A. Patologi

Organ yang biasa terkena endometriosis adalah ovarium, organ tuba dan salah

satu atau kedua ligamentum sakrouterinum, Cavum Douglasi, dan permukaan uterus

bagian belakang dapat ditemukan satu atau beberapa bintik sampai benjolan kecil yang

berwarna kebiru-biruan (Prawirohardjo, 2008).

Gambar 6. Kista cokelat yang pecah pada ovarium sebelah kiri

(http://en.wikipedia.org/wiki/file:Perforierte_EndometrioseZyte.jpg)

B. Gambaran kista endometriosis

Penampakan kasar endometriosis dapat berupa suatu penebalan atau kista yang

berisi darah baru, merah atau biru hitam. Semakin lama lesi-lesi tersebut berubah

menjadi rata dan berwarna coklat tua. Struktur kista besar bisa tetap berisi darah tua dan

disebut kista cokelat. Lesi-lesi yang sudah lama bisa tampak pucat, tersebar, dan

mengerutkan jaringan setempat. Ukuran lesi bervariasi dari kecil kurang dari 1 mm

sampai dengan kista besar berukuran lebih dari 10 cm (Rayburn, 2001). (Gambar 7 dan

Gambar 8.)

Gambar 7. Kista cokelat pada ovarium

(http://img.webmd.com/medscape/netbeacon.html)

Gambar 8. Lesi merah pada berbagai organ

(http://img.webmd.com/medscape/netbeacon.html)

C. Klasifikasi endometriosis

Berdasarkan visualisasi rongga pelvis dan volume tiga dimensi dari endometriosis

dilakukan penilaian terhadap ukuran, lokasi dan kedalaman invasi, keterlibatan ovarium

dan densitas dari perlekatan. Dengan perhitungan ini didapatkan nilai-nilai dari skoring

yang kemudian jumlahnya berkaitan dengan derajat klasifikasi endometriosis. Nilai 1-4

adalah minimal (stadium I), 5-15 adalah ringan (stadium II), 16-40 adalah sedang

(stadium III) dan lebih dari 40 adalah berat (stadium IV) (Rusdi, 2009).

Tabel 2. Derajat endometriosis berdasarkan skoring dari Revisi AFS

Sumber: American Fertility Society, 2007a.

Skema klasifikasi berdasarkan beratnya penyakit endometriosis menurut

American Fertility Society (2007a) dapat dilihat pada gambar dibawah.

Endometriosis <1cm 1-3 cm >1cm

Peritoneum Permukaan 1 2 4

Dalam 2 4 6

Ovarium Kanan Permukaan 1 2 4

Dalam 4 16 20

Kiri Permukaan 1 2 4

Dalam 4 16 20

Perlekatan kavum douglas Sebagian Komplit

4 40

Ovarium Perlekatan <1/3 1/3-2/3 >2/3

Kanan Tipis 1 2 4

Tebal 4 8 16

Kiri Tipis 1 2 4

Tebal 4 8 16

Tuba Kanan Tipis 1 2 4

Tebal 4 8 16

Kiri Tipis 1 2 4

Tebal 4 8 16

Gambar 9. Skema klasifikasi stage 1 sampai stage 3. (American Fertility

Society, 2007a)

Gambar 10. Skema klasifikasi stage 3 sampai stage 4. (American Fertility

Society, 2007a)

Diferensial Diagnosis

Ultrasound Features to Distinguish Endometrioma from Other Pelvic Masses

 

ANIS UR REHMAN, IFFAT MANSOOR*, MUHAMMAD AKRAM DOGAR**

 Department of Radiology, NGHA, Dammam, & *Department of Gynaecology, Astoon

Hospital, Alkhobar, Kingdom of Saudi Arabia

**Department of Surgery, Mayo Hospital, Lahore

Correspondence to Dr. Anis ur Rehman, Radiologist Email: anispims@yahoo.com

ABSTRACT

 

Purpose: To evaluate diagnostic accuracy of ultrasound findings in the diagnosis

and discrimination of endometriomas from other adnexal masses.

Materials and methods: Ultrasound examination of 120 adnexal masses in 98

women was done and findings were recorded on a check list. Philips HDI 5000 and

I21 ultrasound machines were used. Diagnostic features which can discriminate

endometriomas from other pelvic masses were reviewed.

