Preliminary Considerations.—The morning sputum or the whole amount for twenty-four hours should be collected for examination. In beginning tuberculosis tubercle bacilli can often be found in that first coughed up in the morning when they cannot be detected at any other time of day. Sometimes, in these early cases, there are only a few mucopurulent flakes which contain the bacilli, or only a small purulent mass every few days, and these may easily be overlooked.
As a receptacle for the sputum a clean wide-mouthed bottle with tightly fitting cork may be used. The patient must be particularly cautioned against smearing any of it upon the outside of the bottle. This is probably the chief source of danger to those who examine sputum.
When the examination is begun, the sputum should be spread out in a thin layer in a Petri dish, or, better, between two small plates of glass, like photographic plates. It may then be examined with the naked eye—best over a black background—or with a low power of the microscope. The portions most suitable for further examination may thus be easily selected.
After an examination the sputum must be destroyed by heat or chemicals, and everything which has come in contact with it must be sterilized. The utmost care must be taken not to allow any of it to dry and become disseminated through the air.
Examination of the sputum is most convenientlyconsidered under three heads: I. Physical examination. II. Microscopic examination. III. Characteristics of the sputum in various diseases. Chemic examination yields nothing of clinical importance.
I. PHYSICAL EXAMINATION
I. PHYSICAL EXAMINATION
1.Quantity.—The quantity expectorated in twenty-four hours varies greatly: it may be so slight as to be overlooked entirely in beginning tuberculosis; and it may be as much as 1000 c.c. in bronchiectasis.
2.Color.—Since the sputum ordinarily consists of varying proportions of mucus and pus, it may vary from a colorless, translucent mucus to an opaque, whitish or yellow, purulent mass. A yellowish-green is frequently seen in advanced phthisis.
A red color usually indicates the presence of blood. Bright red blood, most commonly in streaks, is strongly suggestive of phthisis. It may be noted very early in the disease. A rusty red sputum is the rule in croupous pneumonia, and was at one time considered pathognomonic of the disease. "Prune-juice" sputum is said to be characteristic of "drunkard's pneumonia." A brown color, due to altered blood-pigment, follows hemorrhages from the lungs.
Gray or black sputum is observed among those who work much in coal-dust, and is occasionally seen in smokers who "inhale."
3.Consistence.—According to their consistence, sputa are usually classified as serous, mucoid, purulent, seropurulent, mucopurulent, etc., which names explain themselves. As a rule, the more mucus and the less pus and serum a sputum contains, the more tenacious it is.
The rusty sputum of croupous pneumonia is extremely tenacious, so that the vessel in which it is contained may be inverted without spilling it. The same is true of the almost purely mucoid sputum ("sputum crudum") of beginning acute bronchitis, and of that which follows an attack of asthma. A purely serous sputum is fairly characteristic of edema of the lungs.
II. MICROSCOPIC EXAMINATION
II. MICROSCOPIC EXAMINATION
The portions most likely to contain structures of interest should be very carefully selected, as already described.The few minutes spent in this preliminary examination will sometimes save hours of work later.Opaque, white or yellow particles are frequently bits of food, but may be cheesy masses from the tonsils; small cheesy nodules, derived from tuberculous cavities and containing many tubercle bacilli and elastic fibers; Curschmann's spirals, or small fibrinous casts, coiled into little balls; or shreds of mucus with great numbers of entangled pus-corpuscles.
The sputum should always be examined, both unstained and stained.
A. UNSTAINEDSPUTUM
A. UNSTAINEDSPUTUM
The particle selected for examination should be transferred to a clean slide, covered with a clean cover-glass, and examined with the two-thirds objective, followed by the one-sixth. It is convenient to handle the bits of sputum with a wooden toothpick, which may be burned when done with. The platinum wire used in bacteriologic work is less satisfactory because not usually stiff enough.
The more important structures to be seen in unstained sputum are: elastic fibers, Curschmann's spirals,Charcot-Leyden crystals, fibrinous casts, the ray fungus of actinomycosis, and molds. Pigmented cells, especially the so-called "heart-failure cells" (p. 43), are also best studied without staining (Plate II, Fig. 1).
