Catches to avoid

Conditions simulating air under thediaphragmChilaiditi syndrome (fig 9)-Interposition of hepatic flexure between liverand diaphragmSubphrenic abscessSubdiaphragmatic fatBasal curvilinear atelectasis

............ ...g. I |

,t. ., .... ..... .................._l S" ::: ..........~~~~~~~~~~~~~... . .... ..... 'XC:... .. .. ......... ...:::::.: 3 "" ~~~~~~~~~~~~~~~~~~....... .........:

|~ ~~~~~~~~~~~~~~~~~~~~~~~~...

,..

FIG O-Chilaiditi syndrome-interposition of colonbetween liver and diaphragm. Air is seen underthe right hemidiaphragm but bowel markingsare evident.

The properitoneal line adjacent to the lateral margin of the livercan be mistaken for a pneumoperitoneum in a left lateral decubitus view.Air in the biliary tree can be due to previous sphincterotomy orsurgery (fig 5). Pelvic phleboliths can often be differentiated from distalureteric stones by their characteristic appearance; they are round witha radio-opaque halo surrounding a small central lucent nidus.

SummaryDiagnostic qualityAlignment of bonesBone margins and densityCartilage and jointsSoft tissuesBowel gas patternPneumoperitoneumAir in the biliary tree or portal veinSize of organsFat-tissue interfacesAbnormal calcification

D A Nicholson is consultant radiologist and P A Driscoll is senior lecturer in emergencymedicine at Hope Hospital, Salford.The line drawings were prepared by Mary Harrison, medical illustrator.The ABC of Emergency Radiology has been edited by David Nicholson and

Peter Driscoll.

Minimally Invasive Surgery

Advanced techniques in abdominal surgery

John RT Monson

Almost every abdominal organ is now amenable tolaparoscopic surgery. Laparoscopic appendicec-tomy is a routine procedure which also permitsidentification of other conditions initially confusedwith an inflamed appendix. However, assessment ofappendiceal inflammation is more difficult. Almostall colonic procedures can be performed laparo-scopically, at least partly, though resection forcolonic cancer is still controversial. For simplepatch repair of perforated duodenal ulcers laparo-scopy is ideal, and inguinal groin hernia can berepaired satisfactorily with a patch of syntheticmesh. Many upper abdominal procedures, however,still take more time than the open operations. Thesetechniques reduce postoperative pain and theincidence of wound infections and allow a muchearlier return to normal activity compared with opensurgery. They have also brought new disciplines:surgeons must learn different hand-eye coordination,meticulous haemostasis is needed to maintainpicture quality, and delivery of specimens may

be problematic. The widespread introduction oflaparoscopic techniques has emphasised the needfor adequate training (operations that were straight-forward open procedures may require considerablelaparoscopic expertise) and has raised questionsabout trainee surgeons acquliring adequate experi-ence ofopen procedures.

At the end of the 1980s, when the first laparoscopictechniques were described, few could have predictedthe developments that have occurred since then. Farfrom being limited to the removal of uninflamedgallbladders, laparoscopic techniques have beenapplied to almost every abdominal organ: oesophagus,stomach, duodenum, small and large bowel, liver,spleen, kidney, ureters, and pancreas have all beeneither resected or repaired.The development of high quality video imaging

systems has been the single biggest advance in recentyears that has allowed many of these new proceduresto be developed. For practising surgeons, however,

This is the second in a series ofarticles on minimally invasivesurgery

Academic Surgical Unit,St Mary's Hospital andImperial College ofScience, Technology andMedicine, LondonW2 INYJohn RT Monson, assistantdirector

BMJ 1993;307: 1346-50

1346 BMJ VOLUME 307 20 NOVEMBER 1993

on 3 February 2021 by guest. P

rotected by copyright.http://w

ww

.bmj.com

/B

MJ: first published as 10.1136/bm

j.307.6915.1346 on 20 Novem

ber 1993. Dow

nloaded from

training in the hand-eye coordination required forendoscopic surgical procedures has been the majorlimiting factor in surgical progress. A further restric-tion has been the range of available instruments: fiveyears ago this was limited to simple graspers andscissors. Since then, many traditional surgical instru-ments have been adapted for laparoscopy to allow

