The calculator in question is the Risk Score for Postoperative Pancreatic Fistula (POPF). This scoring system is specifically designed for patients undergoing pancreatic surgery, particularly pancreaticoduodenectomy, distal pancreatectomy, and other pancreatic resections. The clinical utility of this calculator is to predict the likelihood of a patient developing a postoperative pancreatic fistula, a serious and potentially life-threatening complication. 

The risk score takes into account various factors including patient characteristics, disease characteristics, and operative details. It helps clinicians to stratify patients into low, moderate, and high-risk categories, thereby guiding postoperative management and potentially reducing morbidity and mortality.

Exclusion criteria for its use would include patients not undergoing pancreatic surgery, those with pre-existing pancreatic fistulas, or those with contraindications to surgery. It's also important to note that this risk score may not be applicable in cases where intraoperative findings or postoperative course significantly deviate from the norm.

Risk score for postoperative pancreatic fistula

# Criteria
 ## Gland texture
A. Firm (+0)
B. Soft (+2)
## Pathology
C. Pancreatic adenocarcinoma or pancreatitis (+0)
D. Ampullary, duodenal, cystic, islet cell (+1)
## Pancreatic duct diameter
E. >= 5 mm (+0)
F. 4 mm (+1)
G. 3 mm (+2)
H. 2 mm (+3)
I. <= 1 mm (+4)
## Intraoperative blood loss
J. <= 400 mL (+0)
K. 401-700 mL (+1)
L. 701-1,000 mL (+2)
M. > 1,000 mL (+3)

# Conditions
- score == 0
- score <= 2
- score <= 6
- score >= 7