1.Elastic Fibers.—These are the elastic fibers of the pulmonary substance (Fig. 4). When found in the sputum, they always indicate destructive disease of the lungs, provided they do not come from the food, which is a not infrequent source. They are found most commonly in phthisis: rarely in other diseases. Advanced cases of tuberculosis often show great numbers, and, rarely, they may be found in early tuberculosis when the bacilli cannot be detected. In gangrene of the lung, where they would be expected, they are frequently not found, owing, probably, to the presence of a ferment which destroys them.
The fibers should be searched for with a two-thirds objective, although a one-sixth is needed to identify them with certainty. Under the one-sixth they appear as slender, highly refractive fibers with double contour and, often, curled or split ends. Frequently they are found in alveolar arrangement, retaining the original outline of the alveoli of the lung (Fig. 4,b).Leptothrix buccalis, which is a normal inhabitant of the mouth, may easily be mistaken for elastic tissue. It can be distinguished by running a little iodin solution under the cover-glass (seep. 37).
To find elastic fibers when not abundant boil the sputum with a 10 per cent. solution of caustic soda until it becomes fluid, add several times its bulk of water, and centrifugalize, or allow to stand for twenty-four hours in a conical glass. Examine the sediment microscopically.The fibers will be pale and swollen. Too long boiling will destroy them entirely.
2.Curschmann's Spirals.—These peculiar structures are found most frequently in bronchial asthma, of which they are fairly characteristic. They may occasionally be met with in chronic bronchitis and other conditions. Their nature has not been definitely determined.
Macroscopically, they are whitish or yellow, twisted threads, frequently coiled into little balls (Fig. 5, I.). Their length is rarely over half an inch, though it sometimes exceeds two inches. Under a two-thirds objective they appear as mucous threads having a clear central fiber, about which are wound many fine fibrils (Fig. 5, II. and III.). Leukocytes are usually present within them, and sometimes Charcot-Leyden crystals. The central fiber is not always present.
3.Charcot-Leyden Crystals.—Of the crystals which may be found in the sputum, the most interesting are the Charcot-Leyden crystals. They are rarely found except in cases of bronchial asthma, and were at one time thought to be the cause of the disease. They frequently adhere to Curschmann spirals. Their exact nature is unknown.
They are colorless, pointed, often needle-like, octahedral crystals (Fig. 6). Their size varies greatly, the average length being about three or four times the diameter of a red blood-corpuscle.
Other crystals—hematoidin, cholesterin, and, most frequently, fat needles—are common in sputum which has remained in the body for a considerable time.
4.Fibrinous Casts.—These are fibrinous molds of the smaller bronchi. Their size varies with that of the bronchi in which they are formed. They may, rarely,be three or more inches in length. When large, they can be recognized with the naked eye by floating them out in water; when small, a low power of the microscope must be used. They are easily recognized from their branching, tree-like structure (Fig. 7).
Fibrinous casts are characteristic of fibrinous bronchitis, but may also be found in diphtheria of the smaller bronchi. Very small casts are often seen in croupous pneumonia.
5.Actinomyces Bovis(Ray-fungus).—In the sputum of pulmonary actinomycosis and in the pus from actinomycotic lesions elsewhere small, yellowish, "sulphur" granules can be detected with the unaided eye. The fungus can be seen by crushing one of these granules between slide and cover, and examining with a low power. It consists of a network of threads having a more or less radial arrangement, those at the periphery presenting club-shaped extremities (Fig. 8). This organism, also calledStreptothrix actinomyces, apparently stands midway between the bacteria and the molds. It stains by Gram's method.
Actinomycosis of the lung is rare. The clinical picture is that of tuberculosis.
6.Molds.—The hyphæ and spores of various molds are occasionally met with in the sputum. They are usually the result of contamination, and have little significance. The hyphæ are rods, usually jointed or branched (Fig. 58), and often arranged in a meshwork (mycelium); the spores are highly refractive spheres. Both stain well with the ordinary stains.
B. STAINEDSPUTUM
B. STAINEDSPUTUM
Structures which are best seen in stained sputum are bacteria and cells.
1.Bacteria.—Only those of some clinical importance will be considered. They are: tubercle bacilli; staphylococci and streptococci; pneumococci; bacilli of Friedländer; and influenza bacilli.
