Diagnostic ultrasound ( PDFDrive )

CHAPTER 15 The Uterus 545
A
B
FIG. 15.15 Tamoxifen-Related Changes on TVS. (A) Thick, cystic endometrium caused by endometrial hyperplasia in patient taking tamoxifen.
(B) Thick, cystic endometrium caused by a large polyp in patient receiving tamoxifen.
polyps, and carcinoma. 117,119,120 Cystic changes within the thickened
endometrium are frequently seen (Fig. 15.15). Polyps are
frequently present, have a higher incidence in women receiving
tamoxifen than in untreated women, and can be quite large. 118,121
However, because cancer occurs in polyps in a higher percentage
of women taking tamoxifen than in the general population, focal
lesions in these women should be investigated. 122 As mentioned
previously, in some women taking tamoxifen, the cystic changes
are subendometrial in location and represent reactivation of
adenomyosis in the inner layer of myometrium. 123 Because it is
diicult to distinguish the endometrial/myometrial border in
many of these patients, SHG may be valuable in determining
whether an abnormality is endometrial or subendometrial. 11,124 It
is also important to recognize that this adenomyosis-like change
is a diagnosis of exclusion. When a cystic endometrial appearance
is seen in a woman taking tamoxifen, although the efects of
tamoxifen should be mentioned as part of the diferential diagnosis,
polyps, hyperplasia, and cancer also need to be considered.
Postmenopausal Bleeding
Postmenopausal bleeding is considered to be any vaginal bleeding
that occurs in a postmenopausal woman other than the expected
cyclic bleeding with sequential HRT. Because the prevalence of
endometrial cancer is low and endometrial atrophy accounts for
a large proportion of cases of postmenopausal bleeding, the
negative predictive value of a thin endometrium is high; therefore
a thin endometrium can be reliably used to exclude cancer. Several
studies have shown that in patients with postmenopausal bleeding
who have had endometrial sampling, an endometrial measurement
of up to 3 mm, 125 up to 4 mm, 126-128 or up to 5 mm 129-131 can be
considered normal. he bleeding in these patients is oten related
to an atrophic endometrium.
he majority of women with postmenopausal uterine bleeding
have endometrial atrophy. 127-132 On TVS, an atrophic endometrium
is thin and homogeneous. Histologically, the endometrial
glands may be dilated, but the cells are cuboidal or lat and the
stroma is ibrotic. A thin endometrium with cystic changes on
TVS is consistent with a diagnosis of cystic atrophy, but when
the endometrium is thick, the appearance is indistinguishable
from that of cystic hyperplasia. 133
A meta-analysis of 35 published studies that included 5892
women showed that an endometrial thickness of 5 mm or greater
detected 96% of endometrial cancer and 92% of any endometrial
disease. 134 For a postmenopausal woman with vaginal bleeding
with a 10% pretest probability of cancer, her probability of cancer
is 1% following a normal TVS result. However, many of the
studies used in the meta-analysis were biased by only including
those patients who underwent biopsy. In a recent study by Wong
and colleagues of 4383 women who all underwent an ultrasound
and biopsy ater having postmenopausal bleeding, 3 mm was
found to be the optimal threshold. he sensitivities for the
detection of endometrial cancer at 3-, 4-, and 5-mm cutofs were
97.0%, 94.1%, and 93.5%, respectively. he corresponding
estimates of speciicity at these thresholds were 45.3%, 66.8%,
and 74.0%. 125 However, it should be noted that the incidence of
endometrial cancer was low in this population (3.8%, which is
much lower than the expected rate of 10% in postmenopausal
women with bleeding), so results might not be reproducible in
other populations. Local practice will likely dictate the threshold
that is acceptable to patients and their physicians. It may also
be that in the future, individualized risk ratios will be used,
assessing risk factors such as increasing age, older age at menopause,
body mass index, nulliparity, and diabetes. 135 Regardless,
if a woman has continued postmenopausal bleeding ater a normal
sonogram, then biopsy is typically recommended.
Transvaginal assessment of endometrial thickness has been
shown to be highly reproducible, with excellent intraobserver
and good interobserver agreement. 136 If the endometrium cannot
be visualized in its entirety or its margins are indistinct, the
examination should be considered “nondiagnostic” and lead to
further investigation (e.g., SHG, hysteroscopy). 137 Some recommend
that all women with postmenopausal bleeding should
undergo SHG, even if the TVS indings are normal 138,139 ; however,
if the endometrium is well seen on TVS and is thin with no
morphologic abnormality, we feel this is usually adequate.
Dubinsky and colleagues found that of 81 postmenopausal women
with bleeding and thickness greater than 4 mm within 1 month
ater aspiration biopsy, endoluminal masses were present in 45
(56%) and that 41 of these were false-negative biopsy results. 140
he important question is whether inding and treating these