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The essential radiographic features seen on supine and erect
abdominal X-rays are: gaseous distensionof thebowel proximal to the
obstruction, the presence of air-fluid levels and, in complete SBO, the
absence of gas distal to the obstruction. The presence of parallel
striations(causedbythevalvulaeconniventes)runningtransversely,right
acrossthelumen,arechracteristicofdistendedsmallbowel.Colonicgas
shadowslackthispattern.
Ultrasonography(US)
US has been reported by enthusiaststo defineaccurately thesite of
obstruction and establish whether strangulation is present. It requires
access to an expert, which most institutions lack. We, and presumbly
you,havenoexperiencewithit—sojustforget‘boutit!
CT
Wehavetoadmit—whereverCTisreadilyavailable,ithasreplaced
abdominal X-rays as the primary method of imaging of the abdomen.
ManyofusarecalledtoseepatientssuspectedofhavingSBOonlyafter
aCThasbeenobtained.Butevenifyouarenottheonetoorderthe
CT,trytoeducatethosewhodo,toseetoitthatthe‘oral’(perNG
tube)contrastusediswater-soluble—thewater-solublecontrastwill
actlikea‘Gastrografin®challenge’(tobediscussedbelow).
However,ifyouneeda‘quickCT’anddonothavetimetodecompress
thestomach,theoralcontrastcanbeomitted—thefluidinsidethebowel
lumen acting like ‘contrast’ and the i.v. contrast (given only if renal
functionisOK)delineatingthebowelwall.
WhatyoushouldlookforontheCTislistedin Table21.1.
WhileCThasbeenshownaccuratelytodefinethelevelofobstruction
(the‘transitionpoint’)andidentifystrangulatedbowel segments,itdoes
notmeanthatitisindicatedinall casesofSBO. Take,for instance,
the ‘frequent traveler’ who presents to the ER every other month with
adhesiveSBO,respondingtoadayofNGdecompression—CT-induced
‘radiotherapy’hasnotbeenproventobeavaluablemodeoftreatment...
CT,however,isa‘must’inthefollowingcircumstances:
•
History of abdominal malignancy. A CT finding of diffuse
carcinomatosis indicates that symptomatic management is the
correctoption.
•
The‘virgin’abdomen(seebelow).
•
Clinical picture not consistent with the usualpartial adhesive
SBO.Paralyticileusmaybeeasilyconfusedwith apartial SBO(
Chapter 45): there is air in the large bowel, the contrast may go
through but the patient remains symptomatic; fever and/or
leukocytosismaybepresent.CTwilldocumenttheunderlyingcause
responsiblefortheparalyticileus,suchasacuteappendicitis.
•
EarlypostoperativeSBO( Chapter45).
•
Post-laparoscopicSBO( Chapter45).
You should integratethe CT findingswiththe clinical picturein your little graymatter
laptopwhenmakingdecisions.
Management
Thetimelinematters:apatientwhohasbeenpukingfor3daysat
home is different from the one rushed to the ER after the first
spasms of mid-abdominal colic! Intuitively, the former will require a
more vigorous resuscitation but a shorter spell of non-operative
management—“ifhedidn’topenupbeforenow…”.
Fluidandelectrolytes
There is hardly a need to remind you that SBO results in significant
losses, or sequestration, of extracellular fluid and electrolytes (into the
lumenofthebowel,withinitsedematouswall,and—astheobstruction
progresses — into the peritoneal cavity), which have to be replaced
intravenously. The aggressiveness of fluid management and
hemodynamic monitoring depends on the condition of the individual
patient. The fluid of choice is Ringer’s lactate. The charting of urine
output — in a catheterized patient if indicated — is the minimal
monitoring necessary. Oh, how often we find such patients on the
‘medicalfloors’without a Foleycatheter— nobody knowingthevolume
ofurinetheyhavepassed(sometimesevenwithoutanasogastrictube).
It seems that this will never change — sluggish internisits running
around, glued to their iPhones on which the entire corpus of medical
wisdomisloaded,nurses(sorry,‘patientcareattendants’)everimmersed
in the electronic medical record — and the poor old shriveled lady,
spewing,dryingout,untilyouarrive!
