Diverticula are defined as sac-like protrusions from the large intestine wall due to a combination of anatomical, dietary, motility and structural influences [5]. They are divided in two general anatomical types, true and false. The majority of the colon diverticula are false diverticula (also known as pseudodiverticula), composed of mucosa and submucosa protruding through the muscularis externa, covered only by serosa. They are acquired, multiple and frequently located in the sigmoid colon. True diverticula involve all three layers of the bowel wall (mucosa, submucosa and muscularis externa) as seen in most congenital diverticula such as Meckel’s diverticula and in the diverticula of right-sided large intestine [6, 7]. They are mostly congenital and solitary [8].
When infection of the diverticulum occurs, it can manifest with a spectrum of symptoms such as pain, fever, diarrhoea, nausea, vomiting and bloody stools. Right-sided diverticulitis (RSD) may mimic several abdominal emergencies such as cholecystitis, appendicitis or epiploic appendagitis. The distinction between these conditions and RSD is crucial as the latter is treated conservatively and abscess formation is rare [9, 10]. Within the range of possible investigations, US plays its role being the first imaging study modality performed in patients presenting with abdominal pain. It can safely rule out cholecystitis and identify several abdominal conditions such as epiploic appendagitis (EA), appendicitis, colitis, neoplastic lesion and Crohn’s disease, each of them characterised by specific sonographic aspects.
The sonographic appearance of the inflamed diverticulum is defined as hypoechoic wall thickening, due to oedema and muscular hypertrophy. US can also reveal complications such as inflammation of the pericolic fat and free fluid collection around the target area. Specifically, the pericolic fat stranding consists of hyperechoic non-compressible mass-like finding whether the free fluid has a hypoechoic ultrasound aspect [11]. Give US its crucial role in the decision-making process, the CT remains the modality of choice in the diagnosis of diverticulitis, due to its ability to identity the anatomical location along the large intestine, the involvement of adjacent organs and the presence of complications such as perforation, abscess and fistula [7]. In summary, ultrasound evaluation of abdominal emergencies is a rapid and useful first-level investigation that may lead the next step in the clinical decision-making process, such as a second-level imaging study, surgical or conservative approach. Both imaging modalities have their advantages and limitations, making their combined use crucial for the best appropriate clinical management of patients.