many more procedures to be contemplated. Instru-ments have become more versatile by being able torotate 3600 and to bend up to 900, and the advent oflinear stapling devices has allowed structures such asbowel and large blood vessels to be divided andanastomosed safely with the insertion of rows oftitanium staples. These changes have brought theirown controversies, mosdy of an economic nature.Because instrument design changes rapidly much ofthis equipment has been manufactured in a disposableform to be used only once. Therefore, the widespreadintroduction of laparoscopic techniques and use ofthese instruments will have considerable economicimplications. Some of these increased costs may beoffset by shorter stays in hospital and reduced time offwork, but transfer of these savings to the hospitalservices will probably remain a problem.The term ninimall inva;ive treatment has beeni

borrowed by general surgeons from specialties such asradiology, urology, and orthopaedics, which have beenusing endosurgical techniques for many years. In

Suigem'andscmt be used to manipulate tissues 4ndstnuaes ndanres ar-dbygpsgirng mnmsm

abdominal surgery, however, this term is really amisnomer: many of the advanced laparoscopic tech-niques such as colonic resection or oesophagectomy arenot minimally invasive, but are major resectionalprocedures performed through a snaller incision thanbefore. Although the scar may be smaller and the levelof postoperative discomfort may be less, the operationotherwise remains essentially unchanged with the samelist of potential complications-and a few new onesthrown in for good measure. The term minimal accesssurgery might therefore be more appropriate.The small scars of the operations bring some

problems of their own. In many instances all that apatient (and general practitioner) sees after an opera-tion is a few stab marks so that deciding which organhas been removed can be reduced to guesswork.Education ofpatients and communication with doctorsin the community and primary care sector are thereforeparticularly important after laparoscopic operations.Unfortunately, many surgeons still allow their patientsto leave hospital unaware of the details 'of the surgerythey have just survived. Patient information sheets arevery useful in this regard, and improved communica-tion with general practitioners is vital when theirpatients return to the community sometimes just a fewhours after major surgery. This trend towards shorterstays in hospital has important implications: many ofthe potential postoperative complications that wouldpreviously have occurred during inpatient stays maynow present to doctors in primary care, many ofwhommay be- unable to cope adequately; and undegraduateeducation may have to be modified to give moreemphasis to this new surgical load being transferred tothe community.

Principles oflaparoscopic surgeryEssentially, all laparoscopic surgical techniques

should adhere to all the basic surgical tenets of openprocedures: if something would not be done that wayin open surgery it should not be done that waylaparoscopically. The temptation to take short cutsmust be avoided. From. this basic point, however,some side issues anse.

Selction- of patients-All advancd laparoscopicoperations are performed under general anaesthetic,and patients' cardiovascular fitness is obviously essen-tial. Previous abdominal surgery may be a contra-indication to laparoscopic surgery. For operations suchas cholecystectomy a history of appendicectomy orhysterectomy should not prevent a successful laparo-scopic procedure, but care must be taken during initialinsufflation and port placement to avoid injury to theunderlying bowel, which may be adherent to theabdominal wall. Previous upper abdominal surgerysuch as gastrectomy, however, may prevent laparo-scopic cholecystectomy because of formation of severeadhesion. A history of major abdominal proceduressuch as colectomy or aortic surgery generally implieswidespread formation of adhesion, thereby precludingmost laparoscopic procedures. All patients, however,sbould be considered individually, and an initiallaparoscopy with an open technique for port insertionWill quickly establish a patient's suitability.

Disciplines of laparoscopic surgey-The excellentpicture quality and magnified image provided bymodem video endoscopy systems allow surgeons toperform more careful and delicate dissections, especi-lly in some ofthe more inaccessible areas such as deepin the pelvis. For the operations to be successful acareful technique of tissue retraction and dissectionis required. Unfortunately, the surgeon's hands arenot available in the abdomen to distract tissues andstructures and are replaced by carefully positionedgasping instruments. These instruments are less

