Stanley Medical College and Hospital
A volvulus is twisting of intestinal loops and its supporting mesentery causing varying degrees of bowel obstruction. Symptoms may include acute or chronic abdominal pain/abdominal distension depending on the type of volvulus. Imaging helps in characterizing and differentiating the various types of volvulus and its associated complication. Early diagnosis/timely management reduces morbidity and mortality.
Educational Goals / Teaching Points
Exhibit goals include awareness of characteristic imaging findings; specific signs pertaining to volvulus; discuss the various types and pathology of different types of volvulus; and enumerate the risk factors associated with the volvulus.
Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
Types of volvulus: Gastric volvulus: organo-axial (stomach rotates along the long axis of the cardio pyloric line) or mesentero-axial (stomach rotates perpendicular to the cardiopyloric line). Plain radiographic findings include intrathoracic herniation of the greater portion of the stomach with varying fluid levels. Upper GI series reveals the plane of rotation of the stomach. CT is often performed in acute settings which reveals the gastric volvulus and is helpful to assess associated complications like wall gangrene/perforation. Midgut volvulus: the predisposing factor is due to rotational anomalies of bowel (more common in children, with 75% occurring in the neonatal period and 90% during infancy). GI series reveals abnormal position of the ligament of Treitz, with a major portion of the small bowels in the right side of the abdomen, a cork screw appearance of small bowel loops is noted. US may show abnormal relationship of the superior mesenteric vessels (superior mesenteric vein being located to the left of superior mesenteric artery). Swirl sign, abnormal position of ligament of Treitz and abnormal location of small bowel lops on the right side of the abdomen are the features seen on CT. Caecal volvulus: the risk factor is abnormal fixation of the proximal colon to the retro peritoneum, which comprises 25-40% of colonic volvulus. Abnormal displacement of the dilated caecum and proximal small bowel obstruction with collapsed large bowel loops are seen on CT. Splenic flexure volvulus: the rarest among the large bowel volvulus, comprising less than 5-10 % of cases, due abnormal fixation of transverse colonic mesentery. Due to its rarity, most cases are diagnosed on CT, which shows the transition point and the whirl sign. It carries high mortality rate and early diagnosis is imperative. Sigmoid volvulus: the most common, comprising 60-75% of colonic volvulus cases. Risk factors are long-standing constipation, consumption of high fiber diet, and Chagas disease. It has to be differentiated form caecal volvulus. A dilated sigmoid colon with the apex pointing towards the right upper quadrant, whirl sign, and coffee bean appearance are some of the features encountered.
Volvulus may occur at any age beginning from neonate to the elderly. Most patients present with nonspecific symptoms like abdominal pain. Dedicated radiological evaluation aids in preventing life-threatening complications.