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CAT CLINIC
Charles DiMaggio, PA-C, MPH
DEPARTMENT EDITOR
Critically appraised topics
Diagnosing the acute scrotum
The accuracy of clinical assessment and bedside US compared with the gold standard
Tracy Onega, MA, MPAS, PA-C
Ms. Onega is a doctoral student at the Center for the Evaluative Clinical
Sciences, Dartmouth College, Hanover, NH. The author has indicated no relationships
to disclose relating to the content of this article. Dr. DiMaggio is
Director, Program for Healthcare Systems Preparedness, and Assistant Professor
of Clinical Epidemiology, National Center for Disaster Preparedness, Columbia
University Mailman School of Public Health, New York, NY. He is a member of
the editorial board of JAAPA.
A 26-year-old man is seen at 1 am in the emergency department (ED) of an urban
teaching hospital for acute onset of right testicular pain. The pain began 6
hours previously but had resolved briefly during that time. The patient was
vague about his sexual history but denied dysuria, hematuria, or penile discharge.
He reported an occurrence of blunt testicular trauma earlier that day. Review
of systems revealed no fever, chills, nausea, or abdominal pain. The history
was negative for sexually transmitted diseases, cryptorchidism, urolithiasis,
or hernias, and the family history was unremarkable. The patient took no medications
and had no allergies. Vital signs were within normal limits, and the patient
was afebrile. Urinalysis results were negative.
Physical examination revealed a healthy, well-developed male in some apparent
distress. The heart, lungs, back, and abdominal examinations were normal. Examination
of the genitalia revealed a mildly erythematous scrotum bilaterally. The right
testicle was swollen, normal riding, with an oblique lie. On palpation, the
right epididymis was exquisitely tender and painful, as was the testicle. The
contralateral testis was nontender, and the cremasteric reflex was equivocal.
At this point, the differential diagnosis included testicular trauma, torsion
of the testicle or appendage, epididymitis, and orchitis.
Clinical question
The acute scrotum can present a diagnostic challenge, particularly given the
urgency with which testicular torsion must be identified in order to minimize
morbidity. Testicular salvage is highly time dependent, with rates linearly
decreasing to 50% to 70% at 10 hours.1 When clinical suspicion of
testicular torsion is high, immediate surgical exploration is required to reduce
the risk of testicular loss.
Although the need for emergent surgery versus diagnostic testing is assessed
largely by the history and physical exam, these clinical features may not be
as accurate as previously thought. One series reported a 50% accuracy rate for
physical examination.2 In a pediatric study, features of the history
and physical exam were compared for significance in diagnosing an acute scrotum.3
While duration of pain, testicular lie, cremasteric reflex, and testicular versus
epididymal tenderness were significant factors in distinguishing scrotal pathology,
a substantial amount of overlap in these signs and symptoms was seen.3
Because the clinical presentation of several disease states can overlap, unnecessary
surgery may occur in a large proportion of patients. To minimize the surgeries
performed on patients who do not have testicular torsion and to maximize testicular
viability in those who do, color Doppler ultrasonography (US) has become the
diagnostic modality of choice.4 At many institutions, however, obtaining
US results quickly is rare because of radiology backlogs and after-hours staffing
issues. To facilitate early diagnosis, ED clinicians are increasingly performing
bedside US themselves.5 Because many of these clinicians have not
had formal training in performing testicular US studies, the accuracy of bedside
testing should be characterized for diagnosing the acute scrotum and particularly
for distinguishing testicular torsion from other entities. While the literature
reports numerous studies of radiology-based color Doppler US testicular scans,
with sensitivities ranging from 86% to 100% and specificities from 95% to 100%,4,6-10
there is a paucity of evidence for bedside US. This article presents the only
published study to date comparing the use of bedside US in male children and
adults with the gold standard of color Doppler US performed by board-certified
radiologists for the diagnosis of testicular torsion, along with evidence for
features of the history and physical exam that are significant predictors.
Search criteria and results
I performed MEDLINE, CDSR (Cochrane Database of Systematic
Reviews), ACP (American College of Physicians) Journal Club, DARE
and bibliographic searches for English-language, human studies published between
January 1, 1966, and November 2003. Using the key words testicular torsion
or acute scrotum paired with ultrasound, physical examination,
sensitivity, or specificity, I identified 61, 34, and 18 citations,
respectively. All citations were from MEDLINE, with no
evidence-based medicine reviews present.
