8/21/08njm

**Q. Should we treat asymptomatic trichomonas found on Pap smear?**

A. It depends what type of Pap smear you are using. See details below

**Answer**

If is it was a conventional Pap, then please bring the non-pregnant
patient in for a confirmatory test. If it was a liquid based Pap, then
you can treat the patient without further evaluation.

Treating asymptomatic trichomoniasis is [not]{.underline} recommended in
[pregnant]{.underline} women given the potentially increased risk of
preterm birth associated with antibiotic therapy, but treatment of
symptomatic [non-pregnant]{.underline} women [is]{.underline}
recommended.

**Background**

Treatment is indicated in all nonpregnant women\* diagnosed with
trichomonas vaginitis, even if asymptomatic. The rationale for treatment
of asymptomatic women is that if left untreated, up to one-third become
symptomatic within six months and they continue to transmit the
infection to sexual partners while untreated.

The most sensitive method of detecting trichomonas vaginitis is culture.
Unfortunately trichomonas culture is not available at most sites, plus
one would also need a special medium to even send it to most outside
laboratories.  Microscopy and pH is only 50 to 70 percent sensitive and
is time sensitive secondary to motility. DNA probes are sensitive and
specific, but not available here. Conventional cytology has a
sensitivity of only 60 to 70 percent and false positive results are
common (at least 8 percent). Thus, conventional Pap smear should not be
used to diagnose trichomoniasis. Asymptomatic women with trichomonads
identified on conventional Pap smear should be evaluated by wet mount,
or culture if the wet mount is negative and should not be treated until
the diagnosis is confirmed.

By comparison, the reliability of liquid-based cervical cytology appears
to be higher. Although the sensitivity of liquid-based smears for
trichomonas infection is low (61 percent), specificity is high (99
percent) compared to conventional Pap smear, resulting in a false
positive rate of only 1 percent. Therefore, although liquid-based
cervical cytology is not a sensitive test for diagnosis of
trichomoniasis, we feel treatment of asymptomatic women with
trichomonads noted on liquid-based cervical cytology is a reasonable
approach.

In summary, patients with trichomonas on a conventional Pap need to come
in confirmation before treatment. If you utilize a liquid based prep,
then it is recommended that you treat based on that alone.

\*Treating asymptomatic trichomoniasis is not recommended in pregnant
women given the potentially increased risk of preterm birth associated
with antibiotic therapy, but treatment of symptomatic pregnant women is
recommended.

**Addendum: Diagnostic tools**

**Trichomonas vaginitis**

**DIAGNOSIS** --- As with other types of vaginitis, none of the clinical
features of trichomonas vaginitis is sufficiently sensitive or specific
to allow a diagnosis based upon signs and symptoms alone.

-   

Microscopy and pH --- The presence of motile trichomonads on wet mount
is diagnostic of

infection, but this occurs in only 50 to 70 percent of culture-confirmed
cases. The organisms

remain motile for 10 to 20 minutes after collection of the sample. Other
findings that are almost

invariably present with trichomonas infection, but nondiagnostic,
include an elevated vaginal pH

(\>4.5) and an increase in polymorphonuclear leukocytes on saline
microscopy.

-   

Culture --- Culture on Diamond\'s medium has a high sensitivity (95
percent) and specificity (\>95

percent) and should be considered in patients with elevated vaginal pH,
increased numbers of

polymorphonuclear leukocytes and an absence of motile trichomonads and
clue cells on wet

mount; or when microscopy is unavailable or yields unreliable results.
Alternatively, a commercial

\"In Pouch\" T vaginalis culture system can be used and is readily
available (BioMed Diagnostics,

White City, Oregon).

DNA probes --- No FDA-approved PCR test for T. vaginalis is available in
the United States, but

several rapid diagnostic kits using DNA probes and monoclonal antibodies
have been developed

commercially, with a sensitivity of 90 percent and a specificity of 99.8
percent. These can be

useful in areas of high prevalence where microscopy or culture is not
available (ie, high

prevalence refers to STD clinics and inner city clinics serving the
uninsured).

A point-of-care test for trichomonas antigens, the OSOM Trichomonas
Rapid Test has a

sensitivity of 88.3 percent and specificity of 98.8 percent. Physicians
and staff can read results in

10 minutes. The Affirm VP III Microbial Identification System (Becton
Dickinson) test uses a nucleic acid probe and is read in 45 minutes.

