Sonomorphology of endometriotic cysts

International Journal of Gynecology & Obstetrics 62 Ž1998. 155]165

Article

Sonomorphology of endometriotic cysts A. SurenU , R. Osmers, M. Dietrich, D. Kulenkampff, W. Kuhn Department of Obstetrics and Gynecology, Uni¨ ersity of Gottingen, Gottingen, Germany ¨ ¨ Received 12 February 1997; received in revised form 17 March 1998; accepted 20 March 1998

Abstract Objecti¨ e: The aim of the study was to evaluate prospectively the sonomorphological feature of histologically verified endometriotic cysts. Methods: Transvaginal sonography was performed in 122 patients. Age distribution of the patients, and size and sonomorphology of the lesions were analyzed. Results: Eighty-one percent of the endometriotic cysts occurred in patients between 31 and 50 years old with a peak of 29% between 31 and 35 years. Most of the cysts Ž81%. ranged between 30 and 59 mm in diameter. Forty-three percent of the endometriotic cysts were observed as monolocular cysts with internal echoes. More than half of the findings were observed to be multilocular, partially without any internal echos, partially even with solid parts or purely solid. Conclusion: The so-called ‘typically’ monolocular smooth-walled endometriotic cyst with internal echoes was only found in 43% of the cases. However, data from the literature show that one cannot assume even this special entity to represent endometriomas. Regarding all monolocular cysts with homogeneous internal echoes, one has to be aware of a great amount of functional cysts and a non-calculable residual risk of malignancy. Q 1998 International Federation of Gynecology and Obstetrics Keywords: Transvaginal sonography; Ultrasound; Endometriosis; Endometriotic cyst; Sonomorphology

1. Introduction Endometriosis is one of the most relevant gynecological diseases and denotes the incidence of endometrial glands and cytogenic stroma at heterotopic localizations. In the 1970s, endometriotic

U

Corresponding author. Fax: q49 551 396275.

foci were found with only 11]18% of the women undergoing laparoscopy due to lower abdominal pain w1,2x. However, the description of atypical, non-pigmented lesions has led to a significant increase of incidences w3,4x, so that today a rate of between 38 and 51% can be assumed in patients having chronic lower abdominal pain w5,6x. Pathophysiology and histogenesis have not been completely elucidated. Along with anamnesis and clin-

0020-7292r98r$19.00 Q 1998 International Federation of Gynecology and Obstetrics PII S0020-7292Ž98.00058-7

156

A. Suren et al. r International Journal of Gynecology & Obstetrics 62 (1998) 155]165

ical findings, transvaginal sonography is gaining increasing significance. Guerriero et al. w7x describe the typical endometriotic cyst as an ovarian cyst with homogeneous low-level internal echoes. However, in contrast to that statement endometriotic cysts do offer various sonomorphological features. Thus, the internal structures vary from fine-structured via cystic-solid up to different areas lying next to each other. Due to the rather sparse information concerning sonomorphology of endometriotic cysts in the literature, we investigated the sonographic features of 122 histologically verified endometriotic cysts in a prospective analysis. In our investigation we chose only such criteria which are comprehensible to those less experienced in sonography. 2. Materials and methods The present data are part of a prospective sonographic study in which all ovarian tumors in the pre- and post-menopause were investigated by vaginal ultrasonography and classified according to defined ultrasonographic criteria. From this population we analyzed 122 histologically verified endometriomas with respect to their sonomorphological feature. The patients were not selected and all patients who had endometriotic cysts at surgery were included. Transvaginal sonography was performed with a 5.0 or 7.5 MHz realtime sector scanner Ž2408., Combison 320 ŽKretz, Austria. and a 5 MHz probe of Ultramark 9 ŽATL.. Age distribution of the patients and the size and sonomorphology of the lesions were analyzed. The occurrence of cystic and solid parts with or without internal echoes as well as the number of cystic chambers were the distinctive sonographic criteria. The clinical cut-off level was set at 30 mm mean diameter for surgical intervention in case of a single, unilateral cyst without clinical symptoms. 3. Results While 115 cysts of the 122 histologically verified endometriotic cysts occurred in the premenopause, there were seven post-menopausal endometriotic cysts. The pre-menopausal patients

