Chronic distended abdomen with pain

According to his parents, his "big tummy" was noted shortly after birth. He has been healthy until one day prior to admission, when he began experiencing acute right lower quadrant abdominal pain associated with fever, decreased appetite, and two episodes of emesis that were non-bloody and non-bilious. His parents have noticed his abdomen is slightly firmer and larger than normal. The patient is transferred to your hospital for further evaluation.

A massively distended abdomen

On your examination, his temperature is 99.6° F, his pulse is 142 bpm, respirations 22/min, and his blood pressure is 126/76 mm Hg, obtained by machine while the patient was crying. His weight is 19.4 kg and his height is 104 cm. The child is alert and talkative, with an obviously large abdomen. Head, ears, eyes, nose, throat, respiratory, and cardiac examinations are normal except for tachycardia. You find the abdomen to be massively distended and tense, with hypoactive bowel sounds but no tympany on percussion. A fluid wave is present. It is difficult to palpate the abdomen for hepatosplenomegaly or masses secondary to the large amount of fluid. He is tender when you palpate his abdomen in the right lower quadrant. He has no stigmata of liver disease, and there is no peripheral edema. His neurologic exam is normal.

Based on your exam and the information you have reviewed, you order a computed tomography (CT) scan of the abdomen, which shows a large fluid collection of unknown origin in the peritoneum (Figure 2). The consulting surgeons are concerned about an acute bladder rupture, so radiography of the kidneys, ureters, and bladder with intravenous contrast is obtained after urology is consulted. It shows no extravasation of urine outside the genitourinary system. Unable to determine where the fluid is originating, an abdominal ultrasound is performed that demonstrates a massive, complex fluid collection with internal debris within the abdomen.