What is Pelvic inflammatory disease (PID)?
Pelvic inflammatory disease (PID) refers to the genital tract infection. It involves the upper parts of the female reproductive system including all three organs or any one of uterus along cervix, fallopian tubes and ovaries. The infection is normally due to the sexually transmitted organism, which travels along the genital tract. An acute infection leads to chronic one that then progresses to PID. This ascending trait distinguishes this from other non-sexually transmitted infections.
Generally, non-sexually transmitted diseases occur due to pregnancy, medical procedure related to reproductive organs. These may also occur due to abdominal intervention that can lead to the pelvis. Abdominal cavity and pelvic cavity are linked to each other and infection in one of the cavities can lead to the other.
Often PID also involves the neighboring organs and causes, appendicitis, peri-hepatitis (the Fitz-Hugh Curtis syndrome), peritonitis and tubo-ovarian abscess (TOA).
The overall prevalence of PID has decreased in recent years.
Causes & Pathogenesis
The normal bacterial vaginal flora of a healthy woman contains different pathological organisms and the species involved are:
- Enterobacteriaceae (most commonly Klebsiella, Escherichia coli, and Proteus).
The flora changes under the influence of hormonal changes, pregnancy, menstrual cycles, contraceptive methods, sexual activity and other unknown factors.
The endocervical canal acts as a potential barrier between the upper genital tract and the normal vaginal flora, which protects the vital reproductive organs from infections and inflammations.
Sexually transmitted microbes disrupt this protective barrier making the upper genital tract vulnerable to these potentially harmful microbes from the vaginal flora, which leads to subclinical infection in some women whereas full-blown inflammatory changes in others. These infections then lead to pelvic inflammatory diseases and pose a risk of chronic inflammation to the uterus, cervix, oviducts, ovaries, pelvic cavity, peritoneum and other structures in the pelvis.
The reason why these microbes cause PID in some women and not in others is not fully understood. There is a possibility of an association with the genetic variability that makes some women prone to these infections due to different reasons, the depressed immune system as a hereditary trait can be one of them.
There is a possibility that a patient can have absolutely normal fallopian tubes, ovaries and pelvis. But there can be intratubal inflammation or endometritis, which limits the usefulness of invasive laparoscopic view to diagnose PID. As these patients will have a normal naked eye view, but endometritis and salpingitis will be missed.
Most common pathogens causing PID among sexually active and pre-menopausal women are:
- Neisseria gonorrhoeae.
- Chlamydia trachomatis.
- Mycoplasma genitalium (pre-menopausal group).
- In post-menopausal women infrequently, these can cause PID.
- E. coli.
- Colonic anaerobes.
- Mycobacterium tuberculosis.
- groups A and B streptococci.
- Klebsiella spp.
- Proteus mirabilis.
- Haemophilus spp.
- Prevotella spp.
- Peptostreptococcus spp.
- Campylobacter spp.
In a patient with PID, different organisms can be isolated from different levels, organisms found in the lower genital tract will be different from the ones found in the upper genital tract.
- Sexual activity.
- Multiple sexual partners – monogamy reduces the risk of PID.
- The single spouse with a sexually transmitted infection.
- Early age of losing virginity.
- Previous infection with chlamydia.
- Previous PID.
- African-American or Black-Caribbean ethnicity – this risk factor can be due to multiple reasons and there is a possibility for this to reduce with time.
- Intrauterine devices.
- Bacterial vaginosis – leading to complete disruption of the vagina flora.
- Pregnancy – in the first 12 weeks the risk is more. After that when the mucous plug develops and the barrier is formed between the vaginal flora and uterus, the risk reduces.
Factors Reducing the Risk of PID
- Contraception – barrier contraception including, male and female condoms, reduce the risk.
- Oral contraceptive pills, although OCPs increase the risk of having a chlamydial and gonococcal infection, but studies have shown that OCPs reduce the risk of having PID.
- Tubal ligation decreases the involvement of oviducts in PID, but otherwise has no effect in reducing the risk of PID.
Symptoms & Clinical Signs of PID
- Acute onset of lower abdominal or pelvic pain – cardinal symptom.
- Pelvic organ tenderness.
- Inflammation of the genital tract.
- Pain during/after coitus.
- Post-coital bleeding.
- Inter-menstrual bleeding.
- Abnormal uterine bleeding.
- Urinary frequency.
- Abnormal vaginal discharge.
- Abdominal tenderness on palpation.
- Rebound tenderness.
- Decreased bowel sounds – severe PID.
- Acute cervical motion.
- Uterine, and adnexal tenderness – a classical sign of symptomatic acute pelvic inflammatory disease.
- Purulent endocervical discharge.
- Vaginal discharge.
- Lateralization of adnexal tenderness – uncommon.
Laboratory Test & Other Investigations
- Complete blood count showing peripheral blood leukocytosis.
- Elevated erythrocyte sedimentation rate (ESR).
- High C-reactive protein (CRP).
- Urine Routine examination.
- Blood culture & sensitivity.
- Cervical swab culture & sensitivity.
- In case of abscess or pus collection, the culture of that fluid.
