Sbo-small Bowel Obs

7/31/2019 Sbo-small Bowel Obs

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Case. 74 yo F wit h a h / o breast cancer s/ p mastec t omy, s / p cholecyst ec tomy, hysterec t omy, andmult iple hernia repairs was admit t ed to t he hospit al wit h 3 days of nausea and vomit ing. Upon furt herquestioni ng, she had experienced no BM s or fl at us in t he last 48 hours. On admission, she wasafebril e, BP=79/ 49, P=132, RR=16 on room air. Init ial WBC=6.4, BUN/ Cr=17/ 1.5, up fr om her baseline10/ 1.0. Her K=3.2. Acut e abdominal series xrays showed air-f luid levels wit h dist ended loops of smallbowel .

Small Bowel Obst ruct ion

Er in Sut cli f f e, MD Harborvi ew Medical Center

Definition. Intestinal obst ruct ion may be cat egorized according t o: t he degree of obst ruct ion,t ermed part ial vs. compl ete; t he absence or presence of int est inal ischemia, t ermed simple vs.st rangulat ed; and the site of t he obst ruct ion, small int est inal vs. colonic. A closed loop obst ruct ion is amechanical obst ruct ion in which bot h the pr oximal and dist al parts of t he involved intestinal segment

are occluded.Clinical Presentation. Crampy abdominal pain, nausea, vomit ing, abdominal dist enti on, +/ -obst ipation (a partial or a new complet e can st i l l pass fl atus). A more dist al obst ruct ion will producemore f ecalent em esis, w here a more proxim al one wil l cause less abdominal dist enti on and its emesiswil l be more bilious.

Ddx . SBO, paralyt ic i l eus, Ogilvie s syndrome (int est inal pseudo-obst ruct ion w here chronically di lat edcolon loops over on itself causing an effect ive obst ruct ion, t reated w it h decompression, w it h either NGt ube or colonoscopy).

Causes of obstruction.A) Extrinsic

Adhesions (most common), volvulus, herniasB) IntrinsicTumors, stri ct ures, at resia, stenosis, congenital malf ormat ions

C) Gunk inside the l umenBezoars, f ecal m att er, int ussuscepti on, gallstones.

Physical Exam. Vital signs check for fever, which is consist ent wit h ischemia; hypotension andt achycardia are consist ent w it h dehydration oft en seen in SBO. Bowel sounds can be high tinkling orhypoactive. With prolonged obst ruct ion, mot il i t y of bowel slows and bowel sounds can slow/ disappear.Look f or: hernias; scars from prior abdomi nal surgeries; and abdominal masses, seen in t he sett ing of avolvulus or tum or. Abdomen can be tender or nont ender in the presence of a mass. Look for t ympanywhich is c/ w an air f i l led bowel. Perf orm a rectal exam to evaluate a mass or blood (seen in t umors,int ussuscepti on, ischemia). Serial abdominal exams should be perform ed while the patient is in the

hospital .

Diagnosis. Usually made based on history and PE, but the following can also be used: Labs. Not very helpful in SBO except that you can get labs to assess dehydration, and a

met abolic alkalosis can be seen wit h nausea and vomit ing. Elevat ed WBC, m et abolic acidosis,and elevated lactat e level can be c/ w ischemia/ st rangulat ion. Serial labs recommended.

Imaging studies. CXR t o r/ o free air; upright and supine abdominal fi lm s, aka acute abominalseries, t o look for mult iple air-f luid levels wit h dist ended loops of small bowel seen in SBO, butt hey can occasionally be seen in a paralytic i leus as well . Complet e obst ruct ion > 24 hours


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usually won t have gas in the colon or rectum . CT is a good adj unct t est if x-raysindeterminate; can show different calibers in small bowel proximal and distal to theobstruction, the transition point or zone, which is where the bowel transitions from beingdilat ed t o collapsed and helps t o localize the sit e of obstruct ion. A closed loop can appear as adist ended, fluid-f il led U or C shape. Advanced st rangulat ion can show int est inalpneum atosis or hemorr hagic mesent eric changes. CT cannot show adhesions, t heref ore mostsources of obst ruct ion are not seen. Radiologist s have been known t o diff er on whet her t heyuse oral cont rast, b ut IV contr ast i s almost uni versally used. A barium st udy such as anenterocl ysis is recommended in pati ents wit h a h/ o recurring obst ruct ion or a low-grademechanical obst ruct ion to defi ne the precise locat ion and degree of t he obst ruct ion.