BMJ VOLUAlM 307 20 NovEMBER1993

Surgeons must lam newhand-eye coordinationforlaparoscopy

1347

on 3 February 2021 by guest. P

rotected by copyright.http://w

ww

.bmj.com

/B

MJ: first published as 10.1136/bm

j.307.6915.1346 on 20 Novem

ber 1993. Dow

nloaded from

efficient than fingers and hands and are substantiallymore traumatic. Thus, great care must be taken toavoid damage to structures such as the gastrointestinaltract. In addition, laparoscopic surgery demands meti-culous haemostasis: any pooled blood is tedious toaspirate, and the haemoglobin rapidly leads to absorp-tion of light with resultant loss of picture quality, Ofcourse, open surgery is better performed in a blood freeoperative field, but laparoscopic operations exert a new

discipline in this regard.Delivery of specimens-For tissue specimens of a

benign nature such as a scarred hydronephrotic kidneyit is acceptable to place the specimen in a tissue bag inthe abdomen and to remove it piecemeal with the aid ofan ultrasonic dissector. This technique has also beenapplied to the spleen. For malignant tissue suchas colon cancer, however, this procedure is clearlyunacceptable. Firstly, an intact specimen is requiredfor adequate histological examination to allow diag-nosis and staging. Secondly, there is the danger ofimplantation of malignant cells in the abdomen andabdominal wall if a tumour is broken up. Removal ofan intact specimen generally requires a small laparo-tomy incision to allow delivery of the specimen whileavoiding contamination ofthe wound.

Surgical triningAs minimal access surgery develops the issue of

postgraduate training becomes more pressing. Thewidespread and unlegislated introduction of laparo-scopic cholecystectomy has already resulted in anexcess of injuries to the bile duct and, in New Yorkstate, has led to the implementation of legislationdetermining who is permitted to perform these opera-tions.1 If such a development is to be avoided in Britainthen adequate training must be provided. In Britain itis not possible to use animal models for direct surgicaltraining, but simulators have been developed that can

provide experience in the use of instruments and inperforming some techniques. In addition, some formof proctering for initial cases is a useful adjunct andshould perhaps be more widely adopted. Whethersurgeons should be required to submit to formalaccreditation, however, remains controversial as this isnot generally required in other specialties.The increasing impact of minimal access surgery on

surgical practice has other implications. For example,nearly all patients requiring cholecystectomy nowundergo a successful laparoscopic procedure, and thishas reduced the exposure of surgical trainees to theopen operation. This raises a question about theirability to perform the open procedure when theoccasion demands. There is some evidence that thismay be less of a problem than was first thought.The excellent anatomical view provided by videoendoscopy is often superior to that possible with opensurgery so that when the operation is converted toan open procedure little difficulty is encountered.Although this may be true for cholecystectomy andappendicectomy, it may not be for other proceduressuch as hernia repair and colectomy. In the case ofhernia repair the anatomical approach and method ofrepair undertaken laparoscopically is quite different tothat of the open procedure. Therefore, these operationsat least will have to be taught separately, startingwith the open procedure. For colonic surgery, opensurgery will remain an important element of surgicaltraining. At least 20% of colonic resections cannotbe done laparoscopically for various reasons includingacute intestinal obstruction, adhesions from previoussurgery, and acute inflammatory conditions and per-forations.2 It therefore follows that all surgeons willstill have to be skilled in the traditional operationbefore embarking on endosurgical procedures.

Surgical proceduresAPPENDICECTOMY

Laparoscopic appendicectomy is frequently per-formed and has several advantages over open proce-dures, although there are some apparent disadvantagesas well. Exposure is usually better as laparoscopyavoids the common problem of a small misplacedincision in the right iliac fossa. Furthermore, theappendix can usually be delivered through one of thelaparoscopic ports to avoid direct contact with andpossible infection of the wound, the commonestcomplication of the open procedure. Another advan-tage is the easier diagnosis and treatment of otherconditions that may have led to diagnostic confusion.Tubo-ovarian conditions such as salpingitis or ovariancysts can be dealt with through a traditional incision inthe right iliac fossa, but laparoscopy also allows thesurgeon to deal with conditions such as a perforatedduodenal ulcer or acute cholecystitis without makingfurther incisions. Although open appendicectomyis well tolerated by adolescents, elderly patients greatlybenefit from the early mobilisation and reduced post-operative discomfort associated with the laparoscopicapproach.A series of more than 100 laparoscopic appendicec-

