Differential Diagnoses for Pelvic Inflammatory Disease
When evaluating a sexually active woman with lower abdominal pain and suspected PID, you must actively exclude ectopic pregnancy, acute appendicitis, and functional pain, as these are the most critical alternative diagnoses that require different management. 1
Critical Life-Threatening Differentials
Ectopic Pregnancy
- Must be ruled out first in any woman of reproductive age with lower abdominal pain and pelvic tenderness, as this represents an immediate threat to life 1
- Obtain β-hCG in all women of childbearing potential before initiating PID treatment 1
- Consider transvaginal ultrasound if pregnancy test is positive or clinical suspicion is high 1
Acute Appendicitis
- A surgical emergency that can present with lower abdominal pain and tenderness 1
- Typically presents with right lower quadrant pain, but atypical presentations occur 2
- If surgical abdomen cannot be excluded, hospitalization is warranted 1
Other Gynecologic Differentials
Tubo-Ovarian Abscess
- A complication of PID itself, but requires different management with imaging and possible surgical intervention 1, 3
- Suspect when there is severe illness, palpable adnexal mass, or failure to improve within 72 hours of antibiotic therapy 4
- Requires transvaginal sonography or other imaging modalities 1
Ovarian Cyst Complications
- Ruptured or hemorrhagic ovarian cysts can mimic PID with acute pelvic pain 2
- Ovarian torsion presents with sudden-onset severe unilateral pain 2
Endometriosis
- Can cause chronic or cyclic pelvic pain with dyspareunia 5, 3
- Less likely to present acutely but should be considered in women with recurrent symptoms 6
Non-Gynecologic Differentials
Urinary Tract Pathology
- Urinary tract infection or pyelonephritis can cause lower abdominal pain and dysuria, symptoms that overlap with PID 5
- Obtain urinalysis to evaluate for pyuria, though white blood cells in urine can support PID diagnosis 7
Gastrointestinal Causes
- Inflammatory bowel disease (Crohn's disease, ulcerative colitis) can present with lower abdominal pain 2
- Gastroenteritis with lower abdominal cramping 2
- Diverticulitis in older women 2
Functional Pain
- Functional or non-organic pelvic pain without identifiable pathology 1
- Diagnosis of exclusion after ruling out organic causes 1
Key Diagnostic Approach to Differentiate
If cervical discharge appears normal AND no white blood cells are found on wet prep, the diagnosis of PID is unlikely, and you should aggressively pursue alternative causes of pain. 1
Supporting Features That Make PID More Likely:
- Mucopurulent cervical discharge with white blood cells on saline microscopy 1
- Fever >101°F (>38.3°C) 1, 8
- Elevated inflammatory markers (ESR, CRP) 1, 8
- Laboratory documentation of cervical N. gonorrhoeae or C. trachomatis infection 1, 8
Clinical Pitfall to Avoid:
The CDC guidelines explicitly state that diagnosis and management of ectopic pregnancy, acute appendicitis, and functional pain are unlikely to be impaired by initiating empiric antimicrobial therapy for PID 1. This means you should maintain a low threshold for treating PID empirically while simultaneously ruling out life-threatening conditions, particularly ectopic pregnancy in any woman who could be pregnant.