Alfred Sacchetti
Pelvic inflammatory disease (PID) is a generic term that describes infection-related inflammatory changes of the upper genital tract in women. PID may include any combination of endometritis, salpingitis, tubo-ovarian abscess, or pelvic peritonitis. In the majority of cases Neisseria gonorrhoeae and Chlamydia trachomatis are implicated; however, PID may also be caused by other organisms, including anaerobic bacteria, Gardnerella vaginalis, Haemophilus influenzae, enteric gram-negative rods, Streptococcus agalactiae, Mycoplasma hominis, Mycoplasma genitalium, and Ureaplasma urealyticum (1). More than 100 aerobic and anaerobic bacterial strains have been recovered from the pouch of Douglas or high cervical cultures in patients with PID (2). Sexually transmitted infections (STIs), including PID are most common in the second and third decades of life, with most cases in women under 25 years of age. In 2011 the prevalence of chlamydial infections was 648.9 per 100,000 women and gonorrhea was 104.2 per 10,000 for both sexes (3–5). Child abuse must be suspected in any prepubertal female with the diagnosis of salpingitis.
Most pelvic infections originate from colonization of the vagina or cervix. From this site, the pathogens ascend through the cervical os into the lower uterine segment and uterine cavity. Normal cervical mucus presents a natural barrier to vaginal organisms; however, both N. gonorrhoeae and C. trachomatis appear able to produce uterine infections despite this protection. Certain cervical conditions, including recent menses, surgical cervical procedures, foreign bodies (intrauterine devices [IUDs]), and various hormonal changes during a menstrual cycle, decrease the defensive ability of the cervix. The hormonal changes induced by oral contraceptive agents enhance rather than reduce the bacteriostatic properties of the cervix if administered prior to colonization. There is evidence that oral contraceptives may mask the symptoms of chlamydial infection once it does become established.
Once entry into the uterus has been gained, the uterine lining becomes inflamed. In postpartum patients, the myometrium becomes infected, but in other patients, this inflammation is seldom invasive and is limited to the endometrium. The inflammation may produce uterine bleeding, but in the nongravid uterus, this is seldom clinically significant. The pathogens then continue their migration through the fallopian tubes. In the case of mycoplasmal infection, ascension may occur by way of parametrial structures rather than through the uterine cavity.
Initially, tubal infection is limited to the mucosa of the lumen, but the inflammation rapidly extends through the full thickness of the tubes. This transmural reaction of the fallopian tubes often causes the early pain of pelvic infection. The inflammation initiated by N. gonorrhoeae or C. trachomatis frequently overwhelms the normal uterine defense mechanisms and results in infections from opportunistic pathogens, particularly Bacteroides sp (6).
In severe cases of salpingitis, the purulent material from the fallopian lumens exudes through the open fimbriae into the abdominal cavity, producing peritonitis. The infection of the endometrium and fallopian tubes results in an inflammation of the surrounding parametrial structures. Although these structures may not undergo actual infection by the invading pathogens, their proximity to the true infection produces a severe parametritis in many patients. Escape through the end of the right fallopian tube and ascension to the right colic gutter may result in inflammation around the liver. Fitz-Hugh–Curtis syndrome(perihepatitis) is usually associated with C. trachomatis but may occur in 8% to 10% of all cases of salpingitis. Although typically associated with STIs, this syndrome may result from any intra-abdominal inflammatory process (7).
Inflammation and stagnation of host defenses, particularly in the fallopian tubes, allow for the possibility of unchecked bacterial growth. A tubo-ovarian abscess may develop; originating in the fallopian tube, the abscess may extend to involve the fimbriae and ovary as well. The bacterial content of a tubo-ovarian abscess is mixed, with a preponderance of anaerobes (4).
