**13. Epiploic appendagitis and omental infarction**

Epiploic appendagitis is the inflammation of epiploic appendages arise from the serosal surface of the large bowel. Torsion of the appendages results in venous occlusion, ischemia and inflammation [39]. Although predominantly encountered in adults, it is also described in children and should be kept in mind in the differential diagnosis of acute appendicitis because the treatment is supportive rather than surgery. Characteristic US feature is hyperechoic, fixed non-compressible oval mass-like lesion at the anti-mesenteric side of the bowel. CT is generally needed to confirm the exact diagnosis [57].

### **Figure 7.**

*Ultrasound image (A) of an 11-year-old boy demonstrates thickened hyperechoic mass (asterisk) with indistinct border beneath the anterior abdominal wall. Intravenous contrast enhanced axial CT (B) and sagittal reconstructed image (C) shows hyperdense omentum (white circles), hyperdense dot at the center of lesion (arrows). The dot can be followed on the contiguous images as a linear tortuous hyperdense structure consistent with twisted vein. Surgical removal of necrotic tissue confirmed the diagnosis of omental infarct.*

Omental infarction is a rare cause of acute abdomen in children, even though 15% of all omental infarct cases occur in the pediatric population [3]. As the patients are commonly present with right-sided abdominal pain, it mimics appendicitis. However, associated nausea and vomiting is less frequent than appendicitis [24]. Predisposing factors include obesity, strenuous activity, coagulopathy and history of trauma to the affected region. The characteristic US feature is an ovoid or triangular hyperechoic mass located between the abdominal wall and the bowel, frequently in the right upper quadrant (**Figure 7**) [3]. In some cases, avascular hypoechoic tubular structure can be seen corresponds to a twisted vein. Although, some centers recommend conservative treatment, others prefer surgery to remove the necrotic tissue [24].

### **14. Inguinal hernia**

In the setting of a groin mass or swelling, possible diagnoses are hernia, fluid collection, enlarged lymph nodes, and cryptorchidism, and for those US can be performed to differentiate. The most common type of inguinal hernia in children is the indirect inguinal hernia in which hernia sac protrude into the inguinal canal [41]. Inguinal hernia is more common in preterm neonates and more frequently occurs on the right side because the right processus vaginalis closes later than the left. One-third of all infants with hernias become symptomatic before 6 months after birth, and males are affected more than females with a ratio of 6:1 [58]. Hernia sac frequently includes fluid in the processus vaginalis with or without bowel loops and other abdominal structures such as omentum, testes, ovaries, bladder and fallopian tubes. If hernia sac contains intestine and other abdominal structures; possibility of spontaneous regression reduces and incarceration risk increases. Hence, early diagnosis and surgery is very important in order to prevent complications and possible damage to the ipsilateral testis [6, 58].

The diagnostic accuracy of US to detect inguinal hernia is 97% in surgically confirmed cases with the sensitivity of 92.7% and the specificity of 92.7% [6]. Internal inguinal canal diameter > 4 mm is 95% diagnostic for indirect inguinal hernia. Real-time imaging on US is the biggest advantage among other modalities, with the patient performing a Valsalva maneuver (or provoke to cry in infants or babies) in both supine and upright views that enlarge the hernia sac and protrude through the inguinal canal with increased intraabdominal pressure. US can also be able to reveal peristalsis of herniated bowel segment with dynamic scan. Large inguinal hernias may lead to testicular ischemia by compressing the gonadal vessels within the inguinal canal [59]. Therefore, ipsilateral testis should be evaluated with US and color Doppler to assess intratesticular blood flow in the setting of inguinal hernia. While, evaluating a patient with an inguinal hernia, US should be performed to both inguinal canals because a clinically occult contralateral hernia can be found in 88% of cases [58].

Incarceration is a remarkable complication of indirect inguinal hernia and occurs with a frequency of 31% in children [58]. The most common incarcerated contents of hernia sac are the bowel, ovaries, and fallopian tubes. An incarcerated inguinal hernia may gradually progress to a strangulation, in which vascular supply is compromised and the necrosis of incarcerated contents occur. On US, incarcerated bowel shows circumferential thickening of the wall, aperistalsis, fluid level in the herniated loop, free fluid in the hernia sac and intraabdominal bowel dilatation (**Figure 8**). Incarcerated or strangulated hernias may not demonstrate clear continuity with abdominal bowel loops. Color Doppler may demonstrate absent vascularity in the hernia sac as a late finding of strangulation [41]. The presence of peristaltic activity in the herniated bowel loop is strong evidence against strangulation.

