Chapter IV: Diseases of the Portal Vein

Thrombosis and Embolism of the Portal Vein; Stenosis; Pylephlebitis.

DEFINITION.--By the terms at the head of this section are meant the various pathological processes which induce coagulation of the blood in some part of the portal system. As the portal vein is made up of many branches coming from the various organs of the abdominal cavity except the kidneys, and as it empties, so to speak, into the liver, it is obvious that various and complex derangements will ensue on the formation of thrombi.

CAUSES.--Thrombosis of the portal vein occurs under three general conditions: the blood is in a readily coagulable state; the action of the heart is weak and the blood-current sluggish; the circulation through the vein is impeded by external pressure. The coagulability of the blood is increased in diseases characterized by an excess of its fibrin-producing constituents, of which cirrhosis of the liver may be mentioned as one having this peculiarity. In chronic maladies of a depressing kind there may be simply a weak action of the heart, or the muscular tissue of the organ may be affected by a fatty and atrophic degeneration. The external pressure by which the blood-current through the vein is impeded may be caused by the newly-formed connective tissue of Glisson's capsule, by enlarged lymphatics in the hilus of the liver, or by tumors of various kinds. The first named of these causes of compression--atrophic cirrhosis--is most frequently acting. Very rarely, organized exudations of the peritoneum may be so situated as to compress the portal vein. This result can only happen when the hepatic portion of the peritoneum is involved.

Pylephlebitis exists in two forms: the adhesive and suppurative. The former results in changes not unlike those of simple thrombosis. The blood coagulates in the affected part of the vessel, the clot is organized, and the vessel ultimately forms a solid rounded cord which is permanently occluded. The suppurative variety is so different in its origin and in its results that it requires separate treatment, and I therefore postpone the consideration of it to the next section.

{1096} SYMPTOMS OF THROMBOSIS AND ADHESIVE PYLEPHLEBITIS.--It is a remarkable fact that the biliary function of the liver is not necessarily affected in cases of occlusion of the portal vein. It is true, in advanced cases of cirrhosis, when the interlobular veins are obliterated by the pressure of the contracting newly-formed connective tissue, the functions of the liver are arrested in so far as the damage thus caused extends. Notwithstanding the blocking of the portal, sufficient blood reaches the hepatic cells by the anastomosis between the hepatic artery and the interlobular veins--an anatomical connection demonstrated by Cohnheim and Litten.[209] So long as this anastomosis continues bile will be formed, although the portal vein is occluded.

[Footnote 209: _Virchow's Archiv_, Band lxvii. p. 153, "Ueber Circulationsstörungen in der Leber."]

The most significant symptoms of thrombosis of the portal vein are the sudden formation of ascites, which quickly assumes a very high grade, and equally sudden passive congestion of the gastro-intestinal mucous membrane, enlargement of the spleen, and distension of the superficial veins of the abdominal parietes. When these symptoms succeed to cirrhosis of the liver, or appear after the formation of a tumor in the hepatic region, or come on in the course of phthisis or chronic inflammation of the hepatic peritoneum, the existence of thrombus of the portal vein may be reasonably suspected.

Coincidently with the occlusion of the portal vein the gastro-intestinal mucous membrane becomes the seat of a catarrhal process, and to the fluid thus produced is added a much more abundant transudation from the distended capillaries. Nausea, vomiting, and diarrhoea result, the rejected matters being serous, watery, and in many cases tinged with blood. Now and then quite a severe hemorrhage takes place, and the blood is brought up by vomiting (hæmatemesis) or is discharged by stool. Hemorrhoids form, and, in large masses protruding, much pain is experienced, and free bleeding may result from rupture of a distended vein.

The veins of the abdominal parietes, which in the normal state are invisible or at least not prominent, and which form anastomoses with the portal, when the obstruction occurs dilate, sometimes to a remarkable extent. The most important anastomosis is that between the femoral and saphena and internal mammary and epigastric veins. When the hepatic branches of the portal are closed, but the trunk remains pervious, the parumbilical vein enlarges greatly, and, communicating with the superficial veins of the anterior part of the abdominal walls, forms a radiating network of tortuous veins to which is given the striking title of caput Medusæ.

The most significant symptom of portal thrombosis is a quickly-forming ascites. It is true, ascites is a common symptom in advanced cirrhosis, but the rapid accumulation of fluid and the prompt filling of the cavity after tapping distinguish that which arises from portal thrombosis from all others. Besides its excessive extent, the ascites presents the usual symptoms.

