Indocyanine Green Fluorescence Imaging in Prevention of Colorectal Anastomotic Leakage
Phase: NA
Conditions: Colorectal Cancer, Colorectal Neoplasms, Gastrointestinal Cancer, Gastrointestinal Neoplasms, Diverticulosis, Colonic, Gastrointestinal Disease
Sponsor: Oulu University Hospital

 
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Title:  
Indocyanine green fluorescence imaging in prevention of colorectal anastomotic 
leakage (ICG-COLORAL) 
 
Background: 
Laparoscopic approach is routine method for colorectal bowel resection nowadays. It 
reaches to equal or better results as open surgery in both benign and malign 
conditions (1, 2). Anastomotic leakage (AL) is one of the most devastating 
complications of colorectal surgery. AL can result in increased morbidity and 
mortality and can adversely affect the length of hospital stay, cost and cancer 
recurrence (3). The reported rates of AL after colorectal surgery range from 3-19% 
(4). Risk factors for AL are male sex, level of anastomosis, tobacco use, preoperative 
chemotherapy, preoperative radiation and the occurrence of intraoperative adverse 
events (5). 
  
Adequate vascular perfusion is of paramount importance for successful anastomosis 
and avoidance of intestinal ischemia. Surgeons have several subjective clinical checks 
for vascular perfusion, including examination of the color of the bowel wall, visible 
peristalsis, palpable pulsation and bleeding from the marginal arteries and stapled 
seam (6). Objective and accurate measurements of the intestinal perfusion are 
desirable to reduce AL (7). Near-infrared (NIR) fluorescence technology with 
indocyanine green (ICG) has become the most promising method that allows for an 
accurate evaluation of intestinal perfusion intraoperatively (8, 9) 
  
ICG is a water-soluble, tricarbocyanine compound dye that absorbs NIR light at 800–
810 nm and emits it at 830 nm. Under NIR light intravenous ICG injection becomes 
fluorescent, providing a “real-time” confirmation of intestinal perfusion. Therefore, it 
helps in determining the point of resection after mesenteric division and demonstrates 
the presence of an ischemic perfusion before performing the anastomosis (10). 
 
Aims: 
Main aim: Compare the anastomosis leakage rates in colorectal surgery after using 
ICG or not.  
 

 
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Secondary aims: Severity of anastomosis leakage, hospital readmission rates, 
reoperation rates, Clavien-Dindo score, operation time, length of hospital stay, 30- 
and 90-day mortality rates, time to first bowel movement (days), time to first flatus 
(days). 
 
Methods: 
Study design 
The aims above will be tested in randomized controlled trial performed in seven 
Finnish hospitals (Oulu, Jyväskylä. Lahti, Tampere, Turku, Jorvi, Seinäjoki). Patients 
eligible for the study are those with a diagnosed colonic or rectal pathology needing 
surgery and who are undergoing colon surgery with primary anastomosis, or rectal 
surgery with primary anastomosis.  
 
Patient with right side pathology will be operated without bowel emptying, patient 
with left-side pathology will have clyster and patient with rectal pathology will 
undergo bowel emptying. All patients receive cefuroxime (or clindamycin if 
contraindicated) and metronidazole at induction. No separate preoperative antibiotic 
is given. 
 
Inclusion criteria 
All consenting patients in the catchment area of above mentioned hospitals who 
undergo elective colorectal surgery with planned primary anastomosis are eligible for 
this study. Of rectal cancer patients only those with pathology in the proximal third 
will be included in the study (defined by area proximal from peritoneal fold).  
 
Exclusion criteria 
Emergent patients, patients with proven diverticular abscess and colonic fistulas are 
excluded. Also patients with planned open surgery are excluded.  
 
Patient randomization 
Patients diagnosed with colorectal pathology are randomized at the preoperative visit 
to either ICG+ or ICG- group. Patient information is given and written informed 
consent will be received from all participants before randomization. Number of 
patients refusing to take part in the study is also collected. Total number of patients 

 
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operated due to colorectal pathology in participating centers will be reported, and 
reason for exclusion from the study. 
 
Data collection 
Following baseline data will be collected from all patients during the hospital 
admission or before: sex, age, comorbidity, smoking (no, ex, current), received 
neoadjuvant chemo- or chemoradiotherapy, previous operations (abdomen), reason 
for operation (diagnosis), stage and date of cancer diagnosis. 
 
Following data will be collected regarding the operation: Type of operation, use of 
stoma or not, type of anastomosis, length of surgery, amount of bleeding, blood 
transfusions, peroperative complications, surgeon experience (number of performed 
laparoscopic bowel resections), ICG-staining intensity in planned resection line (scale 
0-2), ICG-staining intensity after primary anastomosis on both sides of the 
anastomosis (scale 0-2), time from ICG injection to maximal intensity (at the planned 
site and after completion of the anastomosis).  
 
