Postgrad Med J: first published as 10.1136/pgmj.25.287.427 on 1 September 1949. Downloaded from 427 THE STORY OF CATGUT By ELDRED J. HOLDER, PH.D., B.PHARM., PH.C.(Edin.) Historical I656 by Louis XIV, who granted letters patent to The dictionary definition of catgut is 'a tough the Guild whose members supplied racquet cord made from the intestines of animals, es- makers, clockmakers, musicians, cross-bow makers pecially sheep.' There may or may not follow and surgeons. an indication of its uses. A short digression may be permissible to make Mention catgut to a surgeon and he thinks of reference to a natural means of wound closure a suture material; to a musician, he recalls the which has been known for hundreds of years, mellow tones of the violin or cello; to a sportsman namely the use of the mandibles of certain species and he wonders if he remembered to replace the of biting ants. The edges of a wound are brought the press on his tennis racquet. Catgut, to Every- together manually, the ant is held by its body and man, prompts speculation as to its feline origin. allowed to bite across the wound edges; the There is, however, in fact no evidence that the moment it has done so the body is twisted away intestine of the cat has ever been used to produce from the head which, with the jaws, is left acting The name can be traced back to like a modern metal clip. This procedure is still catgut strings. Protected by copyright. the Arabic cither, an early stringed instrument. used by the aboriginal natives of central Australia The same root is seen in the old name for the and there are records of its use up to recent times dancing master's fiddle, a kit. From kitgut to in Greece, Serbia and Algeria. catgut is an easy etymological step. To return to catgut, it was in i868, the year No aid to surgery has had such a chequered before he came to Edinburgh University as career as catgut. It has been in and out of favour, Professor of Clinical Surgery, that Joseph Lister sworn by and sworn at, over a period of some 75 experimentally tied catgut round the right carotid years. Catgut for suturing has been ' going out of artery of a 1l. Thirty days later the animal was fashion' since the writer first took interest in it killed and Lister examined the ligature. At first some I7 years ago. Nevertheless, more is being he thought that it was unchanged, but closer in- manufactured and used today than ever before. vestigation revealed the fact that the catgut was no Why should this be so ? The answer lies in one longer present but had been replaced by a ring of special feature-its absorbability in living animal living tissue. Though Lister is mainly remembered tissues. for his introduction of antisepsis into surgery, his Although this absorbability was not realized recognition of the absorbability of catgut has been http://pmj.bmj.com/ until comparatively recently, the use of animal of fundamental importance in the successful intestine as a ' string' dates back as far as there modern use of this material. are records of mankind. Indeed, it is reasonable to He quickly realized also the risk of introducing assume that its utility would have been recognized infection into wounds by the use of' raw' catgut. long before there was evolved the art of twisting There are records that in I869 he was using an vegetable fibres or hairs into thread. The use of aqueous solution of phenol as a sterilizing agent as a suture is undoubted even so for This would be efficient as a dried intestine catgut. fairly on September 25, 2021 by guest. far back in history as the Papyrus of Ebers, circa sterilizing agent (except for resistant spores) but 3750 B.C. Egyptian surgeons at that time appear would leave the sutures in a waterlogged and to have acquired considerable skill in wound weakened condition. Apparently with the idea repair. of overcoming these defects, Lister then used a Susruta, a Hindu writer who lived about 1500 solution of phenol in olive oil. This would un- B.C., refers to the use of cotton, drawn copper, doubtedly obviate loss of tensile strength but horsehair and animal intestines as ligatures. would be even less efficient in sterilization, though Ferrara, an Italian, at the end of the i6th century the catgut would be 'antiseptic' and far less used intestines of tortoises amongst other suture dangerous than untreated material. He further materials; he seems to have had some precognition anticipated the modern process for 'hardening' of the need for sterilizing because he is said to have catgut, that is for delaying its rate of absorption stored his sutures in wine before use. In France in the tissues, by chromicizing by the use of the importance of catgut makers was recognized in mixtures of phenol and chromic acid solution in C