Due to the same cause as the enlargement of the superficial veins, the hemorrhages, the ascites, etc., there occurs considerable hypertrophy of the spleen in many of the cases. It sometimes happens that the new compensatory circulation and the hemorrhages from some part in the {1097} usual route of the portal so dispose of the blood that the spleen does not enlarge sufficiently to be readily made out.

COURSE AND TERMINATION.--It is obvious that a condition such as that induced by thrombosis of the portal must be comparatively quickly fatal; but the cases vary in duration as the compensatory circulation is more or less complete. Whilst the majority of cases terminate within two weeks, instances of several months' duration are not unknown, but a fatal termination, sooner or later, is inevitable in all cases.

Coming on in the course of some chronic affection of the liver or some obstructing cause exterior to the organ, there soon follow ascites, nausea and vomiting, hæmatemesis, bloody stools of a liquid character, enlargement of the spleen, distension of the abdominal veins, and the distressing symptoms produced by an excessive accumulation of fluid in the peritoneal cavity.

DIAGNOSIS.--As there is no symptom of thrombosis of the portal which may not be caused by advanced cirrhosis, the diagnosis rests on the rapid production of the attendant phenomena and their conjoint appearance.

TREATMENT.--A symptomatic treatment is alone possible. The highly irritable and congested intestinal mucous membrane precludes the employment of hydragogue cathartics. Salines which cause outward diffusion from the vessels are the only cathartics which can be used with propriety. Action of the kidneys and of the skin must be maintained. To this end the resin of copaiba in pilular form and pilocarpine subcutaneously may be used. If the strength of the patient will permit, leeches around the anus can be applied, and much relief may be expected from free bleeding. It is probable that opening a swollen hemorrhoid would give the same kind of relief as that caused by a free hemorrhage. In any case the benefit derived from treatment must be merely palliative and temporary.

Suppurative Pylephlebitis.

PATHOGENY.--Primary pylephlebitis rarely if ever occurs. On the other hand, the secondary form is by no means uncommon; it succeeds to ulcerative or purulent inflammation at some point in the circuit of origin of the portal radicles. The most frequently-occurring cause is ulceration and suppuration of some part of the intestinal tube, and hence the most common result is multiple abscess of the liver. Pylephlebitis has often resulted from typhlitis; from ulcers of the large intestine, as in dysentery; from such traumatic injuries as tying hemorrhoids; from proctitis; from ulcers of the stomach and similar morbid processes elsewhere within the range of origin of the portal system. The pathogeny is clear. The inflammatory or ulcerative action extends to and involves the walls of the veins, or some morbid material diffuses through the vein walls. In either case coagulation of the blood in the vessel ensues, and the clot undergoes a series of changes resulting in the formation of emboli, which, carried into the main current, are subsequently lodged in the hepatic capillaries.

There are three steps in the morbid process: the changes in the vein wall; the production and transformation of the thrombus; and the formation of secondary suppurating foci in the liver.

{1098} The appearance of the tunics of the inflamed vessels varies with the stage at which they are examined. At first the walls of the vessels are reddish from congestion, succulent, and swollen, infiltrated by leucocytes and inflammatory exudation and the cellular elements undergoing proliferation. The intima especially is much altered in its appearance and structure, becoming thick, opaque, grayish or yellowish in color, and having adherent to it a thrombus passing through its characteristic changes. Ulceration of the intima then occurs, and the purulent elements, with shreds of tissue, mingle with the degenerating blood-clot, and ultimately there remains a purulent dépôt lined with sloughing, even gangrenous, contents. Emboli detached from such decomposing thrombus are arrested in the vessels of the liver, and there set up a suppurating phlebitis, ending in an abscess formation, or a quantity of pus from the original point of ulcerative phlebitis passes into the portal vein, and is generally distributed through the hepatic branches, here and there foci of suppuration being established by the deposit of decomposing emboli. There may be numerous small abscesses irregularly distributed through the liver, or there may be one or two larger collections of pus. Very often the vessel whose occlusion by a suppurating embolus has caused the mischief is destroyed, and hence no communication with the abscess-cavity can then be traced. These abscesses are not limited by a line of inflammatory demarcation or by a limiting membrane, but the hepatic tissue adjacent is congested and infiltrated with pus.

