Pelvic Inflammatory Disease Workup

Updated: Aug 16, 2021
  • Author: Kristi A Tough DeSapri, MD; Chief Editor: Nicole W Karjane, MD  more...
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Approach Considerations

A number of procedures can be performed to improve the diagnosis of pelvic inflammatory disease (PID) and its complications. These procedures are not necessary, nor are they indicated, in the management of every case of PID. However, because of the difficulty of definitive clinical diagnosis and the number of surgical and gynecologic emergencies that may have similar presentations, the clinician should be aware of these modalities.

Procedures that may be appropriate for some patients, along with the corresponding findings specific for PID, are as follows:

  • Laparoscopic confirmation

  • Transvaginal ultrasonographic scanning or magnetic resonance imaging (MRI) showing thickened, fluid-filled tubes with or without free pelvic fluid or tubo-ovarian abscess (TOA)

  • Endometrial biopsy showing endometritis

Laparoscopy is the criterion standard for the diagnosis of PID, but the diagnosis of PID in emergency departments and clinics is often based on clinical criteria, with or without additional laboratory and imaging evidence. [64] No single test is highly specific and sensitive for PID, but laboratory tests, imaging studies, and procedures may be used to increase the specificity of the diagnosis.

Additional criteria that improve diagnostic specificity include the following:

  • Oral temperature higher than 38.3° C (101° F)
  • Abnormal cervical or vaginal mucopurulent discharge
  • Abundant white blood cells (WBCs) on saline microscopy of vaginal secretions
  • Elevated erythrocyte sedimentation rate (ESR) (≥40 mm/h)
  • Elevated C-reactive protein (CRP) level (≥ 60 mg/L)
  • Laboratory evidence of cervical infection with N gonorrhoeae or C trachomatis (via culture or DNA probe)

In addition, obtaining a sample from the urethra in women with suspected PID can increase the diagnostic yield for gonorrhea and chlamydial infection. This step is recommended only if the more sensitive nucleic acid amplification test (NAAT) is unavailable. [12]


Laboratory Studies

Perform a pregnancy test. If the results are positive, the possibility of ectopic pregnancy must be addressed. Pregnancy also directly influences selection of an antibiotic regimen and consideration of the patient for admission.

On a complete blood count (CBC), fewer than 50% of women with acute PID have a WBC count higher than 10,000/µL. Because of its poor sensitivity and specificity, an elevated WBC count is not among the diagnostic criteria for PID formulated by the Centers for Disease Control and Prevention (CDC). Blood cultures are not helpful in the diagnosis of PID.

In fact, no single test is highly specific and sensitive for PID; however, a number of tests may be used to increase the specificity of the clinical diagnosis. Vaginal secretions that have been treated with saline and potassium hydroxide can be examined for leukorrhea (>10 WBC/high-power field; >1 WBC/epithelial cell), trichomoniasis, and clue cells. [17, 65] The presence of leukorrhea was found to be the most sensitive, laboratory indicator of upper tract infection, though not a specific one; the absence of leukorrhea is a negative predictor of PID.

Gonorrhea DNA probes and cultures are generally used to support the diagnosis and to provide epidemiologic data for public health departments. However, they are frequently negative in later stages of PID. [66]

Chlamydial vulvovaginal or endocervical DNA probes and cultures are generally used to support the diagnosis and to provide epidemiologic data for public health departments, though recovery rates from the cervix vary widely (5-56%). [67] Quantitative culture for Chlamydia identifies rapidly replicating bacteria that appear to be associated with active disease. However, DNA probe and culture results are often not available to the emergency physician at the time of initial evaluation.

One study suggested that women with high titers of immunoglobulin G (IgG) chlamydial antibodies, acute pelvic pain, and a clinical picture suggestive of PID were more likely to have salpingitis than adhesions alone. [68] Those patients with high titers and chronic pelvic pain but with a clinical picture that did not suggest PID were more likely to have adhesions alone. In the investigators’ view, their limited data suggested that serologic testing might help establish the diagnosis.

