THE PANCREAS.
The anatomical features of the pancreas which have most interest for the surgeon are the facts that its head is in contact with the duodenum, and lies usually so closely against the second portion of the former as to surround from one-fourth to one-third of its lumen. Becoming adherent at this point it may then produce obstruction high up in the intestine. In rare instances it may even completely surround the duodenum, and thus may, when swollen, cause tight constriction of the latter. Should this condition be met with a gastro-enterostomy would be the proper measure for relief. These intimate relationships account for the spread of disease from the pancreas to the intestine, rarely in the reverse direction. The pancreas lies also in contact with the stomach along its anterior peritoneum-covered surface, and malignant disease travels easily from one to the other. Ulcers of the stomach, favorably situated, may also be followed by adhesion and inflammatory infiltration of the pancreas, by which the viscera are cemented together, the same result following duodenal ulcer, as well as serious disease about the biliary passages. Thus under a variety of circumstances the operator may find these parts so cemented as to be separated only with the greatest difficulty, or perhaps not at all, without causing laceration or rupture of one or more of them, with escape of contents which are often septic. Therefore when there is reason to fear this accident it will usually be safer to simply make a gastro-enterostomy. (See [Plate LVI].)
The relations of the biliary ducts to the pancreas are most important, the association of the common duct with that of Wirsung having the greatest bearing upon a variety of conditions, which are nearly all essentially surgical. The former, descending along the head of the pancreas, comes in contact with the duct of the latter, and passes alongside of it for a short distance before entering the intestinal wall. In about two-thirds of individuals it is completely enclosed by the pancreas. In the other third it lies in a deep groove upon it. Resting here, as it were like Siamese twins, it will be easily seen how disturbance in one duct or its source may be reflected to the other. When the common duct lies in a groove it is less likely to be seriously compressed by pancreatic engorgement than when actually embedded in pancreatic tissue. The degree of resulting jaundice may thus be dependent upon anatomical conditions not determinable before exploration. Such pressure doubtless accounts for many cases of so-called catarrhal jaundice. When the condition becomes constant, or nearly so, a chronic interstitial pancreatitis may be assumed, which really warrants an operation—i. e., cholecystostomy with drainage. When a gallstone is passing through the common duct, especially when lingering or impacted, it may have in turn reversed this condition, and, by obstructing the pancreatic duct, set up as a consequence pancreatic stagnation and consequent digestive disturbance, and such other internal conditions as invite infection from the duodenal cavity, with a more or less lively pancreatitis, perhaps even of fulminating type, by which life may be jeopardized.
The pancreas, however, being usually provided with two ducts, the second (that of Santorini) is often represented as an additional safeguard, since it usually has a separate opening into the duodenum below the ampulla. Opie carefully studied 100 cadavers and found that in more than 50 of them the accessory duct could be of no use or relief, and that in only 10 instances did two independent ducts enter the intestine, while in the other 90 they were united, and in 21 of the latter the accessory duct had become obliterated. Moreover, in only 6 of the 100 instances was it larger than the duct of Wirsung. This will show, then, how little reliance may be placed upon the duct of Santorini. Moreover, no matter which duct is opened, or whether both are, so long as pancreatic fluid can escape there is an open channel for infection, and when it cannot escape it may be seen that infection has already occurred and is manifesting its pressure consequences. Chemosis of mucous membrane may be the first mechanical result of such infection, but this is sure to be followed by interstitial sclerosing and compressing effects.
The normal duct opening in the duodenum is also a matter of surgical interest. The ampulla of Vater, within the second portion of the duodenum, is usually described as a conical protrusion or papilla, having an average length of 4 Mm., with an opening 2.5 Mm. in diameter, this being the narrowest portion of the common duct, but from this arrangement there are many variations. The ducts may join at some distance from the intestine, or they may open independently into a depression or into a protrusion, and the ampulla be thus totally wanting, all of which has the greatest possible bearing upon what may happen during the passage of gallstones, for instance, or by infection and according to its direction; and may account for the difficulty met in certain cases, as when, for example, it becomes necessary to incise the duodenum and open the ampulla for the removal of a pancreatic or biliary calculus. It will emphasize, too, the necessity for always exploring the common duct by opening the biliary passage and thus making sure of its patency.
ANOMALIES OF THE PANCREAS.
Congenital anomalies include not only those of the ducts above mentioned, but the presence of accessory masses, like the accessory thyroids, which may occasionally lead to confusion and perplexity. Furthermore, accessory nodules of pancreatic tissue may be found alongside the ducts, or even in the walls of the stomach and intestine, where they are probably present more often than is generally appreciated, and are to be explained by the embryology of the parts, since the pancreas is known to take origin from a cluster of cells in the wall of the upper end of the developing intestinal canal. They have been seen also along the line of a persistent vitelline duct. Such small accessories, when present, usually empty by minute independent ducts into the intestine. On the same embryonal grounds are to be explained other anomalies occasionally met, such as separation into detached portions. The existence of accessory pancreatic glands is also held to account for the absence of glycosuria in certain cases where the principal portion of the pancreas is itself extensively diseased.
GLYCOSURIA.
Glycosuria is so associated with the popular conception of pancreatic disease that it seems imperative to state what importance should be attached to it. It is now clearly established that the so-called “islands of Langerhans” have to do with the elaboration of a certain glycolytic ferment, and that the failure in its supply to the blood (it being regarded as an internal secretion) is followed by the appearance of sugar in the urine. These islands are not connected with the ducts, at least not in the vertebrates, and usually escape pressure effects in chronic interstitial pancreatitis of the interacinous as well as of the interlobular form. This explains the accompaniment of diabetes in some instances of pancreatic disease and its absence in others. Again, if only part of the pancreas be affected, as in cancer, the remaining healthy portion may still afford a sufficient amount of this ferment to supply the body needs.
The uncertain symptomatology of the slower forms of pancreatic disease is to be accounted for by the fact that, with the exception of its glycogenic function just mentioned, all its other functions may be vicariously assumed by other organs of the body. Thus as a compound racemose gland it furnishes—