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The next step in assessing this patient should be determining
wheretheobstructionisandthebesttestforthatisaGastrografin
®
enema,althoughthismaybedifficulttoobtainbecauseitisoftenhardto
convincea radiologistto do it.However,it’sthe safestandbest testfor
identifyingthelocationoftheobstruction.Irecommendthatthesurgeon
bepresentwhenthetestisperformed,asitisadynamictestandviewing
theimagesthemselvestoseethelocationoftheobstructionisbestdone
inreal time withtheradiologist. Yourpresence there mayalsomotivate
theradiologisttoleavehisnicecomfybed,astheseemergenciesalways
tendtohappeninthemiddleofthenight.Thisinvestigationalsohelps
determinewhethertheobstructioniscompleteorpartialandthisin
turnmaymarkedlyinfluenceyourplantomanagethepatientinthe
immediatefuture. ACTscancombinedwith an enema is also good
and has the added benefit of defining the surrounding structures and
detecting any metastatic disease. These patients receive both i.v. and
rectal contrast. Whether a Gastrografin® enema or a CT-enema is
performedwillmostlikelydependonwhichtestisofferedatyourhospital
andwhichtest theradiologistfeels morecomfortableperforming.Inthe
end, what is important is that they are inserting contrast via the
anus(notthemouth!)andimaginginsomeway!
Differentialdiagnosis
Dr. Gershon Efron, a very wise surgeon who has been a mentor to
many(Iamnotbiasedeventhoughheismyfather),hasoftenexplained
thattheGItractfromthemouthtotheanusisjustatubeandthatwhen
thinkingaboutwhatcausesablockagein thistube, weneed tothink of
things that can occur outside the lumen of the tube, in the wall of the
tube, and inside the lumen of the tube. This concept is depicted in
Table27.1whichliststhevariousetiologiesofcolonicobstruction.
A key differentiation to be made is whether this is a pseudoobstructionoratruemechanicalobstruction.Pseudo-obstruction
(Ogilvie’ssyndrome) is an adynamic ileus of the colon that rarely requires surgical
resection.Differentiationbetweenamechanicalandpseudo-obstructionisdoneeitherwithan
endoscopeorinthedepartmentofradiology.Beforeoperatingonacolonicobstructionitis
imperativetoruleoutpseudo-obstruction(seebelow).
Butnowletusreturntoour‘classicalpatient’whosuffersfromthemost
commoncauseofcolonicobstruction—cancer.
Management
Theinitialmanagementshouldbeundertakenintheemergencyroom.
Even though we do not think the patient has a small bowel
componentto hisobstruction,placing a nasogastrictubewill help
prevent further build-up of fluid and gases within his colon and
shouldbeundertakenintheER. Itisalsocrucialto ensurethat heis
well hydrated with i.v. fluids; it may also be prudent to correct any
symptomaticanemiawithbloodproducts.
Nowyouhavetodecidehowtoproceedandthisdependsonthelevel
oftheobstructionanditsassumedcause.Italsodependsonthedegree
oftheobstruction.Patientswithcompleteobstructionandsignificant
colonicdistensionresulting in a cecal diameter greater than 10cm
requireurgentintervention—thesepatientsarebestservedwithan
operation. There is another option for patients with incomplete
obstruction,andthatistheplacementofacolonicstent.
Tostentornottostent,thatisthequestion!
Colonic stents (if local expertise is available) are a reasonable
optionforpatients with a left-sided obstruction. However,patients
with an obstruction proximal to the splenic flexure (uncommon
situation) are usually better served by an extended right
hemicolectomyandileocolicanastomosis.Anexceptiontothisruleis
thepresenceof significant metastatic disease.Inthissituation insertion
of a stent may be attempted even for an obstruction proximal to the
splenicflexure.This can limit morbidity and allow the patient to enter a
palliativepathwayofcaremorerapidly.
Inthosewithoutmetastaticdiseaseweviewcolonicstentingasa
temporizing intervention that allows decompression and
mechanicalpreparationofthecolonpriortoanelectiveresection.
