Imaging the postoperative patient: long-term complications of gastrointestinal surgery

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1 DOI /s REVIEW Imging the postopertive ptient: long-term complictions of gstrointestinl surgery Dniel Rmos-Andrde 1 & Luís Andrde 1 & Ctrin Ruivo 1 & Mri Antóni Portilh 1 & Filipe Cseiro-Alves 1,2 & Luís Curvo-Semedo 1,2 Received: 24 Decemer 2014 /Accepted: 24 Novemer 2015 # The Author(s) This rticle is pulished with open ccess t Springerlink.com Astrct Ojectives The ojectives of this review re (1) to ecome cquinted with the long-term complictions of surgery of the gstrointestinl trct, nd (2) to pprecite the pproprite use of imging in the ssessment of long-term complictions. Bckground Gstrointestinl trct surgery comprises group of procedures performed for vriety of oth enign nd mlignnt diseses. In the lte postopertive setting, dhesions nd internl hernis re the most importnt complictions. nd they cn e further complicted y volvulus nd ischemi. At present, computed tomogrphy (CT) is the workhorse for evluting lte postopertive complictions. Accurte imging ssessment of ptients is essentil for dequte tretment plnning. Imging findings or procedure detils In this pictoril essy we will review the most frequent long-term complictions fter gstrointestinl surgery, including dhesions, fferent loop syndrome, closed-loop ostruction, strngulted ostruction, internl hernis, externl hernis, nstomotic strictures nd disese recurrence. Exmples will e depicted using iconogrphy from the uthors imging deprtment. Conclusions Knowledge of the most frequent complictions fter gstrointestinl surgery in the lte postopertive period is of prmount importnce for every rdiologist, so tht potentilly life-thretening situtions cn e promptly dignosed nd dequte therpy cn e plnned. * Luís Curvo-Semedo curvosemedo@gmil.com 1 2 Medicl Imging Deprtment, Coimr Hospitl nd University Centre,Coimr,Portugl Fculty of Medicine, University of Coimr, Coimr, Portugl Teching points Long-term postopertive complictions of gstrointestinl trct surgery cn e divided into procedure-relted nd disese-relted ctegories. The most common procedure-relted complictions re internl hernis nd dhesions. The most frequent disese-relted complictions re minly ssocited with neoplstic or inflmmtory recurrence. Computed tomogrphy is the most useful exmintion when such complictions re suspected. Keywords Postopertive complictions. Intestinl ostruction. Afferent loop syndrome. Adominl herni. Surgicl dhesions Introduction An cquintnce with the types of surgery, including the most common nstomosis, nd with their most frequent complictions re the first steps in preventing misdignosis of potentilly life-thretening complictions following gstrointestinl surgery. The rdiologist is often fced with ltered ntomic findings tht hmper the ility to differentite etween n expected postopertive finding nd rel compliction. Therefore, communiction with the referring surgeon is strongly dvised in such situtions efore performing dignostic exmintion. Gstrointestinl contrst studies re more commonly used to look for immedite postopertive complictions, such s intestinl lek or nstomotic dehiscence. Computed tomogrphy (CT) is currently the workhorse for evluting lte postopertive complictions, with the exception of mgnetic resonnce imging (MRI) for suspected recurrence of rectl cncer or inflmmtory owel disese.