Results: There were 30 endometriomas. Diffuse low-level internal echoes were

present in 29 (97%) of endometriomas and in 5 (17%) nonendometriomas.. The

presence of multilocularity or hyperechoic wall foci further increased the positive

likelihood ratio to 35, allowing the identification of 15 endometriomas (50%).

Conclusion: ultrasound features of diffuse low level echoes, echogenic wall and

multilocularity has a high positive predict value in the diagnosis of endometrioma

and helping it in discrimination from other pelvic masses. Endometriomas exhibits

wide range of ultrasound features, ranging from anechoic to echogenic cysts to

masses containing multiple septations and solid tissue.

Key words: Endometrioma, ultrasound, pelvic masses

 

INTRODUCTION

 

Endometriosis is defined as the presence of endometrial glandular tissue outside of the uterus.

Two main theories exist for the pathogenesis of endometriosis. One theory is that endometrial

tissue is spread by retrograde menstruation or by vascular and/or lymphatic spread. The

second theory holds that the serosal epithelium of the peritoneum undergoes metaplastic

differentiation into endometrium-like tissue.

The theory that retrograde menstruation causes endometriosis is supported by the

analysis of peritoneal fluid in women. As many as 90% of women have blood in the

peritoneal fluid during the perimenstrual period. In addition, endometrial cells have been

found in the peritoneal fluid. The pattern of endometriosis is consistent with retrograde

menstruation and is most common in the ovary, followed by the other dependent areas of the

pelvis. Vascular and/or lymphatic spread is supported by noting the occasional distal

(extraperitoneal) sites of endometriosis, including the lungs and central nervous system

(CNS). In addition, teenage girls with obstructive uterine or vaginal anomalies show

retrograde menstrual bleeding, and endometriosis is common in these patients.

This study is designed to evaluate the accuracy of conventional grey scale ultrasound

examination as a first line diagnostic modality and to evaluate its predictability for the need

of any further diagnostic modality.

 

MATERIALS AND METHODS

 

The study consisted of a retrospective review of the sonograms from 98 women with 120

adnexal masses. Two groups of patients were selected. First group of patients was reviewed

in National Guard hospital, Dammam (52 patients) and second group of patient (46 patients)

examined in Astoon Hospital Dammam. Study period was one year and seven months

(February 2007 to September 2008). Philips HDI 5000 and I21 ultrasound machines were

used. Trans-abdominal and endovaginal probes were used to asses these patients.

Inclusion criteria: All female patient of reproductive age with clinically suspicion of pelvic

mass.

Exclusion criteria: Women who were suspected of having an ectopic pregnancy or pelvic

inflammatory disease.

Two ultrasound examiners blinded to the clinical history of the patient, the information about

follow-up examinations, and the final diagnosis independently reviewed each sonogram. For

each mass, both sonologists recorded US features by using a standardized checklist:

 

 

Ultrasound Findings Check

List

Focal Acoustic Impedance  

Regional Bright Echoes  

Hyperechoic Lines And Dots  

Fluid-Fluid Levels(gravity-

dependent linear interface

between two materials of

differing echogenicity)

 

Fibrinous strands  

Retracting Clot (marginal

clumped echoes with concave

margins)

 

Diffuse Low-Level Internal

Echoes

 

Hyperechoic Wall Foci (punctate

peripheral echogenic foci)

 

Internal Septal Thickness  

 

Masses were categorized as cystic or solid. The sensitivity, specificity, positive predictive

value, negative predictive value, negative likelihood ratio, and positive likelihood ratio were

analyzed for the diagnosis of endometrioma according to each US finding and selected

combinations of findings.

Our study design does not allow for determination of the true sensitivity of disease

detection because patients without ultrasonographically identified adnexal masses were not

surgically evaluated. The negative likelihood ratio is defined as (1−sensitivity)/specificity,

and the positive likelihood ratio is defined as sensitivity (1−specificity). Likelihood ratios are

useful because they do not change with the pretest probability of disease, unlike sensitivity

and specificity.

 

RESULTS

 

Among the 120 masses, there were 30 endometriomas (25% prevalence). Of the 90

nonendometriomas, there were 11 cystic teratomas, 17 benign neoplasms, 5 malignant

neoplasms, 29 hemorrhagic cysts, 26 other nonneoplastic cysts (16 histopathologically

proved nonneoplastic ovarian cysts, 7 self-resolving anechoic ovarian cysts, 2 cases of

hydrosalpinx, and 1paratubal cysts), 1 case of ovarian torsion, and 1 broad ligament myoma.

