tubo-ovarian abscess

**Definition:** A walled-off, pus-filled complex mass involving the fallopian tube, ovary, and sometimes adjacent pelvic structures (bowel, bladder). It is a late complication of PID, found in about 15-35% of hospitalized PID patients.

**Pathophysiology:** - Lower genital tract organisms ascend through the cervix to the endometrium and tubes, causing salpingitis. Purulent exudate and tubal adhesions follow, and the inflamed tube and ovary fuse into a tubo-ovarian complex. Further inflammation and necrosis produce an abscess. - The infection is polymicrobial. Chlamydia trachomatis and Neisseria gonorrhoeae initiate it. Anaerobes (Bacteroides, Peptostreptococcus), E. coli, and other enteric gram-negatives, streptococci, and Gardnerella then predominate within the abscess. - Risk factors: untreated or recurrent PID, multiple sexual partners, prior PID, IUD (especially in the first weeks after insertion), age under 25, and immunosuppression (HIV). Less common causes are pelvic surgery, diverticulitis, appendicitis, and postpartum infection.

**Clinical features:** - Lower abdominal or pelvic pain, fever, chills, and purulent vaginal discharge. - Cervical motion, uterine, and adnexal tenderness (the classic PID triad on exam). - A palpable adnexal mass, with leukocytosis and elevated ESR/CRP. - Possible nausea and vomiting, abnormal uterine bleeding, and dyspareunia. - **Ruptured TOA:** sudden severe pain, peritonitis, and sepsis or septic shock. This is a surgical emergency.

**Diagnosis:** - Pelvic ultrasound (transvaginal) is first-line. It shows a complex, multilocular adnexal mass with thick walls, internal echoes, and debris. - CT is used if the diagnosis is unclear or other causes (appendicitis, diverticulitis) are on the differential. - Do a pregnancy test (hCG) first to exclude ectopic pregnancy. - Test for gonorrhea and chlamydia (NAAT).

**Management:** - Hospitalize and give IV broad-spectrum antibiotics. Regimens include cefoxitin or cefotetan plus doxycycline, or clindamycin plus gentamicin. Anaerobic coverage is essential (clindamycin or metronidazole). Doxycycline covers chlamydia. - Add drainage (image-guided percutaneous or transvaginal) if there is no improvement in 48-72 hours or the abscess is large (>7-8 cm). Surgery is for rupture, failure of drainage, or sepsis. - Treat sexual partners and counsel on safe sex.

**Complications:** - Rupture with peritonitis and sepsis. - Infertility, ectopic pregnancy, and chronic pelvic pain from tubal scarring. - Fitz-Hugh-Curtis syndrome (perihepatitis with "violin-string" adhesions and RUQ pain). - Pelvic adhesions and recurrent PID.

**High-yield pearls:** - TOA = PID complication; think of it when a PID patient does not improve after 48-72 hours of antibiotics. - Ultrasound shows a complex adnexal mass. - Cover anaerobes. Ruptured TOA needs emergency surgery. - Always rule out ectopic pregnancy with hCG. - Differential: ectopic pregnancy, ovarian torsion, endometrioma, appendicitis, diverticulitis, ovarian neoplasm. - Because the abscess is walled off, antibiotics alone often penetrate poorly, which is why drainage is needed for larger or refractory abscesses.