What is the differential diagnosis for a patient presenting with intermittent hypogastric pain, infrequent spotting, and hormonal acne, with a history of daily marijuana smoking and a hormonal intrauterine device (IUD)?

Differential Diagnosis: Hormonal IUD-Related Side Effects vs. Pelvic Inflammatory Disease

The most likely differential diagnosis is hormonal IUD-related side effects (spotting, hormonal acne, and cramping), but pelvic inflammatory disease (PID) must be actively excluded given the new sexual partner and intermittent hypogastric pain. 1

Primary Diagnostic Considerations

1. Hormonal IUD-Related Side Effects (Most Likely)

• Spotting and irregular bleeding are common with levonorgestrel-releasing IUDs, particularly in the first 3-6 months, and generally decrease with continued use 1
• Hormonal acne is a recognized adverse effect of progestagen-containing contraceptives due to androgenic activity of progestagens, even in low doses 2
• Intermittent cramping/pelvic pain can occur with IUD use and is typically managed with NSAIDs 1
• These symptoms were reportedly discussed as "normal" by her provider, which aligns with expected IUD side effects 1

2. Pelvic Inflammatory Disease (Must Exclude)

Critical risk factors present:

• New sexual partner within 6 months (major risk factor for PID) 1
• IUD use increases PID risk, particularly in the first months after insertion 1
• Intermittent lower quadrant pain is consistent with PID presentation 1

Important caveats:

• Partner's negative STD testing does NOT exclude PID risk, as testing timing, completeness, and her own cervical infection status are unknown 1
• 10-40% of untreated cervical chlamydial or gonococcal infections ascend to cause PID 1
• PID can present with subtle symptoms and may be polymicrobial (involving anaerobes, G. vaginalis, and other organisms beyond just gonorrhea/chlamydia) 1

3. Other Gynecologic Causes to Consider

• Ovarian cysts (hemorrhagic or functional) - common cause of intermittent pelvic pain in reproductive-age women 1
• Endometriosis - can cause cyclical or intermittent pelvic pain, though less likely given recent symptom onset 1
• Ectopic pregnancy - must be excluded with β-hCG testing despite IUD use (failure rate exists) 1

4. Cannabis-Related Considerations

Daily marijuana smoking is relevant but less likely causative:

• Cannabinoid hyperemesis syndrome typically presents with cyclical vomiting, compulsive hot bathing, and epigastric/abdominal pain - not isolated hypogastric pain 3, 4
• Cannabis may actually provide pain relief for gynecologic conditions including pelvic pain, though this doesn't explain new-onset symptoms 5, 6
• Smoking status (any type) is noted in contraceptive guidelines but doesn't contraindicate IUD use 1

Recommended Diagnostic Approach

Immediate evaluation should include:

1. β-hCG testing to exclude pregnancy/ectopic pregnancy 1

2. Cervical testing for gonorrhea and chlamydia (NAAT) regardless of partner's testing 1

3. Pelvic examination assessing for:

   • Cervical motion tenderness
   • Adnexal tenderness or masses
   • IUD string visualization
   • Purulent cervical discharge 1

4. Transvaginal ultrasound if examination is concerning or inconclusive - this is the initial imaging of choice for acute pelvic pain in reproductive-age women 1

5. Consider complete blood count to assess for leukocytosis if PID suspected 1

Clinical Decision Point

If PID is excluded (negative cervical testing, no cervical motion tenderness, no fever, normal examination), then IUD-related side effects are the diagnosis and can be managed conservatively with NSAIDs for pain and reassurance about expected bleeding patterns 1.

If PID cannot be excluded clinically, empiric antibiotic treatment should be initiated immediately, as delayed treatment increases risk of tubal infertility, ectopic pregnancy, and chronic pelvic pain 1. The IUD does not need to be removed for PID treatment unless symptoms fail to improve within 48-72 hours 1.