Small bowel obstruction
(Redirected from Intestinal perforation)
Background
- Small bowel obstruction without history of surgery or hernia is malignancy until proven otherwise
- "Never let the sun rise or set on a small bowel obstruction"
Causes
- Adhesions (history of previous abdominal surgeries +LR 3.86 and -LR 0.19)
- Most common cause in developed countries
- Hernia
- Port hernias can occur after laparoscopic surgery
- Malignancy
- Intraluminal strictures
- Crohn's disease
- Radiation therapy
- Mesenteric ischemia
- Intussusception (due to lymphoma as lead point)
- Foreign body (bezoars)
- Trauma (duodenal hematoma)
- Gallstone ileus
- Small bowel volvulus (3-6% of causes of SBO)[1]
Clinical Features
- Abdominal pain
- Colicky
- Periumbilical or diffuse
- Paroxysms of pain occur q5min
- Vomiting
- More common in proximal than distal obstruction
- Bilious (proximal) or feculent (distal ileal)
- Abdominal pain relieved with vomiting positively predictive +LR (4.50-2.82) -LR (0.78-0.35)
- Abdominal distention
- Seen more in distal than proximal obstruction
- +LR (16.8-5.64) -LR (0.43-0.34)
- Inability to pass flatus
- May pass flatus/stool initially
- Takes 12-24hrs for colon to empty
- History of constipation +LR 8.8 and -LR 0.59
- May pass flatus/stool initially
- Dehydration
- Anorexia
- Ischemia (increased intraluminal pressure initially leads to venous obstruction, progresses to frank arterial ischemia)
- Abnormal bowel sounds
- Studies suggest that auscultating bowel sounds is not clinically useful to differentiate between normal and pathologic[2]
Differential Diagnosis
Diffuse Abdominal pain
- Abdominal aortic aneurysm
- Acute gastroenteritis
- Aortoenteric fisulta
- Appendicitis (early)
- Bowel obstruction
- Bowel perforation
- Diabetic ketoacidosis
- Gastroparesis
- Hernia
- Hypercalcemia
- Inflammatory bowel disease
- Mesenteric ischemia
- Pancreatitis
- Peritonitis
- Sickle cell crisis
- Spontaneous bacterial peritonitis
- Volvulus
Constipation
- Behavioral-related
- Lack of exercise
- Diet-related
- Fecal impaction
- Ileus from surgical abdomen
- Bowel obstruction
- Small bowel obstruction
- Large bowel obstruction
- Malignant bowel obstruction
- Specific causes: tumor, stricture, hernia, adhesion, volvulus
- Painful anorectal disorders (e.g. anal fissure, hemorrhoids)
- Medical causes
- Hypothyroidism
- Electrolytes
- Hypokalemia
- Medication-related
- Opiods, antipsychotics, anticholinergics, antacid, antihistamines
- Constipation (peds)
Evaluation
Labs
- CBC
- WBC >20K suggests bowel gangrene, abscess, or peritonitis
- WBC >40K suggests mesenteric vascular occlusion
- Chemistry - degree of dehydration, evidence of ischemia (acidosis)
- Lactate - sensitive (90-100%), though not specific marker of strangulation
Imaging
- Use the 3/6/9 rule for bowel imaging
- Upper limit of 3cm for small bowel, 6cm for colon, and 9cm for cecum
- Xray
- Acute Abdominal Series
- Upright chest film: rule out free air
- Upright abdominal film: air-fluid levels:
- Supine abdominal film: width of bowel loops most visible (estimate of amount of distention)
- String of pearls sign (small pockets of gas along the small bowel that are trapped between the valvulae conniventes) is virtually diagnostic[5]
- Small bowel diameter ≥3cm is associated with obstruction
- Sen 75% Spec 66% +LR 1.6 -LR 0.43
- Air in colon or rectum makes complete obstruction less likely (esp if symptoms >24hr)
- If patient does not tolerate upright position left lateral decub abdominal film can substitute
- CT A/P with IV contrast
- Consider if plain films are non-diagnostic
- Can show closed-loop obstruction, evidence of ischemia
- Per American College of Radiology PO contrast is no longer indicated
- Modern CT Scanner (0.75mm slices): Sen 96%, Spec 100%, +LR infinity -LR 0.04
- Historical CT scanner meta-analysis: Sen 87% Spec 81%, +LR 3.6 -LR 0.18
- Ultrasound for SBO
