Severe, unremitting abdominal pain

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A number of diagnoses were still considered possibilities as the patient underwent laparotomy.

A 9-year-old boy presented to the emergency department (ED) complaining of right upper-quadrant (RUQ) abdominal pain with constipation for four days. He described the pain as severe, continuous, and nonradiating and denied fever, vomiting, diarrhea, or urinary difficulties.

The patient’s mother had been using Fleet enema suppositories for his constipation. His most recent bowel movement, which had occurred that morning, was small in amount and without blood or mucus. At the time of initial assessment in the ED, the patient said he was hungry despite the pain. The review of systems was otherwise significant for a few days of rhinorrhea and productive cough. His history of present illness noted recent decreased activity level.

The past medical history was positive for asthma and obesity (weight 103 lb). Current medications included albuterol and budesonide. The boy had no history of surgery, no known drug allergies, and no known sick contacts; he regularly attended school and had no social problems. Immunizations were up to date for a child his age except that he needed a repeat TB test. His family history was significant for hypertension.

EXAMINATION FINDINGS

On physical examination, the patient was normotensive (BP 120/66 mm Hg), mildly tachycardic (heart rate 104 beats per minute), breathing without distress (respiration rate 24 breaths per minute), and afebrile (temperature 37.2°C orally). The boy appeared well-hydrated. Head and neck exam was unremarkable and without signs of meningeal irritation. Heart auscultation found no murmurs. Bilateral lung sounds were clear with good air movement.

The abdomen was soft with mild RUQ tenderness; there was no guarding or rebound. No costovertebral angle tenderness was noted. Extremities were normal without edema. Skin was warm and dry with normal turgor and without rash or other lesions. Neurologic exam was normal without motor or sensory deficits. The patient’s speech, behavior, and motor skills were appropriate for his age.

LABORATORY STUDIES

Lab results showed a WBC count of 15.6 x 109/L, hemoglobin 13.9 g/dL, hematocrit 38.7%, platelets 369 x 109/L, sodium 139 mmol/L, potassium 4.4 mmol/L, chloride 102 mmol/L, carbon dioxide 25.5 mmol/L, blood urea nitrogen 13 mg/dL, creatinine 0.5 mg/dL, glucose 98 mg/dL, amylase 49 IU/L, and lipase 133 IU/dL. Liver function tests were normal: aspartate aminotransferase 16 IU/L, alanine aminotransferase 32 IU/L, alkaline phosphatase 258 IU/L, total bilirubin 0.45 mg/dL, direct bilirubin 0.16 mg/dL, total protein 8.1 g/dL, and albumin 4.5 g/dL.

Urinalysis showed moderate sedimentation and mucus. Abdominal ultrasound revealed homogeneous hepatomegaly (13.7 cm vertical diameter) without evidence of focal masses, intrahepatic ductal dilatation, cholelithiasis, or acute cholecystitis. Sonographic Murphy’s sign was absent, and the common bile duct, pancreas, and spleen were normal.

Examination revealed a soft abdomen. Also apparent were distension and right lower-quadrant (RLQ) tenderness with voluntary guarding and no rebound. Rovsing and obturator signs were positive. No bowel sounds were heard.

Because of continuing abdominal tenderness, a CT with oral and IV contrast was obtained. It revealed medial displacement of the ascending colon by an RUQ heterogeneous area containing primarily fat, with increasing borders and surrounding stranding suspicious for omental ischemia and/or inflammation (Figure 1). The appendix was air-filled and normal in size. Other CT findings included a few small lymph nodes (largest measuring 6.4 mm) and a small amount of free fluid in the RLQ, along with free fluid in the pelvis and excess fecal material throughout the colon. Findings suggested omental ischemia with probable phlegmon in the RUQ and/or perforated appendix with phlegmon in the region of the omentum in the RUQ. A nonspecific hypoattenuated (5 mm) area was noted in the right upper pole of the kidney. Lung bases, liver, gallbladder, pancreas, adrenal glands, spleen, and left kidney appeared normal.