By scanning the abstracts, I noted that the typical study design was a case
report or small retrospective chart review that focused on a pediatric population.
Most of these studies described either incidence of specific scrotal pathologies
or results from scrotal US. Evidence for the accuracy of history and physical
examination findings in diagnosing the acute scrotum was minimal, particularly
for adults. By selecting an article that explicitly compared the significance
of features of the history and physical exam in diagnosis of the acute scrotum,
I was able to calculate sensitivities and specificities.3 To address
the question of how bedside US compares with that of radiology US, I selected
the only article present in the literature.5
Evaluating the evidence
Accuracy of clinical findings To first address the question
of how accurate history and physical examination are for diagnosis of the acute
scrotum, I focused on a retrospective review of 90 patients younger than 18
years who received a diagnosis of epididymitis (n=64), testicular torsion (n=13),
or torsion of the appendix testis (n=13) at a major tertiary care center from
1994 to 1996. History findings reviewed included age, duration of pain, history
of similar pain, history of fever, nausea, vomiting, dysuria, sexual activity,
and trauma. The physical examination findings reviewed were temperature, presence
of palpable nodule or "blue dot" between the upper pole of the testis and the
head of the epididymis, presence or absence of the cremasteric reflex, testicular
lie, and testicular tenderness. Diagnosis was confirmed by color Doppler US
and/or surgery. Categorical data for these features were compared using the
chi-square test or the Fisher exact test, while continuous non–normally
distributed variables were compared with the Mann-Whitney test, using P <.05
as the level of significance.
Of these clinical indicators, only a history of pain lasting less than 12
hours, abnormal testicular lie, testicular tenderness, and absent cremasteric
reflex were significant in predicting testicular torsion. From the data presented,
I calculated the sensitivity, specificity, positive predictive value (PPV),
and negative predictive value (NPV) for each of these clinical features in diagnosing
testicular torsion (see Table 1). These calculations were based on testicular
torsion data versus the combined data for epididymitis and torsion of the appendix
testis.
TABLE 1
Accuracy of significant features of the history and physical examination
for diagnosis of testicular torsion
|
| Clinical feature |
Sensitivity, %
(95% CI)
|
Specificity, %
(95% CI)
|
PPV, %
(95% CI)
|
NPV, %
(95% CI)
|
| Symptoms <12 h |
69 (42-87)
|
64 (52-73)
|
24 (11-54)
|
92 (81-97)
|
| Abnormal testicular lie |
46 (23-71)
|
100 (95-100)
|
100 (54-100)
|
92 (83-96)
|
| Absent cremasteric reflex |
100 (77-100)
|
88 (79-94)
|
59 (36-81)
|
100 (94-100)
|
| Testicular tenderness |
100 (77-100)
|
38 (28-49)
|
21 (11-40)
|
100 (88-100)
|
| Key: CI, confidence interval; NPV, negative
predictive value; PPV, positive predictive value. |
Because the prevalence of testicular torsion is relatively low (0.125%),1
the PPV of even the most sensitive test will be relatively low, as is seen in
Table 1. The NPV is therefore a more useful clinical measurement for this problem,
yielding a greater capacity to rule out testicular torsion based on clinical
findings. From the Kadish and Bolte data, the four significant clinical features—absent
cremasteric reflex, abnormal testicular lie, testicular tenderness, and symptoms
lasting less than 12 hours—all have a relatively high NPV, with a rather low
PPV. Thus, these clinical findings may best be used to stratify patients according
to the need/urgency for imaging studies. Data are lacking to make clinical predictions
based on a combination of physical criteria, since these data only evaluate
physical examination findings independently of each other.
While this study accounts for its measurements and outcomes on each patient
and contributes a quantitative assessment of clinical findings to the sparse
literature, it also has several limitations. First, the physical findings of
a pediatric population may not be generalizable to adults. Also, small numbers
are likely to limit the robustness of these findings. Enrolling only patients
with a diagnosis of epididymitis, testicular torsion, or torsion of the appendix
testis instead of those presenting with scrotal pain introduces the potential
for an overestimation of accuracy. The author's choice of statistical tests
may also have slightly increased the likelihood of a chance significant finding,
by using a test appropriate for two category comparisons when three were actually
compared. Finally, a retrospective chart review from a single institution is
always potentially subject to bias.