Although the 2015 CDC guidelines mention Mycoplasma genitalium contributing to milder forms of PID, there is no clear consensus on the value of testing for this organism. [69]

Other tests that may be considered include the following:

  • Rapid protein reagin (RPR) test for syphilis (the incidence of which is again increasing in the United States)

  • Hepatitis virus and HIV

  • Urinalysis to help exclude urinary tract infections – Note, however, that a positive urinalysis does not exclude PID, because any inflammatory process in the contiguous pelvis can produce WBCs in the urine


Transvaginal Ultrasonography

Ultrasonographic scanning may be performed for cases of suspected PID in which clinical findings are nondiagnostic. Transvaginal ultrasonography is superior to transabdominal ultrasonography for diagnosing PID, as well as endometrial abnormalities and pelvic masses (see the images below). [65] This modality is readily available and noninvasive and can be performed at the patient’s bedside.

Transabdominal ultrasonogram shows anechoic tubula Transabdominal ultrasonogram shows anechoic tubular structures in adnexa; finding is compatible with hydrosalpinx.
Endovaginal ultrasonogram reveals tubular structur Endovaginal ultrasonogram reveals tubular structure with debris in left adnexa; finding is compatible with pyosalpinx.
Ultrasonogram shows markedly heterogeneous and thi Ultrasonogram shows markedly heterogeneous and thickened endometrium; finding is compatible with endometritis.
Ultrasonogram reveals bilateral complex masses in Ultrasonogram reveals bilateral complex masses in patient who had pyometrium; finding is compatible with tubo-ovarian abscess.
Transabdominal ultrasonogram demonstrates echogeni Transabdominal ultrasonogram demonstrates echogenic region within endometrium with dirty shadowing; finding is compatible with air in endometrium and endometritis. Additionally, bilateral complex masses are present; finding is compatible with tubo-ovarian masses.

There are no large randomized trials addressing the specificity and sensitivity of bedside ultrasonography for the diagnosis of PID. The literature demonstrates that the accuracy of this technique depends on the criteria used to indicate PID, the quality of the equipment, and the experience of the individual operator performing the test.

Transvaginal ultrasonography has poor sensitivity (81%) and specificity (78%) in mild or atypical PID. [65] Helpful findings include thickened (>5 mm), fluid-filled fallopian tubes; thickened cilia; indistinct endometrial borders; ovaries with multiple small cysts; and moderate-to-large amounts of free pelvic fluid in acute, severe PID. [70] Small amounts of free pelvic fluid have not been shown to be a discriminatory finding. These findings alone are not sufficiently specific to permit a definitive diagnosis of PID.

In the patient who appears toxic or has asymmetric pelvic findings, ultrasonographic scanning is an important diagnostic tool for the identification of a TOA. Pelvic abscesses may be seen as complex adnexal masses with multiple internal echoes. The modality has been shown to demonstrate as many as 70% of adnexal masses missed on physical examination.

Pelvic ultrasonographic scanning is also useful in evaluating the possibility of ectopic pregnancy in patients whose differential diagnosis includes both that condition and PID. The modality can also be helpful in evaluating other disorders in the differential diagnosis, including hemorrhagic ovarian cyst, ovarian torsion, endometrioma, and appendicitis. (At some adult academic medical centers, however, ultrasonography is considered adequate as a solo imaging modality to rule out appendicitis.)

Ultrasonographic results in patients with PID may be normal or nonspecific because salpingitis alone is not usually associated with imaging findings. [71] Positive ultrasonographic findings in PID may include the following:

  • The uterus may be ill defined because of inflammation; however, inflammation of the uterus is an unusual finding

  • Endometritis may result in central-endometrial-cavity echo thickening and heterogeneity

  • Hydrosalpinx is depicted as a fluid-filled fallopian tube – If the fallopian tube walls are thickened and if debris is present within the tube, pyosalpinx should be considered in the differential diagnosis, but a pyosalpinx may be imaged as an echoless tube, whereas an imaged echo-filled tube may be from proteinaceous but noninfected fluid in a hydrosalpinx

  • Oophoritis results in enlarged ovaries with ill-defined margins that often appear adherent to the uterus; adjacent free fluid may be present in the adnexa or cul-de-sac

  • TOAs are depicted as complex adnexal masses with thickened walls and central fluid

  • Pelvic infection, with findings of tubal inflammation and hydrosalpinx detected by Doppler studies, is one of the most specific criteria in diagnosing PID [6]

Thickening 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 the following:

  • Endometriomas

  • Ectopic pregnancies

  • Hemorrhagic cysts

  • Ovarian tumors

  • Abscesses from adjacent organs



Laparoscopy is the criterion standard for the diagnosis of PID. It is significantly more specific and sensitive than are clinical criteria alone. The minimum criteria for diagnosing PID laparoscopically include tubal wall edema, visible hyperemia of the tubal surface, and the presence of exudate on the tubal surfaces and fimbriae.