While in the ED, the patient was given a normal saline bolus, piperacillin/tazobactam (Zosyn) 400 mg IV, gentamicin 70 mg IV, and metronidazole (Flagyl) 300 mg IV. He was admitted to the pediatric ward for abdominal pain and allowed nothing by mouth, with IV hydration and antibiotics administered overnight. Repeat abdominal ultrasound the following day showed an ill-defined area in the anterior RUQ inferior to the gallbladder suspicious for omental ischemia and phlegmon with no evidence of abscess formation. No appendix was visualized; however, a moderate amount of free fluid in the pelvis raised suspicions of a perforated appendix.

IN THE OPERATING ROOM

The patient underwent laparotomy, appendectomy, and partial omentectomy. The postoperative diagnosis was partial torsion of the omentum, revealing mild serosal congestion of the appendix as well as marked congestion and focal acute hemorrhage of the omentum. He tolerated surgery well and was discharged five days later after resolution of his postoperative abdominal pain and leukocytosis.

A TRICKY DIAGNOSIS

Omental torsion is an uncommon and difficult diagnosis to make preoperatively. The clinical presentation usually consists of abdominal or flank pain (most often right-sided), ranging in intensity from mild discomfort to an acute abdomen with peritoneal signs. Among the differential diagnoses are constipation, obstruction, cholecystitis, appendicitis, hernia, volvulus, intussusception, necrotizing enterocolitis, tumor, testicular or ovarian torsion, ruptured ovarian cyst, and ectopic pregnancy. Risk factors for omental torsion include obesity, anatomical variations of the omentum, and adhesions.1 Right-sided torsion is more common than left, due to greater mobility and length of the right omentum.2

The most useful imaging modalities to diagnose omental torsion and ischemia are ultrasound and CT scan with oral and IV contrast. Ultrasound with color Doppler can also be used to confirm the presence or absence of blood flow in order to identify areas of omental infarction.3 As with our patient, both modalities are often used in conjunction, and serial imaging may be necessary. CT findings include stranding, concentric streaking, a “whirling” pattern of omental tissue, and free intra-abdominal or intrapelvic fluid, all of which suggest an inflammatory process.4,5 Visualization of a normal appendix and gallbladder in the presence of these findings should raise suspicion for omental pathology. If the appendix appears abnormal or is not visualized and these inflammatory changes are present, it may be difficult to distinguish omental inflammation from appendicitis or a ruptured appendix.

The management of omental torsion is usually surgical resection of the infarcted omentum in order to prevent further ischemia and necrosis. Laparotomy vs. laparoscopic resection depends on the clinical presentation, the certainty of the preoperative diagnosis, and surgeon preference. A few reports have suggested that nonoperative, conservative management is preferred for the treatment of omental torsion,6 but this is controversial. Most patients undergo surgery once diagnosed.

Dr. Nibhanipudi is assistant professor of emergency medicine and pediatrics at New York Medical College, Metropolitan Hospital, in New York City, where Dr. Benson is a resident in emergency medicine and Dr. Matari is chief of radiology.

References

1. Theriot JA, Sayat J, Franco S, Buchino JJ. Childhood obesity: a risk factor for omental torsion. Pediatrics. 2003;112(6 Pt 1):e460.

2. Caprino P, Prete FP, Alfieri S, Doglietto GB. Acute abdomen for omental volvulus. Am J Surg. 2004;187:268-269.

3. Baldisserotto M, Maffazzoni DR, Dora MD. Omental infarction in children: color Doppler sonography correlated with surgery and pathology findings. AJR Am J Roentgenol. 2005;184:156-162.

4. Trombetta LJ. Primary torsion of the omentum: CT appearance. J Am Coll Surg. 2004;198:494.

5. Naffaa LN, Shabb NS, Haddad MC. CT findings of omental torsion and infarction: case report and review of the literature. Clin Imaging. 2003;27:116-118.

6. Miguel Perello J, Aguayo Albasini JL, Soria Aledo V, et al. Omental torsion: imaging techniques can prevent unnecessary surgical interventions [in Spanish]. Gastroenterol Hepatol. 2002;25:493-496.

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