You are in: eMedicine Specialties > Radiology > OBSTETRICS/GYNECOLOGY Pelvic Inflammatory Disease/Tubo-ovarian AbscessArticle Last Updated: Aug 13, 2007AUTHOR AND EDITOR INFORMATIONSection 1 of 11
  Author: Shikha Mudgil, MD, Consulting Staff, Department of Radiology, Riddle Memorial Hospital Shikha Mudgil is a member of the following medical societies: American College of Radiology Editors: Harris L Cohen, MD, FACR, Vice Chairman/Associate Chairman (Research Activities), Director, Division of Body Imaging, Professor of Radiology, Stony Brook School of Medicine; Visiting Professor of Radiology, Johns Hopkins School of Medicine; Bernard D Coombs, MB, ChB, PhD, Consulting Staff, Department of Specialist Rehabilitation Services, Hutt Valley District Health Board, New Zealand; Karen L Reuter, MD, FACR, Professor, Department of Radiology, Lahey Clinic Medical Center; Robert M Krasny, MD, Consulting Staff, Department of Radiology, The Angeles Clinic and Research Institute; Eugene C Lin, MD, Consulting Staff, Department of Radiology, Virginia Mason Medical Center Author and Editor Disclosure Synonyms and related keywords: sexually transmitted disease, endometritis, salpingitis, tuboovarian abscess, peritonitis, PID, TOA abscess, Chlamydia trachomatis, C trachomatis, Neisseria gonorrhoeae, N gonorrhoeae INTRODUCTIONSection 2 of 11
  BackgroundPelvic inflammatory disease (PID) is one of the most serious complications of sexually transmitted diseases. It is an infection of the female upper genital tract that encompasses a broad category of diseases, including endometritis, salpingitis, salpingo-oophoritis, tubo-ovarian abscess (TOA), and pelvic peritonitis. Prompt diagnosis and treatment of this condition are critical because the complications of PID can be life and fertility threatening. For excellent patient education resources, visit eMedicine's Sexually Transmitted Diseases Center, Pregnancy and Reproduction Center, and Women's Health Center. Also, see eMedicine's patient education articles Pelvic Inflammatory Disease, Chlamydia, Gonorrhea, and Female Sexual Problems. PathophysiologyPID most commonly occurs as a result of Chlamydia trachomatis or Neisseria gonorrhoeae infection of the cervix or vagina that then spreads into the endometrium, fallopian tubes, ovaries, and adjacent structures. Less commonly, direct spread from a nearby infection such as appendicitis or diverticulitis may occur. Hematogenous infection is a rare cause of PID except in cases of tuberculous PID. FrequencyUnited StatesAnnually, there are approximately 1 million women who develop PID.1 An estimated 1 in 8 sexually active adolescent girls develop PID before reaching age 20. Because PID may be asymptomatic and this condition is frequently undiagnosed, the incidence rate is likely higher.1, 2 Mortality/MorbiditySerious lifelong sequelae may occur if PID is not diagnosed and treated promptly. More than 25% of women with PID have at least 1 complication, which can include ectopic pregnancy, infertility, and/or chronic abdominal pain. SexPID typically affects sexually active women. AgeThe peak incidence rate is in women aged 20-24 years.3 However, if the incidence rate is corrected for sexually active females, it is highest in adolescent girls aged 15-19 years. Clinical DetailsRisk factors The endocervical canal and the mucus plug are the major barriers to the ascent of the bacteria into the upper genital tract. Changes in the vaginal flora, composition of the mucus plug, and cervical cell type are believed to affect the risk of infection. Endometrial instrumentation also increases the risk of PID. The 2006 Centers for Disease Control and Prevention (CDC) criteria for the diagnosis of PID are as follows2:
Treatment PID is commonly treated as an outpatient disease, with the use of oral antibiotics that cover both aerobic and anaerobic organisms, including C trachomatis and N gonorrhoeae. Treatment is usually started before the endocervical culture results are available (empiric therapy) because negative findings do not exclude a diagnosis of PID in the upper genital tract.2 Empiric treatment is recommended if the minimum criteria above (see Diagnosis) are fulfilled and if no other cause for the patient's symptoms is identified.2 The CDC recommends hospitalization and administration of intravenous antibiotics in patients with the following: uncertain diagnosis, pregnancy, failure to adhere to or respond to oral treatment, severe illness, TOA, immunodeficiency, or human immunodeficiency virus infection.2 Preferred ExaminationUltrasonography should be the first diagnostic imaging examination to be performed in cases of suspected PID in which there are nondiagnostic clinical findings. This modality is readily available and noninvasive and can be performed at the patient's bedside. Transvaginal sonography (TVS) allows detailed visualization of the uterus and adnexa, including the ovaries. The fallopian tubes are usually imaged only when they are abnormal and distended on physical examination, primarily from postinflammatory obstruction. Transabdominal sonography (TAS) is complementary to the endovaginal examination because it provides a more