ADHESIVE SMALL BOWEL

OBSTRUCTION

Leslie KobayashiTrauma Conference 2013

Overview

Background

Pathophysiology/Etiology

Diagnosis

Treatment

Outcomes

Small bowel obstruction (SBO)

Mechanical obstruction of the small bowel preventing free passage of intraluminal material

May be due to: Bowel wall inflammation, edema or tumor Intraluminal obstruction (bezoar, gallstone,

foreign body) Extrinsic compression (adhesion, hernia,

tumor, volvulus)

Background

Obstruction is the most common small bowel pathology requiring surgical consultation

Accounts for 20% of acute surgical admissions

Costs $800 million annually

Background

Most common causes of SBO

Adhesive 60-75% Malignancies 9-11% Hernias 8-18% IBD 5%

SBO in the virgin abdomen

Historically Primary causes: hernia and volvulus

Currently Primary causes: malignancy, IBD

All cases of SBO in a virgin abdomen should be taken for operative exploration due to high failure rate of NOM and concern for malignancy

Adhesive SBO

Pathophysiology Adhesions are fibrous bands of connective

tissue that form in response to trauma, surgical manipulation, or inflammation

Capillaries & Migration of Fibroblasts

Capillaries & Migration of Fibroblasts

Peritoneal Damage

Bleeding Inflammation

Stable Fibrin matrixFibrinogen

AdhesionBarmparas et al, J Gastrointest Surg 2010

Pathophysiology

Postmortem study Minor procedure: 51% had adhesions Major procedure: 72% had adhesions Multiple operations: 93% had adhesions

93% of 210 patients with abdominal procedures, had intra-abdominal adhesions at re-laparotomy.

Weibel MA. Am J Surg 1973Menzies D. Ann R Coll Surg Engl 1990

Risk factors for SBO

Age Comorbid conditions Prior surgery

Stepwise increase with number of prior procedures

Surgical technique Open technique associated with

significantly higher rates of SBO Risk increased 2-8x’s

Surgery Technique Total # of patients

Adhesion-related readmission

AppendectomyOpenLap.

266,6954,445

1.4%1.3%

CholecystectomyOpenLap.

1417,103

7.1%0.2%

ColectomyOpenLap.

121,058930

9.5%4.3%

Ileal pouch-anal anastomosis Open 5,268 19.3%

Laparotomy for Trauma Open 1,913 2.5%

Gynecological procedures

OpenLap.

24,998773

17.1%0%

Procedure related risk

Barmparas et al, J Gastrointest Surg 2010

Trends over time? ↓risk of SBO with laparoscopy compared

to open Laparoscopy rate ↑over time Has this resulted in ↓rate of SBO?

No

Scott, et al Am J Surg 2012 and Angenete, et al Arch Surg 2012

Etiology

Overall incidence of SBO 4.6%

Top operations leading to SBO

Appendectomy 14-30% Colorectal 21-34% Gynecological surgery 12-28%

Diagnosis

Diagnosis: Clinical presentation

Anorexia, nausea, vomiting, obstipation (90%), constipation (80%), abdominal pain

Abdominal distension, high pitched bowel sounds, tympany, TTP, feculant NGT output/vomitus

Hypocholoremic, hypokalemic metabolic alkalosis

Diagnosis: Radiology findings

Plain films

Benefits: rapid, repeatable, no contrast required, patient does not have to be supine for prolonged time period, can be done at bedside

Diagnosis: Radiology findings

Findings:

Distended loops of bowel Air-fluid levels Step laddering of bowel Lack of air in colon, rectum

Diagnosis: Radiology findings

CT scans

Benefits: high sensitivity and specificity (90%), gives information on intra and extraluminal pathology, highly sensitive for free air/fluid, can identify transition zones, hernias, and bowel ischemia

Diagnosis: Radiology findings

Findings:

Dilated bowel Transition zone from dilated to

collapsed Passage of contrast material (partial)

or not (complete) Bezoars, masses

Treatment

Treatment

Initial management of all patients should include:

NGT decompression Judicious fluid resuscitation Correction of electrolyte imbalances Foley catheter and close monitoring or

UOP +/- central venous and/or arterial catheters

Treatment

Majority of cases (60-82%) can be treated conservatively with non-operative management (NOM)

Three indications for Early Operative Management (EOM):

1: Perforation

Any patient with peritonitis or free air-indicating perforation should go straight to OR

TreatmentPeritonitis

Free air?

Yes

OR

2: Ischemia

Any patients with concerning signs/symptoms for gangrenous or ischemic bowel should also go to the OR ASAP

Signs of bowel ischemia

Clinical: sensitivity 40-50%

Hypotension Tachycardia Fever or leukocytosis, Lactic acidosis SIRS response Deterioration in exam

1983

Physical signs Strangulated(N=21) Sensitivity Specificity PPV

Temp (°F) 99 ± 0.9 24 70 36

Pulse 104 ± 23 52 43 39

No bowel sounds 5/20 25 83 50

Peritonitis 6/21 29 97 86

Clinical symptoms, base deficit, leukocytosis, blood glucose, and SIRS were assessed

→SIRS and base deficit were independently associated with gangrenous bowel

Sensitivity: 92%, Specificity: 96%

PPV: 92%, NPV: 96%

2004

Signs of bowel ischemia

Plain films Bowel wall edema, portal venous gas

CT: sensitivity 85-90% Thickened bowel wall, target sign,

mesenteric stranding, congestion, ascites, pneumatosis, portal venous gas, decreased bowel wall enhancement

TreatmentPeritonitis

Free air?

