Biomed Imaging Interv J 2006; 2(4):e42
© 2006 Biomedical Imaging and
Degenerated uterine fibroid mimicking hydrametra: fallacy in CT
CH Tok1,*, MD, MRad,
SI Bux1, MD, MRad,
SI Mohamed1, MBBS, MRad,
BK Lim2 MBBS, FRCOG
1 Department of Biomedical Imaging, Faculty of
Medicine, University of Malaya, Kuala Lumpur, Malaysia
2 Department of Obstetric and Gynaecology, Faculty of Medicine,
University of Malaya, Kuala Lumpur, Malaysia
Fibroids are the commonest uterine neoplasms, occurring in
20% - 30% of women of reproductive age. In women who have pelvic masses of
unknown cause, unusual manifestations of fibroids such as necrosis or
degeneration may simulate a carcinoma or hydrometra resulting in problems with
image interpretation. We report a case of an unsuspected large degenerated
uterine fibroid in a lady mistakenly diagnosed as hydrometra on computed
tomography scanning. � 2006 Biomedical Imaging and Intervention Journal. All
Keywords: CT, Fibroids, hydrometra
A 34-year-old nulliparous woman presented with sudden onset
of severe abdominal pain and a six months history of progressive abdominal
swelling. Her menstruation cycle was normal and regular.� 5 years prior to
admission she had undergone a right oophorectomy for a benign mucinous
cystadenoma.� On admission she was pale (Hb 9.4g/dl) with a large firm, tender
and fixed pelvic mass corresponding to 36-week gravid uterus. Urine pregnancy
test and serum tumour markers were negative. A clinical diagnosis of twisted
ovarian cyst was made.
Contrast enhanced spiral CT scan of the thorax, abdomen and pelvis revealed
an enlarged lobulated uterus with a large (17.1 x 16.0 x 20
cm) fairly oval central hypodense lesion (30 � 70 HU) stretching
the myometrium (Figure 1). In addition, there were several enhancing
oval lesions noted in the lower uterine wall and a separate
smaller inhomogeneously enhancing lesion (6.2 x 5.1 x 10 cm)
in the right adnexa. The cervix was normal. There were no para-aortic,
pelvic or inguinal lymphadenopathy and no ascites. The liver,
spleen, pancreas and kidneys were normal. A diagnosis of a hydrometra
with a right adnexal pathology was made.
Figure 1 Contrast-enhanced
axial CT abdomen demonstrating a large oval hypodense lesion
[HU 30-70] (long arrow) within a large lobulated uterus with
stretching of the myometrium. This is histopathologically
proven as degenerated leiomyoma with large areas of necrosis
and hyalinization, and inflammation is noted in both the fibroid
and the myometrium, which simulates an endometrial fluid collection
or hydrometra. A smaller separate heterogeneously enhancing
lesion with whorl appearance (short arrow) is seen to the
right side of the uterus and which is proven early degenerated
Magnetic resonance (MR) imaging of the pelvis was performed
to determine the cause of endocervical canal obstruction. It showed an enlarged
uterine outline with 2 masses; a large left mass occupying almost the entire
anterior wall of the uterus with compression and displacement of the
endometrium posteriorly (Figure 2), and a smaller right mass. Both masses
showed areas of high signal intensity on the T2WI, homogeneous low signal
intensity on the T1WI and peripheral wall enhancement on the post-Gadolinium
DTPA T1-weighted images (Figure 3). Features were consistent with that of
Figure 2 Sagittal T2-weighted section
of MRI pelvis demonstrating large low signal intensity mass
with multiple areas of high signal intensity within it arising
from the anterior uterine wall. The normal endometrial stripe
(white arrow) noted with normal thickness, differentiates
the mass from gross hydrometra.
Figure 3 Pre-gadolinium-DTPA
sagittal T1-weighted image of MRI pelvis (a) and post-gadolinium-DTPA
image (b) demonstrating a large homogeneous low signal intensity
lesion in the anterior uterine wall (arrow) in keeping with
fibroid, which does not enhance following contrast administration.
Motion artifacts are noted on post-gadolinium sequences showing
in Figure 3(b).
Retrospective 3D multiplanar reformation (MPR) of the CT
dataset, confirmed the MRI findings. In addition numerous blood vessels were
noted in the posterior uterine wall supplying the lesions (Figure 4).