Accuracy of bedside US Given the high degree uncertainty with
a clinical diagnosis and the concomitant need for diagnostic imaging, the next
important clinical question to address was how bedside US compares with radiology
US of the acute scrotum. Blaivas and colleagues report the only study to focus
on this question.5 They also used a retrospective chart review of
their urban teaching ED. From July 1998 to September 1999, 194 patients presented
with scrotal pain (median age, 45 years; range, 10–62 years). Thirty-six
patients received bedside US performed by emergency physicians who had no previous
training in testicular US studies. Board-certified radiologists performed confirmatory
color Doppler US. The bedside US examinations agreed with confirmatory studies
in 35 of the 36 patients, yielding a sensitivity of 95% (95% CI, 0.78-0.99)
and a specificity of 94% (95% CI, 0.72-0.99).
Certainly, a larger enrollment would have strengthened the confidence in the
findings, particularly since the study only assessed the accuracy of diagnosing
the acute scrotum, without power to separate the performance for individual
pathologies. Also, this study may have been conducted in an optimal setting
for ED ultrasonography, given its high volume (approximately 70,000 visits per
year) and an institutional commitment to bedside US. Reporting outcomes of the
158 patients who did not receive bedside US could strengthen interpretations
of this study. Nevertheless, this study is an important early work for evaluating
bedside US in diagnosing the acute scrotum.
Clinical bottom line
These small studies suggest two key points. First, while several features
of the history and physical might identify those patients who do not have testicular
torsion with reasonable accuracy, the inability to accurately predict which
patients do have testicular torsion limits the utility of physical findings.
Second, bedside US by emergency physicians may be a relatively accurate tool
in both diagnosing testicular torsion and differentiating it from other causes
of acute scrotal pain, although further research is needed before bedside US
can be confidently endorsed.
Bedside US is an important adjunctive tool, given that the majority of presentations
are equivocal based on history and physical exam and that radiology US imaging
may not be available emergently. Bedside US is warranted only if it does not
delay a radiology US study or immediate surgical exploration in unequivocal
cases. In clinical settings with bedside US capability and radiology limitations,
there may be a benefit to training PAs to perform testicular scans in order
to facilitate a timely diagnosis of the acute scrotum.
REFERENCES
1. Blaivas M, Batts M, Lambert M. Ultrasonographic
diagnosis of testicular torsion by emergency physicians. Am J Emerg Med.
March 2000;18:198-200.
2. Galejs LE. Diagnosis and treatment of the acute
scrotum. Am Fam Physician. 1999;59:817-824.
3. Kadish HA, Bolte RG. A retrospective review
of pediatric patients with epididymitis, testicular torsion, and torsion of
testicular appendages. Pediatrics. 1998;102(1 pt 1): 73-76.
4. Galejs LE, Kass EJ. Color Doppler ultrasound
evaluation of the acute scrotum. Tech Urol. December 1998;4:182-184.
5. Blaivas M, Sierzenski P, Lambert M. Emergency
evaluation of patients presenting with acute scrotum using bedside ultrasonography.
Acad Emerg Med. January 2001; 8:90-93.
6. al Mufti RA, Ogedegbe AK, Lafferty K. The use
of Doppler ultrasound in the clinical management of acute testicular pain. Br
J Urol. 1995;76:625-627.
7. Baker LA, Sigman D, Mathews RI, et al. An analysis
of clinical outcomes using color doppler testicular ultrasound for testicular
torsion. Pediatrics. 2000;105(3 pt 1): 604-607.
8. Dogra V, Bhatt S. Acute painful scrotum. Radiol
Clin North Am. 2004;42:349-363.
9. Hod N, Maizlin Z, Strauss S, Horne T. The relative
merits of Doppler sonography in the evaluation of patients with clinically and
scintigraphically suspected testicular torsion. Isr Med Assoc J. January
2004;6:13-15.
10. Weber DM, Rosslein R, Fliegel C. Color Doppler
sonography in the diagnosis of acute scrotum in boys. Eur J Pediatr Surg.
August 2000;10:235-241.
Tracy Onega. CAT Clinic. JAAPA December 2004;17:40-42.
Copyright © 2004, Advanstar Medical Economics Healthcare Communications at Montvale, NJ 07645-1742. All rights reserved.
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