A 26-year-old man comes to the clinic due to a 2-week history of persistent abdominal pain in the right upper quadrant, low-grade fever, and anorexia. The patient recently immigrated to the United States from Mexico, where he worked as a mechanic. Several months ago, he had bloody diarrhea for several days, which resolved spontaneously. He takes no medications or herbal preparations. The patient has had no other travel, exposure to animals, or sick contacts. Temperature is 38.7 C (101.7 F), blood pressure is 122/80 mm Hg, pulse is 82/min, and respirations are 14/min. Physical examination shows tenderness to palpation in the right upper quadrant but is otherwise unremarkable. Laboratory results are as follows: Blood cultures are sterile through 48 hours. CT scan of the abdomen reveals a 2x3 cm abscess in the right lobe of the liver. In addition to confirmatory testing, which of the following is the most appropriate next step in management?

Question

A 26-year-old man comes to the clinic due to a 2-week history of persistent abdominal pain in the right upper quadrant, low-grade fever, and anorexia.  The patient recently immigrated to the United States from Mexico, where he worked as a mechanic.  Several months ago, he had bloody diarrhea for several days, which resolved spontaneously.  He takes no medications or herbal preparations.  The patient has had no other travel, exposure to animals, or sick contacts.  Temperature is 38.7 C (101.7 F), blood pressure is 122/80 mm Hg, pulse is 82/min, and respirations are 14/min.  Physical examination shows tenderness to palpation in the right upper quadrant but is otherwise unremarkable.  Laboratory results are as follows:  Blood cultures are sterile through 48 hours.  CT scan of the abdomen reveals a 2x3 cm abscess in the right lobe of the liver.  In addition to confirmatory testing, which of the following is the most appropriate next step in management?

Quizplus · Accepted Answer

11ec25c8_d45f_12e7_bc81_098d24a91aab_MD0003_00 This patient who recently emigrated from Mexico has fever, right upper quadrant pain, elevated alkaline phosphatase, and a hepatic abscess. In association with the history of bloody diarrhea and negative blood cultures, this presentation suggests an amebic liver abscess due to Entamoeba histolytica, a protozoan most commonly found in developing countries (eg, Mexico) that is acquired by consuming contaminated food or water. Men age 20-50 are disproportionately affected. E histolytica infection (amebiasis) is usually asymptomatic but can result in amoebic colitis (eg, bloody diarrhea) or may spread through the bloodstream to the liver, lungs, or brain. The most common extraintestinal manifestation is an abscess on the right lobe of the liver. Similar to other causes of liver abscess (eg, bacterial), amebic liver abscesses usually present with fever, right upper quadrant pain, anorexia, elevated liver enzymes (particularly alkaline phosphatase), and leukocytosis. Eosinophilia is unexpected (usually seen in helminthic infections). Serologic testing for E histolytica antibodies can be used to confirm the diagnosis. Stool microscopy is insensitive in the absence of concurrent diarrhea. Treatment includes an oral tissue agent (eg, metronidazole, tinidazole) followed by a luminal agent (ie, paromomycin) to eradicate intestinal colonization. (Choices A and C) Intravenous antibiotics (eg, ceftriaxone) and percutaneous aspiration or drainage are recommended for the treatment of bacterial (pyogenic) liver abscess. These typically occur in the setting of biliary infection or from hematogenous spread of intraabdominal infections (eg, diverticulitis) in elderly patients with underlying comorbidities (eg, diabetes mellitus). This patient's age, recent emigration from Mexico, history of dysentery, and negative blood cultures make amebic abscess much more likely. Drainage of an amebic abscess is usually reserved for those whose condition fails to improve with appropriate therapy or who have large lesions at risk of imminent rupture. (Choice D) This patient has a hepatic abscess that requires diagnosis and treatment. Reassurance and reimaging would delay therapy, leading to abscess enlargement and possible rupture. (Choice E) Surgical resection can be useful in cases of complicated Echinococcus infection; however, cysts (rather than abscess) are visible on imaging. In addition, Echinococcus infection is frequently asymptomatic and requires contact with animals (eg, dogs, sheep). Educational objective: Entamoeba histolytica infection should be considered in patients with a liver abscess who have lived or traveled in a developing country; abscesses may occur following an episode of dysentery (ie, amebic colitis). Patients typically develop fever, right upper quadrant pain, anorexia, elevated liver enzymes, and leukocytosis. Treatment includes a tissue agent (ie, metronidazole, tinidazole) followed by paromomycin to eradicate intestinal colonization. References: A review of amoebic liver abscess for clinicians in a nonendemic setting. (http://www.ncbi.nlm.nih.gov/pubmed/23061067)

A 26-Year-Old Man Comes to the Clinic Due to a 2-Week