tomies performed in our unit has revealed otherimportant points. Firstly, it can be difficult to deter-mine the degree ofinflammation (ifany) ofan appendix.Examination with the naked eye is a very accurate wayof diagnosing appendiceal inflammation, but this is notso with video laparoscopy, when variables such as thesettings of television monitors and picture resolutionrender colours and tones somewhat artificial. Secondly,the operation requires considerable laparoscopicexpertise, sometimes more than that needed for laparo-scopic cholecystectomy, and is not the straightforwardtraining operation for junior surgeons that the openprocedure usually is. This raises some criticaldilemmas. The emergency nature of acute appendicitismeans that surgery is often performed by juniorsurgeons in training, to whom the operation offers oneof the first steps in a surgical career. If a laparoscopicappendicectomy requires the operating skills of asenior registrar or consultant to be performed safelythen either senior staff will have to underake morenight time operations or many patients will have toundergo a period of conservative management beforehaving the operation on the next elective list.The current procedure requires three ports placed in

the lower abdomen, and the average time taken for theoperation is 30 minutes. Although it is rarely quickerthan the open procedure, many centres have nowshown that operative times differ little between the twoapproaches. With experience even the most difficultappendicectomies can be completed successfully bylaparoscopy.

COLONIC PROCEDURES

Virtually the full range of colonic operations can, atleast in part, be performed laparoscopically (see box)

BMJ VOLUME 307 20 NOVEMBER1993

Laparoscopic Colonic Procedures* Left or right hemicolectomy* Subtotal colectomy* Sigmoid colectomy* Fornation ofdiverting colostomy* Anterior resection ofrectum* Abdominoperineal resection ofrectum* Rectopexy forrectal prolapse* Reduction or resection ofsigmoid volvulus* Left sided resection with transanal specimen

delivery

1348

on 3 February 2021 by guest. P

rotected by copyright.http://w

ww

.bmj.com

/B

MJ: first published as 10.1136/bm

j.307.6915.1346 on 20 Novem

ber 1993. Dow

nloaded from

though some procedures are more suited to thisapproach than others. For example, both right hemi-colectomy and abdominoperineal resection of therectum can alrmost always be successfully- completedlaparoscopically. In contrast, resection of lesions in thetransverse colon can ptove difficult if not impossibledue to the greater onentum preventing mobilisation ofthe colon. Varying amounts of an operation may beperformed laparoscopically depending on a surgeon'sskill, time, availability of equipment, and the indi-vidual requirements of a case. Thus, at one extreme,colonic mobilisation may be all that is performedlaparoscopically, leaving delivery of the colon, divisionofthe mesenteric vesselg and bowel, and reanastomosisto be performed outside the abdomen in the traditionalfashion.The laparoscopic operation should be essentially the

same as the open procedure. A series of ports areplaced in the four quadrants of the abdomen afterplacement of the initial subumbilical port for thecamera. Through these ports grasping forceps are usedto retract the bowel to allow mobilisation by means of acombination of sharp dissection and diathermy. Allvital structures such as the duodenum and ureters mustbe identified and preserved as in the open operation.Although transanal delivery of segments of colon ispossible in certain cases, most colonic resectionsrequire a small laparotomy incision 5-7 cm long fordelivery of resected specimens. Through this sameincision the bowel and its vascular attachments may bedivided extracorporeally if this has not been donelaparoscopically. Re-anastomosis of the bowel can alsobe completed before closure of the abdomen. With thistechnique a right hemicolectomy can be performedthrough a 5 cm incision (in addition to severalstab wounds), and a subtotal colectomy requires alower abdominal transverse incision of no more than7-10 cm. Apart from the cosmetic advantages of thisapproach, it considerably reduces postoperative dis-comfort and allows a much quicker return to mobility.These operations are generally more time con-

suming than open procedures, and there is controversyas to whether laparoscopic resection for cancer givesadequate clearance of the tumour. In a series of nearly70 cases in our unit, which has special expertise in thisoperation, we found that the excellent views providedby the video images have sometimes led to improvedtumour clerance. This prtocedure remains underevaluation, however, and should be restricted tocentres with special expertise in the operation. Onefeature of laparoscopic colectomy performed for neo-plastic disease is worthy of special note. Because thebowel cannot be palpated in tie traditional manner itmay be difficult to identify the lesion to be removed.This is particularly true when resection is beingperformed for large soft polyps or cancers that do notinvolve the serosa. Consequently, the lesion must beaccurately located before surgery. Colonoscopy is notsufficient and may be incorrect in more than halfof cases. Preoperative contrast studies must be con-sidered a minimum and may be supplemented byintraoperative colonoscopy if required. An altermativeaid we have used with some success is injection of thelesion or the adjacent mucosa with methylene blue atthe time of colonoscopy. The blue colour can last forseveral days and can be seen quite easily at laparoscopyto aid localisation.