Two adnexal cystic masses showing diffuse internal low level echoes.

Hemorrhagic cyst of the right ovary in a 33-year-old woman, showing diffuse low level

internal echoes, difficult to differentiate on ultrasound features but usually resolves on follow

up ultrasounds.

Endometrioma in a 25-year-old woman, exhibits diffuse low-level internal echoes and

punctate peripheral echogenic foci

 

 

An endometrioma in a 30-year-old woman. Hyperechoic wall foci (arrow) and low-level

echoes

Multiloculated endometrioma showing low level internal echoes and thin septations in a 32

years old woman.

 

DISCUSSION

 

Ectopic endometrial glandular tissue is influenced by ovarian hormones and undergoes cyclic

bleeding. Over time, the repeated hemorrhaging can produce extensive fibrosis surrounding

the endometrial tissue, which can result in adhesions to adnexal structures or to bowel and

can obliterate the pelvic cul-de-sac.

When the ovaries are involved, they can become enlarged with cystic, blood-filled

spaces that, on gross examination, are termed chocolate cysts, or endometriomas.

Endometriomas can become large and multilocular. The endometrial-cell lining can become

obliterated over time, making the pathologic distinction between an endometrioma and a

hemorrhagic cyst difficult in some cases.

There is a wide spectrum of ultrasound features that can mimic endometrioma which

lead to this false impression that with ultrasound  impossible to achieve a high positive

predictive value in the diagnosis of endometrioma. Several investigators have sought to

identify the diagnostic performance of US in distinguishing endometriomas from other

adnexal masses, with each group using features different than those used by the others.

Clearly, there is a range in what experts have defined as a “classic” endometrioma. These

studies have not addressed which of the criteria used are most important in discriminating

between an endometrioma and other adnexal lesions. While the presence of low-level echoes

is a uniform diagnostic criterion for all studies, diagnostic requirements for the thickness and

contour of the wall and shape and location of the lesion differ among the investigations.

Understanding the degree to which any particular feature or set of features increases or

decreases the likelihood ratio for the diagnosis of endometrioma is important, because one

can then use this knowledge to direct the evaluation toward identifying those features that

have the greatest relevance and avoid effort and confusion in characterizing those features

that have no relevance.

Our study systematically addressed these issues, and our findings confirm that the

presence of diffuse low-level internal echoes is the important feature that helps to

discriminate an endometrioma from other lesions; 97% of endometriomas exhibit diffuse

low-level internal echoes. While the absence of this finding does not exclude endometrioma,

it significantly decreases the likelihood of that diagnosis (negative likelihood ratio, 0.1).

Certain US features (focal acoustic impedance, regional bright echoes, and hyperechoic lines

and dots) are predictive of cystic teratomas . Because most endometriomas do not

demonstrate these features, excluding masses with these features improves diagnostic

performance.

Our data suggest that there is no diagnostic value to the assessment of wall thickness. On

the other hand, we demonstrate considerable benefit from the assessment of wall nodularity, a

feature that is associated with neoplasia. Excluding masses with wall nodularity from the

diagnosis of endometrioma helped to exclude neoplasm, especially malignancy, as a false-

positive diagnosis

Hemorrhagic ovarian cysts can also demonstrate diffuse low-level internal echoes  and

typically do not demonstrate those features discussed above that are associated with dermoids

or other neoplasms. Using only these criteria to predict that a mass is an endometrioma yields

majority of false-positive diagnoses representing hemorrhagic cysts. Hemorrhagic cysts are

almost exclusively nonneoplastic. Thus, they resolve spontaneously and are surgically

removed only when patients have compelling acute symptoms. This has justifiably led to the

practice of follow-up US as a diagnostic strategy to use when a mass is thought most likely to

represent an endometrioma but that alternatively may represent an acutely hemorrhagic cyst,

a strategy that virtually eliminates the possibility that a patient will undergo an unnecessary

operation.