CLINICAL PRESENTATION
A clinical diagnosis of PID may be difficult because of the wide variation in signs and symptoms. No single historical, physical, or laboratory finding is both sensitive and specific for the diagnosis of acute PID. The Centers for Disease Control and Prevention (CDC) estimate that a clinical diagnosis of PID has a positive predictive rate of 65% to 90% for salpingitis when compared to laparoscopy (1). In a separate study, clinicians failed to recognize N. gonorrhoeae or C. trachomatis in 38% of infected women and overtreated 88% of women with no infection from these pathogens (8). Similarly in a review of only emergency department encounters, laboratory specimens confirmed infections for gonorrhea in 4.4%, for chlamydia in 10%, and for both in 2.6% of patients with a diagnosis of PID (9). Mild or nonspecific complaints may go unrecognized by the clinician (e.g., abnormal bleeding, dyspareunia, or vaginal discharge). Most authorities recommend a low threshold for diagnosis of PID because of the long-term effects and potential damage to the reproductive system of women. The CDC now recommends empiric treatment for PID if no other explanation can be found for lower abdominal pain in sexually active females with cervical motion tenderness, uterine tenderness, or adnexal tenderness. Table 130.1 summarizes findings consistent with PID.
TABLE 130.1
Diagnostic Findings in Pelvic Inflammatory Disease (PID)
Although attempts have been made to distinguish between features of infection caused by N. gonorrhoeae and C. trachomatis, they have not been consistent or reliable. N. gonorrhoeae salpingitis develops in the first few days after menses, producing a purulent vaginal discharge and severe pelvic pain. C. trachomatis infection may occur at any point in the menstrual cycle and results in less cervical discharge and milder symptoms. More important, however, is that both of these infections frequently coexist in 35% to 42% of patients (10).
The patient with a pelvic infection almost invariably presents to the ED with a complaint of lower abdominal pain. Inflammation of the endometrium, fallopian tubes, and parametrial structures usually produces diffuse bilateral pelvic pain. When questioned, most women describe a dull, constant, poorly localized pain, although almost any characterization of the pain has been reported. Because of the sensitive nature and social stigma of STIs, physicians should be empathetic and tactful in eliciting the patient’s history. Pelvic pain is seldom the only presenting complaint. N. gonorrhoeae or C. trachomatiscervicitis results in a vaginal discharge in over 50% of patients, whereas abnormal vaginal bleeding is seen in 30%. Gastrointestinal complaints, including nausea and vomiting, are less common but may be present. Urinary tract symptoms are common, with 20% of laparoscopically proven pelvic infections associated with irritative voiding symptoms (10). Pelvic infection should be suspected in patients who complain of dysuria or suprapubic pain that occurs only during micturition. Classic urinary tract presentations including urgency, frequency, and dysuria have been reported in 33% to 53% of women found to have STI.
A temperature greater than 38°C (100.4°F) is found in only 33% of patients. Fever supports the diagnosis but does not confirm it, nor does its absence preclude the diagnosis of PID. The abdominal examination commonly reveals tenderness in both lower quadrants, although one side may be more tender. Peritoneal signs indicate a more severe infection, with free exudate in the pelvis or abdomen, and intraperitoneal extension should be considered. If perihepatitis is also present, there may be tenderness in the right upper quadrant.
Pelvic examination must be approached carefully if meaningful information is to be gained. Because of pain or previous experience, this examination may be very difficult for many patients. Speculum examination may reveal a vaginal discharge. A markedly inflamed purulent cervix is indicative of an acute cervicitis and is supportive of some degree of pelvic infection. Normal appearing cervical discharge, and the absence of white blood cells on either Gram stain or a saline preparation of vaginal fluids, makes the diagnosis of PID very unlikely (1).