REPAIR OF PERFORATED DUODENAL ULCERPerforated duodenal ulcers are becoming more

common in elderly and frail patients taking non-steroidal anti-inflammatory agents.3 For simple patchrepair of the perforation the laparoscopic approach isideal: complete peritoneal lavage is improved, and thelack of an upper midline abdominal incision-the

Abdominoperineal resection of rectum does not require a large incisionwhen performed laparoscopicaly

most painful of all -abdominal incisions-substantiallyimproves postoperative recovery. The patch repair cannow be done with a special stapler rather than by thetedious and time consuming suture repair done bylaparotomy. Most repairs take less than 30 minutes,which is certainly no longer than the open operation.

UPPERABDOMINAL PROCEDURES

All the traditional operations for peptic ulcer diseasecan be performed laparoscopically, including bilateraltruncal vagotomy with or without drainage, highlyselective vagotomy, tuncal vagotomy with seromyo-tomy, and even partial gastrectomy. The proceduresare identical to the open operations but take a con-siderable amount of time to perform. Consequently,most centres prefer the quicker and technically easieroperation of posterior truncal vagotomy and anteriorseromyotomy when some definitive procedure is indi-cated.4 This has been performed in both emergencyand elective cases but has mainly been restricted to theelective setting.Other upper abdominal procedures performed

laparoscopically include fundoplication for gastro-oesophageal reflux.'The procedure is identical to theopen operation, and there is some evidence that theshortened hospital stay and rapid return to normalactivity associated with this operation may see are-emergence of the surgical treatment of complicatedreflux disease. More experimental procedures includesplenectomy and segmental liver resection, in whichdelivery of the resected specimen remains an un-resolved issue, although morcellation of the tissuein a plastic bag and subsequent aspiration are oftenpossible. These operations are also technically chal-lenging in terms ofadequate haemostasis.

REPAIR OF GROIN HERNIA

One of the commonest surgical procedures per-formed by general surgeons is repair of a groin hernia,usually inguinal. When performed laparoscopically,this presents the surgeon with some unique problems.The anatomy of the inguinal canal as seen from theinside of the abdomen is unfamiliar to most surgeons,in contrast to other laparoscopic procedures such ascholecystectomy and appendicectomy, in which theanatomical approach is identical to that of the openprocedure. Early attempts to perform inguinal herniarepair laparoscopically were associated with unaccept-ably high rates of recurrence.' Advances in instrumen-tation, ho'wever, have made it possible and practicalto produce a satisfactory tension free repair usingsynthetic mesh as a patch to cover not only the hernialdefect but also other areas of possible herniation.

BMJ VOLUME 307 20 NOVEMBER1993 1349

on 3 February 2021 by guest. P

rotected by copyright.http://w

ww

.bmj.com

/B

MJ: first published as 10.1136/bm

j.307.6915.1346 on 20 Novem

ber 1993. Dow

nloaded from

Right direct ingunal hetma.

... and isu repair with apatch ofsynthetic mesh

Results have been encouraging with low rates ofrecurrence and, most importantly, an early return tonormal activity.6The laparoscopic approach is ideal for the repair of

bilateral hernia as no further port insertion is requiredand both sides are visualised equally well. For thosepatients with recurrent defects after open repair, theperitoneal approach of the laparoscopic operation isconsiderably easier than a groin approach because allthe tissues dissected are free from the considerablefibrosis associated with a hernia repair (the originaloperation would have, been largely restricted to moresuperficial layers). Postoperative management remainsmuch the same as before though with some specificadditions. Because synthetic mesh is used to completerepairs prophylactic antibiotics are always adminis-tered in order to reduce the risk of infection of theforeign material. With some large hernial defects a

portion of the sac is deliberately left behind becausefull excision is not necessary for successful repair.Blood may sometimes collect in this sac remnant andpresent as a tender lump in the groin. This can bemistaken for 'an early recurrence, but ultrasoundscanning of the groin has proved useful in clarifyingany diagnostic diffiqulties. Such sac haematomas canbe successfillly managed conservatively and resolveover one or two weeks.As with most'- laparoscopic procedures, the early

