Applied Radiology

Prepared by Glenn G. Gray, MD and Alan Tikotsky, MD of the Department of Radiology, Lenox Hill Hospital, New York, NY.

CASE SUMMARY:

A 43-year-old woman presented to the emergency department complaining of severe abdominal pain, nausea, and vomiting which awakened her from sleep 2 hours earlier. Physical examination showed a diffusely tender, distended, tympanic abdomen with decreased bowel sounds. Laboratory test results were within normal limits. The patient's medical history was significant only for a cesarean section 7 years previously. Conventional radiographs of the chest and abdomen were obtained. A computed tomographic scan and barium enema were performed, followed by laparotomy.

DIAGNOSIS:

Cecal bascule with Chilaiditi's sign.

IMAGING FINDINGS:

Supine and upright abdominal radiographs demonstrated dilated loops of small bowel with several short air-fluid levels. Hepatodiaphragmatic colonic interposition was noted. This finding was better seen on the PA chest film, which was otherwise normal (figure l). A CT scan of the abdomen and pelvis was performed with oral and intravenous contrast and showed a loop of markedly distended bowel in the pelvis (figure 2). The possibility of volvulus was raised, but it was unclear which loop of bowel was involved. The patient was sent for a water-soluble contrast enema. Contrast flowed to the level of what initially appeared to represent the cecum; however, the hugely distended loop of bowel located in the pelvis and extending into the mid-abdomen did not fill with contrast. This loop was thought to represent the cecum (figure 3). Cecal volvulus was the leading diagnosis, even though a "birds-beak" sign was not demonstrated.

The patient was taken to the operating room where a diagnosis of cecal bascule was made. The massively distended cecum was folded anteriorly with the appendix anterior in location. Marked redundancy of the colon was noted, especially the transverse portion. The cecum was decompressed and a cecopexy was performed. The patient recovered well without complication.

DISCUSSION:

Demetrius Chilaiditi originally described the radiographic finding of hepatodiaphragmatic interposition in 1910. Since then, Chilaiditi's sign has been regarded as a radiologic curiosity by most physicians. The sign is uncommon, with a reported incidence of <1% of all routine chest radiographs. ^1,2 Men demonstrate this finding more often than women and it is seen rarely in children. ³ Any bowel loop can be interposed, but the hepatic flexure is most commonly involved ⁴ The differential diagnosis includes pneumoperitoneum and subdiaphragmatic abscess.

Hepatodiaphragmatic interposition can be intermittent or permanent and is usually an incidental finding. However, when associated symptoms are present, the term "Chilaiditi's syndrome" has been applied. The syndrome can present with nausea, vomiting, flatulence, anorexia, intermittent obstruction, change in bowel habits, and even respiratory distress and cardiac arrhythmias. ³ Treatment is usually conservative, consisting of bed rest, nasogastric intubation, stool softeners, and enemas. Rarely, surgical indications have been described for patients with Chilaiditi's syndrome, including colonic and gastric volvuli, internal hernia, and subphrenic appendicitis. ^3,5,6

Multiple factors play a role in the formation of Chilaiditi's sign. Colonic redundancy is felt to be the most significant contributing element. Chronic constipation is the most common cause of colonic elongation and redundancy. ⁴ Interestingly, there is a higher reported rate of Chilaiditi's syndrome in certain psychiatric patients. ^7,8 This is probably secondary to aerophagia with resultant intestinal gaseous distention, combined with antipsychotropic medication usage, which causes colonic hypotonia and subsequent constipation, leading to redundancy. ⁷ A reduction in liver volume or laxity of the hepatic suspensory ligaments also is believed to be necessary in the formation of Chilaiditi's sign. ⁵ Other factors that may contribute to hepatodiaphragmatic interposition include elevation of the right hemidiaphragm (e.g., phrenic nerve injury, diaphragmatic eventration) and enlarged lower thoracic cage diameter (e.g., COPD, pregnancy). ^4,5 Additionally, previous surgery can lead to freeing of normal fixation of bowel.

Cecal bascule is a form of volvulus in which the cecum "folds" anteromedially in front of the ascending colon, producing a flap-valve occlusion at the site of flexion. It is a torsion in the transverse plane, and causes cecal distension. The other form of cecal volvulus, axial torsion, is a classic volvulus in which rotation occurs in the longitudinal plane. Bascules represent up to one-third of cecal volvuli. ⁹ Clinically, the two forms have similar presentations and treatments, so distinction generally is not made. ^9,10 Radiographically, however, bascule can be differentiated from axial torsion. ^9,10 In classic axial torsion, the cecum turns upward and usually lies in an ectopic location, often the left upper quadrant, giving the classic "kidney-bean" appearance. With bascule, the cecum usually falls into the pelvis, as in our case, or lies across the lower mid-abdomen, resting centrally. In addition, because of the anterior folding that occurs with bascule, the appendix ends up superiorly. The "birds-beak" sign typically is not present with bascule because there is no true twist. ⁹

Colonic redundancy with an abnormally long mesentery is almost always found in cases of colonic volvulus; whether cecal, sigmoid, or transverse. ¹⁰ During routine barium enemas, however, various degrees of abnormally positioned colon can be found in normal individuals as well. These variations are usually insignificant and are considered normal, but some can have clinical implications. Most of these anatomic variants are congenital in origin, resulting from defective fixation of the primitive dorsal mesentery to the posterior abdominal wall. Defective fusion and fixation can affect any portion of the bowel but abnormalities are most common on the right, resulting in abnormal mobility of the cecum and, in turn, predisposing to volvulus or Chilaiditi's sign. ^9,10

CONCLUSION:

Chilaiditi's sign and cecal bascule can be explained on the basis of similar anatomic variations. Although Chilaiditi's sign usually is an incidental finding, it implies colonic redundancy and, more importantly, some degree of abnormal colonic mobility. If this sign is noted, careful inspection of the gastrointestinal tract should be performed. If abdominal complaints are present, Chilaiditi's syndrome can be included in the differential diagnosis.

References

1. Melester T, Burt M: Chilaiditi's syndrome: Report of three cases. JAMA 254:944-945, 1985.

2. Inagaki S, Ebata K: A roentgenological study of Chilaiditi's syndrome. Nippon ika daigaku zasshi 59(4):302-322, 1992.

3. Risaliti A, De Anna D, Terrosu G, et al: Chilaiditi's syndrome as a surgical and nonsurgical problem. Surg Gynecol Obstet 176:55-58, 1993.

4. Plorde J, Raker E: Transverse colon vovulus and associated Chilaiditi's syndrome: Case report and literature review. AJG 91:2613-2616, 1996.

5. Orangio G, Fazio V, Winkelman E, McGonagle B: The Chilaiditi syndrome and associated volvulus of the transverse colon. Dis Colon Rectum 29:653-656, 1986.

6. Takagi Y, Abe T, Nakada T, et al: A case of Chilaiditi's syndrome associated with strangulated volvulus of the sigmoid colon. AJG 90:905, 1995. Letter.

7. Matsuo T, Kotsubo D, Ichiki S, et al: Chilaiditi's Syndrome in schizophrenic patients. Jpn J Psychiatric Neurol 41:71-75, 1987.

8. Lekkas CN, Lentino W: Symptom producing interposition of the colon. JAMA 240:747-750, 1978.

9. Rabin M, Richter I: Ceacal bascule: A potential clinical and radiological pitfall. S Afr Med J 54:242-244, 1978.

10. Balthazar E: Congenital positional anomalies of the colon: Radiographic diagnosis and clinical implications. Gastrointest Radiol 2:49-56, 1977.