Differential Diagnosis for the 34-year-old Female with RLQ Abdominal Pain

Single Most Likely Diagnosis

• Urinary Tract Infection (UTI): The presence of bilateral pyelonephritis and cystitis, as indicated by multiple cortical hypodensities in the kidneys and a distended urinary bladder with wall thickening, strongly suggests a UTI. The patient's symptoms of RLQ abdominal pain are consistent with this diagnosis.

Other Likely Diagnoses

• Endometrial Polyp: The small linear focus within the endometrium, measuring 9 mm, could represent an endometrial polyp, which is a common finding in women of reproductive age. Further evaluation with pelvic ultrasound is recommended to confirm this diagnosis.
• Endobronchial Infection: The small tree-in-bud densities in the lingula are likely related to an endobronchial infection, which could be a separate entity from the UTI.
• Chronic Pyelonephritis: The presence of multiple cortical hypodensities in the kidneys bilaterally could also suggest chronic pyelonephritis, especially if the patient has a history of recurrent UTIs.

Do Not Miss Diagnoses

• Septic Shock: Although the patient's urine analysis does not show significant evidence of infection, the presence of bilateral pyelonephritis and cystitis could potentially lead to septic shock if left untreated or if the infection is severe. It is essential to monitor the patient's vital signs and clinical status closely.
• Kidney Stones: The patient's symptoms of RLQ abdominal pain could also be caused by kidney stones, which could be obstructing the urinary tract and leading to pyelonephritis and cystitis.
• Appendicitis: Although the appendix is reported as unremarkable, it is essential to consider appendicitis as a potential diagnosis, especially if the patient's symptoms worsen or if the CT scan is not conclusive.

Rare Diagnoses

• Tuberculosis: The small tree-in-bud densities in the lingula could also be suggestive of tuberculosis, although this would be a less common diagnosis in this patient population.
• Fungal Infection: The presence of bilateral pyelonephritis and cystitis could also be caused by a fungal infection, especially if the patient is immunocompromised.
• Genitourinary Malformation: The small linear focus within the endometrium could also represent a genitourinary malformation, such as a uterine anomaly, although this would be a rare diagnosis.