Differential Diagnosis
- Single most likely diagnosis
- Appendicitis: The patient's presentation of lower abdominal pain, particularly tenderness in the right lower quadrant, loss of appetite, mild nausea, fever (38.8°C), and absent bowel sounds, are classic signs of appendicitis. The absence of cervical motion tenderness and normal adnexa and ovaries on exam further support this diagnosis, as it suggests the pain is not primarily of gynecologic origin.
- Other Likely diagnoses
- Pelvic inflammatory disease (PID): Although the patient does not exhibit cervical motion tenderness, PID can present with lower abdominal pain, fever, and vaginal discharge. The fact that she is sexually active and has scant white discharge from the cervical os keeps PID in consideration, though the absence of significant cervical motion tenderness and adnexal tenderness makes it less likely.
- Ectopic pregnancy: Given the patient's sexual activity and the presence of lower abdominal pain, ectopic pregnancy must be considered, especially if there's any chance she could be pregnant despite being on oral contraceptives (which are not 100% effective). However, her last menstrual period was only 3 weeks ago, and the absence of more specific symptoms like vaginal bleeding or more severe pain makes this less likely.
- Do Not Miss diagnoses
- Ectopic pregnancy: Even though it's listed under other likely diagnoses due to the patient's profile, ectopic pregnancy is a "do not miss" diagnosis because it can be life-threatening if not promptly recognized and treated.
- Tubo-ovarian abscess: This condition, often a complication of PID, can present with severe abdominal pain, fever, and sometimes a palpable mass. While the patient's exam does not strongly suggest this, the potential severity of the condition warrants consideration to avoid missing a serious diagnosis.
- Rare diagnoses
- Ovarian torsion: This is a rare but emergency condition that can cause severe abdominal pain. The patient's presentation does not strongly suggest ovarian torsion, given the lack of a sudden onset of severe pain and the normal appearance of the adnexa and ovaries on exam.
- Diverticulitis: Although more common in older adults, diverticulitis can occur in younger individuals and presents with abdominal pain, often in the left lower quadrant, but can be atypical. The patient's symptoms and exam findings do not strongly support this diagnosis, but it remains a consideration in the differential diagnosis of abdominal pain.