Stenting is a more definitive solution if the patient has a burden of
metastatic disease that suggests a limited life span. However, bear in
mindthefollowingpracticalpoints:
•
Patients with a complete obstructionon Gastrografin® enema
are not eligible for stents as it is often not possible to pass
eitherawireorthestentthroughtheobstruction.
•
Ifthepointofobstructionisatthesplenicflexure,oratakinkinthe
sigmoidcolon,placementofastentisoftennotfeasible.Stentsare
insertedwith a ratherinflexibledeployment mechanism, sowhilea
wire can be passed through the obstruction and around a curve,
passingthemechanismthatwill deploythe stentaround thiscurve
is often not possible and indeed not advisable as it can lead to
perforation. Therefore, stenting is a good option when the
obstructionislocatedinarelativelystraightpieceofcolonand
whenthepatientdoesnothaveacompleteobstruction.
Stentingforobstructingcarcinomaoftherectum?
Placingrectalstentsiscontroversial.Idonotlike placingstents in
the rectum if the patient has an obstruction from cancer even if
technically feasible. Modern management of rectal cancer dictates
thatifwehave a large obstructing tumor itshouldbetreatedwith
neoadjuvant therapy. In patients treated this way, the combination of
tumornecrosisfromtheneoadjuvanttherapyandpressurefromthestent
may lead to perforation, converting a curable patient to one with
disseminated disease. These perforations generally occur 4-6 weeks
after completing the radiation, as the cancer continues to undergo
necrosis.Therefore,inobstructingrectalcancer,mypreferenceisto
perform a laparoscopic diverting stoma todecompress the colon,
andpermitneoadjuvanttherapypriortosurgery.
Thereisdebateastowhetheranileostomyorcolostomyshould
be performed. I think that the colon should be decompressed and
thereforeacolostomy should be made. Ideallythe colostomy should
beplacedasdistallyinthesigmoidcolonaspossibletopermitthis
area to be resected when the definitive operation is performed.
However, thismaynot be feasible andamore proximal stoma,evenat
thetransverse colon,may beneeded. Ifthe obstructionisnotcomplete
and the patient is symptomatic, then a diverting loop ileostomy is an
attractive option as gas and some stool will still decompress past the
rectallesionand the tumor itself should shrink — andthelumenof the
bowelwiden—astheradiationandchemotherapyaredelivered.
Anotherdifficultywithcolonicstents,particularlyintherectum,is
that they can migrate. If this happens they can come to rest on the
pelvicfloormusculatureattheleveloftheanorectalringandthiscauses
significantpainandirritation.They can also migrate into the anal canal
andoutoftheanus.Onceastentisdeployeditisverydifficulttoremove
withoutsignificanttraumaandthereforeoperationsareoftenrequiredto
remove migrated stents. So to avoid converting a stage II or stage III
rectal cancer to a stage IV rectal cancer with a perforation, and also
becauseofthe difficulties of stent migrationintherectum, I would not
recommendusingastentforarectalobstruction.
In summary —I apologize for tiring you with such a long spiel — I
think the opportunity to stent these patients with mechanical
colorectalobstructionisrare.Theyneedtohavetheobstructionin
arelativelystraightpieceofcolon,distaltothesplenicflexure,and
notwithintherectum.Italsorequiresasmallopeningtobepresentto
placethestent.Studieslookingattherisksandcomplicationsofstenting
versus surgery have been varied in their results; however, the one
randomizedcontrolledtrialthatwasinitiatedtocomparecolonicstenting
versussurgeryfor acute obstruction was discontinuedearlybecause of
thecomplicationratesinthestentedpatients.
Withalltheaboveinmind,andassumingthatcolonicstentingis
not available to you, the management of patients diagnosed with
mechanicalcolonicobstructionwillbesurgical.