Figure 4 Retrospective reconstructed
CT images in (a) coronal plane and (b) sagittal plane showing
a large fairly oval hypodense lesion with surrounded ring
enhancement (arrows) at the left side of the enlarged uterus.
This is histopathologically proven as inflammation in the
fibroid itself and the myometrium. There are a lot of blood
vessels in the posterior uterine wall supplying to this lesion.
Another smaller heterogenously enhancing lesion (short arrow)
is seen on the right side of the uterus which appeared separate
from the larger collection. (b) The endometrial lining cannot
be identified on the sagittal plane. Another smaller homogeneously
enhancing lesion (arrow) is seen at the posterior uterine
wall, contributing to a nodular contour.
Patient had total abdominal hysterectomy following failure
of a trial of gonadotropin-releasing hormone (GnRH) analogues. Laparotomy
confirmed multiple large uterine fibroids. Histopathological examination showed
well-circumscribed fibroids with large areas of necrosis and hyalinisation with
surrounding inflammation. The endocervical glands and the endometrium were
normal. A diagnosis of multiple fibroids with a large degenerated component was
made. Patient recovered well.
Fibroids are classified as submucosal, intramural or
subserosal based on their location. Intramural fibroids are within the
substance of the myometrium and are the most common type but often
asymptomatic. It has been estimated that 20%-50% of women with fibroids present
with symptoms such as menorrhagia, dysmenorrhea, pressure, urinary frequency,
pain, infertility, or a palpable abdominal / pelvic mass . Pain occurs in
approximately 30% of women with uterine fibroids and is usually the result of
acute degeneration . Degeneraton in fibroids, which occurs secondary to
inadequate blood supply, may be hyaline (commonest), myxomatous, cystic, fatty,
haemorrhagic or malignant in nature. The type of degenerative change seems to
depend on the degree and rapidity of the onset of vascular insufficiency. GnRH
analogues affect only undegenerated fibroids, and are ineffective when there is
degeneration  as was noted in our patient
Even though fibroids are often found incidentally on CT, it
is not the primary modality for diagnosing or evaluating fibroids. The common
CT features include; uterine enlargement with a lobulated outer contour, focal
myometrial thickening, deformed endometrial cavity, foci of punctate or
amorphous coarse calcifications, and abnormal density within the soft tissue
mass .� A fibroid may be hypodense, isodense or hyperdense relative to
normal contrast-enhanced myometrium on CT scanning. Hyaline degeneration may be
accompanied by varying degree of liquefaction thus resulting in a more cystic
appearance  as was noted in our patient. A parasitized blood supply from an
enlarged uterine artery may be responsible for the rare �hyperdense� fibroid
.� Fast volume scanning in CT enables gapless data acquisition and
overlapping images, thus increasing spatial resolution and reducing
partial-volume averaging. 3D MPR enables display of a section of organs in a
coronal or sagittal projection and thus depicting the anatomical structures
more precisely hence reducing misinterpretation.
Other differential diagnoses of a hypodense lesion in the
uterus on CT include leiomyosarcoma and hydrometra. Leiomyosarcoma occur in
less than 1% of all cases and is impossible to distinguish it from a benign
degenerating fibroid on imaging . Hydrometra on CT appears as a symmetrically
enlarged uterus, with a low-attenuation, non-enhancing central mass  while
submocosal fibroids may asymmetrically distort or obliterate the uterine cavity
 as was noted in our patient
In conclusion, fibroid degeneration with varying degree of liquefaction
may simulate a hydrometra on CT. Recognizing the CT features on both hyaline
degenerated fibroid and hydrometra are important.� The application of 3D MPR,
we believe can improve interpretation and diagnostic accuracy of CT.
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|Received 20 October 2005; received in revised form 26 July 2006; accepted 11 August 2006
Correspondence: Department of Biomedical Imaging, Faculty of Medicine, University Malaya, 50603 Kuala Lumpur, Malaysia. Tel: +603-79492069; Fax: +603-79581973;
E-mail: email@example.com (Chung-Hong Tok).
Please cite as: Tok CH, Bux SI, Mohamad SI, Lim BK,
Degenerated uterine fibroid mimicking hydrametra: fallacy in CT, Biomed Imaging Interv J 2006; 2(4):e42
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