Brian P. Jacob, David C. Chen, Bruce Ramshaw, Shirin Towfigh (eds.) - The SAGES Manual of Groin Pain-Springer International Publishing (2016)

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J.M. Miller et al.
Fig. 13.22. Static axial and sagittal T2-weighted MR, and dynamic axial and
sagittal T2-weighted MR of occult femoral hernia not detected on CT or
US. Valsalva maneuver forces a small amount of fat ( black arrows ) through the
femoral triangle on the left.
mation of true negative predictive values. Dynamic examination of the
groin with Valsalva maneuver further strengthens the ability of US to
find small defects, but there is reason to believe that physically undetectable
hernias would be equally difficult to demonstrate with the limited
resolution of US. While it is certainly reasonable to begin radiologic
assessment of suspected occult inguinal hernia with US, the test should
not be considered definitive on account of its operator dependence and
inability to ensure visualization of the entire pelvis [ 25 ].
CT of the pelvis solves this visualization problem and can often elucidate
unconsidered pathologies as the source of groin pain. Yet while
CT is often considered a definitive test for occult inguinal hernia
(Fig. 13.21 ), [ 26 ], the common focus of study design on the hernias that
“require” surgery—indicative of hernias more prone to complication—
likely biases results toward detection of larger hernias. In a recent study
directly comparing all patients operated on for uncomplicated groin
pain, CT was found to be substantially weaker than MR in the evaluation
of occult hernia, with MR correctly identifying 91 % of the hernias
overlooked by CT (Fig. 13.22 ) [ 27 ].
The recommendation is that MR be considered the definitive nonoperative
test for inguinal hernia in patients with history strongly suggestive
of such pathology but lacking clear physical findings. US and CT
still have utility in the evaluation of groin pain due to occult inguinal
hernia; however, in light of negative US or CT result, further diagnostic
workup with MR is indicated as symptoms persist [27] .
References
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media/ACR/Documents/AppCriteria/RadiationDoseAssessmentIntro.pdf . Accessed 9
Mar 2015.