Bimanual examination begins with careful testing for cervical motion tenderness. Gentle motion of the cervix should be attempted initially, as an overly aggressive examination may produce reflexive guarding by the patient and severely limit the remainder of the evaluation. Elicitation of pain with either lateral or anteroposterior motion of the cervix is sensitive but not specific for pelvic infection. The emergency physician must remember that other causes of pelvic irritation: fluid from ruptured cysts, appendicitis, and blood from ectopic pregnancies can also produce this sign. The uterus is frequently firm but tender. Bilateral adnexal tenderness is one of the most consistent physical findings in studies evaluating diagnostic criteria for salpingitis. An adnexal mass may be appreciated but is not a consistent finding. Findings on pelvic examination may be atypical in patients who have had multiple prior infections or tubal ligation. Obstruction of the fallopian tube may prevent extension of the infection beyond the proximal tube, limiting the degree of adnexal tenderness.
DIFFERENTIAL DIAGNOSIS
The differential diagnosis of lower abdominal pain in women should include at least three possibilities: (a) ectopic pregnancy, (b) PID, and (c) appendicitis. Ovarian cyst, urinary tract infection, gastrointestinal hernia, and ovarian torsion should also be considered. Ectopic pregnancy is addressed in Chapter 137, and the approach to pelvic pain is described in Chapter 129. All women with pelvic pain, regardless of their menstrual history, should have a pregnancy test; the only exception is the woman who has had a hysterectomy (1). Salpingitis is the most common incorrect diagnosis in missed ectopic pregnancy and should be considered only after ectopic pregnancy has been excluded (1). The coexistence of infection and pregnancy is possible but unusual, because a mucous plug forms after implantation, preventing the spread of lower genital infections into the upper genital system. However, there is a brief window between insemination and mucous plug formation during which infection may occur. Appendicitis may be differentiated from PID by its unilateral nature, but this is by no means diagnostic.
ED EVALUATION
When PID is suspected, additional support for the diagnosis may be obtained through laboratory analysis. Because of the time interval between the collection of specimens and the return of results, a system should be in place for follow-up of patients undergoing any STI-related testing.
Gonorrhea cultures are obtained by placement of a sterile swab 1 to 2 cm into the endocervical canal, with rotation of the swab for 10 to 30 seconds. Following collection, the swab should be immediately plated on either chocolate agar or Thayer–Martin agar.
Chlamydia detection techniques include culture, antibody detection (enzyme-linked immunosorbent assay [ELISA] and fluorescent), and nucleic acid probes. In contrast to gonorrhea testing, nonculture techniques are the preferred detection procedures for the diagnosis of C. trachomatis.
Nucleic acid probe tests have been developed for both of these organisms. These tests are very sensitive and specific and may be applied not only to cervical specimens but also to urine and vaginal swabs. The additional advantage of this testing technique is that it permits home screening of patients for STIs (11–13).
Additional laboratory studies should include urinalysis to rule out urinary tract infection and a urine or serum pregnancy test. A complete blood count may be obtained for use in some disposition decisions, but the clinician should recognize that the test has limited usefulness. Serology for syphilis and human immunodeficiency virus (HIV) testing should be considered in patients with clinical PID or arranged at follow-up for those with laboratory-proven infections.
Imaging studies are helpful in patients with severe symptoms and those in whom the diagnosis is in question. Ultrasonographic findings indicative of PID include thickened fluid-filled fallopian tubes, free pelvic fluid, and tubal hyperemia. Cases progressing to tubo-ovarian abscesses may also demonstrate a complex adnexal mass, echogenic cul-de-sac fluid, and pyosalpinx (1,14). Computerized tomography may be needed in some patients in whom PID cannot be distinguished from appendicitis or other gastrointestinal pathology.
KEY TESTING
• Urine or serum pregnancy testing
• Gonorrhea and chlamydia testing
• Ultrasound or CT as needed to exclude tubo-ovarian abscess or appendicitis
ED MANAGEMENT
Treatment regimens for PID change periodically and it is advisable to monitor the recommendations of the CDC as well as local health agencies regarding treatment of STIs. N. gonorrhoeae has continued to demonstrate increasing resistance to all classes of antibiotics including quinolones and cephalosporins (15). Table 130.2 contains the 2010 treatment guidelines for PID. The management of acute pelvic infection centers on prompt antibiotic therapy directed against both N. gonorrhoeae and C. trachomatis. The goal of treatment is to prevent continued or worsened infection and limit the complications of PID, including chronic pain, ectopic pregnancy, infertility, and chronic infection.
