Differential Diagnosis for a 13-year-old girl with lower abdominal pain and a pelvic mass
- Single most likely diagnosis:
- Imperforate hymen with hematocolpos: This condition is likely given the patient's symptoms of cyclic lower abdominal pain, rectal pain with bowel movements, and the presence of a smooth, firm mass protruding between the labia majora. The mass is likely blood accumulated in the vagina due to the imperforate hymen, which is a congenital condition where the hymen completely covers the vaginal opening, preventing menstrual blood from flowing out.
- Other Likely diagnoses:
- Ovarian cyst or torsion: Although less likely given the absence of acute severe pain and the presence of a mass, ovarian cysts or torsion could still be considered, especially if the mass is found to be separate from the vagina.
- Pelvic inflammatory disease (PID): Despite the patient's reported lack of sexual activity, PID cannot be entirely ruled out without further investigation, including sexual history and diagnostic tests.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.):
- Ectopic pregnancy: Although the patient denies sexual activity, it's crucial to consider ectopic pregnancy due to its potential severity and the fact that sexual history may not always be reliable.
- Appendicitis: While the patient's symptoms and examination findings do not strongly suggest appendicitis, it's a condition that requires prompt diagnosis and treatment to prevent serious complications.
- Malignancy (e.g., ovarian or vaginal cancer): Although rare in this age group, any pelvic mass warrants consideration of malignancy to ensure timely diagnosis and treatment.
- Rare diagnoses:
- Müllerian duct anomalies: These are congenital anomalies of the female reproductive system that could potentially cause pelvic masses or obstructive symptoms.
- Vaginal or uterine tumors: These are rare in adolescents and would be considered if the mass does not respond to initial treatment for more common conditions.