Pediatric colorectal conditions, such as Hirschsprung's disease (HD) and anorectal malformations (ARM), result in significant disease burden in pediatric populations in Canada. Both conditions are present in approximately 1 in 5000 live births. Surgical correction of these anomalies is typically performed in Children's Hospitals in Canada. Postoperative complications, such as anal stricture and anal stenosis, have been reported to occur in 2-35% and 2-10%, after posterior-sagittal anorectoplasty (PSARP) and laparoscopic-assisted pull through for ARM and HD, respectively. In addition, anastomotic leaks and dehiscence are life-threatening, and should be avoided at all costs. The literature estimates the rate of anastomotic leak in HD to be approximately 2%, but have been reported in as high as 10% in neonatal patients. Wound dehiscence post ARM repair has been estimated as high as 30-40%. It is hypothesized that the above post-operative complications occur due to compromised vascular supply to the bowel undergoing coloanal anastomosis at the time of pull-through.
Traditionally, surgeons evaluate bowel viability with tactile and visual means, including discoloration, bleeding from the cut edge, and peristalsis after resection. With the push towards minimally invasive surgeries over recent decades, the adoption of surgical technology which can replace open or tactile assessments is necessary. One such example is the use of indocyanine green (ICG) for assessing bowel perfusion in laparoscopic surgery. ICG is a nontoxic, nonimmunogenic, water-soluble intravascular imagine agent. It has a short half-life (approximately 3-5 minutes) and when injected intravenously, it binds to plasma proteins and proteins in the lymph fluid keeping it in the intravascular compartment. ICG absorbs light in the near-infrared region (806 nm) and emits fluorescent light at 830 nm. ICG was approved by the Food and Drug Administration (FDA, New Drug Application \[NDA\] 211580 505(b)(2) via fda.gov) for use in adults in the late 1950s and has since been approved for use in adults by Health Canada.
A review article published in 2012 identified over 200 manuscripts describing safe and reliable use of ICG in surgical procedures in adults. More specifically, qualitative analysis of bowel perfusion enhanced by ICG in colorectal cancer patients has been shown to reduce rates of anastomotic leak by approximately 4%. Practically speaking, the use of ICG florescence technique can be useful in identifying clinical vascular anatomy in colorectal surgery, both via open and laparoscopic approaches, allowing surgeons to better preserve important structures.
Several studies have shown that ICG is safe among pediatric populations, with utility demonstrated in cases of difficult cholecystectomy, hydrocele repairs, and localizing metastatic disease. As such, the FDA has approved the use of ICG in paediatric patients. Research studies from the US, have examined the intravenous application of ICG for more than 60 years in adults and children with few reported adverse effects. However, Health Canada has not reported on the safety and efficacy of ICG and does not authorize an indication for its use.
To our knowledge, there have only been two studies that have looked at intraoperative ICG to visualize intestinal perfusion for primary pull-through in Hirschsprung Disease and anorectal malformation repair patients and both were retrospective studies. A previous study included eight patients, diagnosed with HD undergoing transanal, open or laparoscopically-assisted pull-through procedures after biopsy confirmation of aganglionosis. Patients were given a dose of 1.25mg (\<2 mg/kg) of ICG intraoperatively in the operating room. In five of the eight patients, the level of the bowel transection was changed based on the ICG visualization. In the other three patients, ICG confirmed the surgeon's assessment of where the resection should occur. There were no intraoperative complications or complications noted at two-week, one-month, and three-month follow-up visits. Further no leaks, incontinence, or strictures were noted at any of these follow-up visits. Another study 16 included 13 patients in total, nine undergoing cloacal reconstruction, four with HD and one with an ARM. ICG was used to predict the vascular supply during the reconstruction procedure and patients were given an intravenous dose of ICG between 0.1 to 0.3mg/kg in the operating room. There were no intraoperative adverse events or side effects from the ICG. ICG changed the operative plan in four out of 13 cases (31%), one of those four cases being a pull-through for HD. For this HD case, ICG resulted in the detection of 10cm of non-viable colon which may not have previously been detected. Although the level of evidence is limited by study design and small sample sizes, these studies help to provide rationale for the continued study of ICG use in paediatric patients.
Despite the results from these studies, future work is needed before he investigators can determine the effectiveness of ICG in reducing rates of post PSARP and pull-through complications. Practically speaking, the main inhibitors to widespread adoption of ICG in these surgeries is the cost of the technology, and lack of data to support that it truly reduces the rates of complications associated with these surgeries. Our research team, looks to be the first group to explore the feasibility of using ICG in a paediatric population with Hirschsprung's Disease and anorectal malformations. The investigators hope that the results from the study will help to initiate future multicenter, randomized controlled trials to provide high level evidence to support the use of ICG in colorectal surgeries in paediatric patients.
