Clinical History
A 77-year-old female presented with a history of multiple myeloma, refractory gastroesophageal reflux, bloating and early satiety. The patient was referred for evaluation of gastric emptying.
Imaging Findings
A 99mTc Sulfur-Colloid gastric emptying study was obtained. Dynamic images (Fig. 1a) demonstrate passage of the radiotracer from the stomach into the proximal small bowel which is abnormally located in the right abdomen (black arrow). Gastric emptying curves suggest delayed emptying as noted by 30% retention of solids at 3 hours and 27% at 4 hours (Fig. 1b, yellow box). Normal values at 3 hours are >30% and >10% at 4 hours.
Subsequent review of correlative CT of the abdomen with oral contrast was obtained from an outside institution confirmed intestinal malrotation (Fig. 2). Figure 2a demonstrates the duodenum (yellow arrow) taking an abnormal course, wrapping around the superior mesenteric artery (red arrow) before continuation towards the right abdomen. Note the proximal small bowel centered in the right abdomen. Same CT scan in Figure 2b shows left-to-right inversion of the superior mesenteric artery (red arrow) and superior mesenteric vein (yellow arrow).
Discussion
Intestinal malrotation typically presents in childhood in approximately 1 in 500 patients, usually within the first month of life. Uncomplicated malrotation can go unnoticed during childhood and become problematic in adolescence or adulthood. Since the index of suspicion decreases with age, it can be easily overlooked as a cause of nonspecific abdominal symptoms in adults [1].
During development, the gut grows rapidly and ultimately rotates 270° counterclockwise around the superior mesenteric artery before reaching a normal anatomic location. Abnormalities during this process result in malrotation. The associated abnormal locations of the small and large bowel, abnormal fixation, or mesenteric bands can present with volvulus or proximal small bowel obstruction within the first month of life. In older children and adults, many nonspecific presenting symptoms have been reported, including vomiting, intermittent abdominal pain, malabsorption, diarrhoea, gastroesophageal reflux, and delayed gastric emptying [2, 3]. Abnormal positioning of the cecum may cause left-sided localization of pain related to acute appendicitis [1].
Malrotation in adolescents and adults is typically found incidentally on imaging obtained for the workup of other suspected diagnoses. Upper GI fluoroscopy shows malpositioning of the duodenojejunal junction which should reach the level of the duodenal bulb and across midline. Findings of right-sided jejunal folds and lack of air-filled colon in the right lower quadrant on plain radiographs should also raise suspicion. Left-to-right inversion or vertical orientation of the superior mesenteric artery and vein is also commonly seen [1].
Identification of midgut malrotation in adolescents and adults is crucial and should not be dismissed as a normal anatomic variant [1]. Little literature exists to estimate whether an uncomplicated malrotation could present with a future life-threatening volvulus. Thus, the value of surgical intervention is not well established. However, most seem to favour surgery, such as the Ladd’s procedure, regardless of age for patients with uncomplicated intestinal malrotation [1, 4].
In our patient, malrotation was identified on a gastric emptying study as noted by abnormal positioning of the small bowel as 99mTc Sulfur-Colloid emptied from the stomach (Fig 1a, 1b). The malrotation may have contributed to the delayed gastric emptying, which has been described in case reports [3]. Findings were later confirmed on correlative outside-institution CT which showed SMA-SMV inversion, an abnormal duodenal course, and abnormal positioning of the small bowel. This study emphasizes the need to carefully examine small bowel for unexpected findings such as bowel obstruction or malrotation on gastric emptying studies.
Differential Diagnosis List
Intestinal malrotation in the setting of delayed gastric emptying.
Intestinal volvulus
Wandering duodenum
Duodenum inversum
Final Diagnosis
Intestinal malrotation in the setting of delayed gastric emptying.