Evenpatientsscheduledforurgentlaparotomyforstrangulationrequire
adequate pre-operative resuscitation ( Chapter6). Patients with SBO
sometimes have intra-abdominal hypertension (we have seen patients
with distal SBO presenting with a full-blown abdominal compartment
syndrome), which may falsely raise their cardiacfilling pressures (CVP,
wedge).Thesepatientsrequireevenmoreaggressivefluidadministration
tomaintainanadequatecardiacoutput( Chapter33).
Nasogastric(NG)aspiration
“Myworkessentiallyhasbeenthatofplumberofthealimentarycanal.I
have worked on both ends, but largely in between”, wrote Owen H.
Wangensteen, of Minneapolis. And indeed, by the 1930s he had
introduced the NG tube as a crucial and indispensable aid in the
managementof SBO.Sohow sad andpathetic it isto find —80years
later — patients admittedfrom theER with the diagnosis ofSBO, with
theirabdomensdistended, their pajamas stained in green, and notube
stickingfromtheirnose!
A large NG tube(atleast18Fr in diameter) is needed. TheNGtube
hasboththerapeuticanddiagnosticfunctions.Itcontrolsvomiting
(and reduces the risk of aspiration), but its main aim is to
decompress the dilated stomach and gut proximal to the
obstruction.Inasimpleobstruction,decompressionofthebowelresults
inrapidpainreliefandalleviatesthedistension.Essentially,thesegment
ofintestineproximaltotheobstructionanddistaltothegastroesophageal
junction behaves like a‘closed loop’ — decompression of the stomach
withanasogastrictubeconvertsittoasimpleobstruction;pain,nausea
and vomiting are relieved. Note that in strangulation or closed-loop
obstruction,thepainpersistsdespitenasogastricaspiration.
Insertion of an NG tube is extremely unpleasant. Many patients
remember it as the most horrendous experience of their hospital stay
(and would certainly resist fiercely any attempt at re-insertion). The
procedurecanhoweverbemademuch‘kinder’—softentherigidtubeby
immersionfor aminute ortwo inveryhotwater,spraythe nostrilof the
patient with a local anesthetic, and lubricate the tube. There is no
advantageinconnectingtheNGtubetoasuctionapparatus;drainageby
gravityis aseffective.(Longnaso-intestinaltubes [Cantor, Linton,Moss
—youmayhaveheardsomeofthenames]areagimmickwithunproven
benefits—requiringcumbersomemanipulationandcausingdelaywhen
operation is necessary. Those who still mention them in your
departmentalmeetingstendtobesenile.)
Whentooperate?
An hour or two of fluid replenishment is compulsory in the
managementofevery patient.Reassessyour resuscitated and NG
decompressed patient. What is the pattern of pain now? Is there
improvementonabdominalre-examination?
Immediateoperationisrequiredinaminorityofpatientsinwhom
theprobabilityofstrangulationorbowelcompromiseishigh:those
whodonotimprove,thosewhoexperiencecontinuouspain,orthosewith
significant abdominal tenderness combined with the features stated
above (e.g. fecal NG aspirate, SIRS). Of course, radiological features
shouldalsobetakenintoaccount.
An initial non-operative approach is often possible because most
patientsimproveatfirston the‘drip-and-suck’regimen.Itwouldbesafe
tobet,atthisstage,thatpatientswithradiologicalpartialobstructionwill
eventuallyescapesurgery,whereas thosewithcomplete obstructionwill
eventuallyvisittheoperatingroom.Buthowlongisitsafetocontinue
withconservativemanagement?
Some surgeons would abort the conservative trial at 24 hours if the
patient fails to ‘open up’, because of the nagging concern about
strangulationeveninabenign-lookingabdomen.Othersarepreparedto
persevere,upto5daysinacarefullymonitored patient— especiallyin
patientswhogiveahistoryofrepeatedepisodesofadhesiveSBO.
Intheabsenceofanimmediateindicationforoperation,wefavorthe
useofanoralwater-solublecontrastmedium(e.g.Gastrografin®)as
soonasthediagnosisofSBOismade.Gastrografin®,ahyperosmolar
agent that promotes intestinal ‘hurry’, plays, we believe, two roles:
diagnostic-prognosticandtherapeutic.
The‘Gastrografin®challenge’
Aftertheinitialgastricdecompression(anhourortwo),instill100ml
Gastrografin® (make sure that your patient does not get barium —
Chapter4) via the NG tube which isthen clamped. After 4-6 hours,a
plain abdominal X-ray is obtained. This is not a formal radiological
studyunderfluoroscopy.
