Calculous disease of the vermiform appendix
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Transcript of Calculous disease of the vermiform appendix
Gut, 1966, 7, 583
Calculous disease of the vermiform appendixG. B. FORBES AND R. W. LLOYD-DAVIES
From the Kent and Canterbury Hospital, Canterbury
EDITORIAL SYNOPSIS Calculi were found in 29 out of 1,800 vermiform appendices removed atoperation. The high incidence of acute complications associated with a calculus indicates the needto remove the appendix when one is found incidentally on radiological examination of the abdomen.
The formation of true calculi within the lumen of thevermiform appendix is a comparatively rare event,but the condition is of clinical importance because ofthe frequency with which such calculi give rise toserious complications. The main clinico-pathologicalfeatures of calculous disease of the appendix, basedon the examination of 2,000 appendix specimens,are presented in this report with the followingobjectives in view: to clarify the terminology of thevarious formed faecal objects which are found in thelumen of the appendix; to assess the incidence ofcalculous disease and its complications; to draw theattention of surgeons, radiologists, and pathologiststo a disease which deserves wider recognition.
DEFINITION OF TERMS
By reason of its shape and anatomical position, theappendix frequently contains faecal material eitheras a continuous or interrupted cast of the lumen, oras separate small elliptical faecal masses. When theseare formed and hard they are known variously asfaecoliths, coproliths, stercoliths, enteroliths, appen-dicoliths, or concretions. The degree of hardness is ameasure of the quantity of calcium in the faecal mass.It is believed that the presence of a small scybalum ofinspissated faecal material within the appendixlumen acts as a nucleus around which calcium saltsmixed with faecal debris become layered. The calciumsalts are derived from mucus excreted in excessiveamounts by the appendicular mucosa in response tothe local irritant action of the faecal nucleus; in otherwords a local low-grade catarrhal appendicitisdevelops. Faecoliths containing a small to moderateamount of calcium are not uncommon; occasionallyone will become almost wholly calcified and thestony-hard object which results can fairly bedescribed as a true appendicular calculus. Sincegradations of calcification occur, the distinctionbetween calcified faecoliths aud true calculi is
arbitrary and indeed the clinical effects and compli-cations of both types of calcified object, whetherdescribed as faecolith or calculus, are likely to bevery similar. When estimating the incidence ofcalculous disease, however, it is necessary to havemore precise criteria for differentiating the variousformed faecal objects encountered in appendicec-tomy specimens. In the present study all such objectswere grouped on the basis of their physical charac-ters, using the following key as an aid to identifica-tion:
1 FAECAL PELLET This is a formed, firm, but notcalcified, faecal mass. It is brown, smooth, ovoid orcigar-shaped, 'squashable', width equal to or slightlygreater than diameter of appendix lumen, and com-posed of organic material. It is radiotranslucent andvery common.
2 CALCIFIED FAECOLITH (FIG. I a) This is a partiallycalcified ovoid faecal mass, light or dark brown,moderately hard, crushable rather than squashable,with a slightly granular surface with dark brown orblack nodules of calcification, often at the poles.There is patchy laminated radio-opacity, and thewidth is usually greater than the lumen. It is com-posed of organic material and a small to moderateamount ofcalcium phosphate, and is not uncommon.
3 CALCULUS (FIG. Ib) This is a stony hard, denselyradio-opaque object, round, ovoid or irregular inshape, approximately 3 mm. to 3 cm. in maindiameter. It is sometimes faceted when multiple, andbuff to shiny black in colour, sometimes reddish. Itmakes a metallic sound when dropped into an enamelor metal vessel, and is composed mainly of calciumphosphate. It is rare.
Nearly all formed faecal objects found in appen-dices can be placed without difficulty in one of thesegroups. Sometimes a specimen will prove difficult to
G. B. Forbes and R. W. Lloyd-Davies
FIG. 1. Calcified faecolith (a) and calculus (b) from case4.
group because of borderline features, and an addedcomplication is the occasional occurrence of bothcalcified faecoliths and true calculi in one and thesame appendix.