Theoperation
Well, we’ve made the diagnosis of colonic obstruction and are now
proceedingtotheoperatingroom.Thisparticularpatienthasacomplete
obstruction in the sigmoid colon (non-stentable) confirmed by
Gastrografin® enema; his cecum is 12cm in diameter and he is fairly
tender,sohisoperationshouldnotbedelayed.Ontheotherhand,ina
patient with an incompetent ileocecal valve, without significant
cecaldistensionIwouldprefertooperateduringthedaytime…
Nowwhatshouldwedo in the operating room? When operating on
thesepatients,Iliketosortthemintotwogroups,thesickonesand
thenotsosickones.Ourpatientisinrelativelygoodshape—withfluid
resuscitation, he has become less dehydrated, his tachycardia has
resolved,andhehasagoodurineoutput—therefore,wecouldattempt
toperformadefinitiveprocedureaswillbedetailedlater.
Operatingon‘sick’patients
Whenpatientsaresickwefirstmustresuscitatethemadequately(
Chapter 6). This may require a trip to the intensive care unit for more
invasive monitoring, such as arterial lines and even (the controversial)
SwanGanzcatheterplacement.
Forsickpatients,wereallymustdothequickest,safestthing.Ifit
issafeto resecttheobstructinglesion,thatshouldbedoneand anend
colostomyformed. Inotherwords,Hartmann’sprocedureistheway
to go. There are patients who are too ill even to undergo a
Hartmann’s procedure and therefore a diverting loop colostomy
shouldbefashioned.
Evaluationoftherestoftheabdomenincludingtheviabilityofthe
colon is essential. For massive distension with necrosis either in the
cecum or in other parts of the colon, the patient may require a total
colectomy regardless of how sick they are at the time of presentation.
Perforation of the cecum secondary to distension found in
associationwithaleft-sidedlesionrequirestotalcolectomy—with
anendileostomyandclosureoftherectalstump.
Afewwordsaboutstomas(seealso Chapter14)
Stomas can either be end stomas, loop stomas, or end loop
stomas.Afourthkindofstomathatcanbecreatedinthecolonisablow-
hole colostomy. Finally, a cecostomy is also an option, though not
preferredinthissituation.Mychoiceinformingstomaswouldbeanend
colostomyifpossible(partoftheHartmann’sprocedure).However,ifthe
patientcannotundergoresectionoftheprimarymass,aloopcolostomy
should be fashioned. These may bequite largegiven thedistension of
theproximalcolonandmaybedifficulttomanagebecauseoftheirsize.
Theyalsoarepronetoprolapsewhichcancausefurthercomplicationsin
thefuture.Therefore,weliketoavoidloopcolostomies,ifpossible.
When you have a really sick patient who will not tolerate much of
anything, a blow-hole colostomy — where you merely fashion an
openinginthetransversecolon,toeither theright orleft ofthe midline,
maturing the anti-mesenteric colonic wall to the dermis — can be
performed.Itwillallowfordecompressionofgasandstool,andperhaps
permit the patient to recover somewhat, so that they may eventually
undergoamoredefinitiveprocedure.Finally,cecostomiesarenoteasy
tomanageandarenotfavouredinthissituation.Ifacecalperforationis
found, and it is felt not tobe safe to performa total colectomy,then a
betteroptionthanacecostomy wouldbeaquickileocolicresectionwith
the formation of an end ileostomy and a mucous fistula, to allow for
decompression.
We,on the other hand, have had a favorable experience with cecostomy to decompress the
coloninsickpatientswithbigobstructivemasses—cancerordiverticular—asthefirststage
oftheirmanagement.(See Chapter14and Figure14.5.)MosheandDanny
Whenyouarenotsosurewhatiscausingtheobstruction…
Sometimes you don’t know whether cancer (common) or diverticular
disease(rare) isthecause oftheobstruction. Diverticularobstruction
may be caused by a phlegmon that is stuck to everything in the
pelvis and this can look very much like cancer. Before undertaking a
‘mass resection’ involving ovaries,ureters or the uterus, I like to make
absolutely sure that this is necessary. Such a resection for benign
disease would be rash. If the patient is not sickthen performing a
flexibleendoscopyintheoperatingroomandvisualizingthelumen
of the obstructed colon gives you a good idea of the cause of
obstruction.IfIcan’ttellifthemassisbenignormalignant(anditis
stuck to other structures) then I divert proximally, take multiple
biopsiesand returntoaddressthemassata laterdate—just as I
mightdoifthepatientweretoosicktowithstandamajorresection.