2 Tle 1 Long-term postopertive complictions of GI trct surgery Lte postopertive complictions cn e clssified s procedure- or disese-relted [1] (Tle1). Adhesions nd internl hernis re the most importnt procedure-relted complictions in the lte postopertive period, nd cn e further complicted y volvulus nd ischemi. Anstomotic strictures re lso reltively frequent following GI trct surgery. Disese-relted complictions re typiclly relted to disese recurrence involving oth neoplstic nd inflmmtory conditions. Procedure-relted complictions Internl hernis Procedure-relted: Hernition (internl nd externl) Adhesions Afferent loop syndrome Anstomotic strictures Disese-relted: Neoplstic recurrence Inflmmtory owel disese recurrence Internl hernis (IH) re defined s the protrusion of the viscer through norml or norml peritonel or mesenteric perture within the peritonel cvity [2 4]. These hernis cn e either congenitl or cquired. The mjor clssifictions of internl hernis include prduodenl (53 %), pericecl (13 %) nd trnsmesenteric hernis (8 %), hernis through the formen of Winslow (8 %) nd intersigmoid hernis (6 %) [2, 4]. Although prduodenl hernis re clssiclly regrded s the most prevlent, the incidence of trnsmesenteric hernis (TMH) hs een growing given the incresed numer of opertive procedures tht involve Roux-en-Y surgery, such s gstric ypss surgery nd liver trnsplnts [2, 3]. In fct, IH re lmost s frequent cuse of ostruction s dhesions in ptients who receive liver trnsplnts with Roux-en-Y nstomosis confection [5]. Cliniclly, IH cn e symptomtic, or cuse nonspecific intermittent dominl pin or full-fledged strngulted ostruction (the most common presenttion). As these hernis re difficult to identify cliniclly, imging plys pivotl role in their evlution. Hernition of the owel loops through the defect cn e trnsient phenomenon tht cn further confound dignosis. Clinicl or imging evlution performed during symptomtic period is more likely to revel the normlity [6]. Trnsmesenteric hernis re prticulrly prone to complictions (volvulus nd strngultion), nd symptom onset is usully more cute thn in other types of internl hernis [2, 6]. They occur in the dult popultion who hs hd dominl surgery, especilly Roux-en-Y surgery, which is now the most frequent type of cquired internl herni ccording to recent study [2, 3, 6]. Trnsmesenteric internl hernis cn e divided into three groups: through defect in the trnsverse mesocolon with retrocolic Roux lim (the most common type), through defect in the smll-owel mesentery t the jejuno-jejunl nstomosis, nd posterior to the Roux jejunl loop (Peterson defect) [7, 8]. It is importnt to differentite smll-owel ostruction (SBO) due to internl herni from ostruction due to dhesions, since the former requires emergent surgicl tretment [9]. A comintion of clinicl nd imging criteri cn help distinguish etween the two. In SBO secondry to dhesions, n rupt ngultion of owel segment is more likely to occur. Smll owel ostruction due to IH tends to present much longer fter surgery, nd collection of dilted smllowel loops lying djcent to the dominl wll, without overlying omentl ft nd with centrl displcement of the djcent colon, ssocited with crowding, distortion, nd engorgement of mesenteric vessels, is seen on CT [7]. A cluster of loops of smll owel cephlic to the trnsverse mesocolon etween the stomch nd spleen in the left upper qudrnt is typicl of the trnsmesocolic sutype, nd group of smllowel loops in peripherl dominl loction is typicl of the trnsmesenteric jejuno-jejunl type [7, 10]. The Peterson type of TMH hs no distinctive findings, ut ecuse the c Fig. 1 c Surgiclly-proven TMH in ptient with dominl pin. There is no ft etween the fluid-filled dilted smll-owel loop nd the nterior dominl wll (curved rrow in ). The smll-owel loops re plced lterl to the descending colon with medil devition of it (rrows in ). There is twisting of the owel loops nd mesentery whirl sign (rrowhed in c)

3 Fig. 2, Ptient with dominl pin ecuse of closed-loop SBO. Both ends of fluid-filled distended closed loop tper fusiformly, in wy similr to ek the ek sign (rrows in ). Mesenteric edem (str in ), peritonel fluid nd reduced enhncement of the owel wll comprtively to other smll-owel loops (rrowhed in ) re lso evident, findings tht suggest strngultion. A slightly crnil imge shows the twisting of the mesenteric vessels t the mesenteric root whirl sign (curved rrow in ) hernition most often occurs from right to left, there my lso e cluster of dilted loops in the left upper qudrnt [2, 7]. Multi-plnr reformtion (MPR) oriented to the Bintestinemesentery-directed plne^ nd verticl to this plne should e performed in order to increse the likelihood of detection of the hernil orifice. This cn e identified s n re where the mesentery of the closed loop converges on given multiplnr view; on the plne verticl to the ffected intestine, the hernil orifice shows round/ovl configurtion of the converged mesentery [8]. Among other signs of internl hernis following Rouxen-Y gstric ypss surgery, which include smll-owel ostruction, clustered smll-owel loops, smll owel other thn duodenum locted ehind the superior mesenteric rtery, presence of the jejunl nstomosis to the right of the midline, nd engorged mesenteric lymph nodes, the swirling of the mesenteric vessels is most predictive [11] (Fig. 1). Trnsmesenteric hernis re generlly more difficult thn other IH to dignose y CT ecuse they lck confining sc nd thus re locted potentilly nywhere within the domen [2, 6]. Left-sided prduodenl IH is the leding differentil dignosis of TMH, ut hs different distinctive chrcteristics, such s sc-like mss of dilted owel lterl to the ligment of Treitz tht displces nd indents the trnsverse colon nd stomch [6]. Volvulus nd ischemi of the hernited smll owel re frequent complictions of TMH. Typicl findings of strngulted closed-loop ostruction re seen (whirl Fig. 3 Ptient with closed-loop ostruction of the smll owel. Fluidfilled dilted loops of smll owel with rdil distriution (strs) nd stretching of the mesenteric vessels (rrows) reseen Fig. 4 Sme ptient s Fig. 3. Fluid-filled dilted loop of smll owel with U/C shpe configurtion representing closed-loop ostruction. There is lso reduced enhncement of the owel wll (rrows), densifiction of the mesentery (str) nd free fluid (rrowhed) suggesting strngultion