- Vaginal discharge culture & sensitivity with KOH prep to exclude bacterial vaginosis and trichomonas vaginalis.
- Pregnancy test.
- Microscopy of vaginal discharge (where available).
- Nucleic acid amplification tests (NAATs) for C. trachomatis and Neisseria gonorrhoeae.
- NAATs for Mycoplasma genitalium (where available).
- HIV screening.
- Serologic testing for syphilis.
- Ultrasound abdomen and pelvis.
- CT Scan and MRI are not routinely used to diagnose PID unless the patient is acutely ill and there is no improvement in patient’s condition after 72hrs of initiating the empiric treatment, as the alternate diagnosis is suspected, or a tubo-ovarian abscess is a possibility. Abscess or other pathology will be more pronounced on CT/MR.
- Doppler ultrasound can also be used to show increased blood flow in areas with inflammation but is routinely not used in the diagnosis of PID.
Laparoscopic or transcervical endometrial biopsy can confirm the diagnosis of PID but these modalities are not commonly used.
Laparoscopic view of the pelvic region has never been the gold standard test. Because it has a low sensitivity and high specificity. Along with that the information which is available on histological view after biopsy of the involved region is more than what is observed by the naked eye on laparoscopy. It is an invasive procedure not available in every acute setting and not required in the diagnosis of PID as such because there is a possibility that endometrial or intra-tubal inflammation is missed on this procedure. The only benefit of this invasive procedure is taking a biopsy for the microscopic view which when combined with history, risk factors and clinical features can make a final diagnosis.
It can be a useful fragment of the investigative work-up for Pelvic Inflammatory Disease when imaging studies are not providing definitive information, this can happen in the following situations:
- In a female, who didn’t respond to out-patient treatment of PID and now an alternative diagnosis is a possibility for the cause of the signs and symptoms.
- In an admitted patient, whose symptoms didn’t improve or have worsened after 72 hours of in-patient treatment.
Transcervical Endometrial Biopsy
This procedure is used to detect the endometritis, which earlier mentioned can be missed on laparoscopic view, though it’s not used routinely because it requires expert skills and the histological diagnosis is also difficult due to patchy inflammation.
Diagnosis of Pelvic Inflammatory Disease
The presumptive clinical diagnosis of PID is made in sexually active young women, especially women at high risk for sexually transmitted infections (STIs), who present with pelvic or lower abdominal pain and have evidence of cervical motion, uterine, or adnexal tenderness on exam.
Addition to the diagnostic criteria increases the specificity but decreases the sensitivity of the criteria. Additional points which are helpful in making the diagnosis of PID are as follows:
- Body temperature >101°f.
- Vaginal or cervical mucopurulent discharge.
- Cervical friability.
- Presence of abundant numbers of white blood cells on saline microscopy of vaginal secretions (>15 – 20 WBCs per hpf).
- Cervical infection with gonorrhoeae or chlamydia on culture.
According to CDC, raised ESR and CRP are also added to the diagnostic criteria and it increases the specificity of the criteria to diagnose PID, but these tests are not that specific and not routinely done for PID.
Findings such as normal cervical discharge or a normal number of white blood cells in vaginal secretions go against the diagnosis of PID and an alternate may be present.
Findings on Different Diagnostic Procedures
Pelvic imaging – Transvaginal ultrasound, CT, or MRI:
- Thickened, fluid-filled oviducts with/without pelvic ascites.
- Tubo-ovarian complex or abscess.
- Doppler studies – hyperemia suggestive of pelvic inflammation.
Findings consistent with PID on laparoscopy include:
- Tubal erythema.
- Purulent exudate.
- Cul-de-sac fluid.
- Abnormal fimbriae.
- Endometritis in the biopsied tissue.
Diagnostic criteria for subclinical PID is not determined yet, in view of some experts’ women having infertility due to a tubal factor might be having subclinical PID. It is sometimes diagnosed in women undergoing for laparoscopy or an invasive procedure for some other test or diagnosis, most commonly diagnosed as an incidental finding.
- Centers for Disease Control and Prevention (CDC). Pelvic Inflammatory Disease (PID). http://www.cdc.gov/std/pid/stats.htm (Accessed on January 05, 2015)
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- Molander P, Finne P, Sjöberg J, et al. Observer agreement with a laparoscopic diagnosis of pelvic inflammatory disease using photographs. Obstet Gynecol 2003; 101:875. https://www.ncbi.nlm.nih.gov/pubmed/12738143
- Wiesenfeld HC, Sweet RL, Ness RB, et al. Comparison of acute and subclinical pelvic inflammatory disease. Sex Transm Dis 2005; 32:400. https://www.ncbi.nlm.nih.gov/pubmed/15976596
- Peipert JF, Ness RB, Blume J, et al. Clinical predictors of endometritis in women with symptoms and signs of pelvic inflammatory disease. Am J Obstet Gynecol 2001; 184:856. https://www.ncbi.nlm.nih.gov/pubmed/11303192
- Workowski KA, Bolan GA, Centers for Disease Control and Prevention. Sexually transmitted diseases treatment guidelines, 2015. MMWR Recomm Rep 2015; 64:1.