Ulceration, abscesses, or purulent inflammation occurring at any point within the area of origin of the radicles of the portal vein may induce pylephlebitis and consequent hepatic abscess. There are two points at which, suppuration established, secondary pylephlebitis is most apt to occur: the cæcum; the rectum. As respects the former, the symptoms of typhlitis precede the hepatic disturbance; and as respects the latter, usually dysentery, or rather proctitis, is the initial disease. In both sources of the hepatic trouble the inferior hemorrhoidal veins are chiefly concerned--a fact explicable by reference to the sluggishness of the circulation and the distended condition of these veins, whence it is that thrombus is very readily induced. Numerous instances of pylephlebitis following suppurative lesions of the cæcum have been reported. One of the most recent, and at the same time typical, examples of such conditions is that published by Bradbury[210] of Cambridge, England. The initial lesion was "an ulcer the size of a split pea" situated near "the junction of the vermiform appendix and cæcum." "The hemorrhoidal veins and the inferior mesenteric above were filled with breaking-down clot and pus," and "the liver contained many abscesses of various sizes, the largest about the size of a lemon, which had burst through the diaphragm." As is so often the case, the ulcer of the cæcum produced no recognizable disturbance, and important symptoms were manifest only when the emboli lodged in the liver set up suppuration, when there occurred the usual signs of hepatic abscess. In the West and South hepatic abscess due to pylephlebitis, induced by proctitis, with ulceration of the rectum, is a common incident. Various examples of this kind have fallen under my own observation. The relatively greater frequency of this form of pylephlebitis is due to the fact above {1099} stated, that the inferior hemorrhoidal veins are voluminous, have a sluggish current, and are liable to over-distension by pressure of feces and by external abdominal bands and clothing. Cases of a corresponding character arise from suppuration and ulceration elsewhere within the portal circuit. Thus, Bristowe[211] reports a case in which pylephlebitis resulted from an ulcer of the stomach, the neighboring veins becoming implicated and the usual results following.

[Footnote 210: _The Medical Times and Gazette_, Sept. 27, 1884, p. 450, "Proceedings of the Cambridge Medical Society."]

[Footnote 211: _Transactions of the Pathological Society of London_, vol. ix. p. 278.]

When inflammation has begun in a radicle of the portal vein, it may proceed to the liver by contiguity of tissue, the whole intervening portion of the vessel being affected. Probably more frequently the intra-hepatic portion of the portal is inflamed by emboli, and the adjacent hepatic tissue then undergoes suppuration, as has been already set forth.

SYMPTOMS.--There being two points of disease--the primary lesion of the peripheral vessel and the secondary results in the hepatic portion of the portal--the symptomatology must have a corresponding expression. The stomach, the cæcum, or the rectum, or some other organ or tissue, being occupied by a morbid process, there will be a characteristic complex of symptoms. Taking up the most usual primary disturbance, a typhlitis or an ulcer of the cæcum, there will be pain, tenderness, and possibly fever, occupying in point of time the period proper to such a malady and an amount of disturbance of function determined by the extent of the lesion. The symptoms caused by a single small ulcer of the cæcum, as in the example narrated by Bradbury, may present no characteristic features and may have little apparent importance, and yet the lesion is productive of very grave consequences.

When from any of the causes mentioned above a thrombus forms in a vein of the portal system in consequence of the extension of the inflammation about it, the case, what importance soever it previously had, now takes on new characters. The onset of the inflammation of the vein walls and the puriform degeneration of the thrombus is announced by a chill--a severe rigor, or chilly sensations at least. At the time of the chill, and sometimes before it, pain is felt, significant of the lesion in the vein. When proctitis or typhlitis precedes the pylephlebitis, pain appropriate to the malady is a significant symptom; but the pain which comes on with the beginning of the inflammation in the liver is a new sign. The most frequent sites of the pain are the right hypochondrium and the epigastrium, but it may also be felt in the left hypochondrium or in either iliac fossa. Unless there be diffuse peritonitis the pain is accompanied by a strictly-localized tenderness to pressure. The situation of the pain may afford an indication of the vein attacked, and when there are two points at which pain is experienced, one may originate at the first situation of the morbid action; the other will be due to pylephlebitis.

The fever succeeding the chill is decided, and in some cases may attain to extraordinary height--a manifestation indicative of the pyæmic character of the affection. The fever intermits or remits, with a more or less profuse perspiration. The febrile phenomena are similar in their objective expression to malarial fever, but there is an important difference in respect to the periods of recurrence of the chills. The paroxysms are very irregular as to time: there may a daily seizure at different hours, or there may be several chills on the same day. In other words, the {1100} paroxysms have the pyæmic characteristics rather than the malarial. After a time the intermittent phenomenon ceases, and there occurs a remission merely, the exacerbation being preceded by chilliness and succeeded by sweating. The sweats are characteristically profuse and exhausting. During the sweating the temperature begins to decline, and reaches its lowest point just before the chilly sensations during the early morning announce the onset of the daily exacerbation of the afternoon and evening. The thermal line exhibits many irregularities until the febrile movement assumes the remittent type, when there occur the morning remission and nocturnal exacerbation. The maxima may be from 103° F. to 105°, even to 106°.

