Intraoperative Consultation During Pancreato-Biliary Surgery

Introduction

Intraoperative/frozen section consultations on pancreaticobiliary surgeries are mainly performed for the assessment of resection margins of the specimens and to rule out the possibility of metastatic disease at sites such as liver, peritoneum, omentum, mesentery, and lymph nodes. Only rarely a core biopsy of the pancreas is received for frozen section to help make the intraoperative diagnosis of a mass lesion because most often the surgeons have the preoperative radiographic and/or pathologic diagnosis or they have committed to a certain surgical procedure which is not altered by frozen section analysis. Table 13-1 lists the indications for frozen section on pancreaticobiliary specimens. Table 13-2 summarizes the work flow related to pancreaticobiliary intraoperative consultations.

Table 13-1

Indications for Intraoperative Consultation (IOC)

Assessment of resection margins for invasive carcinoma and high-grade dysplasia in a pancreaticobiliary resection specimen with a preoperative diagnosis of pancreatobiliary carcinoma and intraductal papillary mucinous neoplasm

Frozen section of any suspicious metastatic focus at sites such as the liver, peritoneum and mesentery

Frozen section of a pancreatic mass lesion sampled by a core biopsy or wedge resection with no preoperative diagnosis

Benign vs. malignancy

Type of neoplasm: adenocarcinoma/neuroendocrine tumor/lymphoma

Pancreatic pseudocyst vs. neoplastic cyst

Frozen section of lymph nodes for possible metastasis in a patient undergoing ampullectomy and pancreatic enucleations/limited resections

Ampullectomy specimens: assessment of resection margins and presence of invasive carcinoma

Nesidioblastosis

Table 13-2

Pancreaticobiliary Resection Specimen for IOC

Work Flow

Preoperative diagnosis: adenocarcinoma/IPMN/ neuroendocrine tumor/pancreatic cyst/pseudocyst

Demographics: age, sex and location of the lesion are important for diagnostic considerations

Specimen orientation: critical for margins assessment

Sectioning of the margins: check the requisition form to find out which margin is being requested; refer to Table13-3

Frozen section assessment of the margins for carcinoma; see Table 13-4

IPMN, Intraductal papillary mucinous neoplasm.

For an ampullectomy specimen, usually performed for ampullary adenoma, a frozen section may be requested for the evaluation of margins and for any evidence of invasive carcinoma.

Identification of the Margins and Orientation of the Specimen

The resection margins vary depending upon the type of specimen ( Table 13-3 ). Proper orientation of the specimen is a key to accurate frozen section assessment of the margins.

Table 13-3

Margin Assessment Depending on the Type of Resection Specimen

Type of Surgery	Type of Margin	Sectioning of Margin
Whipple resection	Bile duct margin	Shaved
	Pancreatic resection margin	Shaved
	Uncinate margin	Perpendicularly sectioned after inking the uncinate surface
Central pancreatectomy	Proximal and distal resection margin	Both shaved
Distal pancreatectomy	Proximal resection margin	Shaved
Enucleation	Circumferential resection margin	Perpendicular section of the closest margin
Ampullectomy	Pancreatic duct margin	Shaved
	Bile duct margin	Shaved
	Duodenal mucosal margin	Perpendicularly sectioned
	Radial resection margins	Perpendicularly sectioned

Pancreaticoduodenectomy (Whipple Procedure)

The resection margins for the Whipple specimen on which frozen section is requested are pancreatic body/neck resection margin, bile duct resection margin, and uncinate/retroperitoneal margin. Depending upon the location of the tumor (ampullary, pancreas, or bile duct), the surgeon may elect to freeze one or all of the three margins.

Orientation

The specimen can usually be oriented as follows: the longer segment of the resected bowel is the distal aspect of the specimen; the pancreatic uncinate process margin, often rough and cauterized, is located at the inferior-posterior aspect of the head of the pancreas; and the pancreatic body/neck resection margin is at the distal end of the pancreatic specimen, which is identified by appreciating the cut surface of the pancreatic parenchyma with pancreatic duct in the center ( Figure 13-1 ). The bile duct is present between the pancreatic body/neck resection margin and the proximal portion of the bowel. The ampulla can be probed to identify both bile duct and pancreatic resection margin ( Figure 13-2 ). For complex specimens, the surgeons should be encouraged to designate the margins with suture. This is especially true in cases in which vascular structures are removed en bloc with the specimen because these are often difficult to appreciate unless clearly indicated. Frozen section is usually not requested for the uncinate margin because the surgeons quite often cannot remove any more of the pancreatic tissue in this area even if the margin is positive. In addition, positivity along the uncinate is generally considered a poor prognostic sign, and adding additional risk by trying to extend this margin surgically is unlikely to be useful. In rare cases where the consistency of the tissue along the uncinate margin is fibrotic or otherwise atypical, such as in a patient that has received neoadjuvant chemoradiation, there may be utility to frozen section to see if wider resection should be performed. Since the uncinate margin consists of a large surface area, it is best to perform the frozen section at the most suspicious area marked by the surgeon.

Figure 13-1, The longer bowel segment is the distal aspect of the specimen. The circled area is the pancreatic resection margin (small circle) with the pancreatic duct in the center (arrow) . The cauterized surface (large circle) is the uncinate margin.

Figure 13-2, Pancreatic and bile duct resection margins can be identified by probing the ampulla.

Difficulties/Caveats in Identification of the Margins

The pancreatic resection margin may be difficult to identify in severe chronic pancreatitis when the normal lobularity of the pancreas is lost due to marked atrophy and fibrosis. Uncinate margin can be confused as the pancreatic resection margin when a small portion of the pancreatic head is removed. It can be difficult to identify the bile duct resection margin when a short segment of bile duct is removed, the duct is retracted, or when it is stapled or tied with a purse-string suture. Occasionally, a dilated pancreatic duct in an atrophic pancreas can resemble the bile duct resection margin. In these circumstances, it is imperative that the specimen is oriented with the surgeon’s assistance.

Distal Pancreatectomy

The distal pancreatectomy specimen will generally be provided as an isolated portion of pancreas either with or without an attached spleen. Variable amounts of omentum or nodal tissue may be adherent. Commonly proximal margin is requested for frozen section. If a spleen-preserving approach has been utilized, there may be a separate distal staple line or suture line where vascular structures along the tip of the pancreas are divided. In these cases, the distal pancreas is an important margin, and analysis may be requested intraoperatively. Critical to this process (unless the spleen is attached) is that suture or some other marker is placed to orient distal and proximal aspect of the specimen. Attached tissue such as stomach or colon should be indicated also with suture, but intraoperative assessment is rarely required.

Central Pancreatectomy

Central segmental pancreatic resection is a relatively uncommon procedure which involves removal of the mid-pancreas with reattachment of the distal pancreatic remnant back to stomach or intestine. As such, all segmental resection specimens must be accurately oriented by the surgical team (preferably with suture) to indicate proximal and distal margins and anterior or posterior aspects.

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