(1)Tubercle Bacillus.—The presence of the tubercle bacillus may be taken as positive evidence of the existence of tuberculosis somewhere along the respiratory tract, most likely in the lung. In laryngeal tuberculosis they are not easily found in the sputum, but can nearly always be detected in swabs made directly from the larynx.
Recognition of the tubercle bacillus depends upon the fact that it stains with difficulty; but that when once stained, it retains the stain tenaciously, even when treated with a mineral acid, which quickly removes the stain from other bacteria. The most convenient method for general purposes is here given in detail:
Gabbet's Method.—(1) Spread suspicious particles thinly and evenly upon a slide or a cover-glass held in the grasp ofcover-glass forceps. Cover-glasses are easier to handle while staining. Do not grasp a cover too near the edge or the stain will not stay on it well. Tenacious sputum will spread better if gently warmed while spreading.
(2) Dry the film in the air.
(3) Fix in a flame;i.e., pass the cover-glass rather slowly, with film side up, three times (a slide about twelve times) through the flame of a Bunsen burner or alcohol lamp. Take care not to scorch. Should the film be washed off during future manipulations, fixation has been insufficient.
(4) Apply as much carbol-fuchsin as will stay on, and hold over a flame so that it will steam for three minutes or longer, replacing the stain as it evaporates. If the bacilli are well stained in this step, there will be little danger of decolorizing them later.
(5) Wash the film in water.
(6) Apply Gabbet's stain to the under side of the cover-glass to remove excess of carbol-fuchsin, and then to the film side. Allow this to act for one-fourth to one-half minute.
(7) Wash in water.
(8) If, now, the thinner portions of the film are blue, proceed to the next step; if they are still red, repeat steps (6) and (7) until the red has disappeared. Too long application of Gabbet's stain will decolorize the tubercle bacilli.
(9) Place the preparation between layers of filter-paper and dry by rubbing with the fingers, as one would in blotting ink.
(10) Put a drop of Canada balsam upon a clean slide, place the cover-glass film side down upon it, and examine with a one-twelfth objective. Cedar oil or water may be used in place of balsam for temporary preparations. Smears on slides may be examined directly with an oil-immersion lens, no cover being necessary.
Carbol-fuchsinis prepared by mixing 10 c.c. of a saturated alcoholic solution of fuchsin with 90 c.c. of 5 per cent. aqueous solution of phenol.
Gabbet's stainconsists of methylene-blue, 2 gm.; 25 per cent. sulphuric acid, 100 c.c.
Both stains can be purchased ready prepared.
In films stained by Gabbet's method tubercle bacilli, if present, will be seen as slender red rods upon a blue background of mucus and cells (Plate II, Fig. 2). They average 3 to 4 µ in length—about one-half the diameter of a red blood-corpuscle. Beginners must be warned against mistaking the edges of cells, or particles which have retained the red stain, for bacilli. The appearance of the bacilli is almost always typical, and if there seems room for doubt, the structure in question is probably not a tubercle bacillus. They may lie singly or in groups. They are very frequently bent and often have a beaded appearance. It is possible that the larger, beaded bacilli indicate a less active tuberculous process than do the smaller, uniformly stained ones. Sometimes they are present in great numbers—thousands in a field of the one-twelfth objective. Sometimes several cover-glasses must be examined to find a single bacillus. At times they are so few that none are found in stained smears, and special methods are required to detect them. The number may bear some relation to the severity of the disease, but this relation is by no means constant. The mucoid sputum from an incipient case sometimes contains great numbers, while sputum from large tuberculous cavities at times contains very few. Failure to find them is not conclusive, though their absence is much more significant when the sputum is purulent than when it is mucoid.
When they are not found in suspicious cases, one of the following methods should be tried:
(1) Take a few drams of the sputum in a test-tube, add hotwater, and heat until the albumin is coagulated. Let settle for twenty-four hours, or centrifugalize at once, and examine the sediment for tubercle bacilli.
(2) Boil the sputum with just sufficient weak caustic soda solution to render it fluid; neutralize with acetic acid; add several times its volume of water; centrifugalize; and stain the sediment, adding a little of the untreated sputum to make the smear adhere to the cover-glass.
