Radiology Resident Case of the Week
Etiology/Pathophysiology
Early in gestation the midgut herniates outside the abdominal cavity. As the abdominal cavity enlarges, the bowel rotates a total of 270 degrees as it returns. This process begins at the end of the third month of gestation and ultimately places the ligament of Treitz to the left of the SMA and the cecocolic junction in the right lower quadrant. A long mesenteric attachment adhering to the posterior abdominal wall is present between these two sites.
Arrests in rotation less than 270 degrees results in a malrotation. Because the broad mesenteric attachment is replaced by a much shorter band, the bowel is permitted to twist about the superior mesenteric artery resulting in a volvulus and ultimately obstruction. In addition, peritoneal bands (Ladd bands) connecting the malpositioned cecum to the posterior abdominal wall under the liver form. Proximal bands may cause kinking at the duodenojejunal junction resulting in obstruction.
Pathology:
The pathology findings are those of either congestion or ischemia and/ or necrosis depending on how severe the volvulus is. Initially, the venous supply is occluded leading to congestion. If the volvulus is more severe, arterial supply is occluded resulting in changes of necrosis.
Miscellaneous
A history of bilious vomiting in a neonate requires immediate investigation with plain film and upper GI study. With midgut volvulus, time is of the essence and a delay in diagnosis can lead to destruction of the entire midgut leaving the patient either dead, or with only a stomach, duodenum and left colon.
Imaging
Plain film
DDX
None
Key references
1. Caffey's Pediatric X-Ray Diagnosis: An Integrated Imaging Approach; 9th Edition; Silverman, F; Kuhn, J; Mosby 1993; Pgs. 2050-2055.
2. Shimanuki Y, Aihara T, Takano H. Clockwise Whirlpool Sign at Color Doppler US: An Objective and Definite Sign of Midgut Volvulus. Radiology 1996; 199: 261-264.
3. Langman's Medical Embryology; 5th Edition; Sadler, TW; Williams & Wilkins 1985; Pgs. 235-238.
ACR Code
Keywords:
UGI figure 1
UGI figure 2
Ultrasound
Sonography