Differential Diagnosis for Left Flank Pain in Pregnancy
Single Most Likely Diagnosis
- Pyelonephritis: This is a common condition in pregnancy, especially in the second and third trimesters, due to urinary stasis and ureteral dilation. The symptoms of pyelonephritis, such as flank pain, fever, and dysuria, align closely with the presentation of left flank pain.
Other Likely Diagnoses
- Nephrolithiasis (Kidney Stones): Pregnancy increases the risk of kidney stones due to increased urine calcium excretion and urinary stasis. Severe pain, often radiating from the flank to the groin, is a hallmark symptom.
- Musculoskeletal Strain: The growing uterus can cause a shift in posture and increase the strain on the back muscles, leading to musculoskeletal pain that can be perceived as flank pain.
- Urinary Tract Infection (UTI): While not as severe as pyelonephritis, lower urinary tract infections can cause discomfort and pain that might be felt in the flank area, especially if the infection is severe or ascending.
Do Not Miss Diagnoses
- Placental Abruption: Although more commonly associated with vaginal bleeding and abdominal pain, placental abruption can sometimes present with back or flank pain. It's a critical condition that requires immediate attention.
- Preeclampsia with HELLP Syndrome: While primarily characterized by hypertension and proteinuria, preeclampsia can lead to HELLP syndrome, which includes hemolysis, elevated liver enzymes, and low platelet count. Right upper quadrant pain is more common, but flank pain can occur, especially if there's significant liver involvement or hemolysis affecting the kidneys.
- Ovarian Torsion: Although rare in pregnancy, ovarian torsion is an emergency that can cause severe, sudden-onset flank or abdominal pain. It requires immediate surgical intervention to preserve the ovary.
Rare Diagnoses
- Renal Cell Carcinoma: While rare, any new onset of flank pain in pregnancy should prompt consideration of renal cell carcinoma, especially if accompanied by hematuria or a palpable mass.
- Spontaneous Rupture of the Renal Artery Aneurysm: This is an extremely rare but potentially catastrophic event that could present with sudden, severe flank pain and hemodynamic instability.