- Sen 97%, Spec 90%, +LR 9.5, -LR 0.04 (four studies, 2 done by EM residents and 2 by radiology residents)
- MRI for SBO - Sen 92%, Spec 89% +LR 6.7 -LR 0.11
Management
Volume resuscitation
- IV fluid resuscitation with electrolyte repletion
- Assessment of need for operative vs nonoperative management
Nasogastric tube
- 14 French
- Intermittent low wall suction
- Nasogastric fluid losses can be replaced with NS + KCL (30-40 meq)
- There is some evidence to suggest nasogastric tube decompression was not associated with decreased bowel ischemia or need for surgery[6]
Oral Contrast
- Both diagnostic and therapeutic (draws water into the bowel stimulating peristalsis)
- Associated with decreased hospital stay, more rapid resolution of symptoms
- Repeat CT scan may be helpful to detect early signs of bowel ischemia
- Repeat plain films are not helpful (only detect perforation)
Gastrografin PO
- Alternative to operative management if early obstructive process
- Gastrografin through NG or OG decreases bowel wall edema and increases bowel motility[7]
- Diagnostic and therapeutic[8]
- 100 cc of gastrografin through NG tube
- Transit may be observed through serial radiographs
- Contrast within the large bowel within 24 hrs suggest partial SBO
- Contrast failing to reach large bowel within 24-48 hrs suggests complete obstruction, requiring laparotomy
- Therapeutic, may reduce necessary operative rate by ~75%[9]
- Avoid barium as it becomes inspissated in bowel, causing complete obstruction[10]
- Gastrografin is water-soluble and relatively safer if perforation occurs
Non-operative Management vs. Operative
- 75% of patients are amenable to non-operative management
Operative Management
- 25% of patients admitted for SBO require surgery
- Surgery is indicated for patients with:
- Increasing pain, distention, or peristent high NGT output
- Necrotic bowel
- Closed-loop obstruction (incarcerated hernia, small bowel volvulus, cecal volvulus)
- Fever, leukocytosis, peritonitis
Antibiotics
- Not typically indicated, unless evidence of concurrent ischemia or infection
- See peritonitis antibiotics
Disposition
- Admit
Prognosis
- In the context of advancing malignancy with widespread peritoneal metastases, bowel obstruction is common and often indicates a poor prognosis
- A less interventional and more comfort based approach to treatment may be appropriate
- See Malignant bowel obstruction for details
See Also
References
- ↑ Roline CE and Reardon RF. Disorders of the Small Intestine. Rosen's. Edition 8. Chapter 92. 2014. 1216-1224.
- ↑ Felder S, Margel D, Murrell Z, et al. Usefulness of Bowel Sound Auscultation: A Prospective Evaluation. J Surg. 2014; 71(5):768–773.
- ↑ http://www.thepocusatlas.com/bowel/
- ↑ http://www.thepocusatlas.com/bowel/
- ↑ Maglinte DDT, Reyes BL, Harmon BH, et al. Reliability and role of plain film radiography and CT in the diagnosis of small-bowel obstruction. AJR 1996; 167:1451-1455
- ↑ Berman, DJ et al. Nasogastric decompression not associated with a reduction in surgery or bowel ischemia for acute small bowel obstruction. Am J Emerg Med. 2017 Dec;35(12):1919-1921.PMID: 28912083
- ↑ Assalia A, Schein M, Kopelman D, et al. Therapeutic effect of oral Gastrografin in adhesive, partial small-bowel obstruction: A prospective randomized trial. Surgery 1994; 115: 433-437.
- ↑ Chen SC, Lin FY, Lee PH, et al. Water-soluble contrast study predicts the need for early surgery in adhesive small bowel obstruction. Br J Surg 1998; 85: 1692-1694.
- ↑ Choi HK et al. Therapeutic Value of Gastrografin in Adhesive Small Bowel Obstruction After Unsuccessful Conservative Treatment: A Prospective Randomized Trial. Annals of Surgery. 2002;236(1).
- ↑ Choi HK et al. Therapeutic Value of Gastrografin in Adhesive Small Bowel Obstruction After Unsuccessful Conservative Treatment: A Prospective Randomized Trial. Annals of Surgery. 2002;236(1).