Key points

Introduction

Immunocompromised patients include those with chronic illnesses being treated with immunomodulatory medications and those with the more severe form caused by impairment of a patient’s own immune responses. Box 1 lists examples of immunosuppressed states. In immunocompromised patients, abdominal pain is a nonspecific symptom arising from extra-abdominal or retroperitoneal pathologic conditions, including genitourinary or pulmonary etiologies. Diagnosis of peritonitis in immunosuppressed patients is delayed because of delayed presentation and lack of definitive physical examination findings. This is all secondary to the inability to mount an immune response. It is important to maintain vigilance and a broad approach in these patients.

Introduction

Immunocompromised patients include those with chronic illnesses being treated with immunomodulatory medications and those with the more severe form caused by impairment of a patient’s own immune responses. Box 1 lists examples of immunosuppressed states. In immunocompromised patients, abdominal pain is a nonspecific symptom arising from extra-abdominal or retroperitoneal pathologic conditions, including genitourinary or pulmonary etiologies. Diagnosis of peritonitis in immunosuppressed patients is delayed because of delayed presentation and lack of definitive physical examination findings. This is all secondary to the inability to mount an immune response. It is important to maintain vigilance and a broad approach in these patients.

Human immunodeficiency virus/AIDS

Patients with chronic immunosuppression secondary to human immunodeficiency virus (HIV)/AIDS who have abdominal pain warrant significant consideration when being evaluated in the emergency department. Although the advent of highly active antiretroviral therapy (HAART) has greatly diminished the incidence of opportunistic infections in this population, the emergency provider must still have a high index of suspicion owing to potential poor adherence to medication regimens and unknown HIV/AIDS status. Furthermore, because HAART has resulted in increased survival in those with this disease, further diagnostic challenge is presented in an aging and elderly HIV population.

Cytomegalovirus

Cytomegalovirus (CMV) is a common infection found in the gastrointestinal tract of HIV-positive patients, and the colon is the most common site of involvement (47%). Common presenting symptoms include abdominal pain, anorexia, fever, diarrhea, and weight loss. CMV has also been linked to appendicitis. CD4 count is an important consideration in this infection, as patients with a count less than 50 cells per international unit are at higher risk for life-threatening complications, namely, perforation of the colon and rarely the small bowel. CMV ileocolitis with subsequent bowel perforation or other surgical complications is reported to be responsible for most emergency laparotomies in AIDS patients and directly responsible for the deaths in 54% to 87% of all such patients. Initial presentation may be insidious with isolated hematochezia as the only symptom. Thus, a high index of suspicion is recommended in these patients owing to the potentially devastating outcomes. Diagnostics in the emergency department rely on computed tomography (CT) imaging for evaluation of colitis or ulceration, with further inpatient diagnostics as needed. CT imaging in CMV often shows transmural colonic wall thickening, spanning from isolated involvement in recto-sigmoid or cecal regions to pan-colitis, with small bowel involvement typically presenting in terminal ileum. A 3- to 6-week course of ganciclovir or foscarnet is recommended treatment ; however, because histopathology confirmation is often required, patients suspected of this disease will benefit from admission to the hospital for further studies and monitoring regardless of CT findings in the emergency department.

Mycobacterium avium complex

Mycobacterium avium complex (MAC) is an opportunistic infection that involves the gastrointestinal tract. MAC is seen in patients with a CD4 count of less than100 cells per international unit. In the context of a low CD4 count, CT imaging shows significant involvement of lymphoid tissue and mesenteric lymph nodes, splenomegaly, and small bowel thickening predominantly involving the jejunum. In contrast, CMV involves mesenteric lymphadenopathy only 16% of the time. Secondary to antibiotic resistance, in treatment of MAC, it is recommended to initiate antibiotic therapy with double antibiotic coverage of clarithromycin and ethambutol.

Abdominal tuberculosis

Increasing in frequency in developed countries, abdominal tuberculosis (ATB) should be considered in the HIV population with less severe immunosuppression (200–500 CD4 cells per international unit). Elucidating historical risk factors for contraction of this infection may raise suspicion. Although the abdomen is a less common anatomic location for this infection, it is disproportionately found to be present in immunosuppressed patients. Eighty percent to 85% of HIV patients with ATB will have no signs of pulmonary involvement. Up to 90% of cases favor the ileocecal region as the site of infection with presenting symptoms of right lower quadrant pain or mass. Classically, ATB presents in a wet form with ascites or a dry form with adhesions and possible obstruction. Current recommendations suggest a minimum of a 6-month multidrug therapy for treatment, consisting of ethambutol, rifampin, isoniazid, and pyrazinamide for 2 months followed by 4 months of isoniazid and rifampin.

Amebic colitis

Parasitic infections with ameba may be considered in the HIV-positive patient with a travel history or recent immigration from geographic regions with high incidences, including India, Africa, and parts of South and Central America. Those at risk for obtaining this infection include HIV-positive people, those younger than 50 years, men who have sex with men, and commercial sex workers. Amebic colitis secondary to this infection bears mentioning, as it is difficult to differentiate from other infectious colitis sources both through clinical examination and CT imaging. However, it is treatable with metronidazole. Intestinal collections of this infection may be misinterpreted as a nonspecific mass or cancer on CT.