Tubo-Ovarian Abcess and Pelvic Inflammatory Disease
Synonyms/Description
Pelvic infection
Pelvic abcess
Pyosalpinx
Etiology
Pelvic inflammatory disease (PID) is an ascending pelvic infection causing inflammation of the upper genital tract, including cervicitis, endometritis, salpingitis, pelvic peritonitis, and occasionally resulting in development of a tubo-ovarian abscess (TOA). Inflammation damages the fallopian tubes, leading to infertility, ectopic pregnancy, and chronic pelvic pain. Acutely, the fallopian tubes swell and become congested, leading to salpingitis and potentially pyosalpinx if the tube fills with pus. Untreated PID may progress from inflammation of the tubo-ovarian complex to the formation of a tubo-ovarian abscess (TOA).
Most cases of PID are sexually transmitted and caused by Chlamydia trachomatis, Neisseria gonorrhoeae, or other similar causative agents. Pelvic inflammatory disease can also occur as a result of a gynecologic or abdominal procedure or surgery, as well as tuberculosis and appendicitis.
Ultrasound Findings
Ultrasound is very sensitive for detecting ovarian and tubal involvement of PID (sensitivity of 90% and 93%, respectively). When infected, the uterus enlarges and the echogenicity of the endometrium becomes heterogeneous and blotchy. The endometrial cavity often contains small amounts of echogenic fluid (exudate). The outer border of the uterus is often indistinct, with loss of clear separation between the uterus and adnexa.
Inflamed fallopian tubes are typically thick walled and dilated, filled with echogenic fluid and debris. The walls are irregular, and the tubes are elongated and tortuous with abundant blood flow on color Doppler examination. Milder infections may result in thickening of the tube without the presence of fluid (salpingitis). These thickened tubes are very tender during the transvaginal ultrasound examination.
A TOA is usually a solid, cystic or complex multiseptate mass, most often hypoechoic with areas of mixed echogenicity and thick septa.
Adhesions form within the pelvis, causing the tubo-ovarian complex to be adherent to nearby bowel, giving the appearance of a large, complex, adnexal mass with indistinct borders. Abundant blood flow is typical on Doppler studies.
Differential Diagnosis
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