When the pain and chill come on, disturbances of the digestive organs ensue. When a large vein of the portal system is occluded, the remaining veins must be over-distended, and congestion of a part or of all of the digestive tract will be a result. An acute gastric catarrh is set up. The appetite is lost, the stomach becomes irritable, and vomiting is a usual incident. Sometimes the disgust for food is extreme, and the nausea and vomiting are almost incessant. The vomited matters consist of a watery mucus mixed with thin bile after a time, and now and then of a bloody mucus. Thrombosis of a stomach vein may occur, to be followed by an acute ulcer, and from this considerable hemorrhage may proceed, when the vomit will consist of blood. Such an accident, happening to the mucous membrane of the intestine, will be indicated by bloody stools if the ulceration is low down, or by brownish, blackish, or chocolate-colored stools if higher up in the small bowel.

The tongue has usually a characteristic coating in these cases. Large patches of a rather heavy and darkish fur form, and, cast off from time to time, leave a glazed and somewhat raw surface. Sometimes there is a profuse salivary flow, but more frequently the mouth is dry. The lips are fissured or contain patches of herpes, and the buccal cavity may be more or less completely lined by patches of aphthæ.

Diarrhoea is a usual symptom, the stools being dark when mixed with blood, or grayish and pasty or clay-colored when there is jaundice.

Three-fourths of the cases of pylephlebitis are free from jaundice. This symptom may occur at the onset when the common duct is obstructed by a calculus, but in other cases it appears when the formation of pus in the liver exerts sufficient compression of the hepatic ducts to prevent the passage of the bile.

When jaundice occurs, it is accompanied by the usual symptoms. The urine, previously unchanged, is now colored by bile-pigment, and the alterations in the renal structure and function belonging to jaundice also take place.

It sometimes happens that the obstruction of the portal vein is sufficient to cause enlargement of the superficial veins of the abdomen, but the duration of the disease is usually too brief to permit much deviation from the normal, except rarely. In the cases characterized by the occurrence of diffuse peritonitis the abdomen will present a swollen and tense appearance, and there will be acute tenderness to pressure. The area of hepatic and splenic dulness is not increased from the outset, but is evident, as respects the spleen, soon after the obstruction at the liver, and as respects the liver when the formation of abscesses occurs.

{1101} COURSE, DURATION, AND TERMINATION.--The course of pylephlebitis is compounded of the disturbance at the original point of disease, and of the secondary inflammation at the several points in the liver where emboli set up purulent inflammation. There are, therefore, two distinct symptom-groups, and a short intervening period in which the first is being merged into the second. The duration is variable, but the extreme limits are not remote from each other, the condition of pylephlebitis terminating in from two weeks to three months, the shorter being the more usual. The termination is death, doubtless invariably; for, as in true pyæmia arising from other causes, the septic changes in the blood are such as to preclude the possibility of a return to the normal condition.

DIAGNOSIS.--The main point in the diagnosis consists in the occurrence of an evident local inflammation, followed by the signs of suppuration in the hepatic region coming on subsequent to ulceration and suppuration at some point in the peripheral expansion of the portal system. Thus, when a proctitis with ulceration of the rectum has been in existence for some time, there occur pain and tenderness in the hepatic region, accompanied by an irregularly intermittent fever and by profuse sweating, it can be assumed with considerable certainty that emboli have been deposited in some one or more of the terminal branches of the portal. The evidences of hepatic trouble--swelling of the organ, jaundice, etc.--and of portal obstruction, which then supervene, indicate with some precision the nature of the case.

TREATMENT.--Although pylephlebitis wears a most unfavorable aspect, the possibility of a favorable result should always be entertained by the therapeutist.

As absorption of medicaments must be slow--indeed, uncertain--by the gastro-intestinal mucous membrane when there is portal occlusion, it is well to attempt treatment by the skin and subcutaneous connective tissue. Gastro-intestinal disturbance--nausea, vomiting, and diarrhoea--should be treated by a combination of bismuth, creasote, and glycerin--remedies acting locally chiefly. Ammonia--the carbonate and solution of the acetate--is indicated, and should be given for the purpose of dissolving thrombi and emboli. Corrosive sublimate, carbolic acid, and quinine can be administered by the subcutaneous areolar tissue. Quinine may also be introduced by friction with lard, and in considerable quantity.