4 point of trnsition etween dilted nd collpsed owel loops) nd dditionl signs, such s: Fig. 5 Ptient with strngulted ostruction. Engorged mesenteric veins (rrows) ssocited with mesenteric edem (str) nd free fluid (rrowhed) re seen sign, engorged lood vessels, mesenteric edem, scites nd owel wll thickening) [6]. Closed-loop owel ostruction nd incrcertion A closed-loop owel ostruction or incrcertion is type of mechnicl intestinl ostruction in which segment of owel is occluded t two seprte points long its length, lmost lwys djcent to ech other, s the result of single constrictive lesion. This ntomicl configurtion cn led to twisting of the loop long its long xis, nd therey produce owel volvulus, with susequent compromise of the vsculr supply nd ischemi strngulting ostruction. Although incrcertion nd strngultion re relted phenomen, incrcertion my occur without strngultion nd my resolve spontneously [12]. Closed-loop ostruction is most commonly cused y postopertive dhesive nds, nd is less frequently due to internl or externl hernis [13]. CT findings of closed-loop ostruction (incrcertion) include the clssicl sign of mechnicl ostruction ( distinct The ek sign, representing the ek-shped morphology of the dilted loop towrd the ostruction, when imged in longitudinl orienttion (Fig. 2) The whirl sign, which corresponds to the whirled ppernce of the mesenteric vessels in the middle of the ostruction point (Fig. 2). The tightness of the whirl pttern reflects the degree to which the mesentery nd vessels re rotted. Although hmpered y low sensitivity (60 %), recent study hs shown tht if this sign is present on CT scn, ptient is 25 times s likely s ptient without it to undergo surgery [13, 14]. A rdil distriution, which refers to stretched mesenteric vessels converging towrd the centrl point of ostruction (Fig. 3). The U/C sign, which refers to the shpe of the incrcerted distended loop (Fig. 4). Although it hs een descried on xil imges when the loop is horizontlly oriented, it cn lso e well depicted on sgittl nd coronl reformtions when the loop is verticlly oriented [13]. Multiplnr reformtted imges my prove decisive in chieving correct dignosis of closed-loop ostruction [13]. CT findings of strngulted ostruction include wll thickening, ltered pttern of enhncement of the owel wll, dilted mesenteric veins, mesenteric edem, scites, pneumtosis intestinlis, pneumtosis portlis nd pneumoperitoneum. The most common CT finding in owel ischemi, lthough nonspecific, is owel wll thickening. It is cused y murl edem (low ttenution efore contrst dministrtion), hemorrhge (high ttenution efore contrst dministrtion) nd/ or superinfection of the ischemic owel wll. If unenhnced CT is not performed prior to contrst-enhnced CT, the ility to differentite etween intrmurl hemorrhge nd hyperemi nd/or hyperperfusion is impired [15]. c Fig. 6 c Ptient with owel ischemi secondry to strngulted ostruction. Gs inside the mesenteric veins (rrowheds in ) coming from owel segment tht lso presents intrmurl gs (curved rrows in, ) fter perfortion of gngrenous owel wll re seen. Portl venous gs (rrows in c) nd pneumoperitoneum (strs in, c) re lso evident

