Signs of peritonitis on x-ray and ultrasound

The article was consulted with Specialist Doctor I Nguyen Thanh Hai - Radiologist - Department of Diagnostic Imaging and Nuclear Medicine - Vinmec Times City International Hospital.

Peritonitis is an infection that occurs in the epithelial lining of the abdominal wall and abdominal organs. Any damage to these organs can result in peritonitis. It is a severe, dangerous condition with a high mortality rate. Accordingly, it is necessary to examine and promptly detect signs of peritonitis on x-ray and normal local ultrasound.

The abdominal cavity is covered by the parietal peritoneum and also the visceral peritoneum to cover the abdominal organs. The total surface area of ​​the peritoneum is about 1.7 square meters. Under normal conditions, the peritoneum is sterile and contains 50 mL of a yellow liquid containing several macrophages, mesothelial cells, and lymphocytes.
Peritonitis is the reaction of the peritoneum against bacterial contamination or intrinsic chemical toxins in the abdominal cavity. This response is initially characterized by congestion and increased secretion of fluid and macrophages into the peritoneal cavity. Neutrophils will arrive within 2-4 hours and become the predominant cell of the peritoneal cavity for the first 48–72 hours. These cells release large amounts of cytokines: the synergistic effect of these mediators contributes to the inflammatory response, resulting in the creation of a fibrin network that temporarily reduces and prevents fluid reabsorption from the peritoneal cavity and “trap” bacteria. This phenomenon can create an abscess. This sequence of reactions can be controlled and the peritonitis may resolve or may continue to cause progressive peritonitis, resulting in septic shock, systemic toxicity, and multiple muscle failure. mandarin.
Regarding classification, peritonitis is divided into primary peritonitis and secondary peritonitis. Primary peritonitis, which is caused by an extraperitoneal source, is common in both children and adults and can be life-threatening, especially in patients with cirrhosis or in children. I have nephrotic syndrome. In contrast, secondary peritonitis is an infection caused by inflammation or damage to the integrity of the intestine or urogenital tract, thereby exposing the peritoneal cavity to the resident flora of the gastrointestinal tract. Secondary peritonitis seen in the setting is acute perforation peritonitis, postoperative peritonitis, or post-traumatic peritonitis.

2.1 Primary peritonitis Primary peritonitis is less common than secondary peritonitis. In adults, the disease occurs mainly in association with cirrhosis or nephrotic syndrome.
The cause of idiopathic bacterial peritonitis is unknown but is thought to involve hematogenous spread of organisms whose growth is facilitated by diseases The liver and the portal circulation are altered.
Accordingly, the diagnosis of peritonitis should be considered in any cirrhotic patient. At this time, signs of infectious peritonitis on ultrasound include localized ascites or ascites containing debris, gas, or septal formation. Simultaneously, ultrasonography can also observe diffuse thickening of the peritoneum, peritoneum, and mesentery. In this setting, ultrasound has many advantages over computed tomography (CT) in analyzing the properties of the peritoneal fluid in these cases.
2.2 Abscess Delay in treating peritonitis can lead to the development of an intraperitoneal abscess. Due to gravity, abscesses tend to form and develop in the lower regions of the abdomen and pelvis, such as the hyporenal region, the subhepatic region, and the sac of Douglas. In addition, abscesses can also be found interspersed between loops of bowel.
Distinguishing features of an intra-abdominal abscess by ultrasound include a circular or oval fovea with an irregular and clear wall. Abscesses usually contain an internal septum and debris; however, an abnormal collection of fluid that does not produce echogenicity can also become infected. Sometimes, ultrasonography also shows small air sacs in the abscess, which becomes diagnostic evidence of infection.
Nevertheless, the limitations of ultrasonography in detecting intra-abdominal fluid and distinguishing sterile and infectious fluid have been recognized, especially in obese or postoperative patients. At the same time, distinguishing a gas-filled abscess from an adjacent gas-filled loop of bowel by ultrasound can also be difficult. At this time, CT scan will be the alternative.

2.3 Tuberculosis peritonitis TB peritonitis still needs to be mentioned because TB is still common in developing countries. Patients at risk of developing peritonitis with this agent are alcoholics and those with cirrhosis, AIDS patients, or in the immigrant community. Therefore, before patients with high suspicion factor, common features on ultrasound will allow earlier diagnosis of this potentially curable disease, thereby reducing morbidity and mortality.
Three types of tuberculous peritonitis have been described: (a) "wet" with free or localized fluid; (b) the "dry" type with nodules and adhesions and (c) the fibrous fixation type with mass formation including tumor and loops of bowel or mesentery, sometimes with ascites. Abdominal ultrasound can distinguish these three types. In addition, ultrasonography can also be used as a guide for aspiration and aspiration of enlarged lymph nodes for culture and cytology, as well as for long-term follow-up.
2.4 Sclerosing peritonitis One of the main complications of acute peritonitis when it becomes chronic is sclerosing peritonitis, a condition characterized by the formation of a membrane of connective tissue that covers the peritoneum and eventually encloses loops of intestine. Patients with abdominal pain, intestinal wall damage, and symptoms of acute or subacute bowel obstruction require surgical intervention.
At this point, abdominal ultrasonography is useful in the diagnosis of sclerosing peritonitis with features such as increased bowel motility and thin echogenic fibers seen in ascites. As the disease progresses, the intestinal wall thickens and may become calcified, adding fibrous bands that adhere the intestine to the abdominal wall.

Abdominal x-ray is the initial imaging method in the process of approaching the diagnosis and treatment of patients with peritonitis. At the same time, x-rays also help to distinguish common causes from those that require aggressive medical intervention.
In particular, in elderly patients with acute abdominal pain, the general usefulness of x-ray alone for the diagnosis of peritonitis is limited mainly to the assessment of free intraperitoneal air, signs of obstruction or swallowing, foreign body entrapment. Despite relative sensitivity and specificity, x-ray is still indicated as a general screening tool in elderly patients with abdominal pain.
In addition, some signs suggestive of serious pathology may be found on plain radiographs in peritonitis such as megacolon, signs of biliary disease such as cholecystitis, emphysema and calcified aorta.

In summary, peritonitis with the general perception is a severe inflammation in the abdomen, requiring aggressive treatment according to the cause, preventing dangerous complications. Along with the advent of modern imaging tools, x-ray and ultrasound are the initial choices in diagnosing peritonitis because of their availability and convenience. With these advantages, doctors need to recognize early signs of peritonitis on x-ray and ultrasound for differential diagnosis in cases of initial clinical suspicion, especially in elderly patients in acute abdominal pain.
Currently, Vinmec International General Hospital is one of the health care centers with professional quality assurance with a team of leading medical doctors. The hospital has actively brought in modern equipment and advanced machines to best serve the medical examination and treatment process in order to provide clear images, minimizing the impact on health. patient health.
Therefore, you can rest assured when conducting an examination at Vinmec. After the test results are available, the doctor will advise and give the best treatment.