MDCT findings in small bowel obstruction: implications of the cause and presence of complications on treatment decisions

Abstract

Small bowel obstruction (SBO) accounts for a considerable proportion of emergency room visits, inpatient admissions, and surgical interventions in the United States. Multi-detector computed tomography (MDCT) plays a key role in imaging patients presenting with acute symptoms suggestive of SBO, which helps in establishing the diagnosis, elucidating the cause of obstruction, and detecting complications, such as ischemia or frank bowel necrosis and perforation. Recently, management of patients with SBO has shifted toward a more conservative approach with supportive care and nasogastric tube decompression, as the obstruction in many cases can resolve spontaneously without the need for operative intervention. However, management decisions in SBO remain notoriously difficult, relying on a combination of clinical, laboratory, and imaging factors to help stratify patients into conservative or surgical treatment. Imaging is often an important factor assisting in the decision-making process since traditional clinical signs of vascular compromise, such as acidosis, fever, leukocytosis, and tachycardia are often unreliable in predicting the need for operative intervention. Thus, it is critically important for radiologists to identify imaging features that suggest or indicated high likelihood of bowel vascular compromise in order to help optimize management prior to the development of bowel ischemia and eventually necrosis. By excluding signs of potentially ischemic or necrotic bowel on MDCT, patients may be spared unnecessary surgery, thus decreasing postsurgical complications and averting potential increase for the risk of future SBO and repeated surgery. Conversely, if imaging features indicate potential vascular compromise of the bowel wall that may lead to bowel ischemia, urgent surgical intervention may prevent progression to bowel necrosis and subsequent perforation.

A Systematic Review of the Clinical Presentation, Diagnosis, and Treatment of Small Bowel Obstruction

“…"Free" intraperitoneal air (pneumoperitoneum) usually indicates bowel perforation [42]. Coronal and/or sagittal multiplanar reformations help identify the transition point, assess for volvulus, and detect closed-loop obstruction.…”

“…SBO is more accurately diagnosed if radiographs are obtained in both dependent (supine or prone) and non-dependent (upright or decubitus) positions [41]. However, radiographs cannot reliably determine the site or etiology of obstruction or detect early bowel ischemia [41,42]. Abdominal radiographs in a patient with SBO typically demonstrate dilatation of small bowel out of proportion to that of the colon.…”

“…In these circumstances, CT enterography with neutral oral contrast may be substituted. CT should be performed with IV contrast, in the absence of contraindications, such as contrast allergy or renal insufficiency, to assess mesenteric vessel patency by mural enhancement [42]. Identifying mesenteric branches by contrast-enhanced CT helps detect vascular engorgement or swirling that can occur in certain types of obstruction, such as volvulus [42].…”

“…CT should be performed with IV contrast, in the absence of contraindications, such as contrast allergy or renal insufficiency, to assess mesenteric vessel patency by mural enhancement [42]. Identifying mesenteric branches by contrast-enhanced CT helps detect vascular engorgement or swirling that can occur in certain types of obstruction, such as volvulus [42]. The usual clinical symptoms and signs of mural ischemia, such as pyrexia, rigors, intense abdominal pain, leukocytosis, tachycardia, and metabolic acidosis, and the clinical experience of surgeons are neither sensitive nor specific for the diagnosis of strangulation or requirement for surgery.…”

The Clinical Presentations and Patterns of Management of Bowel Obstruction in Northern Saudi Arabia

“…Multi-detector computed tomography (MDCT) plays a key role in imaging patients presenting with acute symptoms suggestive of SBO, which helps in establishing the diagnosis, elucidating the cause of obstruction, and detecting complications, such as ischemia or frank bowel necrosis and perforation [7] [8]. However, a real surgical challenge is not a decision whether to perform a surgery, but a decision when and how to perform it [6].…”