Pelvic Inflammatory Disease

• List and describe the etiology and risk factors associated with pelvic inflammatory disease (PID).

• Describe the progression of PID, and identify the specific sequelae of PID.

• Describe the sonographic appearances of PID, including endometritis, salpingitis, pyosalpinx, hydrosalpinx, and tuboovarian abscess.

• Identify Doppler findings associated with PID.

• Identify pertinent laboratory values and related diagnostic studies associated with PID.

CLINICAL SCENARIO

A 21-year-old woman presents to the emergency department with lower abdominal pain and fever. The patient states that the abdominal pain has become increasingly severe since her period finished 3 days ago. She has been using an over-the-counter treatment for what she thought was a vaginal infection that somewhat improved her symptoms of itching and burning. Physical examination reveals abdominal guarding and rebound tenderness. Manual pelvic examination elicits such severe pain that a thorough examination of the pelvic organs cannot be completed. Laboratory test results show elevated white blood cell (WBC) counts and a negative human chorionic gonadotropin level. The patient also denies pregnancy.

A sonogram of the pelvis is ordered. Transabdominal scanning shows bilateral complex masses, fluid in the cul-de-sac, and ovarian enlargement (Fig. 15-1). Thickening of the endometrium is also noted. Endovaginal scanning is attempted, although only a limited amount of information is gained, because the patient experiences severe pain during the procedure. What is the possible diagnosis?

FIGURE 15-1 Transverse scan of the uterus shows bilateral adnexal masses, pyosalpinx, and thickened endometrium.

Pelvic inflammatory disease (PID) is a type of sexually transmitted disease, although bilateral infection may be associated with the use of an intrauterine device (IUD).¹ Less commonly, unilateral PID may result from direct extension of primary lower abdominal or pelvic abscesses or complications following abortion or childbirth. The diagnosis of PID is usually made clinically through the assessment of patient history and symptoms, pelvic examination, urine test, and culture of vaginal secretions.² Early and vigorous antibiotic treatment is needed to stop the progression of the disease and prevent the development of infertility.

Chlamydia is more common than gonorrhea as a source of infection, but numerous aerobic and anaerobic organisms may also be present. In many cases, the symptoms of chlamydia and gonorrhea are mild or nonexistent in both female and male patients; however, men are more likely to seek treatment when symptoms are present.

Normally, the endocervical mucous plug provides a barrier against the ascension of both normal vaginal flora and pathogens. Chlamydia and gonorrhea can damage the endocervical canal and allow an easier ascent of these infectious bacteria into the uterus.³ It also has been noted that other factors may allow for easier spread of disease. Bacteria can gain easier access through the cervical canal shortly after menstruation, when the mucous plug is normally expelled. Easier access also can occur with cervical ectopy, which is the extension of endocervical columnar epithelium beyond the cervix. Cervical ectopy also is more common in teenagers, who represent the age group with the highest incidence of PID.³

Risk factors for PID include female gender, age younger than 35 years, sexual activity (two or more partners), and use of an IUD. The risk of recurrent infection is high, and the consequences of PID include chronic pelvic pain from adhesions, peritonitis, ectopic pregnancy, maternal death from ectopic pregnancy, and infertility (risk increases with each occurrence of PID). Early and appropriate treatment is usually with two antibiotics to cover the possibility of multiple organisms; the patient’s partners also must be treated. Symptoms may abate without the infection being cured, which can lead to the patient not completing the course of medication.

Because PID is readily diagnosed with assessment of the patient’s symptoms and signs, sonography of the pelvis may not provide additional diagnostic information because the anatomy often appears normal. However, pelvic sonography is frequently performed because of physical findings such as fever, severe pain with manipulation of the cervix or adnexal areas, presence of purulent vaginal discharge, abdominal or rebound tenderness, and possible elevated WBC count and erythrocyte sedimentation rate (ESR). Sonography shows the presence and extent of endometritis, salpingitis, pyosalpinx, hydrosalpinx, and tuboovarian abscess (TOA). Occasionally, the only sonographic feature of PID is a loss of definition of the posterior uterine border.

Both transabdominal and endovaginal scanning techniques are recommended for evaluation of the presence and extent of PID. With transabdominal scanning, the entire pelvis can be evaluated and large structures and masses can be delineated. With endovaginal scanning, high-resolution evaluation of the uterus and endometrial cavity, fallopian tubes, ovaries, cul-de-sac, and adnexal areas can be performed. However, the patient’s condition (i.e., pelvic pain) may make full distention of the urinary bladder or insertion and manipulation of the endovaginal transducer impossible. The sonographer must be aware of these possibilities and should tailor the examination to decrease pain for the patient and increase information gained. Gentle and slow scanning motions are imperative, and a thorough explanation of the procedure may help to increase patient compliance.