All three types of inclusion may contain radio-opaque material in amounts varying from a trace insome faecal pellets to complete dense radio-opacityin the case of true calculi. For this reason we considerthat the demonstration of radio-opaque material bystraight radiographic examination of the organ aftersurgical removal is not a reliable guide to the inci-dence of true calculus formation, at any rate whenused as the sole criterion. This technique has beenused in some cases by Bowers (1939), Steinert,Hareide, and Christiansen (1943) and more routinelyby Felson and Bernhard (1947), Felson (1949), andShaw (1965), and the frequency with which theseauthors found radio-opaque objects in acutely in-flamed appendices (33 to 44 %) suggests that the testis too sensitive. Indeed Bowers found 'stones' in 25 %of normal appendices. Shaw, using the same tech-nique, found 'calculi' in 79 of240 inflamedappendicesan incidence of 33 %, but most of the objects were'compressible between finger and thumb, fairly softin consistency and cut easily with a knife'; onlyoccasionally did he find calculi which were firm orhard and demonstrable on radiological examinationof the abdomen before operation. Shaw believes thatthe term 'calculus' should be applied to all objectscontaining calcium, irrespective of the amount; wefind this unacceptable and prefer to apply the termonly to an object which fulfils the physical charactersof a stone or calculus in the generally-acceptedconnotation of this term, the main character beingstony hardness.The term 'calculus of the appendix' is used in
several reports in the literature to describe objectswhich were radio-opaque on pre-operative radio-
graphs of the abdomen, and yet, after removal, couldbe cut with a knife (e.g., Candy, 1959). Such radio-opaque objects would not qualify for inclusion in thetrue calculus group as defined above, because of theirrelatively soft consistence. At the same time one mustremember that radio-opaque biliary calculi can some-times be cut with a knife and no one would suggestthat these should be distinguished from gall-stonesbylabelling them 'calcified choleliths'. It would seemreasonable then to include in the category of trueappendicular calculi, calcified faecoliths of sufficientdensity to be readily detectable on pre-operativeradiographic examination of the abdomen.
In 1742 Santorini studied the anatomy of the appen-dix and his descriptions were accompaniedbyillustra-tions of faecal concretions and worms which werefound in some of his specimens. Wegeler (1813) usedthe term 'calculosi concrementi' to describe hardfaecal concretions, resembling gall-stones, which hefound in the lumen of the appendix. One of the firstBritish surgeons to operate on a patient with acuteappendicitis was Hancock (1848); at operation hefound that the lumen of the appendix was obstructedby two concretions.
Weisfiog (1906) was the first to make a correct pre-operative diagnosis of appendicular calculus radio-logically. Similar reports came from Fittig (1907) inGermany and Seelig (1908) in America; Seelig admitsthat he misdiagnosed his case pre-operatively asureteric calculus. In 1913 Roux wrote a thesis on thediagnosis of appendicitis by radiological methods; hewas able to demonstrate foreign bodies and faecalconcretions in a number of cases.A few papers on the subject of appendicular
lithiasis appeared in the literature during the periodbetween the world wars, mainly from Germansources (see Wells, 1930), and since 1940 some 20 orso papers have been published mainly in American orcontinental journals. In 1947 Felson and Bernhardestimated that just over 100 cases had been reported;this number had increased to 120 by 1951 (Laforet,Greenler, and O'Brien), and to between 130 and 155by 1957 (Berg and Berg, 1957; Brady and Carroll,1957).About a dozen reports have appeared in British
journals, and most of these have dealt with only oneor two cases (Wells, 1930, one case; Levi, 1934, onecase; Moloney, 1947, one case; Airth, 1948, one case;Chapple, 1951, two cases; Clark, 1952, one case;Smith, 1954, four cases; Atwell and Pollock, 1960,two cases; Butler, 1959, one case; Candy, 1959, twocases; Meyerowitz, 1960, one case; Fox, 1962, onecase; and Shaw, 1965, 79 cases).
Calculous disease of the vermiform appendix
GENERAL The frequency with which calculi arefound in the appendix can be gauged from incidencefigures reported by various authors in this countryand abroad (Table I). The data in the upper part ofthe table refer to cases of calculous disease observedas a result of radiological examination of the abdo-men in cases of suspected acute appendicitis. Thedata in the middle part of the table refer to casesdiagnosed by means of radiographic examination ofthe appendix or calculi after surgical removal. As al-ready stated we consider that these figures give anexaggerated incidence oftrue calculous disease becausethe technique used to demonstrate the presence ofcalcified material is over-sensitive. As acute inflam-mation is the usual sequel to the presence of a stonein the appendix, it is not surprising that the incidencein this type of material is appreciably higher thanthat found in routine surgical material. As one mightexpect, the incidence rates tend to be higher in studiescarried out during recent years. Improved diagnosticfacilities and standards provide a ready explanationfor this trend, in particular the increasin