Our data document the usefulness of this strategy. Hemorrhagic cysts are

Demonstration of hyperechoic wall foci in a mass with low-level echoes and absence of

neoplastic features is strongly predictive of an endometrioma. We separately evaluated “wall

nodularity” from “hyperechoic wall foci.” Thirty-five percent of endometriomas in our series

demonstrated these foci, while only 6% of nonendometriomas did so. Thus, our data indicate

that a mass with low-level internal echoes, hyperechoic wall foci, and no neoplastic features

is 30 times more likely to be an endometrioma than another adnexal mass and that US follow-

up in such lesions is a low-yield course of action

Another feature of diagnostic usefulness is the presence of septations without nodularity,

also known as multilocularity. However, when used as a feature in addition to low-level

echoes and absence of neoplastic features, multilocularity increased the likelihood that a mass

was an endometrioma. As a result, a mass with low-level echoes, without neoplastic features,

and with multilocularity is 58 times more likely to represent an endometrioma than another

adnexal mass.

This study analyzed adnexal masses that were not related to pelvic inflammatory disease

or ectopic pregnancy. While these entities may manifest US features similar to those

discussed here, the clinical presentations in patients with pelvic inflammatory disease and

ectopic pregnancy differ.

 

CONCLUSION

 

Gray-scale US can achieve a high degree of accuracy in the diagnosis of endometrioma. An

adnexal mass with diffuse low-level internal echoes and absence of particular neoplastic

features is highly likely to be an endometrioma if there are no features of acute hemorrhage

and especially if multilocularity or hyperechoic wall foci are present.

In addition, a diagnosis of endometrioma is highly unlikely when no component of an

adnexal mass contains low-level internal echoes.. For those masses with low-level internal

echoes, follow-up US appears most useful when the mass has no wall nodularity, is

unilocular, and does not possess hyperechoic wall foci.

MR imaging may be useful in discriminating between endometriomas and neoplasms

when wall nodularity is present.

 

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Endometriomas

Transvaginal sonography (TVS) is universally most frequently used imaging tool for

evaluation of endometriomas. USG features of chocolate cysts are diverse. The classical

appearance is that of a cystic structure with diffuse low level internal echoes and echogenic

wall foci. The cyst may be unilocular or multilocular. It may contain thin or thick septa.

Sometimes there may be wall nodularity. Wall nodularity if present requires further

investigation to rule out malignancy. Imaging alone cannot exclude malignant neoplasm.

It is interesting to note that out of 20% of the endometriomas exhibiting wall nodularity, 35%

had hyperechogenic wall foci (Patel et al). Effort should be made to distinguish between wall

nodularity and the hyperechogenic foci within the wall. The latter when present in lesion with

low level echoes and no features of malignancy is indicative of endometrioma.

Differential diagnoses of chocolate cyst include haemorrhagic cyst, dermoid cyst and cystic

neoplasms. Dermoid cyst usually exhibit either echogenic shadow due to its fat content or

acoustic shadowing due to calcium which aids in the diagnosis. To differentiate between

haemorrhagic cyst and chocolate cyst can be a difficult task. The haemorrhagic cyst usually

displays high level internal echoes within a thin walled cyst which may advance with time

and emerge as a more complex cyst. Formation of fibrin may imitate thin septa but these

lesions usually resolve on follow up.

The accuracy of USG can be further improved by color Doppler flow studies. Blood flow in

the endometrioma is through the regularly spaced vessels running in the hilar region and the

pericystic space.

MRimaging is another tool for identifying endometriomas. Due to the cyclical bleeding

endometriomas contain blood products at different age. They are seen as bright or

hyperintense lesions on T1 weighted image. On T2 they appear more hypointense or dark

with foci of hyperintensity, imparting it the classical appearance of ‘shading’. Shading is

effect of degenerated blood products present at different stage within the same cyst. It can

range from subtle layering to a complete signal void (black).

Since both the haemorrhagic cysts and the chocolate cyst contain blood products, it can be

difficult to distinguish between them except for the fact that hemorrhagic cysts do not display

shading, are mostly unilocular and resolve on interval imaging. In contrast dermoid cysts are

easily diagnosed on MRI since they lose the signals and become dark on fat suppressed

sequences.

After contrast administration, the periovarian peritoneal surface of the cyst can be enhanced

which can help in identification of torsion ovary. Endometrioma in an enlarged but poorly

enhancing ovary with peripherally located follicles is suggestive of torsion ovary on

MRimaging.