Chilaiditi sign is a radiological finding that occurs when a segment of a large bowel loop or small intestine is interposed between the liver and a diaphragm. When this causes gastrointestinal symptoms, it is known as Chilaiditi syndrome.
Normally, suspensory ligaments and fixation of the colon will prevent the interposition of the colon between the liver and diaphragm. Variations in this anatomy lead to the pathological interposition of the colon seen in Chilaiditi syndrome. These variations can include the absence, laxity, or elongation of the suspensory ligaments of the transverse colon or falciform ligament. Other factors that can predispose one to developing Chilaiditi syndrome include congenital malpositions, functional disorders such as chronic constipation caused by colonic elongation and redundancy, gaseous distension of the colon, small liver due to cirrhosis or hepatectomy, ascites due to increased intraabdominal pressure, substantial weight loss in obese patients and abnormally high diaphragm or diaphragmatic paralysis (which can present in conditions such as diaphragmatic muscular degeneration or phrenic nerve injury), chronic obstructive lung disease that causes enlargement of the lower thoracic cavity, and multiple pregnancies. Intellectual disability and schizophrenia are also associated with anatomic variations that result in Chilaiditi sign. There has been a couple of cases describing iatrogenically induced Chilaiditi syndrome from bariatric surgery, enteral feeding tube insertion, and colonoscopy.
This syndrome was first defined in 1910 by Demetrius Chilaiditi, a Greek radiologist after he reported three cases of patients who were found to have intra-abdominal free air on radiological imaging caused by the interposition of the bowel between the right hemidiaphragm and liver. Chilaiditi sign has a 0.025% to 0.28% incidence worldwide with a male to female ratio of 4:1. It most commonly occurs in the elderly population, where there is a 1% incidence. However, it has documentation in patients from 5 months of age to 81 years of age. There is also an 8.8% incidence in mentally ill patients.
The most common presenting symptoms in patients with Chilaiditi syndrome are abdominal pain, anorexia, nausea, vomiting, flatulence, constipation, changes in bowel habits followed by respiratory distress, and less frequently cardiac symptoms such as angina like chest pain and arrhythmias. These symptoms are usually worse at night while the patient is supine. Rarely, a patient will present with a combination of these multiorgan symptoms. The gastrointestinal symptoms may range from mild to severe (e.g., acute abdomen).
Chilaiditi sign is mostly an incidental finding on chest x-ray or abdominal computed tomography. There are reports that between 1.18% to 2.40% of cases demonstrated with abdominal CT, and between 0.025% to 0.280% were found on plain chest and abdominal films. These findings can present temporarily or permanently. The following criteria must be med to diagnose Chilaiditi sign based on radiological findings: the right hemidiaphragm must be elevated above the liver by the intestine, the bowel must be distended by air to illustrate pseudo-pneumoperitoneum, and the superior margin of the liver must be depressed below the level of the left hemidiaphragm. The sign can divide into anterior and posterior types depending on the position of the interposed bowel relative to the liver. Usually, the part of the bowel that most commonly interposes is the hepatic flexure, ascending colon, or transverse colon, but there have been reports of small bowel involvement. If free air is visible on abdominal plain films, it is advisable to obtain an abdominal CT to confirm the presence of the free air (which would indicate surgery) versus Chilaiditi syndrome, which would receive conservative treatment. 
aIn asymptomatic patients with Chilaiditi sign, intervention is not necessary, and treatment is usually conservative; however, more serious conditions should be ruled out first. Initial management of patients with the syndrome includes intravenous fluids, nasogastric bowel decompression, bed rest, stool softeners, and enemas. It is advisable to repeat radiographic imaging after bowel decompression to observe the resolution of the air below the diaphragm. If this is the case, it would confirm the diagnosis of Chilaiditi syndrome. Surgical intervention is indicated when the patient does not respond to conservative management, the obstruction does not resolve, or there is evidence of bowel ischemia. There is no clear consensus on the optimal surgical approach to correct bowel interposition. Ceceopexy is an option to prevent recurrence in an uncomplicated cecal volvulus unless surgical resection is indicated, and if so, colonic resection is the best option to treat a volvulus of the transverse colon. Colonoscopic reduction is not recommended due to a high frequency of gangrene with these types of volvulus. If the patient is to receive a colonoscopy, it must be done with great caution due to the risk of progressive air entrapment in an acutely angulated and interposed bowel because it could potentially lead to perforation. Administrating carbon dioxide as an insufflating agent would decrease this risk.
Differential diagnosis of Chilaiditi syndrome include:
If normal plicae circulares or haustral markings of the colon under the diaphragm are seen, entities like subphrenic abscess can be ruled out. When using ultrasound, changing the position of the patient would not change the location of the gas, which would not be in the case of a pneumoperitoneum. It is important to make the correct diagnosis as confusing Chilaiditi syndrome with another more serious condition can lead to unnecessary surgical intervention. It is also important to recognize Chilaiditi sign or syndrome in a patient undergoing liver biopsy as the abnormally positioned bowel is at risk for perforation, especially during percutaneous transhepatic procedures.
If mistaken for pneumoperitoneum, it can lead to unnecessary surgical intervention. Other complications include volvulus of the cecum, splenic flexure, or transverse colon. Cecal perforation, mesentery ischemia, peritonitis, and subdiaphragmatic appendicitis have also been reported as complications of this condition and require emergency surgery.
Chilaiditi syndrome is benign. However, when Chilaiditi sign appears on imaging, it is essential to exclude other serious conditions that would require surgical intervention. Chilaiditi syndrome treatment is with conservative management, but if symptoms do not improve, more invasive treatment options are necessary.
Free air under the diaphragm is often an emergency and warrants surgical exploration. However, there are some findings, such as Chilaiditi sign and syndrome, which are benign and do not warrant surgical intervention. The radiologists, primary physicians, and surgeons must consider this syndrome in their differential before deciding to take a patient to the operating room. Identifying pseudo-pneumoperitoneum from pneumoperitoneum could decrease the incidence of unnecessary exploratory laparotomies [Level 4].
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