5 Fig. 7, Ptient with n incisionl externl herni. A cluster of fluid nd ir-filled dilted owel loops is found inside the hernil sc on the right flnk (strs). Nrrowing of the fferent nd efferent ends of the closed loop t the site of hernil neck cn lso e pprecited the ek sign (rrows in ). Stretching of the mesenteric vessels is seen on the coronl reformtion (rrowhed in ) On contrst-enhnced CT, highly specific ut less sensitive finding is sent or diminished prietl contrst enhncement. In some cses, prolonged enhncement due to delyed return of the venous lood, with susequent slowing of the rteril supply, cn lso e seen [16]. As ischemi dvnces, venules in the mesentery ecome engorged with lood. Mesenteric ft strnding due to edem nd/or scites is lso nonspecific CT finding in cute owel ischemi (Figs. 4 nd 5). In recent prospective study, fluid in the mesentery djcent to norml (thickened, dilted or oth) owel loops ws the individul sign most frequently ssocited with strngultion (88 %) nd hd n extremely high negtive predictive vlue [17]. When owel wll thinning rther thn thickening occurs, trnsmurl smll-owel infrction hs proly lredy ensued. In this setting, it is lso more likely for pneumtosis intestinlis, pneumtosis portlis nd pneumoperitoneum to develop (Fig. 6).Pneumtosisintestinlis iscusedydissection of luminl gs into the owel wll cross the compromised mucos. Portomesenteric venous gs is due to the propgtion of tht gs to the mesenteric venous system, towrds the liver. Free intrperitonel ir represents perfortion of the gngrenous owel loop [15, 16, 18]. Clinicl nd lortory differentition etween simple ostruction nd incrcertion/ strngultion is very difficult, nd tretment dely is mjor prognostic fctor for incresed moridity nd poor survivl. CT is extremely useful in discriminting etween these two entities, nd it plys n instrumentl role in determining pproprite ptient tretment (medicl versus surgicl). Findings of Fig. 8 Type 0 Bprstoml herni^: the peritoneum follows the wll of the owel, with no sc formtion (rrows). Type I Bprstoml herni^: onlythe owel forming the colostomy is seen, with sc <5 cm (rrows). c Type I prstoml herni: the hernil sc contins only the owel loop forming the colostomy, ut its width is lrger thn 5 cm (rrows). d Type II prstoml herni: there is omentum (str) within the hernil sc (rrows). e Type III prstoml herni: there re owel loops (rrowhed) other thn the one forming the stom (rrows) t the right flnk; note lso n incisionl herni t the midline in the umilicl region (curved rrow) c d e

6 Tle 2 Type 0 Type I Type I Type II Type III Prstoml herni CT clssifiction Peritoneum follows the wll of the owel, with no sc formtion Only owel forming the colostomy, with sc <5 cm Hernil sc contining only owel forming the colostomy, with sc >5 cm Hernil sc contining omentum Hernil sc contining intestinl loop other thn the owel forming the stom closed-loop ostruction should result in close monitoring, nd if clinicl symptoms persist, erly surgery is suggested. In ptients in whom signs of strngultion re lredy evident, emergency surgery is mndtory [12]. Externl hernis An incisionl herni is type of externl herni cused y n incompletely heled surgicl wound. Typiclly, peritonel ft, with or without incorportion of owel loops, protrudes through the hernil defect (Figs. 7 nd 8e). Stoml nd prstoml hernis re sutype of incisionl hernis tht involve hernition of the owel or the mesentery t the site of or djcent to stom [19]. Even fter closure of the enterostomy, the ostomy site cn remin potentil re of hernition [20]. Most prstoml hernis occur within 8 months of surgery. The etiology is multifctoril nd includes chrcteristics such s oesity, mlnutrition, incresed intrdominl pressure nd chronic respirtory disese [21]. Prstoml hernis re quite common, with n expected prevlence of %, depending on clinicl or CT Fig. 10 Smll-owel diltion due to n dhesion in ptient with dominl pin. There is n rupt nrrowing nd cute ngultion of the loop, with no identifile underlying lesion (rrow). There is lso scites (str) nd mesentery densifiction due to edem (rrowheds), findings suggestive of strngulted ostruction evlution. However, unless ostruction, perfortion or stom mlfunction occur, there is no need for surgicl repir [19 22]. A recent study suggested CT clssifiction for prstoml hernis ccording to the possile contents of the hernil sc, s follows: type I (hernil sc contining the stom loop), type II (sc contining omentum), type III (sc contining owel loop other thn stom) (Tle 2). Type 0 nd Type I re considered norml findings nd not true hernis [21] (Fig.8). Incrcertion nd strngultion cn supervene with incisionl hernis, s with ny other dominl wll hernis Fig. 9, Adominl CT of ptient with ostructive symptoms. There is diffuse fluid diltion of smll-owel loops (rrowheds in ) proximl to smll segment of dilted smll owel incrcerted t the hernil sc (rrow in ). The presence of ft strnding nd moderte mount of free fluid t the site (curved rrows in, ) should rise suspicion of strngulted herni