(3) Inoculate guinea-pigs.
There are a number of bacilli, calledacid-fast bacilli, which stain in the same way as the tubercle bacillus. Of these, the smegma bacillus is the only one likely ever to cause confusion. It, or a similar bacillus, is sometimes found in the sputum of gangrene of the lung. It occurs normally about the glans penis and the clitoris, and is often present in the urine. The method of distinguishing it from the tubercle bacillus is given later (p. 127).
Other bacteria than the acid-fast group are stained blue by Gabbet's method. Those most commonly found are staphylococci, streptococci, and pneumococci. Their presence in company with the tubercle bacillus constitutesmixed infection, which is much more serious than single infection by the tubercle bacillus. It is to be remembered, however, that a few of these bacteria may reach the sputum from the upper air-passages. Clinically, mixed infection is evidenced by fever.
(2)Staphylococcus and Streptococcus(p. 262).—One or both of these organisms is commonly present in company with the tubercle bacillus in the sputum of advanced phthisis (Plate II, Fig. 2). They are often found in bronchitis, catarrhal pneumonia, and many other conditions.
(3)Pneumococcus(Diplococcus of Fränkel).—The pneumococcus is the causative agent in nearly all casesof croupous pneumonia, and is commonly found in large numbers in the rusty sputum of this disease. It is sometimes met with in the sputum of catarrhal pneumonia, bronchitis, and tuberculosis. It has been found in the saliva in health. Pneumococci are about the size of streptococci. They are ovoid in shape, and lie in pairs, end to end, often forming short chains. Each is surrounded by a gelatinous capsule, which is its distinctive feature (Fig. 9). Diplococci without capsules are common in the sputum, but have no special significance.
Recognition of the pneumococcus depends upon its morphology, the fact that it is Gram-staining, and the presence of a capsule. Numerous methods for staining capsules have been devised, but few are satisfactory. Buerger's method is excellent. It is especially useful with cultures upon serum media, but is applicable also to the sputum. Smith's method usually gives good results, as does also the more simple method of Hiss (p. 263). The sputum should be fresh—not more than three or four hours' old.
Buerger's Method for Capsules.—(1) Mix a few drops each of the sputum and blood-serum on egg-albumin solution (egg-albumin, distilled water, equal parts; shake and filter through cotton). Make thin smears from the mixture and just as the edges begin to dry, cover with Müller's fluid (potassium bichromate, 2.5 gm.; sodium sulphate, 1.0 gm.; water 100 c.c.) saturated with mercuric chlorid (ordinarily about 5 per cent.). Gently warm over a flame for about three seconds. This rapidly fixes the bacteria while still living.
(2) Rinse very quickly in water.
(3) Flush once with alcohol.
(4) Apply tincture of iodin for one to two minutes.
(5) Thoroughly wash off the iodin with alcohol and dry in the air.
(6) Stain about three seconds with weak anilin-gentian-violet freshly made up as follows: Anilin oil, 10; water, 100; shake; filter; and add 5 c.c. of a saturated alcoholic solution of gentian violet.
(7) Rinse off the stain with 2 per cent. solution of sodium chlorid, mount in this solution, and examine with a one-twelfth objective.
Buerger suggests a very useful variation as follows: After the alcohol wash and drying, the specimen is stained by Gram's method (p. 39), counter-stained with aqueous solution of fuchsin, washed, and mounted in water. The pneumococcus holds the purple stain, while all capsules take on the pink counter-stain.
Smith's Method.—This somewhat complicated, but not difficult, method is very useful as a routine stain for the sputum. It brings out well all cells and all bacteria except the tubercle bacillus.
(1) Make thin smears, dry, and fix in a flame in the usual manner.
(2) Apply anilin-gentian-violet a few seconds, gently warming until steam rises.
(3) Rinse in water.
(4) Apply Gram's iodin solution for thirty seconds.
(5) Wash in 95 per cent. alcohol until the purple color ceases to come off.
(6) Wash with equal parts of ether and absolute alcohol, or with ether and absolute alcohol successively.
(7) Apply a saturated aqueous solution of eosin for a minute or two.