Pelvic masses consistent with TOA or ectopic pregnancy can be directly visualized. Hepatic abscess exudate or adhesions may be visible. Material can be obtained for definitive culture and histologic studies.

The main drawbacks of laparoscopy are that the procedure is expensive and invasive, exhibits interobserver variability, and requires an operating room and anesthesia. [61] In addition, findings on laparoscopy do not necessarily correlate with the severity of illness, in that only the surfaces of structures are visible through the scope. In as many as 20% of cases, laparoscopy may not define PID fully.


Computed Tomography

Computed tomography (CT) may also be used as the initial diagnostic study for the investigation of nonspecific pelvic pain in a female, and PID may be found incidentally. Because of concerns about radiation exposure, ultrasonography is preferred to CT as the triaging tool in a female child or adolescent with right lower quadrant or pelvic pain.

In cases of PID in which no evidence of an abscess is found, CT scan findings are nonspecific. Inflammation obliterates the pelvic fat planes, with thickening of the fascial planes. Endometritis manifests as enlargement of the uterine cavity. If hydrosalpinx is present, a fluid-filled tubular structure may be seen in the adnexa.

Typically, a TOA is visualized as a mass; the mass may have regular margins and contain debris similar to that seen in endometriomas or hemorrhagic cysts. 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. [72] Many adult centers prefer CT to ultrasonography when a diagnosis of appendicitis is in question.

Tubular, 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.


Magnetic Resonance Imaging

Although MRI has relatively high specificity (95%) and sensitivity (95%) in this setting, [65] it is costly and is rarely indicated in cases of acute PID.

Hydrosalpinx is visualized on MRI as a tubular structure with low signal intensity on T1-weighted scans and high signal intensity on T2-weighted images. If the walls are thickened, pyosalpinx should be considered in the differential diagnosis. [73] 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, TOAs may be isointense or hyperintense on T1-weighted images and may have heterogeneous signal intensity on T2-weighted images.



Culdocentesis can be performed rapidly in the emergency department. With the advent of transvaginal ultrasonographic scanning, culdocentesis is rarely performed today, but it remains valuable in settings where current technology is unavailable.

For the procedure, an 18-gauge spinal needle attached to a 20-mL syringe is inserted transvaginally into the cul-de-sac. Normally, this yields only 2-4 mL of clear to straw-colored free pelvic fluid; purulent fluid indicates an infectious or inflammatory process.

The potential positive findings of leukocytes and bacteria are nonspecific: They may indicate PID, or they may be a product of another infectious or inflammatory process in the pelvis (eg, appendicitis or diverticulitis), or they may result from contamination with vaginal contents. A yield of more than 2 mL of nonclotting blood is consistent with ectopic pregnancy.


Endometrial Biopsy

Endometrial biopsy can be used to determine the histopathologic diagnosis of endometritis, a condition that is uniformly associated with salpingitis. Endometrial biopsy is approximately 90% specific and 90% sensitive. The procedure is performed with an endometrial suction pipette or curette and is well tolerated. Specimens for culture may also be obtained during the procedure, but these are frequently contaminated with vaginal flora.

Current CDC guidelines recommend endometrial biopsy in women undergoing laparoscopy who have no visible signs of salpingitis, on the grounds that endometritis may be the only sign of PID. [6] Diagnostic use of endometrial biopsy in the emergency department is limited; significant operator training is required, and the results of the procedure are not immediately available to the clinician.

Endometrial biopsy findings usually confirm the presence of infection but rarely identify the causative organism. Chronic endometritis is more commonly seen than acute endometritis.