Small bowel volvulus: Time is of the essence

Surgical Rounds®, August 2007, Volume 0, Issue 0

Matthew A. Wert, Surgical Resident, Orthopedic Surgery, Kingsbrook Jewish Medical Center, Brooklyn, NY, St. Vincent's Hospital, New York, NY; Umut Sarpel, Surgical Oncology Fellow, Department of Surgery, The Mount Sinai Medical Center, New York, NY; Celia M. Divino, Chief, Division of General Surgery, Department of Surgery, The Mount Sinai Medical Center, New York, NY

Matthew A.Wert, MD

Surgical Resident

Orthopedic Surgery

Kingsbrook Jewish Medical Center

Brooklyn, NY

St. Vincent's Hospital

New York, NY

Umut Sarpel, MD

Surgical Oncology Fellow

Department of Surgery

The Mount Sinai Medical Center

New York, NY

Celia M. Divino, MD

Chief

Division of General Surgery

Department of Surgery

The Mount Sinai Medical Center

New York, NY

Small bowel volvulus is a rare condition that can become life-threatening very quickly. The exact cause remains unknown, but dietary habits or the presence of small bowel diverticula may contribute. The symptoms are usually nonspecific, and the surgeon must quickly diagnose and treat the condition to prevent intestinal damage secondary to vascular compromise. Although no gold standard exists for diagnosing small bowel volvulus, computed tomography (CT) scanning is the most reliable diagnostic tool to date. Treatment is almost always surgical and must be performed immediately to ensure an optimal outcome. We report a case of small bowel volvulus that developed independently of the patient's embolic and thrombotic risk factors for mesenteric ischemia.

Case report

A 52-year-old, thin, muscular, Hispanic man presented to our institution with a 4-hour history of severe, constant, and diffuse abdominal pain. The pain had woken him in the middle of the night and was accompanied by nausea, vomiting, and two episodes of nonbloody diarrhea. There appeared to be no alleviating or exacerbating factors, and he reported no other recent episodes of abdominal pain. The patient had undergone no prior surgery, but his medical history was significant for coronary artery disease with an ejection fraction of 20%, atrial fibrillation, and gout. His medications included digoxin, warfarin, furosemide, colchicine, lisinopril, celecoxib, and allopurinol. His social history was significant for a 15-pack-year history of smoking.

On physical examination, the patient was afebrile and normotensive but exhibited sinus tachycardia at 110 beats per minute. Pulses were palpable in all four extremities. His abdomen was soft and nondistended, and the abdominal pain was not exacerbated by palpation. There was no evidence of peritonitis. A rectal examination was unremarkable and negative for occult blood. The patient was in obvious distress, but his symptoms seemed out of proportion to the physical examination findings.

Laboratory tests were unrevealing. A CT angiogram demonstrated a widely patent celiac trunk and superior mesenteric artery. An abdominal CT scan showed a swirling of the mesentery distal to the take-off of these vessels, with disruption of arterial blood flow and venous congestion of the distal small bowel (Figure). These findings were thought to be consistent with small bowel volvulus.

The patient underwent emergency laparotomy. On entering the abdomen, no ascites were seen. Most of the small bowel was well-perfused, but there was a 3-ft segment of dusky-appearing ileum. The mesentery of this segment was twisted on itself. Detorsion of the mesentery restored immediate reperfusion of the bowel, and the ischemia rapidly reversed. A thorough examination of the abdomen did not reveal any other anatomical abnormalities, such as internal hernias or malrotation.

The patient had an uneventful recovery and was discharged to home on postoperative day 5. He was readmitted to the hospital 1 week later due to a complete small bowel obstruction, which required adhesiolysis. The patient made a full recovery after this procedure.

Discussion

Small bowel volvulus refers to the abnormal twisting of a loop of bowel around the axis of its own mesentery.1 This twisting may produce mechanical obstruction, vascular compromise, or both. When small bowel volvulus produces torsional strain around the mesenteric vasculature, it can lead to bowel ischemia and ultimately gangrene. In strangulating obstructions, venous obstruction is usually the initiating factor, which can lead to arterial occlusion and result in rapid ischemia of the bowel wall. Although small bowel volvulus is rare, it has a mortality rate between 9% and 35%, depending on whether underlying necrosis is present.2,3