Postgrad Med J: first published as 10.1136/pgmj.25.287.427 on 1 September 1949. Downloaded from 428 POST GRADUATE MEDICAL JOURNAL September I949 which the catgut was steeped for varying the reader is confidently referred to ' Le Catgut' periods. by Dr. A. Fandre (I944). Surgical catgut is not easy to make. The raw material, sheep's intestine, varies from animal to Manufacture animal in quality, width and toughness ; it varies There are two main stages in the production of according to age, to feeding and so on, and cannot a sterile suture; first the manufacture of the be bulked in order to obtain uniformity. In its strand, then its sterilization and preparation for natural state it is loaded with bacteria, both use at operation. pathogenic and non-pathogenic. The problem A cross section of sheep's intestine reveals three lies in its complete sterilization without the main layers; the outer mesenteric coat whereby destruction of the natural properties of the gut. It the intestine is ' slung' within the abdominal is manufactured in this country only under cavity; the middle (sub-mucous and muscular) Government licence, and the conditions and in- layer which is thin, elastic and muscular; and spections required leave no doubt as to the the inner, absorptive mucous layer. bacteriological safety of the final product. Its rate In preparation the gut is split longitudinally into of absorption in the human body is hard to ribbons and by carefully controlled scraping opera- control; the same strand divided into two pieces tions the outer mesenteric and inner mucous coats and implanted in similar locations in two in- are removed. The sub-mucous, muscular rib- dividuals may have different absorption periods bons are twisted, sometimes singly, more often due to idiosyncrasy, sensitivity, vitamin deficiency in twos, threes or fours, then stretched and dried or cachexia. to form an almost solid filament. Thereafter the Many arguments have been used for and against strings must be polished to give uniformity of non-absorbable suture materials. They are often diameter along the strand and a smooth surface, less expensive and more easily sterilized than cat- but not too smooth or the knot may slip after Protected by copyright. gut, they can be of absolutely standard size and suturing with the risk of a disaster such as a tensile strength. If buried, however, they remain 'burst abdomen.' Finally the strands are sorted permanently in the tissues and may at any time into gauges to agree with the size standards in the subsequently become a focus for infection. British Pharmaceutical Codex and the United Two further points regarding non-absorbable States Pharmacopoeia. sutures are worth noting. First, the harshness of Until I944 British manufacturers each had their monofilaments such as silk-worm gut. Harshness, own catgut size standards with the result that one that is, to the patient, for if the stitches are on the maker's No. I might be equivalent to another surface the cut ends tend to harden and may catch maker's No. 3, and so on. During the recent war, in the dressings; if such materials are used for standards for gauge and tensile strength were buried sutures there is a grave risk of the sharp drawn up and included in the Sixth Supplement, points of the cut ends doing damage to adjacent I944, to the British Pharmaceutical Codex, 1934 tissues, particularly to blood vessels. The other edition. The B.P.C. size standards are nearly point concerns the softer and generally preferable identical with those of the United States Pharma- http://pmj.bmj.com/ braided materials such as braided silk. Even in copoeia which, in addition to reducing confusion interrupted sutures of such materials there is the amongst British makes, was a useful contribution possibility of bacteria finding refuge in their inter- towards international co-operation. stices, whilst in continuous sutures the movement Deliberate hardening to delay the rate of of serum along the suture material by capillary absorption in the tissues is referred to later and is action favours the spread of any incidental in- usually done during manufacture of the raw catgut fection. If, to eliminate this wick-like action, the strings. braided material has been rendered non-capillary, on September 25, 2021 by guest. the disadvantage disappears and gives probably the Sterilization ideal form of non-absorbable suture. A phrase often used by makers and users of The ideal suture material is one which will surgical catgut is ' the catgut problem.' This ex- retain its holding power until healing is complete expression summarizes the difficulty of devising a and will then disappear with a minimum of dis- sterilizing process which is rigorous enough to kill turbance to the tissues.