eMedicine Specialties > General Surgery > Abdomen

Omental Torsion

Alan A Saber, MD, MS, FACS, Chief, Minimally Invasive Surgery and Bariatric Surgery, Associate Professor, Department of Surgery, Michigan State University
Raymond D LaRaja, MD, Chairman, Program Director, Clinical Professor, Department of Surgery, Cabrini Medical Center, Mount Sinai School of Medicine

Updated: Oct 23, 2009

Introduction

Torsion of the omentum is a condition in which the organ twists on its long axis to such an extent that its vascularity is compromised. (See image below and Image 1.)

This is an example of primary torsion of the omentum. A normal-appearing omentum can be seen above the torsion point. The omentum below that point is edematous and congested.

Problem

Although omental torsion is rarely diagnosed preoperatively, knowledge of the entity is important to the surgeon because it mimics the common causes of acute surgical abdomen.

Frequency

Eitel first described omental torsion in 1899; since then, fewer than 250 cases have been reported.

Etiology

Torsion of the omentum may be primary or secondary. In primary torsion, a mobile segment of omentum rotates around a proximal fixed point in the absence of any associated intra-abdominal pathology. Although the precise cause is unknown, both predisposing and precipitating factors in the pathogenesis of the condition can be identified.

Factors that predispose a patient to torsion include anatomical variations of the omentum itself, eg, accessory omentum, bifid omentum, irregular accumulations of omental fat (in patients who are obese), and narrowed omentum pedicle. Any redundancy of omental veins may lead to kinking and twisting around the shorter and tenser arteries. The higher incidence of torsion on the right side of the omentum is related to the greater size and mobility of that side.

Precipitating factors are those causing displacement of the omentum, including trauma, violent exercise, and hyperperistalsis with resultant increased passive movement of the omentum.

Secondary torsion is more common than primary torsion and is associated with preexisting abdominal pathology, including cysts, tumors, foci of intra-abdominal inflammation, postsurgical wounds or scarring, and hernial sacs. Most cases of secondary torsion occur in patients with inguinal hernias.

Pathophysiology

The omentum twists around a pivotal point, usually in a clockwise direction. Venous return is compromised, and the distal omentum becomes congested and edematous. Resultant hemorrhagic extravasation creates a characteristic serosanguineous fluid in the peritoneal cavity.

As the torsion progresses, arterial occlusion leads to acute hemorrhagic infarction and eventual necrosis of the omentum occurs. Spontaneous derotation may be possible and may explain omental adhesions in the right lower quadrant, which are often found during laparotomy and have no clear cause.

Presentation

Torsion of the omentum is difficult to clinically diagnose preoperatively. Accurate preoperative diagnosis was reported in the range of 0.6-4.8%.

In a report from Greece, for example, a 14-year-old boy who was admitted to the hospital for acute appendicitis was found during surgery to be suffering from omental torsion on the long axis.¹

Omental torsion usually occurs in adults (of either sex). The twisted portion of the omentum tends to be localized to a right-sided segment, thereby giving rise to the sudden onset of pain and signs of peritoneal irritation on the right side of the abdomen. The condition may be associated with nausea, vomiting, or low-grade fever. An abdominal mass may be palpable in half of the patients.

This right-sided acute pain and rebound tenderness is often mistaken for acute appendicitis, acute cholecystitis, or twisted ovarian cysts.

At laparotomy, the finding of free serosanguineous fluid in association with a normal appendix, gallbladder, or pelvic organs should alert the surgeon to the possibility of omental torsion.

Workup

Laboratory Studies

CBC counts may reveal moderate leukocytosis, which occurs in two thirds of cases.

Imaging Studies

Reports suggest that ultrasonography and computed tomography (CT) scanning may show a characteristic appearance of twisted omentum; however, because the disease may mimic other surgical emergencies, extensive radiologic studies are usually not indicated.
- CT scanning may show a concentric distribution of fibrous and fatty folds converging radially toward the torsion.²
- Ultrasonography, on the other hand, may show a complex mass and mixture of solid material and hypoechoic zones.

Diagnostic Procedures

Laparoscopy is a safe diagnostic and therapeutic modality. In a report from Italy, for example, ultrasonographic and radiologic findings in 3 patients who presented with acute abdominal symptoms were unclear, prompting the use of diagnostic laparoscopy.³ Because laparoscopic examination allowed exploration of the entire peritoneal cavity, an accurate diagnosis of omental torsion, and laparoscopic resection of necrotic omentum, was achieved in each patient, according to the report.

Histologic Findings

Acute hemorrhagic infarct and fat necrosis

Treatment

Surgical Therapy

Torsion of the omentum is usually discovered during laparotomy or laparoscopy for an acute abdomen.

Consider omental torsion if preoperatively diagnosed acute appendicitis is not found and if the gallbladder and ovaries reveal no disease. In addition, the presence of serosanguineous fluid in the peritoneal cavity mandates inspection of the omentum to exclude torsion.

Treatment consists of resection of the affected portion of the omentum. Correct any disease process associated with secondary torsion.

Preoperative Details

Preoperative differential diagnosis includes acute appendicitis, acute cholecystitis, and twisted ovarian cysts.