(8) Rinse off the eosin with Löffler's methylene-blue, then cover with the methylene-blue, and heat until steam rises.
(9) Wash in water.
(10) Rinse quickly with absolute alcohol.
(11) Apply xylol a half minute or longer.
(12) Mount in balsam.
By this method organisms which stain by Gram's method (staphylococci, streptococci, pneumococci, etc.) are purplish-black; organisms which decolorize by Gram's method (bacilli of Friedländer, influenza bacilli, etc.) are blue; capsules are pink; nuclei of all cells are blue; and granules of eosinophilic cells are bright red.
Anilin-gentian-violet.—Ehrlich's formula is the one generally used, but this keeps only a few weeks. Stirling's solution, which keeps much better and seems to give equal results, is as follows: gentian-violet, 5 gm.; alcohol, 10 c.c.; anilin oil, 2 c.c.; water, 88 c.c.
Gram's Iodin Solution.—Iodin, 1 gm.; potassium iodid, 2 gm.; water, 300 c.c.
Löffler's alkaline methylene-blueis a very generally useful stain for bacteria. It is composed of 30 parts of a saturated alcoholic solution of methylene-blue and 100 parts of a 1:10,000 aqueous solution of caustic potash. It keeps indefinitely.
(4)Bacillus of Friedländer(Bacillus mucosus capsulatus).—In a small percentage of cases of pneumonia, this organism is found alone or in company with the pneumococcus. Its pathologic significance is uncertain. It is often present in the respiratory tract under normal conditions. Friedländer's bacilli are non-motile,encapsulated rods, sometimes arranged in short chains (Fig. 10). Very short individuals in pairs closely resemble pneumococci, from which they are distinguished by the fact that they are Gram-decolorizing.
(5)Bacillus of Influenza.—This is the etiologic factor in true influenza. It is present, often in large numbers, in the nasal and bronchial secretions, and is also found in the local lesions following influenza. Chronic infection by influenza bacilli may be mistaken clinically for tuberculosis, and they should be searched for in all cases of obstinate chronic bronchitis.
Their recognition depends upon the facts that they are extremely small bacilli; that most of them lie within the pus-cells; that their ends stain more deeply than their centers, sometimes giving the appearance of minute diplococci; and that they are decolorized by Gram's method of staining (Fig. 11).
They are stained blue in Gabbet's method for tubercle bacilli, but are more certainly recognized by Smith's method or by Gram's method, followed by Bismarck brown or fuchsin, as follows:
Gram's Method.—(1) Make smears, dry und fix by heat.
(2) Apply anilin-gentian-violet two to five minutes.
(3) Wash with water.
(4) Apply Gram's iodin solution one-half to two minutes.
(5) Wash in alcohol until the purple color ceases to come off.
(6) Apply a saturated aqueous or alcoholic solution of Bismarck brown one-half to one minute, or a weak solution of fuchsin until the film become pink. The latterprobably gives a better contrast stain, but there is danger of overstaining.
(7) Wash in water, dry, and mount.
By this method Gram-staining bacteria are purple; Gram-decolorizing bacteria and nuclei of cells are brown or red.
2.Cells.—These include pus-corpuscles, epithelial cells, and red blood-corpuscles.
(1)Pus-corpusclesare present in every sputum, and at times the sputum may consist of little else. They are the polymorphonuclear leukocytes of the blood, and appear as rounded cells with several nuclei or one very irregular nucleus (Fig. 8andPlate II, Fig. 2). They are frequently filled with granules of coal-dust and are often much degenerated. Such coal-dust-laden leukocytes are especially abundant in anthracosis, where angular black particles, both intra- and extra-cellular, are often so numerous as to color the sputum (Plate II, Fig. 2,B). Occasionally mononuclear leukocytes are present.
Eosinophilic leukocytesare quite constantly found in large numbers in the sputum of bronchial asthma near the time of the paroxysm, and constitute one of the most distinctive features of the sputum of this disease. They resemble ordinary pus-corpuscles, except that their cytoplasm is filled with coarse granules having a marked affinity for eosin. Large numbers of free granules, derived from disintegrated cells, are also found (Fig. 12).