The symptoms of acute PID include fever (low or high), shaking chills, abdominal pain (mild, moderate, or severe), nausea, vomiting, vaginal discharge, and irregular vaginal bleeding. Signs of acute PID include abdominal guarding, rebound tenderness, increased pain with cervical or adnexal manipulation, dyspareunia, leukocytosis, elevated ESR, paralytic ileus, and shock from peritonitis.⁴ Symptoms of chronic PID are persistent pelvic or lower abdominal pain, irregular menses, and possibly infertility. Chronic PID often results in a hydrosalpinx and may include presence of an adnexal mass without fever.³ Peritoneal inclusion cysts also may be seen in women with a history of PID, endometriosis, or prior pelvic surgery or trauma.⁵ These cysts are created by the trapping of fluid arriving from the ovary by adhesions that are created by an inflammatory process.⁵

• Urine test, cultures of vaginal secretions or discharge, culdocentesis, laparoscopy, and computed tomography (CT) and magnetic resonance imaging (MRI)

• Endometrial biopsy and histology showing evidence of endometritis—these are the most specific studies for diagnosis of PID ²

• Transvaginal sonography or MRI showing thickened, fluid-filled tubes with or without free pelvic or tuboovarian complex or Doppler studies suggesting pelvic infection (tubal hyperemia)

• Laparoscopy showing abnormalities consistent with PID

Sonographic Findings

Fallopian Tubes

The fallopian tubes are contained within the broad ligament and are not appreciated with sonography unless surrounded by ascites or involved in a disease process, such as salpingitis, pyosalpinx, or hydrosalpinx. Fallopian tubes are best shown with radiographic salpingography, which involves pressure injection of radiopaque contrast material through the tubes.

Salpingitis

Salpingitis is an infection of the fallopian tubes that may be acute, subacute, or chronic. The sonographic appearance of acute salpingitis includes nodular thickening of the walls of the fallopian tubes with diverticula. Hyperemia is also present and can be shown with color Doppler imaging. Anechoic or echogenic (pus-containing) fluid may be seen in the posterior cul-de-sac (pouch of Douglas), as may uterine enlargement with endometrial fluid or thickening (endometritis). Subacute salpingitis indicates that infectious changes have occurred without significant clinical signs and symptoms.

Chronic salpingitis is related to recurrent bouts of PID and may result in significant tubal scarring and the presence of hydrosalpinx (Fig. 15-2). The patient may have pain during intercourse or bowel movements (from adhesions involving the bowel and peritoneal surface) and during menses. Tubal scarring may be seen sonographically as several cystic structures extending from the uterus to the adnexa; this is sometimes referred to as the “chain of lakes” or “string of pearls” sonographic appearance (Fig. 15-3). Infertility and ectopic pregnancy may result from the tubal scarring.

FIGURE 15-2 Hydrosalpinx. No flow is seen in the anechoic tubular structure; blood flow is seen in vessels around the structure.

Pyosalpinx

Pyosalpinx is a progression of PID in which the fallopian tubes become swollen with purulent exudates (Fig. 15-4). The sonographic appearance of pyosalpinx is consistent with visualization of thick-walled tubular or serpiginous structures surrounding the ovaries. The interstitial portion of the tube is tapered at the cornu of the uterus. The tube also may be described as sausage-shaped. Echogenic material or debris related to the presence of pus may be seen within the fallopian tubes. In addition, blurring of the normal tissue planes in the pelvis can occur, making delineation of the organs and structures difficult.

Endovaginal scanning can differentiate pyosalpinx from other pelvic masses by showing the tubular nature of the tube. Pyosalpinx also can be differentiated from fluid-filled bowel with visualization of peristalsis in the bowel. Color Doppler imaging shows increased flow in the pelvic structures.

Hydrosalpinx

Hydrosalpinx is a consequence of PID in which the fallopian tube or tubes become closed at the fimbriae, and the pus within a pyosalpinx gradually liquefies, leaving serous fluid. In addition, the walls of the tubes become thinner, and the tubes may dilate to twice the normal diameter. The patient may be asymptomatic or may have colicky pain. Hydrosalpinx may be present for a significant length of time before diagnosis of infertility from blockage of the fallopian tubes.

Sonographically, the fallopian tubes appear as anechoic thin-walled structures with a multicystic or fusiform mass effect (Fig. 15-5). Color Doppler is useful to differentiate hydrosalpinx from bowel or prominent pelvic veins. The sonographer should take care to show the pathway of the tube and the ovary. Three-dimensional (3D) endovaginal sonography has increased the ability of imaging abnormal fallopian tubes, which may be tortuous and be positioned in a plane that is not easily accessible by standard two-dimensional sonography. In the regular two-dimensional image, multiple cystic areas are seen medial to the right ovary (Fig. 15-6). In the 3D image, a tortuous, fluid-filled tube is easily identified (see Fig. 15-5).