From the Guidelines
An enlarged bowel with gas on a lumbar X-ray is highly suggestive of sigmoid volvulus, and I strongly recommend an urgent diagnostic workup including plain abdominal radiographs to confirm the diagnosis, as recommended by the WSES consensus guidelines 1. The presence of gas in the bowel on X-ray can be a normal finding, but in the context of an enlarged bowel, it raises concerns for a pathological condition such as sigmoid volvulus. According to the WSES consensus guidelines, the initial evaluation should include a focused history and physical examination, as well as a full panel of blood tests including blood gas and lactate levels to look for suggestions of bowel ischemia 1. Key symptoms to look out for include abdominal pain, constipation, and vomiting, which are commonly seen in sigmoid volvulus, as well as a history of previous episodes of abdominal distention 1. The classic patient is often elderly, institutionalized, and under psychotropic medications that cause chronic constipation. Diagnostic imaging should be done expediently, with plain abdominal radiographs being the initial imaging modality of choice, showing a classic coffee bean sign in cases of sigmoid volvulus 1. If the diagnosis is in doubt or if ischemia or perforation is suspected, CT imaging can be used, with the addition of intravenous contrast to facilitate the diagnosis of colonic ischemia 1. It is essential to note that the absence of peritonitis does not indicate the absence of bowel ischemia, and blood testing of electrolytes and renal function is necessary, especially in patients with comorbidities who may be at risk of renal insufficiency 1.
- Key findings on physical examination include abdominal distension, diminished bowel sounds, and an empty rectum on digital examination, although the examination can be challenging due to the presence of abdominal distension 1.
- The duration of symptoms can range from a few hours to several days, and any vomiting and dehydration can tip patients over into renal insufficiency, highlighting the need for urgent medical evaluation 1.
From the Research
Enlarged Bowel from Gas on Lumbar X-ray
- The provided studies do not directly address the topic of an enlarged bowel from gas on a lumbar X-ray.
- However, the studies discuss the use of computed tomography (CT) in assessing bowel obstruction and ischemia 2, 3, 4, 5.
- CT scans can provide important information about the cause and site of obstruction, as well as the presence of a closed-loop obstruction or ischemia 2.
- The studies also highlight the importance of CT scans in differentiating between benign and malignant lesions in the bowel 3, and in identifying masses, malignancies, and features of strangulation 4.
- Additionally, the use of unenhanced CT in addition to contrast-enhanced CT can improve the diagnostic performance of decreased bowel wall enhancement as a sign of ischemia complicating mechanical small bowel obstruction 5.
Diagnostic Techniques
- CT scans are a powerful tool for assessing patients with small bowel obstruction (SBO) 2.
- The technique involves administering oral, rectal, and intravenous (IV) contrast agents, and imaging the abdomen from the diaphragm to the pubic symphysis 3.
- The use of specific CT criteria, such as pattern of attenuation, bowel wall thickness, extent of lesion, and symmetry of lesion, can help differentiate between benign and malignant lesions 3.
- Unenhanced CT can be used in addition to contrast-enhanced CT to improve the diagnostic performance of decreased bowel wall enhancement as a sign of ischemia 5.
Clinical Applications
- CT scans can help identify patients with SBO who require urgent surgery 2.
- The technique can also help identify patients with benign lesions who do not require surgical intervention 3.
- In patients with equivocal findings of small bowel obstruction, CT should be used initially, followed by small bowel follow-through if CT is not diagnostic 4.