The appearance of water-soluble contrast in the cecum on an abdominal radiograph within 24 hours of it being given by mouth predicts resolution of an adhesive small bowel obstruction with sensitivity of 97% and specificity of 96%.Colonoscopy, small bowel investigation with ingested camera or push endoscopy, and laparoscopy are other diagnostic options. Differential diagnosis
Differential diagnoses of bowel obstruction include:

Ileus
Pseudo-obstruction or Ogilvies syndrome
Intra-abdominal sepsis
Pneumonia or other systemic illness

Treatment
Some causes of bowel obstruction may resolve spontaneously; many require operative treatment. In adults, frequently the surgical intervention and the treatment of the causative lesion are required. In malignant large bowel obstruction, endoscopically placed self-expanding metal stents may be used to temporarily relieve the obstruction as a bridge to surgery, or as palliation. Diagnosis of the type of bowel obstruction is normally conducted through initial plain radiograph of the abdomen, luminal contrast studies, computed tomography scan, or ultrasonography prior to determining the best type of treatment.Further research is needed to find out if parenteral nutrition is of benefit to people with an inoperable blockage of the bowel caused by advanced cancer. Small bowel obstruction
In the management of small bowel obstructions, a commonly quoted surgical aphorism is: "never let the sun rise or set on small-bowel obstruction" because about 5.5% of small bowel obstructions are ultimately fatal if treatment is delayed. Improvements in radiological imaging of small bowel obstructions allow for confident distinction between simple obstructions, that can be treated conservatively, and obstructions that are surgical emergencies (volvulus, closed-loop obstructions, ischemic bowel, incarcerated hernias, etc.
Large bowel obstruction
Causes of large bowel obstruction include:
Neoplasms / cancer
Diverticulitis / Diverticulosis
Hernias
Inflammatory bowel disease
Colonic volvulus (sigmoid, caecal, transverse colon)
Adhesions
Constipation
Fecal impaction
Fecaloma
Colon atresia
Intestinal pseudoobstruction
Endometriosis
Narcotic induced (especially with the large doses given to cancer or palliative care patients)

Outlet obstruction
Outlet obstruction is a sub-type of large bowel obstruction and refers to conditions affecting the anorectal region that obstruct defecation, specifically conditions of the pelvic floor and anal sphincters. Outlet obstruction can be classified into four groups. Functional outlet obstruction
Inefficient inhibition of the internal anal sphincter
Short-segment Hirschsprungs disease
Chagas disease
Hereditary internal sphincter myopathy
Inefficient relaxation of the striated pelvic floor muscles
Anismus (pelvic floor dyssynergia)
Multiple sclerosis
Spinal cord lesions
Mechanical outlet obstruction
Internal intussusception
Enterocele
Dissipation of force vector
rectocele
Descending perineum
Rectal prolapse
Impaired rectal sensitivity
Megarectum
Rectal hyposensitivity

Diagnosis
The main diagnostic tools are blood tests, X-rays of the abdomen, CT scanning, and ultrasound. If a mass is identified, biopsy may determine the nature of the mass.Radiological signs of bowel obstruction include bowel distension and the presence of multiple (more than six) gas-fluid levels on supine and erect abdominal radiographs. Ultrasounds may be as useful as CT scanning to make the diagnosis.Contrast enema or small bowel series or CT scan can be used to define the level of obstruction, whether the obstruction is partial or complete, and to help define the cause of the obstruction.