*Ultrasound of the Pediatric Gastrointestinal Emergencies DOI: http://dx.doi.org/10.5772/intechopen.99759*

### **Figure 8.**

*Ultrasound of an indirect inguinal hernia of an 8-week-old baby (A,B,C). Along with bowel, blind ending appendix (arrow) is herniated into the inguinal canal, called as Amyand hernia. (B) There is some fluid (dashed arrow) within the hernia sac and (C) transverse section of distal appendix is seen at the same level with penile shaft (asterisk).*

### **15. Foreign bodies and gastric bezoar**

Coins are the most common foreign material ingested, and most of them are not able to reach intraabdominal GI tract [41]. Two-third of those is located at the level of cricopharyngeus muscle that requires urgent endoscopic removal. In the radiologic evaluation of the ingested foreign body, plain radiographs are frequently the modality of choice. Nevertheless, all foreign bodies are not visible on plain films, depending on composition of the material and location within the body. US may provide additional information about the foreign bodies trapped in the intraabdominal GI tract [60]. However, diagnostic performance of US to detect intraabdominal foreign body is not known to date. Most of the foreign bodies in bowel appear as fixed, hyperechoic structure that often demonstrate posterior acoustic shadowing with a cleaner shadow than bowel gas [6]. Linear, high frequency transducers should be used with graded compression to evaluate intraluminal contents. Administration of 200–300 mL of oral water before the examination may facilitate the detection of foreign bodies within the stomach [41].

A bezoar consists of ingested foreign objects that cluster within the GI tract. The most common types are trichobezoars (composed of hair) and phytobezoars (composed of greengrocer fibers) and they usually accumulate in the stomach [39]. Sometimes enlarged bezoars reach to the small bowel and cause obstruction. Prior history of gastric surgery is an important predisposing factor to develop bezoar due to delayed gastric emptying [41]. On US, regardless of the originated fiber, bezoar is shown as an intraluminal mass with hyperechoic arc-like (curved or "inverted U" shape) anterior surface and prominent acoustic shadowing (**Figure 9**). Color Doppler

### **Figure 9.**

*A 12-year-old girl with a history of compulsive trichophagia disorder. Upper abdomen sonography with convex-array transducer (A) and linear-array transducer (B), demonstrates curvilinear echogenicities beneath the anterior wall of the stomach (arrow) and duodenum (dashed arrow) with clear, marked black posterior shadow. On endoscopy (C), trichobezoar was removed from her stomach and proximal duodenum.*

can be used as a supportive modality which demonstrates 'twinkling artifact' behind the hyperechoic surface [39]. Bowel obstruction and proximal dilatation may be revealed as associated features.

## **16. Conclusion**

While evaluating the etiology of acute abdominal pain in pediatric patients, US should be the initial imaging modality, as US is sufficient to diagnose several diseases that cause abdominal pain, far beyond only appendicitis and intussusception. Even if the underlying cause has not been identified, US will show indirect signs that indicate the need for a surgical exploration or provide supplemental information for CT and MRI. Therefore, it is crucial to be aware of the full potential of targeted bowel US with proper selection of the transducers, optimal positioning and the application of graded compression technique. Good quality examination requires experience, training, time and attention to perform a detailed evaluation of as many bowel loops as possible, minding their morphological features and their functional characteristics. Radiologists should be familiar with the sonographic appearance of both the normal and abnormal GI tract in order to provide the optimal treatment options for pediatric patients with acute abdominal diseases.

### **Acknowledgements**

I thank Dr. Fatma Demirbas (Diyarbakır Children's Hospital) for providing endoscopic image of the trichobezoar case.

### **Author details**

Ercan Ayaz Department of Radiology, Diyarbakır Children's Hospital, Diyarbakır, Turkey

\*Address all correspondence to: ercan.ayaz1@gmail.com

© 2021 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

*Ultrasound of the Pediatric Gastrointestinal Emergencies DOI: http://dx.doi.org/10.5772/intechopen.99759*