TABLE 130.2
Antibiotic Therapy of Pelvic Inflammatory Disease
Treatment of uncomplicated cervicitis or urethritis with single-dose antibiotic regimens has been described. Options reported include oral azithromycin (1 g), plus cefpodoxime (400 mg) or cefuroxime axetil (1 g). In penicillin-allergic patients, the use of a single 2-g dose of azithromycin has also been described, although there are fears that this may only precipitate resistance (16). The clinician may consider such therapies more convenient; however, none of these have been formally endorsed by the CDC for upper tract or established pelvic infections (1).
Patients coinfected with HIV do not require any significant modifications in their treatment regimens for PID. These patients are more likely to have infections with M. hominis, Candida and Streptococcal sp, and human papillomavirus (HPV). However, disposition and determination of the need for hospitalization should be based on the patient’s overall clinical condition and not the presence of both PID and HIV.
The presence of an IUD has been reported to increase the incidence of pelvic infections, although this effect appears to be limited to the first 3 weeks after insertion of the device. There is no evidence that an IUD needs to be removed in a patient diagnosed with an acute upper genital tract infection. However, close follow-up with gynecologic consultation appears prudent in these patients (17).
Because infected males may be asymptomatic or deny symptoms, women with pelvic infections are at risk for reinfection if they continue relations with an infected male. Empiric treatment is recommended for any male who has had sexual contact with a woman diagnosed with a pelvic infection in the 60 days prior to her manifestation of symptoms (1).
CRITICAL INTERVENTIONS
• Rule out tubo-ovarian abscess in patients with PID and severe unilateral pelvic tenderness.
• Initiate parenteral antibiotics for toxic patients with PID and for those with tubo-ovarian abscess.
• Initiate empiric antibiotic treatment for patients suspected of having PID, pending return of confirmatory test results and having early follow-up arranged.
DISPOSITION
Suggested criteria for admission are listed in Table 130.3. Hospitalization is frequently indicated for pregnant patients. There are no data to recommend inpatient management over outpatient therapy for adolescent patients.
TABLE 130.3
Admission Criteria for Patients with PID
Outpatient management is appropriate for those patients not meeting criteria for admission shown in Table 130.3. All discharged patients should receive follow-up care to ensure response to treatment. If cultures are obtained, a mechanism should be in place to ensure that patients and their physicians or the public health department are notified of positive results.
Common Pitfalls
• The differential diagnosis of women thought to have PID must include ectopic pregnancy and appendicitis.
• The clinician should question the diagnosis of PID in any patient with unilateral pelvic pain.
• Pregnancy must be ruled out.
• Serologic testing for syphilis and HIV testing counseling are indicated for most women with a documented sexually transmitted disease.
REFERENCES
1. CDC. Sexually Transmitted Diseases Treatment Guidelines 2010. Available online at http://www.cdc.gov/std/treatment/2010/pid.htm. Accessed on June 30, 2014.
2. Eschenbach DA, Wolner-Hanseen P, Hawes DE, et al. Acute pelvic inflammatory disease: Associates of clinical and laboratory findings with laparoscopic findings. Obstet Gynecol. 1997;16:157.
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4. CDC. Incidence, Prevalence, and Cost of Sexually Transmitted Infections in the United States. Available online at http://www.cdc.gov/std/stats/STI-Estimates-Fact-Sheet-Feb-2013.pdf. Accessed on June 30, 2014.
5. CDC. Sexually Transmitted Diseases Surveillance 2011. Available online at http://www.cdc.gov/std/stats11/gonorrhea.htm. Accessed on June 30, 2014.
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