Operatingon‘fit’patients—thedefinitiveoperation
Whatto dowiththe fitpatient?This dependsonthe levelofthe
obstruction:
•
Whentheobstructionisfoundproximaltothesplenicflexure,
the best operation is anextended righthemicolectomy —usually
withanileocolicanastomosistothedescendingcolon.
•
Whentheobstructionisfounddistallyinthecolon,theoptions
formanagementare:
resectionwithprimaryanastomosis;
resection with intra-operative colonic lavage and primary
anastomosis;
aHartmann’sprocedure(likein‘sick’patients…);
when performing a primary anastomosis there is always the
option of adding a diverting loop ileostomy to protect your
anastomosis.
Of course, before the operation you have discussed with the patient
that placing a stoma may be necessary. But whether to construct a
primaryanastomosisordoastomaissometimesnotaneasydecisionas
depictedin Figures27.1aand27.1b.
Figure27.1a.“Idiot!Whydidyouanastomose?”
Figure27.1b.“Idiot!Whydidn’tyoudoananastomosis?”
Theconductoftheoperation
Decompressionofthecolon
IdoamidlinelaparotomybecauseIdon’tfindaroleforlaparoscopyin
colonic obstruction. It is advisable to have a means of rapidly
decompressing the colon. The abdominal wall provides counter
pressuretothecolonduringobstructionandonenteringtheabdomenat
operation the colon, relieved of this counter pressure, will significantly
distend and may even perforate. Serosal tears can certainly happen
ratherquickly.
Ialwayshaveavailablea2-0silktoplaceapursestring,together
withalarge14-gaugeAngiocath™connectedtosuction,toperform
adecompression.Itistherapidexpansionofcolonicgas,notstool,that
causes perforation or serosal tears when opening up the abdomen.
Therefore,itisimperativetoevacuatethegasrapidly.Soonopeningthe
abdomen, we drape blue towels around the bowel and insert a purse-
string suture on the anti-mesenteric taenia — just above the level of
obstruction,asthis areawillbe resectedwiththespecimen.Sometimes
this is not possible and then we have to do it more proximally, in the
transversecolon.WealsohavePoolesuction1availableincasethe14gaugeAngiocath™isnotlargeenoughtodecompresseffectively.Once
we place the purse-string suture, wejust stabthe Angiocath™into the
colon,removetheneedleanddecompressusingthesuctionattachedto
thecatheter.Iftheneedleisrapidlyoccludedbythinfluidys**t,wemake
asmall colotomywithin thepurse-string sutureand insertthesucker—
and watch with great satisfaction as the suction bottle rapidly fills with
litersofbrowneffluent.Oncetheneedleorsuckerisremoved,thepursestringsutureissecureddown,andinverted—ifthissectionisnottobe
resected. This procedure prevents further distension of the colon and
greatlyreducestheriskofserosaltearsandperforationofthececum.
Commonly,inlessadvancedobstruction, thecolonisdistendedmainly withgas:takealarge-
boreneedle,insertitholefacingupthroughtheteniacoliabout4cm,turn180°sothatthehole
faces down, push it through mucosa and let the air out. The smell tells you that it works!
Removetheneedleandthevalveeffectsealsthehole,withnoneedforsutures.Ari
Decompressionalsohelpswithmobilizationofthecolon,whichis
otherwisedifficultin the face of massive distension. Once thathas
beencompleted,wecanproceed.
If the obstruction is from a cancer that is not fixed to other
structures; if the patient is stable and healthy and in reasonable
nutritionalstatus; ifthecondition oftheproximalbowel isoptimal
— it is notsignificantlythinned or inflamed— then resection and
primaryanastomosisarepossible.
Iusuallyinitiatemobilizationofthecolonawayfromtheaffected
area.Thismeansfirstmobilizingthedescendingcoloniftheobstruction
is in the sigmoid. This is especially true if there is an inflammatory
processinthecoloncausingittoadheretotheleftlateralabdominalwall
orpelvicsidewall.
Ifthecolonismassivelydistended,butviableandhealthyanda
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