Abstract
Case
A 45-year-old woman presented to the emergency department with severe epigastric pain and vomiting. Physical examination revealed distended abdomen and tenderness over epigastrium. Bowel sound was positive but sluggish. Blood test was normal initially. The patient’s condition deteriorated rapidly, and repeated blood test showed elevated white cell count. Chest radiograph was normal with no free gas under diaphragm. An urgent computed tomography (CT) of abdomen and pelvis with contrast was performed (Figures 1 and 2).
Axial image of post contrast CT abdomen.
Coronal image of post contrast CT abdomen.
Questions
What are the salient findings in this CT study?
What is the diagnosis?
What is the appropriate management?
Answers
The small bowel loops are diffusely dilated. The wall of small bowel is hypo-enhancing and edematous looking, likely due to ischemia. Presence of tiny gas pocket within the bowel wall is suggestive of pneumatosis intestinalis. The stomach is also distended with oral contrast. No oral contrast is seen in the small bowel or large bowel, compatible with high-grade intestinal obstruction. There is whirl-pattern of the small bowel loops and adjacent mesenteric fat. In the coronal image, the duodenojejunal junction is located to the right side of the midline/spine. The whirl-like pattern is again observed at the mesenteric root. There is also presence of large amount of ascites.
Overall findings are suggestive of midgut volvulus due to malrotation, complicated by small bowel ischemia.
This is a surgical emergency. The surgeon should be informed and patient has to undergo emergency operation.
Discussion
Midgut volvulus is a rare condition with twisting of small bowel around the axis of superior mesenteric artery (SMA) due to short mesenteric attachment of small bowel.1,2,3
It is most commonly seen in neonate or young infant who are presented with signs of acute intestinal obstruction. It is rarely seen in older child or adult, who usually have signs of chronic bowel obstruction. 1
Small bowel volvulus can be classified into two types. In primary or idiopathic volvulus, no predisposing anatomical abnormality can be identified. It is 5 to 10 times more common in Africa, Asia, and Middle East. Some speculate that this is due to ingestion of large amount of fiber-rich food after prolonged fasting.2,4
In secondary volvulus, it is caused by anatomic variation or anomalies. These can either be congenital, as in our case with malrotation, or secondary to adhesion from previous surgery.2,5
In patient with malrotation, midgut volvulus is the leading cause of small bowel obstruction.2,6,7 Malrotation is the failure of the bowel to undergo a normal 270° counter-clockwise rotation and fixation during embryonic development. The mesentery would appear shorter than usual, below the ligament of Treitz, which provides the leading point for the torsion of the bowel around the SMA.1,3
The signs and symptoms of the midgut volvulus are usually related to bowel obstruction. Diagnosis is difficult as the symptoms are non-specific and are not easy to differentiate from other causes of acute abdomen. Laboratory findings are also non-specific. Imaging plays an important part in making a correct diagnosis. Abdominal radiograph may show signs of bowel obstruction with double bubble sign (air-fluid in both stomach and duodenum).
In upper gastrointestinal (GI) study, classical sign includes an abnormal duodenojejunal junction located lower than duodenal bulb to the right of the expected position. The midgut loops will show a spiral course beyond the point of obstruction, which give rise to the “corkscrew” appearance.
CT is the best modality for investigation as it can depict anatomical detail and cause of volvulus. CT can provide a diagnostic accuracy of up to 80% in some studies.3,4 The classical appearance of small bowel volvulus is the whirl-like pattern of small bowel loops and mesenteric fat towards the point of torsion. The reversal of SMA/superior mesenteric vein (SMV) relationship (SMV to the left of SMA) may also be seen in some cases.1,2,3
Ultrasound can also demonstrate this clockwise whirlpool sign, as well as the transposition of SMA/SMV relationship in Doppler study.1,3
Angiogram is also able to demonstrate the aforementioned vascular abnormalities. The tapering or abrupt termination of mesenteric vessels, or spiraling of SMA (barber pole sign), is also helpful in making the diagnosis. 1
Small bowel volvulus is a surgical emergency, and bowel necrosis can occur in up to 50% of patients. 4 Our patient underwent emergency laparotomy with the gangrenous small bowel resected and had an uneventful recovery.
In conclusion, midgut volvulus is a rare surgical condition with high morbiditiy and mortality. Clinical exam and laboratory tests are non-specific. CT scan is the best imaging modality for making the correct diagnosis and sorting the underlying cause for this condition.