Chylous ascites

September 1, 2010
Diagnostic Imaging Europe Vol 26 No 5, Volume 26, Issue 5

A 31-month-old girl presented for abdominopelvic CT to rule out suspected tumor.

CLINICAL HISTORY

A 31-month-old girl presented for abdominopelvic CT to rule out suspected tumor. She had previously been referred to the outpatient department with bruising and had been extensively investigated for a suspected hematological problem, but no diagnosis had been made. This time she had been admitted to hospital with diarrhea, vomiting, and abdominal distension.

Physical examination suggested the presence of ascites and a peritoneal tap was performed. Biochemical analysis determined that the fluid was chylous in nature. Chylomicrons were also detected. Further clinical and biochemical investigation of the gastrointestinal tract and liver yielded no further information to explain her chylous ascites.

The patient was treated empirically with total parenteral nutrition and medium-chain triglyceride milk. Her symptoms settled, and she was discharged to be monitored as an outpatient.

The patient presented acutely three months later, complaining of abdominal pain and vomiting. She was obviously distressed and her abdomen was firm and tender to palpation. Radiography of the chest and abdomen was performed.

An emergency laparotomy found peritoneal fluid stained with fecal matter. The operative note went on to describe multiple areas of small bowel serosal inflammation and an ileal perforation. Multiple sites of omental necrosis and a thickened and fibrotic small bowel mesentery were documented.

The perforation was repaired and a temporary defunctioning ileostomy fashioned. Pathology reports confirmed the surgical findings of both acute and long-standing intra-abdominal disease. The combination of repeated episodes of abdominal trauma alongside healing rib fractures was thought highly suspicious for NAI (nonaccidental injury) and a full skeletal survey was performed.

A consensus clinical diagnosis of NAI was made following a case conference, and child protection procedures instigated.

DISCUSSION

Chylous ascites is an uncommon condition in children, with around 100 cases reported in the literature. It is caused by leakage of chyle into the abdominal cavity, usually as a result of a pathological process. Trauma is a less common cause, and chylous ascites following blunt abdominal trauma in cases of NAI is rarer still.1-5

The condition was first described in a child by Morton in the late 17th century.6 It refers to the presence of chyle, a milky fluid, within the peritoneal cavity; its color being secondary to the presence of fat.

Chylous ascites is not a diagnosis per se, but a sign of an underlying disorder. It may result from trauma and (accidental or nonaccidental) damage to the lymphatic vessels, most commonly those at the base of the mesentery.1 This allows chyle to escape into the peritoneal cavity. Obstruction to lymphatic flow, often as a result of lymphadenopathy, can also lead to chylous ascites, as can structural lymphatic abnormalities, such as lymphangiomatosis and lymphangiectasia.

Patients with chylous ascites present in the same way as those with ascites due to other causes: abdominal distension, vomiting, and diarrhea are the most common signs and symptoms.1 Although imaging cannot readily distinguish chylous ascites from other forms of ascites, ultrasound may show the fluid in chylous ascites to be echobright. Aspiration reveals fluid with a milk-like appearance, which will separate into layers if left standing. Analysis of the fluid shows a high triglyceride count.4

Treating chylous ascites requires maintaining adequate nutrition. This can be difficult due to the mass effect of the fluid upon the gastrointestinal tract, which, in turn, leads to reduced nutritional intake and vomiting. Total parenteral nutrition can help to maintain the patient’s nutritional status. Medium-chain triglycerides, which are absorbed by the portal system rather than lymphatics, may also be given to reduce the accumulation of chyle. Surgery is usually reserved for those who do not improve by conservative management, or for cases in which a surgical cause is identified.1,4

This case serves to remind clinicians and radiologists that chylous ascites may be the presenting sign of NAI. If the cause of chylous ascites is not apparent, then the existing clinical information and imaging studies must be scrutinized for signs of injury. A full skeletal survey should also be considered in younger patients.

Case submitted by Jonathan A. Soye, FRCR, Anne Paterson, FRCR, and Louise E. Sweeney, FRCR, all in the radiology department at the Royal Belfast Hospital for Sick Children in Belfast, U.K., and Joanna Turner, FRCR, of the radiology department of Ulster Hospital in Dundonald, U.K.