return to normal activity probably represents thegreatest advantage of laparoscopic hernia repair, and,although immediate and long term results and compli-cations may be expected to be similar to those ofopen surgery, laparoscopy also reduces postoperativediscomfort and gives better cosmetic results. Manypatients may have a traditional open hernia repairperformed under local anaesthetic as a day case, butthe groin wound provides a source of considerablediscomfort for several weeks. In contrast, laparoscopichernia repair requires general anaesthetic so that anovernight stay is often necessary, but many patients arepain free within 48 hours and have returned to normalactivity in less than a week. It should be noted,however, long term follow up is not available for suchpatients, and the optimum time of avoiding strenuousactivity to prevent recurrence is not known. Sevendays seems a reasonable time since most patients arereluctant to remain inactive for any longer.These points have significant economic implications

for hospital practice since the universal adoption oflaparoscopic hernia repair will more than double theuse of laparoscopic equipment compared with chole-cystectomy.7 Hospitals' costs are likely to be substan-tially higher for the laparoscopic approach, but thesemay be offset by patients' much earlier returns tonormal productive activity. The absence of a formalgroin incision should also reduce postoperative painand the incidence of wound infections. Manyrandomised trials are now in progress to address theseissues.

1 Society of American Gastrointestinal Endoscopic Surgeons. Guidelines onprivileging and credentialling standards of practice and continuing medicaleducation oflaparoscopic cholecystectomy. AmJ^Surg 1991;161:324-5.

2 Monson JRT, Carey PD, Darzi A, Guillou PJ. Preliminary experience withlaparoscopic colectomy. Lancet 1992;340:831-3.

3 Kurata JH, Haile BM. Epidemiology of peptic ulcer disease. Clin Gasroemerol1984;13:289-307.

4 Dubois F. Laparoscopic vagotomies. In: Berci G, Cuschieri A, Sackier JM, eds.Problems in general surgey. Vol 8. Laparoscopic surgesy. Philadelphia: J BLippincott, 1991:348-57.

5 Corbitt JD. Laparoscopic herniorrhaphy. Surgical Laparoscopy and Endoscopy1991;1:23.

6 Arregui ME, Navarree J, Davis CJ, Castro D, Naean RF. Laparoscopicinguinal herniorrhaphy-techniques and controversies. Surg Clin North Am1993;73:513-27.

7 Polister P, Cunico F, eds. Socio- mic factbook for suwyety. Chicago:American College ofSurgeons, 1989:348-57. (Sections B-L.)

UNDERSTANDING EPIDEMIOLOGY

ConfoundingIn an ideal laboratory experiment the investigator altersonly one variable at a time, so that any effect he observescan only be due to that variable. Most epidemiologicalstudies are observational, not experimental, and comparepeople who differ in all kinds of ways, known andunknown. If such differences determine risk of diseaseindependently of the exposure under investigation, theyare said to confound its association with the disease.For example, several studies have indicated high rates

of lung cancer in cooks. Though this could be a conse-quence of their work (perhaps caused by carcinogens infumes from frying), it may be simply because professionalcooks smoke more than the average. In other words,smoking might confound the association with cooking.Confounding determines the extent to which observed

associations are causal. It may give rise to spuriousassociations when in fact there is no causal relation, or atthe other extreme, it may obscure the effects of a truecause.Two common confounding factors are age and sex.

Crude mortality from all causes in males over a five yearperiod was higher in Bournemouth than in Southampton.However, -this difference disappeared when death rateswere compared for specific age groups. It occurred notbecause Bournemouth is a less healthy place thanSouthampton but because, being a town to which peopleretire, it has a more elderly population.From Geoffrey Rose, D J P Barker, D Coggon. Epidemiologyfor the Uniniatd, 3rd edition, 1993. Available from the BMJBookshop, price C6.95.

1350 BMJ VOLUME 307 20 NOVEMBER1993

on 3 February 2021 by guest. P

rotected by copyright.http://w

ww

.bmj.com

/B

MJ: first published as 10.1136/bm

j.307.6915.1346 on 20 Novem

ber 1993. Dow

nloaded from