Ordinary pus-cells are easily recognized in sputum stained by any of the methods already given. For eosinophilic cells, some method which includes eosin must be used. A simple method is to stain the dried and fixed film two or three minutes with saturated solution of eosin, and then one-half to one minute with Löffler's methylene-blue; nuclei and bacteria will be blue, eosinophilic granules bright red.
(2)Epithelial cellsmay come from any part of therespiratory tract. A few are always present. They have little diagnostic value, although a considerable excess would indicate a pathologic condition at the site of their origin. Any of the stains mentioned above will show them, and they can usually be identified in unstained sputum. In general three forms are found:
(a)Squamous cells:large, flat, polygonal cells with a comparatively small nucleus (Fig. 13,i). They come from the upper air-passages, and are especially numerous in laryngitis and pharyngitis. They are frequently studded with bacteria—most commonly diplococci.
(b)Cylindric cellsfrom the nose, trachea, and bronchi (Fig. 13,f,h): These are not usually abundant, and,as a rule, they are not identified because much altered from their original form, being often spheric.
(c)Alveolar cells:rather large, round, or oval cells with one or two round nuclei (Fig. 13). Their source is presumably the pulmonary alveoli. Like the leukocytes, they frequently contain particles of carbon (normal lung pigment). In chronic heart disease, owing to long-continued passive congestion, they may be filled with brown granules of altered blood-pigment, and are then called "heart-failure cells" (Plate II, Fig. 1). Alveolar cells commonly contain fat-droplets and, less frequently, myelin globules. The latter are colorless, rounded bodies, sometimes resembling fat droplets, but often showing concentric or irregularly spiral markings (Fig. 13,c,g). They are also found free in the sputum. They are abundant in the scanty morning sputum of apparently healthy persons, but may be present in any mucoid sputum.
(3)Red blood-corpusclesmay be present in small numbers in almost any sputum. When fairly constantly present in considerable numbers, they are suggestive of phthisis. The corpuscles when fresh are shown by any of the staining methods which include eosin. They are commonly so much degenerated as to be unrecognizable, and often only altered blood-pigment is left. Ordinarily, blood in the sputum is sufficiently recognized with the naked eye.
III. SPUTA IN DISEASE
III. SPUTA IN DISEASE
Only those conditions which give fairly characteristic sputa are mentioned.
1.Acute Bronchitis.—There is at first a small amount of tenacious, almost purely mucoid sputum, frequently blood-streaked. This gradually becomes more abundant,mucopurulent in character, and yellowish or gray in color. At first the microscope shows a few leukocytes and alveolar and bronchial cells; later, the leukocytes become more numerous. Bacteria are not usually abundant.
2.Chronic Bronchitis.—The sputum is usually abundant, mucopurulent, and yellowish or yellowish-green in color. Nummular masses—circular, "coin-like" discs which sink in water—may be seen. Microscopically, there are great numbers of leukocytes, often much degenerated. Epithelium is not abundant. Bacteria of various kinds, especially staphylococci, are usually numerous.
In fibrinous bronchitis there are found, in addition, fibrinous casts, usually of medium size.
In the chronic bronchitis accompanying long-continued passive congestion of the lungs, as in poorly compensated heart disease, the sputum may assume a rusty brown color, owing to presence of large numbers of the "heart-failure cells" previously mentioned.
3.Bronchiectasis.—The sputum is very abundant at intervals, sometimes as high as a liter in twenty-four hours, and has a very offensive odor when the cavity is large. It is thinner than that of chronic bronchitis, and upon standing separates into three layers of pus, mucus, and frothy serum. It contains great numbers of miscellaneous bacteria.
4.Gangrene of the Lung.—The sputum is abundant, fluid, very offensive, and brownish in color. It separates into three layers upon standing—a brown deposit, a clear fluid, and a frothy layer. Microscopically, few cells of any kind are found. Bacteria are extremely numerous; among them may sometimes be found an acid-fast bacillus probably identical with the smegma bacillus. As beforestated, elastic fibers are less common than would be expected.
5.Pulmonary Edema.—Here there is an abundant, watery, frothy sputum, varying from faintly yellow or pink to dark-brown in color; a few leukocytes and epithelial cells and varying numbers of red blood-corpuscles are found with the microscope.