In ICG intensity scale zero means no detected fluorescence and two means similar 
fluorescence as observed in proximal non-operated bowel area. Intensity of one is 
between these two. 
 
Photograph is taken at the site of planned anastomosis and after the completion of the 
anastomosis. 
 
If after ICG-staining the location of the resection line is changed, or if a new 
anastomosis is performed this will be collected also. 
 
If anastomosis shows zero intensity a new anastomosis will be performed. With 
medium intensity (1) the operating surgeon decides the need for reanastomosis 
according to clinical situation. 
 
All patients are followed for anastomosis leakage rates, severity of the anastomosis 
leakages, other complications (Clavien-Dindo score), time to first bowel movement 

 
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and flatus, length of hospital stay, hospital readmission rates, reoperation rates, and 
30- and 90-day mortality rates. 
 
Full-time study coordinator will collaborate weekly with all participating centers, 
collecting needed information of all newly operated / discharged patients. Afore 
mentioned parameters will be collected at preoperative visit (Table 2), at the operation 
room by nurse (Table 3) and at the time of discharge (by doctor dictating the epicrisis) 
supplemented at 90-days after the operation (by study assistant), Table 4. 
 
Power analysis: 
Total number of elective colorectal operations in above mentioned six centers is 
approximately 1000 patients / year. Of these all are screened and recruited for the 
study. We believe that majority of patients are willing participate the study, but some 
dropouts (estimated as 10%) will exist because of technical difficulties with ICG 
equipment and early conversion to laparotomy. Therefore power calculations have 
been made with 1000 patients / year. According to previous reports, anastomosis 
leakage rate after colon surgery is approximately 6-8% and after rectal surgery 10%. 
With ICG-staining we hypothesize that most anastomosis leakages can be 
significantly reduced. In recent systematic review van den Bos et al. (Journal of 
laparoendoscopic & advanced surgical techniques) reported anastomosis leakage rates 
of 7.4% without NIR imaging and 3.5% with performed NIR imaging. With these 
numbers the sample size of 1062 patients is needed with power of 80% and alpha 
0.05. Both groups will include 531 patients. The study will need approximately 1.5 
years until all patients have been recruited. 
 
Exposures 
Group 1: Colorectal surgery with primary anastomosis without ICG-use (reference 
group) 
Group 2: Colorectal surgery with primary anastomosis with ICG-use (test group) 
 
Study outcomes 
Primary outcome 
 Anastomosis leakage rate between groups. 
Secondary outcomes 

 
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 Severity of anastomosis leakage, timing of anastomosis leakage, deep surgical 
site infections, hospital readmission rates, reoperation rates, Clavien-Dindo 
score, operation time, length of hospital stay, 30- and 90-day mortality rates, 
time to first bowel movement (days), time to first flatus (days) and hospital 
costs. 
 
Anastomosis leakage is diagnosed by triple contrast CT in case of suspected 
ananstomosis leakage. Additionally colonoscopy may be performed. Anastomosis 
severity is graded as follows: local infection without abscess, abscess without clear 
intraluminal bowel connection, abscess with intraluminal bowel connection, free 
perforation to abdominal cavity.  
 
Possible confounders 
Because of the study design (randomized controlled trial including all patients with 
planned laparoscopic colorectal surgery with primary anastomosis) confounding 
factors should be excluded. 
 
The following baseline information will be reported (See Table 2): 
(1) Age (at the time of operation); 
(2) Sex: male – female; 
(3) Charlson Comorbidity Index: 0, 1, ≥2  
(4) Tumor stage according to AJCC 8th edition. 
 
 
 

 
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1) Comorbidity 
Comorbidity was defined as any disease the patient had before operation (maximum 3 
years), or at the time of the operation. These will be classified as 0, 1 and ≥2 
according to the Charlson Comorbidity Index (based on presence or absence of the 
following comorbidities (Table 3). 
 
 Table 3: The diagnoses used to calculate the Charlson’s comorbidity index. 
Disease 
ICD-10 codes 
Myocardial infarction 
I21*, I22*, I23*, I252 
Congestive cardiac failure 
I11, I13, I255, I42, I43, I50, I517 
Peripheral vascular disease 
I70–I73, I770, I771, K551, K558, K559, R02, 
Z958, Z959 
Cerebrovascular disease 
G45, G46, I60–I69 
Dementia 
A810, F00–F03, F051, G30, G31 
Chronic pulmonary disease 
I26, I27, J40–J45, J46*, J47, J60–J67, J684, J701, 
J703 
Rheumatological disease 
M05, M06, M09, M120, M315, M32–M36 
Liver disease 
B18, I85, I864, I982, K70, K71, K721, K729, K76, 
R162, Z944 
Diabetes mellitus 
E10–E14 
Hemiplegia or paraplegia 
G114, G81–G83 
Renal disease 
I12, I13, N01, N03, N05, N07, N08, N171*, 
N172*, N18, N19*, N25, Z49, Z940, Z992 
Any malignancy 
C00–C26, C30–C34, C37–C41, C43, C45–C58, 
C60–C76, C80–C85, C88, C90–C97 
Metastatic solid tumour 
C77–C79 
AIDS/HIV infection 
B20–B24 
*Will be only taken into account for previous, not current, hospital admissions 
 
Colorectal cancers are not counted as comorbidites. The prevalence of metastatic 
diseases among the study is assessed first (sensitivity analysis) and then the inclusion 
or exclusion of these diseases into the Charlson’s score is determined. 
 