7 Insights Imging Fig. 11, Adhesion-relted SBO in ptient with cute dominl pin. Dilted smllowel loops closely pplied to the nterior peritoneum (strs in ), stretching of the owel loop (curved rrow in ) nd trction deformities of the owel loop (rrow in ) re seen elsewhere. Strngultion occurs with typicl findings s descried ove, such s owel wll thickening, free fluid nd ft strnding [19] (Fig. 9). Adhesions Adhesive nds re funiculte structures tht form etween the peritoneum of tissues nd orgns, often s result of injury during surgery. They re composed of firous tissue nd undnt ft [8]. Adhesions re the most common cuse of owel ostruction fter surgery, nd they constitute the leding cuse of Fig. 12 Ptient with chronic dominl pin nd smll-grde owel ostruction. A ft density nd is seen crossing the owel loop in oth the coronl nd xil plnes ft-ridging sign (circles) long-term reopertion following dominl nd pelvic surgery. Bowel loops tht pss through the orifice etween the dhesive nd nd the peritoneum form type of internl herni tht cn evolve to closed-loop ostruction. CT findings in this sitution re similr to those in other internl hernis (cf. "Internl hernis"). Overt ostructive smll-owel disese relted to dhesions cn e further sudivided into simple ostruction nd closed-loop or strngulted ostruction [23]. Nevertheless, non-ostructive sutype cn lso e found. These ptients my hve intermittent or lowgrde smll-owel ostruction, for which CT hs poor

8 Fig. 13 Upper gstrointestinl series of ptient with dominl pin nd vomiting who hd undergone prtil gstrectomy with Billroth II reconstruction following gstric denocrcinom 9 yers erlier. There is nonfilling of the fferent loop (str) nd filling defect t the loction of the nstomosis (rrows) sensitivity. CT enteroclysis or dynmic MRI my e importnt options for etter demonstrting the trnsition point [8, 23]. The dignosis of smll-owel ostruction due to dhesions is presumed when ll other cuses of ostruction hve een ruled out on CT. The min CT findings tht suggest dhesions s the culprit of the ostruction include nrrow zone of trnsition without n identifile lesion (such s mss, wll thickening or denopthy), cute ngultion of the smllowel loops, trction deformities, stretching of the owel loops, smll-owel loops closely pplied to the nterior dominl wll nd the Bft-ridging sign^ which represents the dhesive nd itself s cord-like structure contining mesenteric ft tht ridges two peritonel surfces [8, 9](Figs.10, 11, nd12). Smll-owel ostruction cused y dhesions lmost lwys requires surgery. When intestinl strngultion supervenes, immedite dominl surgery is mndtory. However, the risk of dditionl dhesions increses s the numer of surgeries increses. Fig. 14, Adominl CT of the sme ptient s in Fig. 13. A fluidfilled tuulr structure (strs in ) crossing the midline etween the ort nd the superior mesenteric vessels (rrowheds in ) is seen, with ssocited gllldder distension (curved rrow in ) fferent-loop syndrome cused y tumor recurrence, depicted s n irregulr enhncing mss t the nstomosis site (rrow in )

