Differential Diagnosis for Large Bowel Obstruction

Given the clinical presentation and imaging findings, the differential diagnosis can be categorized as follows:

• Single most likely diagnosis

  • Sigmoid volvulus: The "coffee bean" appearance on the erect abdominal film is a classic radiographic sign of sigmoid volvulus, making it the most likely diagnosis. This condition occurs when the sigmoid colon twists around its mesentery, leading to obstruction.

• Other Likely diagnoses

  • Carcinoma: Colorectal cancer can cause large bowel obstruction, either by the tumor itself or by intussusception. Although less likely than sigmoid volvulus given the specific radiographic findings, it remains a common cause of large bowel obstruction.
  • Stricture: A stricture, which could be due to inflammatory bowel disease, ischemia, or previous surgery, can also lead to large bowel obstruction. The history and additional imaging might help differentiate this from volvulus or carcinoma.

• Do Not Miss diagnoses

  • Ischemic bowel: Although less common, ischemic bowel disease can present with obstruction and is critical to diagnose early due to its high morbidity and mortality. It might not have specific radiographic signs but should be considered, especially in patients with risk factors for vascular disease.
  • Toxic megacolon: This is a life-threatening condition often associated with inflammatory bowel disease or infectious colitis. It can present with signs of obstruction and requires prompt recognition and treatment.

• Rare diagnoses

  • Intussusception: Although more common in children, intussusception can occur in adults and cause large bowel obstruction. It is less likely than the other diagnoses but should be considered, especially if there's a lead point like a tumor.
  • Foreign body obstruction: This could be considered in the differential, especially if there's a history suggestive of ingestion of a foreign body. However, it's less common and typically presents with a more acute onset.
  • Hernias: Internal or external hernias can cause bowel obstruction, including large bowel obstruction, though they are less common causes compared to volvulus, carcinoma, or stricture.