Primary Iliopsoas Abscess and Drug-Induced Acute Liver Failure in the Emergency Department: A Common Symptom, an Uncommon Diagnosis

1. Background

The occurrence of an iliopsoas abscess (IPA), a suppurative collection in the compartment of the psoas and iliacus muscles, was initially documented by Mynter et al. in 1881 [1]. It continues to be a rare condition, with a global reported incidence of only 12 cases per year [2].

There are two classifications for iliopsoas abscesses based on their origin: primary and secondary. Primary abscesses occur when an infection from a distant site spreads through the bloodstream or lymphatic system. A single organism typically causes these abscesses and may be hidden. On the other hand, secondary abscesses result from the direct extension of infection from nearby structures such as the gastrointestinal or genitourinary tract, lumbar spine, or hip region. It has been reported that secondary iliopsoas abscesses have a higher mortality rate compared to the primary ones [3].

The symptoms of iliopsoas abscess can be unclear and diverse. The traditional triad of fever, back pain, and restricted hip movement (or limp), known as the psoas-muscle sign, is only observed in 30% of cases, making diagnosis challenging [1,4]. Consequently, the condition is often missed during the initial visit to the emergency department [4].

Previous reports need to adequately discuss the diagnostic complexities associated with iliopsoas abscess, mainly when it refers to emergency physicians. Therefore, this report aims to share our firsthand experience in our emergency department in diagnosing this uncommon but important disease.

Case Report

A 49-year-old female patient presented to our Emergency Department with complaints of pain in the lower left abdomen, specifically in the left iliac fossa and right hypochondriac region, accompanied by fever and vomiting. Upon physical examination, the patient exhibited normal breathing (16 breaths per minute) and was stable regarding hemodynamics. However, she had jaundiced skin and sclera, with a blood pressure reading of 130/80 mmHg, a heart rate of 80 beats per minute, a body temperature of 38.8 °C, a Glasgow Coma Score (GCS) of 15/15, and a peripheral oxygen saturation (SpO2) of 97% while breathing ambient air.

The patient complained of pain in the left lumbar region and fatigue that started two weeks before this presentation, claiming that, during the previous night, the pain suddenly worsened. From her medical history, she mentioned essential hypertension under treatment and untreated hypercholesterolemia. Regarding living and working conditions, the patient lives in the country with her family as a housewife. Also, the patient denies vicious behaviors such as smoking, alcohol, or drugs.

The patient performed an abdominal ultrasound, which revealed multiple gallstones, but the main bile duct was in normal range value (Figure 1), so acute cholangitis was initially suspected.

Blood was taken for lab tests, and she was scheduled for an abdominal and pelvis computed tomography (CT) scan with a contrast substance. She received an intravenous perfusion with 1 g acetaminophen, 40 mg pantoprazole, 40 mg drotaverine, and 500 mL normal saline (0.9%) solution, but she remained unresponsive to the administration of the antalgic and antispastic treatment. Until the CT was performed, the blood tests arrived, which were severely increased (Table 1). The patient had leukocytosis with neutrophilia. Reactive thrombocytosis associated with infection. Hepatocytolysis syndrome. Hyperbilirubinemia with the predominance of indirect bilirubin. There is no modification on a urine test.

Figure 2. Laboratory test values evolution from ED admission until reassessment (day 31) in the ED in collaboration with our general surgery department.

Figure 2. Laboratory test values evolution from ED admission until reassessment (day 31) in the ED in collaboration with our general surgery department.

After analyzing the laboratory test results, we repeated and performed a more detailed medical history and anamnesis of the patient. As a result of increasing pain, the patient had taken several medications over the last five days, including acetaminophen, naproxen, ketoprofen, metamizole, amoxicillin + clavulanic acid, diclofenac, and ibuprofen. However, she could not provide us with the exact dosage of these medications but mentioned that she had consumed a significant number of pills. Based on these findings, we also considered the diagnosis of drug-induced acute hepatitis.

Further, the abdominal and pelvis CT scan with contrast substance performed showed the cholelithiasis observed on abdominal ultrasound with common bile duct diameter in normal limit values and fused abscess-type collections at the interfibrillar level of the left iliopsoas muscle (Figure 3).

In the emergency department, she received intravenous fluid resuscitation, metamizole 500 mg, drotaverine 80 mg, and an empiric antibiotic (ceftriaxone). Based on the following table (Table 1), where we performed a short literature review of the documented origins of secondary spread to the psoas muscles, we decided to take additional chest radiography and blood tests in the ED to identify the cause of the patient's left iliopsoas abscess.

The chest radiography showed clear lungs, a healthy heart, and a clearly outlined chest cavity (Figure 4), thus excluding tuberculosis and, implicitly, Pott's disease and tuberculous spondylitis as causes of iliopsoas abscess. Despite a thorough CT scan examination, no evidence of colonic micro perforations was found, leaving the cause uncertain. Additionally, the patient explicitly denied any past involvement in intravenous drug abuse. Furthermore, we requested an evaluation of the patient by the general surgeon on duty, who indicated hospitalization and surgical drainage.

Following this, it was decided that the patient should be transferred to the general surgery department. After the preoperative preparation, surgical intervention is performed, and the Dos Santos incision is practiced. After dissection of the anatomical planes, a voluminous abscess is drained from the level of the left psoas muscle, taking cultures from this level simultaneously. It continues with the debridement and washing of the operative area, placing drain tubes at this level, one with the tip located in the left paravesical pelvis (Figure 4A) and one with an ascending trajectory along the left iliopsoas muscle (Figure 4B) and the tip on its ventral side, next to the L3 vertebral body, as it can be seen on the second abdominal and pelvis CT scan with contrast substance performed after surgical drainage.

The fluid culture from the iliopsoas abscess was positive for methicillin-sensitive Staphylococcus aureus (MSSA). According to the antibiogram, the identified germ was sensitive to Linezolid. Thus, it has been decided that treatment should be started with Linezolid 600 mg twice a day for ten days. During hospitalization, the patient was screened for possible sources of infection. Blood and urine cultures were normal, as well as the hepatitis A, B, C, and HIV infection. She performed a gastroscopy and colonoscopy with normal results. Also, a magnetic resonance imaging (MRI) of the thoracic and lumbar spine did not identify a secondary cause for her left iliopsoas abscess (Figure 5).

Figure 2 depicts the patient's laboratory test values during hospitalization, demonstrating the favorable postoperative evolution. After 12 days of hospitalization in the general surgery department, she was discharged in good general condition, appetizing, and afebrile. After 30 days, she was medically and clinically reassessed in the Emergency Department in collaboration with the general surgeon, where no sign of infection was observed, and laboratory tests were in the normal range.