•
The presence of contrast in the large bowel proves that the
obstructionispartial.Inmostoftheseinstances,theGastrografin®is
verysoonpassedperrectumaswell.InpartialSBO,Gastrografin
®
isoften therapeuticas itexpedites theresolution oftheobstructing
episode.
Ontheotherhand,failureofGastrografin®toreachthe
colon within 6 hours indicates a complete obstruction. The
probability of spontaneous resolution after a failed Gastrografin
®
challengeisverylow;mostofthesepatientswillrequiresurgery
anywaysowhynotoperateonthemnow?
•
AnothersignofafailedGastrografin®challengeisthefailureofthe
contrasttoevacuatefromthestomachandenterthesmallbowel—
itsignifiessignificantbackpressureintheobstructedbowel.Thus,if
you see the stomach full of Gastrografin®, you know that further
delayisfutile—youneedtooperate!
These days a CT Gastrografin® challenge works the same way
and provides more information. So if we admit a patient during the
evening hours with a suspected adhesive SBO, and without features
mandating an immediate operation, we perform the Gastrografin
®
challenge, and if by the morning the contrast has not reachedthe
colonwewouldoperate.Ifyouseethecontrastinthecolon,expectthe
patient to defecate very soon. If CT without Gastrografin® has been
obtained, we would order the challenge in the morning and plan to
operateearlyafternoon—thatisiftheobstructionisnotrelieved.
Of course, the results of the Gastrografin® challenge test should be
correlated with the whole clinical picture. Note that Gastrografin® may
pass across a chronicsmall bowelnarrowing. Thus,for theobstructive
episodetobeconsidered‘resolved’,theabdominalsymptomsandsigns
shoulddisappearaswell.
Thisapproachhasledustomodifythatoldaphorism;thenewversion
should read: “Never let a patient with a complete intestinal
obstructionescapeanoperationformorethan24hours.”
The Gastrografin® challenge is safe. The most feared potential
complication is aspiration of the hyperosmolar Gastrografin® into the
lungs,causingedemaandpneumonitis.However,aslongasyourpatient
canprotecthis airways (he is not obtunded and the stomach has been
decompressedbeforehand),thisshouldnothappen.
Antibiotics
In animal models of SBO, systemic antibiotics delay intestinal
compromiseanddecreasemortality.Inclinicalpractice,thereisnoneed
for antibiotics in patients treated conservatively, and we operate
whenever the suspicion of intestinal compromise is entertained. A preoperativedoseofantibioticsisadministeredprophylactically;beyondthis
thereisnoneedforpostoperativeantibioticsevenifbowelresectionhas
been performed. The only indication for postoperative antibiotic
administration would be longstanding bowel gangrene with
establishedintra-abdominalinfection.
Theconductoftheoperation
Most surgeons still prefer the open approach. About the
laparoscopicone—pleaseseethesectionbelow.
Hereisouradvicefortheconductoftheoperation:
•
The incision for abdominal re-entry has been discussed in
Chapter 10 but we need to remind you to be careful in avoiding
iatrogenic enterotomies with their associated postoperative
morbidity.Finding yourwayintothe peritonealcavitymaytake
time, but be patient, for this is the longest part of the
procedure. The rest isusually simpler.In thisscenario the gentle
handofthe‘slow’surgeonismuchpreferredoverthatofthemacho
cowboy—hastemayopenthegatetoanighmare.
•
Findaloopofcollapsedsmallbowelandfollowitproximally.It
will lead you to the point of obstruction just distal to the dilated
obstructedintestine.Nowdealwiththecauseofobstruction,beita
simpleband or a bowel kink.Mobilizethe involved bowel segment
using sharp and blunt dissection with traction applied on the two
structurestobeseparated.
•
Resectonlywhenbowelisnon-viableoritisimpossibletofreethe
obstructedsegment.Frequently,an ischemic-looking loop of bowel
isduskyafterbeingreleased.Donotrushtoresect;coverthebowel
with a warm, wet laparotomy pad and wait patiently; it will usually
pinkupwithin10minutes.Ifnot,itrequiresresection.
