Use of ureteric catheters and indocyanine green in complex pelvic surgery: a must or a luxury in 2023?

Ureteric injuries are a devastating, dreaded but recognized complication of pelvic surgery. The rate of ureteric injury in colorectal surgery is reported to be as high as 5% in some series,1 with the majority being recognized post-operatively. This can lead to long-term urological sequelae such as pelvic sepsis, strictures and in cases of irreversible renal damage may necessitate nephrectomy.2 Ureteric injuries are associated with higher morbidity and mortality, longer length of stay, and increased hospital costs.3 What strategies are available in the 21st century to mitigate these risks? The ureters are at risk during pelvic surgery for advanced pelvic malignancies (e.g. T4 rectal cancer), redo surgery, inflammatory conditions such as Crohn's or chronic diverticulitis, and previous radiotherapy.3-6 Historically, ureteric catheters/stents have been used to aid in identification of ureters and thus potential early recognition of injuries. Despite the reported advantages, they are not universally used in day-to-day practice due to impracticalities such as availability of a Urologist (especially in after-hours emergency surgery), increased operative time and cost, as well as paucity of high-level evidence to support their routine use. Meta-analysis of the limited studies would suggest that stents/catheters do not prevent ureteric injuries but merely facilitate intraoperative recognition.4 In open surgery, a standard ureteric catheter/stent ($18 and $188 AUD respectively) can be easily palpated yet their utility is diminished in the minimally invasive surgery (MIS) setting due to reduced haptic feedback. To overcome this, the use of intraureteric indocyanine green (ICG) and fluorescence imaging has enabled utilization of ureteric catheterisation in MIS surgery as a visual tool. There is some evidence to suggest that the rates of ureteric injury are higher in MIS compared with open surgery.7, 8 The use of lighted ureteric stents is expensive ($400 per stent) and is rarely utilized in MIS. The increasing uptake of near-infrared (NIR) imaging technology thanks to vascular and lymphatic imaging applications,9 as well as the high affinity of ICG to transitional epithelium of the urinary tract,10 has allowed for fluorescence guided identification of ureters. ICG is a water-soluble dye that binds with plasma proteins, has almost exclusive hepatic metabolisation and is excreted in bile.11 ICG molecules demonstrate fluorescent properties in the NIR spectrum (750–950 nm). It is relatively affordable ($245 per 25 mg vial) and has an excellent safety profile, but is crystallized using iodised salts rendering it unsuitable in patients with iodine or shellfish allergies. The technique for ICG-guided ureteric identification involves instilling ICG into each ureter through a ureteric catheter, and is generally performed by a urologist. If identification of the entire ureter is required, transureteric catheter injection of ICG dye into the renal pelvis is performed and antegrade flow stains the entire ureter. If only the pelvic ureter is at risk, ICG can be injected directly into the ureteric orifice thus minimizing the additional morbidity of ureter instrumentation. Most studies report using 5 mL of 2.5 mg/mL ICG solution in each ureter.11 There is an increasing body of evidence within MIS supporting the use of ICG-aided ureteric identification compared to ureteric stents, in particular in challenging pelvic surgery.12 Mean operative times for ureteric stent/ICG were only 9.5–20 min longer.13, 14 A recent systematic review of studies over the last two decades demonstrated lower rates of both iatrogenic ureteral injury (IUI) and urinary tract morbidity with ICG compared to ureteric stents.15 Namely, mean rates of IUI, acute kidney injury and urinary tract infections were reported as 0.3%, 3.6% and 1.1% respectively. In open surgery, ICG-stained ureters can be viewed with NIR cameras, such as the Stryker SPY portable handheld imager (Stryker, MI, USA; ~$47 000 AUD) or the Medtronic EleVision™ IR (Medtronic, MN, USA) platform. MIS systems include the Stryker 1688 AIM 4 K/PINPOINT platform, the Karl Storz Rubina®/IMAGE1 S products, and the da Vinci® FIREFLY imaging vision system. All systems display the fluorescent image as a live augmented reality (AR) video feed thus allowing context with surrounding anatomy during surgery. Early diagnosis of ureteric injuries is considered the single most important factor for an excellent prognosis. In an era of quality improvement and patient safety, utilization of technology to improve standardization of techniques is important. ICG is relatively cheap, has good utility and an excellent safety profile. As NIR imaging becomes more widely available, the use of ureteric catheters and more so ICG may become a more standardisable and reproducible operative component. In the current climate, surgeons should consider these risk mitigation strategies in patients with complex or challenging pelvic surgery. The future likely consists of the evolving use of novel renally excreted fluorophores (such as UreterGlow and sodium fluorescein) that can be injected intravenously and avoids the requirement for ureteric instrumentation. Dr Warrier and Dr Smart are proctors for Da Vinci, and Dr Pham has previously undertaken a Device sponsored robotic fellowship. Bushra Othman: Writing – original draft; writing – review and editing. Toan Pham: Writing – review and editing. Helen Mohan: Writing – review and editing. Amrish Rajkomar: Resources. Alexander G. Heriot: Supervision. Philip Smart: Resources; writing – review and editing. Satish Warrier: Conceptualization; writing – review and editing.