Omental torsion leading to omental infarction is a relatively rare condition, categorized into primary and secondary types, with the secondary form being more prevalent (1). Secondary omental torsion typically arises from underlying abdominal pathologies, such as appendicitis or other inflammatory processes, and is often identifiable (2). The greater omentum, a large apron-like structure composed of fatty and areolar tissue, is prone to torsion due to its mobility and variable attachments (3). This condition predominantly occurs on the right side due to the anatomical length of the right omentum.

The clinical presentation of omental torsion can be deceptive, often mimicking other acute abdominal conditions like appendicitis, leading to misdiagnosis (4). Pain is initially diffuse due to the stimulation of omental autonomic nerves and becomes localized as ischemia progresses and necrosis sets in. Ultrasound imaging is a valuable tool for detecting omental abnormalities, including omental thickening, increased echogenicity, and the characteristic “whirlpool sign.” However, differentiating omental torsion from other conditions can be challenging, especially when coexisting pathologies are present (5).

Congenital midgut malrotation, a developmental anomaly of intestinal rotation and fixation, can profoundly alter the anatomical relationships within the abdomen. These changes may predispose to atypical localization of the appendix and to unusual patterns of omental involvement. This case highlights the diagnostic complexity of secondary omental torsion in a pediatric patient with midgut malrotation and underscores the importance of a high index of suspicion and comprehensive imaging for accurate diagnosis and management in a tertiary pediatric center.

A 12-year-old child presented to a tertiary pediatric referral center in Southwest China in May 2024 with more than 48 h of abdominal pain and 24 h of fever. Symptoms began after heavy intake of indigestible meat-based snacks. The pain was constant and non-radiating, without a clear relationship to movement or meals. The child had reduced appetite, malaise, and loose stools but no vomiting and maintained normal urine output. Intermittent fever peaked at 38.7°C and recurred despite antipyretics administered at a local facility.

On admission, the working diagnosis was acute abdominal pain with suspected peritonitis, and laboratory tests and abdominal ultrasound were arranged.

Omental torsion is rare in children and most often occurs as a downstream event secondary to other intra-abdominal pathology. In our patient, congenital midgut malrotation—without volvulus—established an atypical left-sided ileocecal position that predisposed to left-sided appendicitis and localized peritonitis; the resulting inflammation likely triggered secondary torsion of the adjacent greater omentum. This causal hierarchy reconciles the imaging and operative findings and also explains why the initial ultrasound, although sensitive to omental abnormalities, did not immediately reveal the underlying anatomic variant. The comparison summary table of primary and secondary greater omentum torsion is shown in Table 2.

To our knowledge, this combination of congenital midgut malrotation, left-sided perforated appendicitis, and secondary omental torsion has rarely been reported in children.

Mechanistically, malrotation alters cecal and small-bowel fixation, narrows the mesenteric base, and reconfigures the spatial relationship between bowel and omentum. These changes can facilitate tethering or torque on the omentum in the presence of adjacent inflammation (e.g., appendicitis), predisposing to secondary torsion. A closely analogous presentation has been described by Emanuwa et al., where a left-sided cecum was found tethered by torted omentum at laparotomy, supporting the same causal sequence proposed here (6).

From an imaging perspective, both ultrasound and computed tomography (CT) play essential roles in the diagnosis and evaluation of omental lesions. Ultrasound can delineate the characteristic echogenic thickening of the greater omentum and is particularly advantageous in identifying focal hypoechoic regions with absent internal Doppler signals. These features are critical for distinguishing the nature of omental pathology. For instance, in cases of inflammatory myofibroblastic tumor (IMT), ultrasound may reveal a hypoechoic mass, consistent with the typical sonographic appearance of omental lesions (7). However, when the child is hemodynamically stable, an upper gastrointestinal (UGI) contrast study remains the reference investigation for establishing the diagnosis of malrotation (with or without volvulus) (8). In our emergency setting, a preoperative UGI was not obtained, which is a recognized limitation that can reduce anatomic certainty before surgery.

The Ladd procedure is widely regarded as the standard treatment for intestinal malrotation. It entails division of the Ladd bands, widening of the mesenteric base, repositioning the small bowel to the right and the colon to the left, and appendectomy, with the goal of preventing volvulus and future obstructive events. With advances in minimally invasive surgery, laparoscopic Ladd has become an increasingly feasible option, particularly in the absence of midgut volvulus (9). The laparoscopic approach offers the advantages of minimal invasiveness and a shorter recovery period. Studies demonstrate that laparoscopic Ladd in adults and adolescents is safe and effective, relieving symptoms and improving quality of life (10). In addition, it is associated with shorter operative and hospital times and a lower rate of postoperative complications, making it an attractive therapeutic choice (11). Given this child's perforated appendicitis and purulent peritonitis, our index operation prioritized source control (appendectomy, lavage, drainage), with planned interval assessment for the need and timing of Ladd based on recovery and follow-up.

In our patient, the index operation prioritized source control in the context of perforated appendicitis with purulent peritonitis. Extensive adhesions, gross contamination, and the lack of obvious omental necrosis led us to manage the omental torsion conservatively. This approach was justified by the subsequent ultrasound, which demonstrated preserved omental perfusion and resolution of edema. In children with partial omental torsion and severe peritonitis, limiting operative time and avoiding additional resection may be reasonable, provided that close postoperative imaging and clinical follow-up are ensured.

When contextualizing this case, we found only a few pediatric reports describing the combination of congenital malrotation, left-sided appendicitis, and secondary omental torsion. Most published pediatric series of omental torsion involve primary right-sided lesions without malrotation. Our case therefore adds to the limited literature and underscores that left-sided omental abnormalities in children should prompt deliberate consideration of malrotation, especially when imaging suggests an atypical location of the appendix or ileocecal region.

This report has several limitations. No intraoperative photographs were captured because of the emergent and contaminated field; a schematic illustration (Figure 3) is therefore used to depict the malrotated anatomy and left-sided appendix. Although this limits direct visual corroboration, the integrated clinical, imaging, and operative data provide educational value and highlight a practical diagnostic pitfall—namely, that left-sided omental abnormalities with appendiceal signs should trigger careful assessment for malrotation in the preoperative differential diagnosis. Longer-term follow-up is also needed to determine whether and when a Ladd procedure will be required to mitigate future volvulus or obstruction risk.

In children with left-sided appendicitis and omental abnormalities, congenital midgut malrotation should be considered early as the primary anatomic substrate to optimize diagnosis and operative planning. Ultrasound and CT rapidly characterize inflammation and abnormal localization, whereas a UGI series remains the reference test for confirming malrotation in stable patients. In contaminated emergencies, operative priorities should focus on source control, with interval assessment of the need and timing of a Ladd procedure under close clinical and imaging follow-up.