Yes

OR

NoIschemia?

Fever, Tachycardia, Acidosis

Portal air, pneumatosis, ascites mesenteric stranding

Yes

OR

3: High grade, or closed loop SBO

Patients with high grade SBO, or those with closed loop obstruction should be strongly considered for early operative management

Signs of high grade SBO

> 25mm

Air-fluid levels of differential heightin the same loop

Air fluid width of25 mm or more

Accuracy of plain X-ray to diagnose a high grade SBO

Sensitivity 66-75%

Results of this technique are: Equivocal in about 20%–30% Normal, nonspecific, or misleading in

10%–20%

Maglinte AJ, AJR Am J Roentgenol 1997

Signs of high grade SBO

Sensitivity 80-93%

Contrast does not pass transition zone

Colon with little gas or fluid

Fecalization of small bowel

Diagnosis: Radiology findings

EAST Guidelines 2012

Level 1 recommendation for CT scans in SBO as they can provide incremental increase in information compared to plain films in differentiating grade, severity and etiology that may lead to changes in management

Treatment Peritonitis

Free air?

Yes

OR

No

Ischemia?

Fever, Tachycardia, Acidosis

Portal air, pneumatosis, ascites mesenteric stranding

Yes

OR

No

Closed loop or high grade

SBO?

Yes-OR

Summary: treatment

Three indications for early operative management:

Perforation Ischemia Closed loop or high grade obstruction

All others can be considered for NOM

Treatment Peritonitis

Free air?

Yes

OR

No

Ischemia?

Fever, Tachycardia, Acidosis

Portal air, pneumatosis, ascites mesenteric stranding

Yes

OR

No

Closed loop or high grade

SBO?

Yes-OR No-obs

Principles of NOM

Bowel rest, NGT decompression, fluid resuscitation

Serial abdominal exams and blood tests, consider serial abdominal films

Explore if deterioration in clinical exam, or new e/o ischemia or perforation

Keep in mind…

NOM

Delay to OR is associated with:

Longer LOS Increased incidence of bowel

necrosis and need for bowel resection Increased mortality Increased morbidity

NOM

Given risks of delay to surgery:

How long should NOM trial last?Studies suggest 48hrs although can

be longer in pSBO

NIS data suggest delay of ≥4d associated with 64% increase in mortality and increased LOS

Schraufnagel et al, J Trauma 2013

Are there any decision making aids?

NOM

EAST Guidelines 2012

Level 2 recommendation

Consider water soluble contrast administration for prognosis and/or treatment in patients who fail to improve within 48hrs

Water soluble contrast

Hyperosmolar radiopaque agent

Potential aid in prognosis Passage of contrast into LB may predict

successful NOM Failure of progression predicts need for OR

Theoretically decreases bowel wall edema and may promote resolution of SBO

Br J Surg. 2010 Apr;97(4):470-8.

Water-Soluble Contrast (WSCA) – Diagnostic and Therapeutic role

• 50–100ml Gastrografin or 40ml Urografin administered orally

• Abdominal plain radiographs after 4 h, 8 h or 24 h to follow contrast through the GI-tract

Br J Surg. 2010 Apr;97(4):470-8.

Water-Soluble Contrast (WSCA) – Diagnostic and Therapeutic role

Meta-analysis of 14 prospective randomized controled studies

If the contrast reaches the colon within 4–24 h, obstruction will resolve without operation in 99% of patients.

Br J Surg. 2010 Apr;97(4):470-8.

Water-Soluble Contrast (WSCA) – Diagnostic and Therapeutic role

Timing n Sensitivity Specificity PPV NPV

4-8h 312 95 99 100 85

24h 196 99 97 99 97

Effect of WSCA: Need for surgery

Effect of WSCA: Hospital length of stay

Conclusion

Water-soluble contrast was effective in predicting the need for surgery in adhesive SBO (sensitivity 96%, specificity 98%)

In addition, it reduced the need for operation and shortened hospital stay.

Br J Surg. 2010 Apr;97(4):470-8.

Water-Soluble Contrast (WSCA) – Diagnostic and Therapeutic role

Outcomes

Outcomes

Mortality 3-8%

Rates of recurrence 15-20% over 5 years

Rate of recurrence, # of recurrences, and time to recurrence significantly better in Operatively Managed compared to NOM group

Outcomes California OSHPD database 32,583 patients admitted in 1997 with

SBO 76% NOM 24% OM

OM group associated with Decreased mortality, decreased rate of

readmissions, fewer readmissions, and longer time to readmission

Foster, et al JACS 2006

Summary

1. Adhesions account for the majority of SBO in the US

2. Clinical exam and xrays reliably diagnose SBO

3. Early OM should be undertaken in patients with perforation, ischemia, and high grade or closed loop SBO

Summary: When to operate?

4. NOM successful in majority of patients, but shouldn‘t exceed 4d

5. Consider use of Water-soluble contrast agents for both diagnostic and therapeutic purposes

6. Operative management can decrease the rate and number of recurrences, and prolong the time to recurrence