Cervical cytology --- Trichomonads are sometimes reported as an
incidental finding on

conventional Papanicolaou (Pap) smears. Conventional Pap smears are
inadequate for diagnosis

of trichomoniasis because this technique has a sensitivity of only 60 to
70 percent and false

positive results are common (at least 8 percent) . Thus, Pap smear
should not be used to

diagnose trichomoniasis. Asymptomatic women with trichomonads identified
on conventional Pap

smear should be evaluated by wet mount, or culture if the wet mount is
negative and should not

be treated until the diagnosis is confirmed.

By comparison, the reliability of liquid-based cervical cytology appears
to be higher. One study performed both liquid-based cervical cytology
and culture for T. vaginalis on 203 consecutive women . Forty-four women
had a positive culture and 28 women had a positive liquid-based smear
for trichomonads. Although the sensitivity of liquid-based smears for
trichomonas infection was low (61 percent), specificity was high (99
percent) compared to conventional Pap smear, resulting in a false
positive rate of only 1 percent. Therefore, although liquid-based
cervical cytology is not a sensitive test for diagnosis of
trichomoniasis, we feel treatment of asymptomatic women with
trichomonads noted on liquid-based cervical cytology is a reasonable
approach.

**Resources**

**Trichomonas vaginitis , UpToDate**

<http://www.uptodateonline.com/utd/content/topic.do?topicKey=gen_gyne/28379>

**Diagnosis of trichomoniasis. Comparison of conventional wet-mount
examination with cytologic studies, cultures, and monoclonal antibody
staining of direct specimens.**

The accuracy of (1) conventional wet-mount examination, (2)
Papanicolaou-stained gynecologic smears, (3) a direct slide test using
fluorescein-conjugated monoclonal antibodies against Trichomonas
vaginalis, and (4) two different culture media for the diagnosis of
trichomoniasis in a high-risk population of 600 women was compared. Use
of Feinberg-Whittington or Diamond\'s culture medium resulted in a
diagnosis of 82 and 78 cases, respectively, and the combination of two
cultures identified 88 infected women. In comparison, wet-mount
examination detected only 53 (60%) of the cases. Cytologic smears were
interpreted as positive for T vaginalis in 49 (56%) of the 88 cases but
also resulted in seven false-positive smears, and specimens from 18
women with negative cultures were interpreted as \"suspicious\" for
trichomoniasis. Monoclonal antibody staining detected 76 (86%) of the 88
positive specimens, including 27 (77%) of the 35 cases missed by
wet-mount examination. In summary, wet-mount and cytologic studies were
insensitive, and cytology study was the least specific method for
diagnosis of trichomoniasis. Direct immunofluorescence with monoclonal
antibodies holds promise as a sensitive and specific alternative to
cultures for rapid detection of T vaginalis in clinical specimens.

Krieger JN; Tam MR; Stevens CE; Nielsen IO; Hale J; Kiviat NB; Holmes KK
Diagnosis of trichomoniasis. Comparison of conventional wet-mount
examination with cytologic studies, cultures, and monoclonal antibody
staining of direct specimens. JAMA 1988 Feb 26;259(8):1223-7.

<http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlus&list_uids=2448502>

**Accuracy of detection of trichomonas vaginalis organisms on a
liquid-based papanicolaou smear**

OBJECTIVE: The study was undertaken to determine the accuracy of the
liquid-based Papanicolaou (Pap) smear in the detection of Trichomonas
vaginalis organisms in women. STUDY DESIGN: Two hundred three
consecutive patients who had the liquid-based Pap smear also underwent a
culture for T vaginalis. A wet mount was performed if symptomatic.
Results were analyzed for sensitivity, specificity, and positive and
negative predictive values. RESULTS: Forty-four patients (21.6%) had a
positive culture. On the liquid-based Pap smear, 28 patients (13.8%)
were positive for T vaginalis, showing a sensitivity of 61.4%, a
specificity of 99.4%, a positive predictive value of 96.4%, and a
negative predictive value of 90.8%. When wet mount and culture were
compared, a sensitivity of 50%, a specificity of 93%, a positive
predictive value of 77%, and a negative predictive value of 80% were
obtained. CONCLUSION: The presence of T vaginalis organisms, as stated
by the liquid-based Pap smear pathology report, is accurate and warrants
treatment without further testing.

Lara-Torre E; Pinkerton JS Accuracy of detection of trichomonas
vaginalis organisms on a liquid-based papanicolaou smear. Am J Obstet
Gynecol 2003 Feb;188(2):354-6.

<http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlus&list_uids=12592239>