One of the most interesting details of small bowel volvulus is its increased proclivity for certain ethnic groups. In North America and Western Europe, the annual incidence is 1.7 to 5.7 cases per 100,000, but much higher rates of 24 to 60 cases per 100,000 have been observed in Africa, Asia, the Middle East, and India.2,3 The increased rate in these populations has been attributed to regional dietary habits. The ingestion of large volumes of fiberrich foods after periods of prolonged fasting may play a role. For example, the incidence of small bowel volvulus is higher during the month of Ramadan, when Muslims fast during the day and then ingest a large meal after sunset.4 In Ethiopia, the typical patient with primary volvulus of the small intestine is a young adult male from a rural area whose diet is bulky and consists mainly of cereals.4 A study that examined 235 patients of Southern Ethiopian descent found that 98 (41.7%) of those undergoing surgery to address acute intestinal obstruction had small bowel volvulus.5 This condition occurred most often in farmers, who are known to consume fiber-rich foods.5

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A large diverticulum of the small bowel also has been proposed to cause small bowel volvulus.6 The incidence of small bowel diverticula in one study of patients with small bowel volvulus was 35%, which is significantly higher than the rate of 1% observed in the control group ( < .01).7 The diverticulum may serve as a lead point, causing torsion around the mesentery.

Our patient's clinical presentation and history of atrial fibrillation and smoking led to the presumed diagnosis of mesenteric ischemia from an embolic or thrombotic event. In addition, he was taking digoxin, which is known to induce intestinal ischemia by vasoconstriction of the splanchnic circulation.8 This patient's mesenteric ischemia, however, was not caused by any of these etiologies.

Diagnosing small bowel volvulus is challenging, because its chief symptoms—abdominal pain, nausea, and vomiting—are nonspecific.8 The degree of abdominal pain depends directly on the duration of vascular compromise and not on the degree of underlying intestinal obstruction.3 The laboratory values are equally nonspecific, and abnormalities occur inconsistently.

While it is possible to rely on conventional radiographs to obtain a diagnosis of small bowel obstruction, it is insufficient for establishing a diagnosis of small bowel volvulus. CT scanning is more effective, because it shows the twisting of the mesenteric artery and vein from their normal proximal location to a reversed distal orientation. Often, a "whorl sign" can be visualized where the mesenteric folds and bowel encircle the superior mesenteric vein.9,10 The whorl sign is useful in making decisions about the need for surgery, in conjunction with other clues, such as bowel ischemia, which is suggested by bowel wall thickening or pneumatosis.

Various medical treatments are available to manage intrapelvic endometriosis, all of which depend primarily on creating a hypoestrogenic environment that deprives the endometriosis of nourishing hormonal stimulation. Low-dose estrogen oral contraceptives are often used to alleviate pain from endometriosis and limit the extent of cell growth. Medical treatment for extrapelvic endometrioma, however, has generally been found to be ineffective.2,13 This was true for our patient, who was taking oral contraceptive pills but still experienced tumor growth and symptoms. Since medical treatment is ineffective, surgical excision remains the treatment of choice. Surgery is curative for extrapelvic endometrioma in the vast majority of cases.

A plain abdominal radiograph is not sufficient for determining when conservative management is warranted for a bowel obstruction or when operative management becomes necessary. To date, the most reliable diagnostic tool is CT scanning, and the surgeon must diagnose the condition quickly to prevent bowel necrosis.1 Immediate surgery is the treatment of choice to prevent progression to irreversible ischemia.

Conclusion

Although small bowel volvulus is a rare diagnosis, the condition is life-threatening and generally requires emergency surgical treatment to prevent serious morbidity or mortality. The development of small bowel volvulus has been associated with diverticula and eating fiber-rich foods. Patients often present with nonspecific symptoms that include abdominal pain, nausea, and vomiting. Laboratory test results may vary and are rarely conclusive. In cases of bowel obstruction, CT scanning is the most effective imaging modality to help diagnose the condition and suggest appropriate treatment. Often a whorl sign will be present, where the mesenteric folds and bowel encircle the superior mesenteric vein. When the diagnosis is small bowel volvulus, immediate surgery is advisable to prevent serious complications, such as ischemia and necrosis.

References

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  9. Iwuagwu O, Deans GT. Small bowel volvulus: a review. J R Coll Surg Edinb. 1999;44(3):150-155.
  10. Fujimoto K, Nakamura K, Nishio H, et al. Whirl sign as CT finding in small-bowel volvulus. European Radiology. 1995; 5(5):555-557.