution has built-in redundancy with third-, fourth-, and fifth-order mesenteric arcades off terminal branches of the superior mesenteric artery (SMA) (see Fig. 17.1 ). Clinically significant jejunal or ileal vascular abnormalities are rare. In contrast, aberrant colonic blood supply occurs more frequently, and identifying variations proves important to ensuring adequate supply to any anastomosis.

The SMA supplies the entire small bowel, with the cecum and ascending colon supplied by the ileocolic artery (ICA) and the transverse colon supplied by the middle colic artery (MCA) with both right and left branches. A study by Gamo and colleagues evaluated both computed tomography (CT) imaging and cadaveric SMA branches; the vascular pattern consisting of a singular MCA, right colic artery (RCA), and ICA branches is expected, but Gamo and colleagues found that this was variable (between 40% and 73%). Additional variations center around a common trunk: RCA and MCA as one, with a separate ICA (20%); ICA and RCA with a separate MCA (32%); and a common trunk for all three (0.35%). The RCA is absent in approximately 8% of patients. They did not find any patients with an accessory RCA, but this has been reported in up to 18% of patients. The MCA also is absent in 2% to 21% of patients. Rarely, the IMA may originate from the SMA in a few individuals, with most originating from the anterior aorta.

The branches of the IMA typically consist of a left colic artery (LCA), with both left ascending and left descending colic arteries, several sigmoid branches, and the continuation of the IMA into the pelvis as the superior hemorrhoidal artery (SHA) (see Fig. 17.2 ). Often, these branches can be originating together at one large common trunk, making their dissection, identification, and control difficult. The inferior mesenteric vein (IMV) courses just laterally to the IMA branch point and ascends cranially along the left ascending colic artery to join the splenic vein. This normal anatomy can be confusing without proper identification, leading to frustratingly significant hemorrhage if not identified correctly before injury occurs.

Given that normal anatomy occurs less frequently than previously described, knowledge of aberrant vasculature is key to proper dissection and avoidance of inadvertent injury that may lead to vessel ligation or insufficient tissue perfusion and subsequent ischemia. Built-in arcades such as the marginal artery of Drummond (SMA to IMA) and the inconsistent meandering mesenteric artery (of Moskowitz), also known as the arc of Riolan (MCA to IMA), provide collateral supply to remaining bowel when major vessels are ligated, but this should not be relied on without sound understanding of each individual’s vascular supply ( Fig. 18.1 ). Close attention to and review of preoperative CT scans or magnetic resonance imaging (MRI) findings will provide the surgeon with the necessary vascular road map to the viscera and optimum operative plan.

After vascular ligation and hemostasis, it is necessary to ensure adequate arterial supply to the planned anastomosis. Methods include palpation of the terminal arcade, such as the marginal artery for the colon, Doppler ultrasound of vessels to ensure arterial pulsatile flow, and use of fluorescence with a Wood lamp to confirm tissue perfusion. Newer technologies such as intravenous administration of indocyanine green (ICG) with laser immunofluorescence can also show tissue perfusion at anastomotic sites. Although these methods are appropriate, there is nothing more confirmatory than controlled, sharp transection of the vessel to visualize pulsatile flow. If this flow is confirmed, adequate blood supply has been confirmed for an anastomosis to heal. The authors routinely use this last method in their practice. Hemostasis is then achieved with ties. If less than pulsatile bleeding is encountered, more proximal transection should be considered to ensure adequate blood flow; as a principle in bowel surgery, this should always be followed.