9 Fig. 15, Adominl CT of ptient with progressively worsening dominl pin, nuse nd vomiting who hd undergone Billroth II prtil gstrectomy for gstric crcinom 5 yers erlier. There is mrked fluid-filled diltion of the duodenum (strs in ), ssocited with gllldder distension (rrow in ) nd intrheptic nd extrheptic iliry diltion (rrowheds in, ), cused y n internl herni with volvulus s shown y the twisted configurtion of the owel loops t the left upper qudrnt (rrow in ). The scites (curved rrow in ) suggests supervened ischemi Afferent loop syndrome Afferent loop syndrome (ALS) represents mechnicl ostruction of the fferent loop, occurring in %of gstroenterostomies, oth in Billroth II surgery (the duodenum is the fferent loop) nd Whipple or Roux-en-Y procedures (the Roux segment is the fferent loop) [9, 24, 25]. Most cses of ALS re due to dhesions, internl herni, nstomotic stricture or recurrent tumor [9]. It cn lso e secondry to preferentil gstric emptying into the fferent loop due to norml surgicl nstomosis or ecuse of efferent loop ostruction resulting in fluid ccumultion t the fferent loop [24, 26]. The ck pressure from the dilted fferent loop cn cuse iliry dilttion nd cute pncretitis [26]. The dignosis my not e cliniclly suspected, s ALS my present mny yers fter the initil surgery [27]. Although gstrointestinl contrst studies cn e helpful in the dignosis of this condition y showing non-filling of the fferent loop, non-ostructed fferent loops re not normlly filled in 20 % of cses. Preferentil filling nd retention of orl contrst in dilted fferent lim for t lest 60 min is nother finding consistent with fferent loop syndrome [24, 26] (Fig. 13). CT is the most importnt imging tool in estlishing the dignosis nd determining the site, degree nd cuse of ALS. A fluid-filled tuulr or C-shped structure contining smll ir ules in the right upper qudrnt or crossing the midline etween the ort nd the superior mesenteric vessels, with vlvule conniventes projecting into the lumen, in symptomtic ptients fter gstroenterostomy is chrcteristic (Fig. 14). Recognition of these distinctive findings should prevent the misdignosis of pncretic pseudocyst [24, 27]. The coronl plne is most helpful in detecting the cuses of ALS so tht dequte tretment cn e chosen [24]. Complictions of ALS such s iliry dilttion, pncretitis or strngultion re lso redily identified on CT [26] (Fig.15). Anstomotic strictures Fig. 16 Wter-solule enem shows short nstomotic stricture (rrow) nd proximl dilttion in ptient who hd undergone nterior resection of the rectum some months erlier The incidence of nstomotic strictures depends on the type of surgery performed. The cuses for the stricture re not yet clerly understood. For exmple, in gstric ypss ptients, it is thought tht the period of time during which the nstomosis is exposed to n inppropritely lrge volume of gstric cid results in ongoing inflmmtion, ulcertion nd stricture formtion [28]. Severl studies lso suggest n increse in the incidence of strictures with the use of stpler versus hndsewn

10 Insights Imging Fig. 17, Ptient with complete lower intestinl ostruction who hd undergone nterior resection of the rectum some yers erlier. Wter-solule enem showed no progression of contrst eyond the colonl nstomosis (rrow in ). Pelvic CT reveled diffuse wll thickening (rrows in ) of the colonl nstomosis (note the surgicl stples) due to histologiclly proven firotic stenosis Fig. 18 Pelvic CT scn of ptient who underwent dominl perinel resection. Posteriorly to the ldder, there is n ill-defined irregulr soft tissue mss corresponding to post-surgicl firosis (rrow). Note the posterior displcement of the ldder (str) into the pre-scrl spce Fig. 19 Contrst-enhnced pelvic CT of 79-yer old womn with ostructive symptoms who hd undergone sigmoidectomy for denocrcinom 1 yer erlier. There is symmetric thickening of the owel wll nd hypodense mss djcent to the colorectl nstomosis (rrows), cusing proximl owel distension (rrowheds), confirmed s tumor recurrence t surgery

11 Fig. 20 Thorcic-dominl CT of ptient who hd undergone totl gstrectomy for denocrcinom some yers erlier. There is evidence of soft tissue mss next to the surgicl nstomosis, encircling the descending ort (rrows) nd corresponding to non-resectle neoplstic recurrence nstomosis, oth for gstrojejunostomy nd colorectl nstomosis [1, 29]. For ilel pouch nl nstomosis, metnlysis found n incidence of nstomotic strictures of 9.2 % [30]. The resulting symptoms reflect the degree of luminl stenosis, nd include dominl pin, distention, nuse nd vomiting. Gstrointestinl contrst studies re the clssicl method for dignosing nstomotic strictures. They llow cler depiction of the stenosis with delyed pssge of contrst mteril, pre-stenotic owel distension nd possile perinstomotic fistule (Figs. 16 nd 17). CT hs ecome incresing importnt when n nstomotic stricture is eing considered, nd is now the preferred imging modlity in this prticulr setting, since it is le to demonstrte not only the nstomotic normlity ut extr-wll structures s well [1]. CT findings include focl owel wll thickening t the nstomosis nd distended proximl owel loops filled with fluid or desiccted stool [31] (Fig.17). Depending on the loction, strictures cn e treted with mnul/endoscopic diltion or surgery [31]. Disese-relted complictions Neoplstic recurrence Tumor recurrence cn e the cuse of ostruction severl months or yers fter surgery. CT is the modlity of choice in this setting, s it clerly shows n enhncing mss or symmetric wll-thickening ner the site of the initilly resected tumor. Most ptients who undergo dominl perinel resection or nterior resection of the rectum will present n ill-defined prescrl midline mss 3 to 5 cm in dimeter tht decreses in size with time (lthough it cn persist indefinitely) nd ecomes progressively more distinct in seril imging firosis / grnultion tissue finding tht cn esily e mistken for tumor recurrence [19] (Fig. 18). In contrst, tumor recurrence mnifests s welldefined soft tissue mss tht grows on seril imging nd ecomes ill-defined s it ecomes more infiltrtive [19] (Figs.19 nd 20). Fig. 21, CT enterogrphy of ptient with Crohn s disese who hd previously undergone segmentl enterectomy. Note the surgicl mteril t the ilel-ilel nstomosis (curved rrows in, ). There is fistulous trct etween the thickened ilel segment ner the nstomosis nd the duodenum (rrows in ). MIP coronl reformtion () shows mesenteric engorgement (strs in ) nd lymphdenopthy (rrow in ) in the vicinity of thickened owel wll segment (rrowheds in )