Intraoperative Details

An incision centered over the site of maximal tenderness facilitates the operative diagnosis and eases resection of the infarcted omentum. When a healthy appendix is found, search for the cause of the abdominal pain.

Inspect the cecum for a perforated diverticulum.
The terminal ileum is then examined for Meckel diverticulum and regional enteritis.
The pelvic organs are inspected and palpated for disease.
Visualize the gallbladder and duodenum.
Evaluate the mesentery for mesenteric lymphadenitis.
Continue to explore the abdomen until the cause of acute abdominal symptoms has been identified. This may require extension of the original incision or creation of a new incision.

Outcome and Prognosis

Postoperative recovery is usually rapid, and morbidity is minimal. If left untreated, the natural process of omental torsion is necrosis and fibrosis.

Future and Controversies

With the advent of diagnostic laparoscopy and the increased demand for laparoscopic appendectomy, omental torsion may become a more frequently recognized clinical entity.

Multimedia

Media file 1: This is an example of primary torsion of the omentum. A normal-appearing omentum can be seen above the torsion point. The omentum below that point is edematous and congested.

References

Efthimiou M, Kouritas VK, Fafoulakis F, et al. Primary omental torsion: report of two cases. Surg Today. 2009;39(1):64-7. [Medline].
Jeon YS, Lee JW, Cho SG. Is it from the mesentery or the omentum? MDCT features of various pathologic conditions in intraperitoneal fat planes. Surg Radiol Anat. Jan 2009;31(1):3-11. [Medline].
Costi R, Cecchini S, Randone B, et al. Laparoscopic diagnosis and treatment of primary torsion of the greater omentum. Surg Laparosc Endosc Percutan Tech. Feb 2008;18(1):102-5. [Medline].
Adams JT. Primary torsion of the omentum. Am J Surg. Jul 1973;126(1):102-5. [Medline].
Basson SE, Jones PA. Primary torsion of the omentum. Ann R Coll Surg Engl. Mar 1981;63(2):132-4. [Medline].
Beattie GC, Irwin ST. Torsion of an omental lipoma presenting as an emergency. Int J Clin Pract Suppl. Apr 2005;130-1. [Medline].
Lipsett PJ. Torsion of the greater omentum: report of 2 cases. Ann Surg. 1941;114:1026-34.
Mainzer RA, Simoes A. Primary idiopathic torsion of the omentum. Arch Surg. 1964;88:974-81.
Tompkins RK, Sparks FC. Primary torsion of the omentum: mimic of appendicitis. Am Surg. 1966;32:399-402.
Young TH, Lee HS, Tang HS. Primary torsion of the greater omentum. Int Surg. Apr-Jun 2004;89(2):72-5. [Medline].
Zager JS, Gadaleta D, De Noto G. Primary omental torsion in adults: a small series of cases. Contemp Surg. 1999;55(5):261-63.

Keywords

omental torsion, omentum, omental, omental infarction, volvulus of the omentum, twisted omentum, acute abdomen, accessory omentum, bifid omentum, omental fat, omentum pedicle

Contributor Information and Disclosures

Author

Alan A Saber, MD, MS, FACS, Chief, Minimally Invasive Surgery and Bariatric Surgery, Associate Professor, Department of Surgery, Michigan State University
Alan A Saber, MD, MS, FACS is a member of the following medical societies: American College of Surgeons, American Society for Gastrointestinal Endoscopy, and American Society for Metabolic and Bariatric Surgery
Disclosure: Nothing to disclose.

Coauthor(s)

Raymond D LaRaja, MD, Chairman, Program Director, Clinical Professor, Department of Surgery, Cabrini Medical Center, Mount Sinai School of Medicine
Raymond D LaRaja, MD is a member of the following medical societies: American College of Surgeons, American Medical Association, New York Academy of Medicine, and New York County Medical Society
Disclosure: Nothing to disclose.

Pharmacy Editor

Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: eMedicine Salary Employment

Managing Editor

Amy L Friedman, MD, Professor of Surgery, Director of Transplantation, State University of New York Upstate Medical University College of Medicine, Syracuse
Amy L Friedman, MD is a member of the following medical societies: American College of Surgeons, American Medical Association, American Medical Women's Association, American Society for Artificial Internal Organs, American Society of Transplant Surgeons, American Society of Transplantation, Association for Academic Surgery, Association of Women Surgeons, International College of Surgeons, International Liver Transplantation Society, New York Academy of Sciences, Pennsylvania Medical Society, Philadelphia County Medical Society, Society of Critical Care Medicine, and Transplantation Society
Disclosure: Nothing to disclose.

Chief Editor

John Geibel, MD, DSc, MA, Vice Chairman, Professor, Department of Surgery, Section of Gastrointestinal Medicine and Department of Cellular and Molecular Physiology, Yale University School of Medicine; Director of Surgical Research, Department of Surgery, Yale-New Haven Hospital
John Geibel, MD, DSc, MA is a member of the following medical societies: American Gastroenterological Association, American Physiological Society, American Society of Nephrology, Association for Academic Surgery, International Society of Nephrology, New York Academy of Sciences, and Society for Surgery of the Alimentary Tract
Disclosure: AMGEN Royalty Other

Further Reading