•
Concentrate on the loop which is responsible for the obstruction;
thereis no needtofreethe wholeintestinebydividing allthe
remaining innocent adhesions. This maneuver may be
cosmetically appealing, but adhesions lysed today will reform
tomorrow. As aptly stated by Timothy Fabian: “Lysis of all small
boweladhesionsisnotrequiredbecauseIbelievethatthebowelis
‘lockedintheopenposition’bythesechronicadhesions.”
Wedisagreeslightly;ifwehavetoperformabowelresection,wefreealltheadhesionsdistalto
theanastomosis to preventa second narrowpart causing backpressure on theanastomosis
andthenperhapsleadingtoaleak…Ari&Jon
•
Occasionally,multiplepointsofobstructionappeartobepresent
with no clear area of demarcation between dilated and collapsed
bowel.Thisismorecommoninpatientsaftermultipleoperationsfor
SBO or those with early postoperative SBO. In this situation the
wholelength of the‘frozen’gut has tobeunraveled — again,very
carefully and patiently in order not to damage the bowel. This is
tedioussurgeryindeed!
•
In this day and age, with so many patients having mesh
implanted in their tummies you will occasionaly have to deal
withit.Anexistingmesh,withthevisceraadherenttoit,couldmake
anyabdominalre-entrydreadful,evenifitisnotthedirectcauseof
obstruction.Whenopeninga‘meshedabdomen’,trytogainaccess
totheperitonealcavityaboveorbelowthemesh,andworkyourway
fromthere.Often,youwillneedtocutthemeshatitscenter.When
separating the intestine from the mesh remember that it is
preferabletoleaveatinybitofmeshadherenttothebowelthan
toleave apieceof bowelonthemesh. Removethe segment of
meshwhichcausedtheobstructionbutthereisnoneedfora‘total
meshectomy’ — any incorporated mesh away from the problem
zoneshouldbeleftundisturbed.Whenclosingtheabdomenyoucan
includethemeshinthesutureline.
•
WhattodowithaventralherniaassociatedwiththeSBOwillbe
discussed in the next chapter. Remember, your main aim is to
relieve the SBO — don’t be obsessed withfancy hernia repairs at
thisstage.
How to manage an iatrogenic intestinal injury during
adhesiolysis
Transmural enterotomies should be repaired transversely. We
recommendarunning,one-layered,absorbablemonofilamenttechnique.
Someusetwolayers…Ari
Interruptedsutures would do as well. Superficialserosaltears should
beleft alone.Areaswhere themucosa poutsthroughthe defectshould
berepaired.
Decompressornot?
Ah yes, the proverbial double-edged sword. On the one hand,
excessive bowel distension impedes abdominal closure and
contributes to postoperativeintra-abdominal hypertension with its
well-known deleterious physiological consequences. On the other
hand, bowel decompression may contribute to postoperative ileus and
even cause peritoneal contamination. We, like most others, would
decompress the distended bowel if abdominal closure seems to need
excessive tension. Gently milk the intestinal content towards the
stomach,fromwhereitis sucked throughtheNG tube by the unhappy
anesthetist. Milk the bowel very gently by successively squeezing the
loops between your fingers in a sequential manner, as the obstructed
bowelisthin-walledandveryeasilyinjured.Donot pulltoo hardon the
mesentery—itmaytear(rememberthatinjurytotheperitonealsurfaces
promotesformationofadhesions).Palpatethestomachfromtimetotime
—iffull,gentlysqueezeandshakeittorestorepatencyoftheNGtube.
ForadistalSBO,youmayalsomilkthesmallbowelcontentstowardsthe
collapsed colon. Open decompression through an enterotomy is
unwise (nay, it is stupid), given the risk of gross bacterial
contamination. Needle decompression is not effective with the thick
bowelcontents. Obviously, open decompressionshouldbe performed if
bowelis being resected— insert aPoole sucker or a large sumpdrain
connectedtothesuctionthroughtheproximallineofboweltransection
and gently ‘accordion’ the bowel onto your suction device. Watch with
satisfaction how the suctionbottle is being filled with fluidy s**t — one
sensesagreataccomplishment.
Beforeclosing,runthebowelagainformissedenterotomies.Checkfor
hemostasis, as extensive adhesiolysis leaves large oozing raw areas;
intraperitoneal blood promotes ileus, infection and more adhesion
formation. Close the abdomen safely. SBO is a set-up for wound
dehiscenceandatickettotheM&Mconference.
Awordaboutpatience
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