12 Fig. 22 A fluid collection with thickened, hyper-enhncing wll corresponding to n scess (str) is seen nteriorly to owel wll segment with thick wlls t the level of the neo-terminl ileum (rrows) in ptient who hd lredy undergone surgery due to Crohn s terminlileitis Inflmmtory owel disese recurrence Crohn s disese Most ptients with Crohn s disese (CD) require surgery t some point in their lives, nd cn develop relpses either t the intestinl nstomosis or fr from it, t ny other segment of the GI trct. These relpses cn occur in the form of new strictures, fistule or scesses [1]. A comintion of symptom ssessment plus endoscopy is still the gold stndrd for ssessment of recurrence in postopertive CD ptients [32]. CT enterogrphy/enteroclysis should e the first rdiologic procedure performed in ptients with cute symptoms when recurrence is suspected. MR enterogrphy/enteroclysis is incresingly eing considered s the first-choice exmintion in cute excertion in child or young dult with known CD, ecuse it is rdition-spring technique in ptient who will likely e sujected to multiple seril exmintions [33]. MRI is lso the technique of choice for the dignosis nd chrcteriztion of perinl fistule. The ility to directly demonstrte the owel wll, djcent orgns, mesentery nd retroperitoneum renders CT nd MR superior to ny other exmintion in dignosing the complictions of CD. Both methods cn evidence hyper-enhncing owel wll thickening, mesenteric edem, prominent mesenteric vessels (the Bcom sign^) nd lymphdenopthy, s well s possile fistule or scesses (Figs. 21 nd 22). Although CT is y fr the most frequent exmintion undertken in this setting, we cnnot simply discrd gstrointestinl contrst studies just yet. A recent study found smll owel follow-through (SBFT) to e more sensitive nd specific thn CT for detecting recurrent CD in the neo-terminl ileum ecuse of its ility to depict phthoid ulcers not detectle on CT. Other findings of Crohn s recurrence t SBFT re luminl nrrowing, thickened folds nd deep ulcertions (Brose thorn^ ulcers) [34] (Fig. 23). Fig. 23 Brium follow-through of ptient with ctive Crohn s disese: there is severe irregulr nrrowing of the neo-terminl ileum, with seprtion from djcent owel loops nd with some res of colestoning (curved rrow) nd liner deep ulcers (rrows)

13 Ulcertive colitis Ulcertive colitis is normlly continuous from the rectum to the colon. Totl proctocolectomy is the definitive tretment for the disese, ut two other types of surgery re usully performed to ovite the disdvntges of permnent colostomy. Ptients who receive totl colectomy with ileorectl nstomosis re t risk for disese recurrence t the rectum, nd thus clinicl nd endoscopic follow-up re dvised. When proctocolectomy with ilel-nl pouch is chosen, there is n incresed proility of the ptient developing pouchitis (ilel pouch inflmmtion). The dignosis depends on clinicl, endoscopic nd histopthologicl dt, nd there is usully no role for dignostic imging in this setting [1]. Conclusions In conclusion, knowledge of the norml ppernce of the domen nd pelvis fter GI trct surgery is mndtory for every dignostic rdiologist, prticulrly in n emergency setting. 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