global view of the pelvic contents. Whether TAS (bladder filling required) or TVS (bladder filling not required) is performed first and whether the complementary examination is needed for a final diagnosis is a matter of individual clinical imaging practice. Magnetic resonance imaging (MRI) serves as an excellent imaging modality in cases in which the ultrasonographic findings are equivocal. In a study by Tukeva et al, the authors compared findings from MRI with sonograms and found that MRI was more accurate than ultrasonography in the diagnosis of PID.4 However, the study was limited to a select group of patients. Occasionally, computed tomography (CT) scanning may be used as the initial diagnostic study for the investigation of nonspecific pelvic pain in a female, and PID may be found incidentally. Most often, ultrasonography is preferred over CT scanning as the triaging tool in a female child or adolescent with right lower quadrant or pelvic pain, particularly because of concerns about radiation exposure. If the diagnosis of PID is still in question, confirmation with ultrasonography is suggested. Limitations of TechniquesTVS may be limited by the patient's inability to tolerate the transvaginal examination (although this is not usual). In such cases, only transabdominal findings may be available. Occasionally, the higher frequency and the lower position of the transvaginal transducer limits penetration of the sound beam, and TVS imaging of an unusually high adnexa may not be possible. Sometimes, a patient's large body habitus or abdominal wall scarring limits penetration of the sound beam, adversely affecting TAS. DIFFERENTIALSSection 3 of 11
Appendicitis Ectopic Pregnancy Endometrioma/Endometriosis Inflammatory Bowel Disease Mesenteric Adenitis Nephrolithiasis/Urolithiasis Ovarian Torsion Other Problems to Be ConsideredChronic Pelvic Pain RADIOGRAPHSection 4 of 11
FindingsRadiographic findings are noncontributory. CT SCANSection 5 of 11
FindingsCT scan findings are nonspecific in cases of PID in which there is no evidence of an abscess. Inflammation obliterates the pelvic fat planes, with thickening of the fascial planes. If hydrosalpinx is present, a fluid-filled tubular structure may be seen in the adnexa. Typically, a TOA is depicted as a mass; the mass may have regular margins and contain debris similar to that seen in endometriomas or hemorrhagic cysts. Sometimes the margins may be thick and irregular. There may also be an associated low-attenuation area that may represent an adjacent or contained fluid-filled fallopian tube. Degree of ConfidenceTubular fluid-filled nonvascular structures in the pelvis that are associated with an adnexal mass are suggestive of dilated fallopian tubes that correlate with cases of PID. A finding of an adjacent or surrounding complex mass confirms the diagnosis of TOA. False Positives/NegativesOther conditions that can mimic pelvic abscess/TOA include necrotic pelvic neoplasm, hematoma, hemorrhagic physiologic cyst, and endometrioma. MRISection 6 of 11
FindingsHydrosalpinx is depicted as a tubular structure with low signal intensity on T1-weighted MRIs and high signal intensity on T2-weighted images. If the walls are thickened, pyosalpinx should be considered in the differential diagnosis. Oophoritis may be evidenced by enlarged, polycystic-appearing ovaries with ill-defined margins and adjacent fluid. TOAs often appear as thick-walled masses with low signal intensity on T1-weighted images and high signal intensity on T2-weighted images. Occasionally, the TOA may be isointense or hyperintense on T1-weighted images, and they may have heterogeneous signal intensity on T2-weighted images. ULTRASOUNDSection 7 of 11
FindingsUltrasonography is the most frequently ordered imaging examination when PID is suspected. Most commonly, the ultrasonographic results for PID are normal, because salpingitis alone is not usually associated with imaging findings. Positive ultrasonography findings of PID may include the following:
Degree of ConfidenceThickening of the endometrium is nonspecific for PID because this finding may also be seen with endometrial hyperplasia, polyps, or cancer. Knowledge of the patient's clinical findings and other signs of infection can help in the differential diagnosis. Hydrosalpinx and pyosalpinx can usually be readily distinguished from pelvic veins and bowel by visualizing the color flow within the patent blood vessels and peristalsis within the bowel. Imaging findings in TOAs are usually nonspecific and must be distinguished from endometriomas, ectopic pregnancies, hemorrhagic cysts, ovarian tumors, and abscesses from adjacent organs. INTERVENTIONSection 8 of 11
Some significant pelvic abscesses may be drained percutaneously or surgically. Most cases of PID improve with an antibiotic regimen alone. Special ConcernsPrompt diagnosis and treatment of PID are critical because the complications of this condition can be life and fertility threatening, particularly in adolescent girls and young women of childbearing age. TEST QUESTIONSSection 9 of 11
MULTIMEDIASection 10 of 11
REFERENCESSection 11 of 11
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