6.Bronchial Asthma.—The sputum during and following an attack is scanty and very tenacious. Most characteristic is the presence of Curschmann's spirals, Charcot-Leyden crystals, and eosinophilic leukocytes.
7.Croupous Pneumonia.—Characteristic of this disease is a scanty, rusty red, very tenacious sputum containing red corpuscles or altered blood-pigment, leukocytes, epithelial cells, usually many pneumococci, and often very small fibrinous casts. This sputum is seen during the stage of red hepatization. During resolution the sputum assumes the appearance of that of chronic bronchitis. When pneumonia occurs during the course of a chronic bronchitis, the characteristic rusty red sputum may not appear.
8.Pulmonary Tuberculosis.—The sputum is variable. In the earliest stages it may be scanty and almost purely mucoid, with an occasional yellow flake, or there may be only a very small mucopurulent mass. When the quantity is very small there may be no cough, the sputum reaching the larynx by action of the bronchial cilia. This is not well enough recognized by practitioners. A careful inspection of all the sputum brought up by the patient on several successive days, and a microscopic examination of all yellow portions, will not infrequently establish a diagnosis of tuberculosis when physical signs are negative.Tubercle bacilli will sometimes be found in large numbers at this stage. Blood-streaked sputum is strongly suggestive of tuberculosis, and is more common in the early stages than later.
The sputum of more advanced cases resembles that of chronic bronchitis, with the addition of tubercle bacilli and elastic fibers. Caseous particles containing immense numbers of the bacilli are common. Far-advanced cases with large cavities often show rather firm, spheric or ovoid masses of thick pus in a thin fluid—the so-called "globular sputum." These globular masses usually contain many tubercle bacilli.
Preliminary Considerations.—The urine is an aqueous solution of various organic and inorganic substances. It is probably both a secretion and an excretion. Most of the substances in solution are either waste-products from the body metabolism or products derived directly from the foods eaten. Normally, the total amount of solid constituents carried off in twenty-four hours is about 60 gm., of which the organic substances make up about 35 gm. and the inorganic about 25 gm.
The chief organic constituents are urea and uric acid. Urea constitutes about one-half of all the solids, or about 30 gm. in twenty-four hours.
The chief inorganic constituents are the chlorids, phosphates, and sulphates. The chlorids, practically all in the form of sodium chlorid, constitute one-half, or about 13 gm., in twenty-four hours.
Certain substances appear in the urine only in pathologic conditions. The most important of these are proteids, sugars, acetone and related substances, bile, hemoglobin, and the diazo substances.
In addition to the substances in solution all urines contain various microscopic structures.
While, under ordinary conditions, the composition of urine does not vary much from day to day, it varies greatly at different hours of the same day. It is evident,therefore, thatno quantitative test can be of value unless a sample of the mixed twenty-four-hour urine be used. The patient should be instructed to void all the urine during the twenty-four hours into a clean vessel kept in a cool place, to mix it well, to measure the whole quantity, and to bring four to eight ounces for examination. When it is desired to make only qualitative tests, as for albumin or sugar, a "sample" voided at random will answer. It should be remembered, however, that urine passed about three hours after a meal is most likely to contain pathologic substances. That voided first in the morning is least likely to contain them.
The urine must be examined while fresh. Decomposition sets in rapidly, especially in warm weather, and greatly interferes with all the examinations. Decomposition may be delayed by adding five grains of boric acid (as much of the powder as can be heaped upon a ten-cent piece) for each four ounces of urine. Formalin, in proportion of one drop to four ounces, is also an efficient preservative, but if larger amounts be used, it may give reactions for sugar and albumin, and is likely to cause a precipitate which greatly interferes with the microscopic examination.
Normal and abnormal pigments, which interfere with certain of the tests, can be removed by filtering the urine through animal charcoal, or precipitating with a solution of acetate of lead and filtering.
A suspected fluid can be identified as urine by detecting any considerable quantity of urea in it (p. 66). Traces of urea may, however, be met with in ovarian cyst fluid, while urine from very old cases of hydronephrosis may contain little or none.
Clinical examination of the urine may conveniently be considered under four heads: I. Physical examination. II. Chemic examination. III. Microscopic examination. IV. The urine in disease.