How do I know thi s i sn t j ust an il eus? While t he clinical pr esentat ion may be very simi lar t o SBO,paralyti c i leus does not have a source of obst ruct ion. I leus wil l show gas in t he colon and rectum onxrays, CTs show no source of obstruct ion. I leus has abdominal dist enti on, but not usually cram py pain.+/ - bowel sounds present. Look for secondary causes, e.g. post-op, narcoti cs, inf ection, i nflam mat ory.

Treatment. IVF, nasogast ric t ube t o prevent aspirat ion and decompress. Correct any met abolicabnormalit ies, be aggressive about K+ replacement. Nonoperative m anagement is more l ikely t o besuccessful in pat ients wit h part ial compared t o complet e SBO.

What ki nd of anti emet ics can I give? Met oclopromide and other prokinet s are contraindicated inobst ruct ion, and antiem eti cs in general have not been shown t o be effect ive in i leus or SBO. If yout hink ileus is secondary to narcot ics, t x nausea wit h po naloxone, 10 mg qid.When can I d/ c t he NG t ube? Once bowel funct ion re turns, f i r st put the tube t o gravi ty. I f no n / v af t era t r ia l of gravi ty, t he tube can be removed.

STRANGULATION/ ISCHEMIA St rangulat ion is usually seen only in compl ete obst ruct ion, also seen in Richter s hernia where 1

side of t he bowel pokes t hrough a defect where t hat segment can be st rangulated w it houtcausing obstruction

10% of SBO s pr ogress t o str angulat ion No specific sign or sympt om t hat d eclares a patient as st rangulated or a surgical emergency,

but f ever, elevat ed WBC wit h left shift , elevat ed lactat e level & t achycardia can be associated

wit h i t . Pain progressing from crampy t o const ant is also a source of concern. The physicalexam early i n ischemia may not change, but as i t progresses, t he patient wil l show signs ofperit onitis , e . g. localized tenderness, r ebound, guarding.

When do I cal l t he surgeons? Roughly 1/ 2 to 3/ 4 of patient s admit t ed for SBO require operation, involving a laparotom y or

occasionall y a laparoscopy. Surgeri es can includ e a lysis of adhesions, fr eeing of hern ias,removal of sick gut, decompression of bowel and bypassing of lesions.

The risks are t hat as the small bowel di lates, blood f low can be compr omised, causingst rangulat ion, w hich can lead t o necrosis, sepsis, or perf oration.

Call if :A) Patient not r esponding to conservati ve management aft er 48-72 hoursB) Patient has a closed loop obstruct ion

C)

Signs of st rangulat ion are presentD) Patient has a complet e obst ruct ion Some surgeons wil l r ecommend pr e-operative br oad spectr um ant ibiot ics.

Case follow-up. The pat ient w as init ially t reated conservati vely wit h IVF, NG t ube. Her labs andclinical status improved and she had flat us. The next day she st opped having fl atus and had emesiseven wit h the NG t ube connected t o suction. CT scan wit h IV and oral contr ast w as perf ormed,showing complete obstruct ion, and she was t aken to t he O.R. that night. She did well post-operatively, recovering flat us and BM s.


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Clinical Pearls. Continuously monitor SBOs for signs of ischemia with serial vitals, labs, and physical exams Call surgeons imm ediately i f ischemia, cl osed loop, or complet e obst ruct ion present, or if

patient not i mproving aft er 48-72 hours of conservative m anagement . Avoid proki net ic agent s in SBO Be aggressive wi t h rehydrat ion and electr olyt e replacement

References.1. Townsend: Sabiston Textbook of Surgery, 16 t h ed., Copyr ight 2002 W.B. Saunders Company2. Metoclopr amide: Drug Infor mation, Lexi -Comp Onli ne, 1978-present.3. Feldman: Slei senger & Fordt ran s Gast roint estinal and Liver Disease, 7 t h ed., Copyri ght 2002 Elsevier, pp.

2113-2128.4. Delabrousse et al, CT of small bowel obstruct ion in adults , Abdominal Imaging, 2003, Mar-Apr; 28(2):

257-66.5. Frager D, Intestinal Obstr ucti on role of CT , Gastr oenter ology Clini c Nort h America, Sept. 1, 2002;

31(3): pp. 777-99.6. Quickel and Hodin. Cli nical Manifest ati ons and Diagnosis of Small Bowel Obstruct ion. In: UpToDate,

Rose, BD (Ed), UpToDate, Wellesley, MA, 2004.7. Quickel and Hodin. Treat ment of Small Bowel Obstruct ion. In: UpToDate, Rose, BD (Ed), UpToDate,

Wellesley, MA, 2004.

Last update: May 11, 2005/ ES

2005 UW GIM

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Sbo-small Bowel Obs