 
 

 
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Statistical analyses 
Descriptive statistics of patient characteristics will be presented separately for the two 
groups (ICG or not). 
The amount of primary and secondary outcomes will be tested by chi-square test, 
Students T-test or Mann-Whitney U test as appropriate. 
 
Subgroup analysis 
Subgroup analyses will be conducted for the primary outcome by 
1) Separately patients with colon and rectal pathology. 
2) Separately patients with preoperative chemo/radiation. 
3) Separate analysis according to Stage (I-III vs IV) 
4) Separate comparison of patients in which the location of anastomosis was 
changed due to ICG staining to patients with performed ICG staining but no 
change in the anastomosis location, and to patients in no-ICG group. 
5) Separate comparison of patients with slow appearing ICG-staining versus fast 
staining (divided with median time). 
6) Separate analysis of patients with low and high comorbidity (CCI ≥ 2) 
7) Separately according to age (≥70 years). 
8) ICG staining intensity in smokers vs non-smokers and correlation with 
leakage rate. 
9) Separately patients with right and left resection 
10) Separate analysis according to diagnosis 
 
 

 
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Handling of missing data: 
There will be number of missing data due to inadequate data collection in all study 
centers. This will be minimized with active weekly data collection by study assistant 
and the researchers. Missing data will be reported. 
 
Collaborators: 
First Author: Juha Rinne 
Last Author: Jyrki Kössi 
Other: Olli Helminen, Heikki Huhta, Matti Kairaluoma, Tero Rautio 
Statistician: Pasi Ohtonen. 
 
 

 
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Tables 
 
Table 1. Clinical variables by surgical technique in n patients operated with colorectal 
cancer resection with and without ICG. 
Variable 
Anastomosis with 
ICG 
Anastomosis 
without ICG 
 
Patients (%) 
n= 
Patients (%) 
n= 
Mean age (SD) 
 
 
Sex 
 
 
Male 
 
 
Female 
 
 
Charlson comorbidity index 
 
 
0 
 
 
1 
 
 
≥2 
 
 
BMI 
 
 
 
 
 
Anastomosis leakage(AL) (n) 
 
 
Severity of AL1 
 
 
No leak 
 
 
Grade A 
 
 
Grade B 
 
 
Grade C 
 
 
 
 
 
Need of blood pressure support 
 
 
Intraoperative blood transfusion 
(units) 
 
 
Postoperative blood transfusion 
(units) 
 
 
Intraoperative bleeding 
 
 
Length of surgery 
 
 
Hospital stay (days) 
 
 
ICU stay (days) 
 
 
Re-operation rate 
 
 
Re-admissions 
 
 
First bowel moment (day) 
 
 
First flatus (day) 
 
 
30d mortality 
 
 
90d mortality 
 
 
Clavien-Dindo score 
 
 
Grade I 
 
 
Grade II 
 
 
Grade IIIa 
 
 
Grade IIIb 
 
 
Grade IVa 
 
 
Grade IVb 
 
 
Grade V 
 
 
 
 
 
Primary ICG staining intensity at 
the planned site 
 
 
Primary ICG staining intensity 
after performed anastomosis 
 
 
Time from ICG injection to 
maximal intensity 
 
 
 
 
 
Changing of anastomosis location 
 
 

 
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according to ICG staining 
 
 
 
 
 
 
Preoperative chemotherapy 
and/or radiation 
 
 
 
 
 
Type of surgery 
 
 
Left hemicolectomy 
 
 
Right hemicolectomy 
 
 
Sigmoid resection 
 
 
Proximal rectum resection 
 
 
 
 
 
Formation of stoma 
 
 
 
 
 
Tobacco use 
 
 
 
 
 
Surgeon experience 
 
 
 
 
 
Tumor stage 
 
 
 
 
 
Location of the tumor 
 
 
 
 
 
Circular, linear, hand sued, intra- 
or extracorporeal anastomosis 
 
 
 
 
 
Anastomosis type 
 
 
1Grade A = No change in patient management, Grade B = leakage requires active 
therapeutic intervention but is manageable without re-laparotomy, Grade C = leakage 
requires re-laparotomy 

 
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