Differential Diagnosis
The patient's presentation of left flank pain, fever, loss of appetite, and bilious vomiting, along with laboratory findings and physical examination results, suggests a range of possible diagnoses. These can be categorized as follows:
Single Most Likely Diagnosis
- Pyelonephritis: This is the most likely diagnosis given the patient's symptoms of flank pain, fever, and the laboratory findings of leukocytosis with a high percentage of neutrophils, positive leukocyte esterase, and elevated BUN and creatinine. The absence of dysuria and hematuria does not rule out pyelonephritis, especially in pregnancy, where the presentation can be atypical.
Other Likely Diagnoses
- Kidney Stone (Nephrolithiasis): The patient's flank pain and vomiting could suggest a kidney stone, although the lack of hematuria and the presence of fever make this less likely. However, it remains a consideration, especially if the pain is severe and colicky.
- Cholecystitis: The bilious vomiting and left upper quadrant tenderness could suggest cholecystitis, although this would typically be associated with right upper quadrant tenderness. The presence of fever and leukocytosis supports this diagnosis, but the left-sided pain is atypical.
- Pancreatitis: The abdominal pain and vomiting could also suggest pancreatitis, but the lack of specific indicators such as elevated pancreatic enzymes makes this less likely.
Do Not Miss Diagnoses
- Appendicitis: Although the patient's pain is in the left flank, appendicitis can present atypically, especially in pregnancy. The presence of fever, vomiting, and leukocytosis necessitates consideration of this diagnosis to avoid missing a potentially life-threatening condition.
- Placental Abruption: This is a serious condition in pregnancy characterized by vaginal bleeding, abdominal pain, and sometimes back pain. Although the patient does not have vaginal bleeding, the presence of abdominal pain and fever warrants consideration of this diagnosis due to its potential severity.
- Sepsis: Given the patient's fever, tachycardia, and leukocytosis, sepsis should be considered, especially if there is a delay in diagnosing and treating the underlying cause of her symptoms.
Rare Diagnoses
- Diabetic Ketoacidosis (DKA): Although less common in this context, DKA can present with abdominal pain, vomiting, and fever. The elevated plasma glucose could suggest this diagnosis, but it would be unusual without a history of diabetes.
- Pneumonia: The patient's symptoms and laboratory findings do not strongly suggest pneumonia, but it could be considered if there were respiratory symptoms or findings on physical examination that were not mentioned.