ranged from 21 to 55 years old and the postmenopausal patients ranged from 41 to 78 years old, but 81% of the cysts occurred in the 31- to 50-year-old age group with an incidence peak of 29% in the 31- to 35-year-old age group. The oldest patient with a histologically secured endometriotic cyst was 78 years old ŽFig. 1.. Eightyone percent of the cysts were between 30 and 59 mm in diameter. The sizes varied between 20 and 100 mm in diameter, with 34% of the cysts being between 30 and 39 mm, 24% between 40 and 49 mm and 23% on a scale between 50 and 59 mm. In the post-menopause, the largest cyst was 79 mm in diameter ŽFig. 2.. Fig. 3 shows the distribution of the sonomorphological criteria. Forty-three percent of the endometriotic cysts were observed as monolocular cysts with internal echoes. However, approx. 38% of the cysts did not have any internal echoes. Multilocular cysts with or without internal echoes were found in 24% and cystic-solid findings in approx. 16% of the cases. Three findings were observed to be purely solid. 4. Discussion Endometriosis is a special entity among the gynecological syndromes. Its first description was in 1899. It took, however, another 20 years until ‘hemorrhagic cysts’ and endometrial tissues were related to each other. In 1957, Hughesdon w8x proved by means of histological serial sections that endometriomas are due to invagination of the ovarian surface and formation of pseudocysts. In more than 90% of cases, the ovarian surface can be identified and it forms a pseudocyst having chocolate-mash-like contents as a residuum of repeated bleeding-in. These contents are, however, not pathognomonic for endometriomas. From the differential diagnostic point of view, hemorrhagic lutein cysts and even neoplastic tumors may be considered w9x. The incidence rates are unknown } instead, only frequency areas for special subgroups can be indicated. Thus the frequency in the female population during the reproductive phase is estimated to be 2]3%, in infertile women it is 15]24% and in women with inexplicable sterility the incidence

A. Suren et al. r International Journal of Gynecology & Obstetrics 62 (1998) 155]165

Fig. 1. Age distribution of pre- and post-menopausal women.

157

A. Suren et al. r International Journal of Gynecology & Obstetrics 62 (1998) 155]165

Fig. 2. Size distribution Žmm. of the endometriomas in pre- and post-menopausal women.

158

A. Suren et al. r International Journal of Gynecology & Obstetrics 62 (1998) 155]165

Fig. 3. Sonomorphological findings. Number of mono-, bi- and multilocular cysts with or without internal echoes. 159

160

A. Suren et al. r International Journal of Gynecology & Obstetrics 62 (1998) 155]165

is approx. 70]80% w10x. The typical age at the time of a primary diagnosis is indicated as 20]40 years w10x. For our clientele the corresponding incidence peak lies between the 31st and the 35th year of life. The rising number of diagnoses concerning ‘younger women’ is probably due to the increasing use of vaginal sonography in check-up screenings and the more generous indication of diagnostic pelviscopy for clearing up sterility, unspecific lower abdominal complaints and secondary dysmenorrhea w11x. Approximately 10% of the endometrioses were proved in women younger than 20 years and approx. 1]2% of postmenopausal women are estimated to have an endometriosis w10x. In our analysis, only 4.4% of the endometriotic cysts turned out to be in the age group between 20 and 29 years and 6% with post-menopausal patients. In 60% of cases, the ectopic implants are found in the Douglas andror at the ligamenta sacrouterina; in approx. 50% of the patients the ovaries are affected w10x. The prevalence of endometriomas amounts to 24% of all ovarian cysts w7x. Vaginal sonography plays an increasingly important role in the differential diagnostic clearing up of adnex findings. Endometriomas can be observed as smoothly limited, so-called simple cysts ŽFig. 4. or as structures with a solid appear-

ance ŽFig. 6.. These different sonographic stigmata are caused by the immediate neighborhood of bleeding-ins, resorption processes as well as older, clotted blood. The dissociation from the surrounding tissue varies. There are smooth ŽFig. 4. as well as unsharp, partially echogeneous peripheral structures ŽFig. 10., which can be produced by a thick peritoneal pseudo-capsule due to inflammation. In many cases, several endometriotic cysts lying next to each other can be found in or at the ovary ŽFig. 10.. Blood also has a variable sonographic feature ŽFigs. 8,11., depending on the sequence of the formation of thrombi and their dissolution. Usually, fresh blood is anechoic in sonographic examinations ŽFig. 4.. With the onset of clotting processes it later gets an intensive or mixed echogeneity, and it finally becomes less echoic again or even anechoic. For an assessment of the echogeneity, a precise examination technique is required. If the formation appears anechoic, the total gain should be raised in order to amplify fine internal echoes. If such internal echoes are found, the structure is not anechoic and thus does not correspond to a simple cyst w12x. An amplified ultrasonic transmission with dorsal sonar amplification can be observed with 92% of the hemorrhagic cysts. As a distinctive criterion concerning the ultrasonic picture, it is as

Fig. 4. Monolocular endometriotic cyst without internal echoes.

A. Suren et al. r International Journal of Gynecology & Obstetrics 62 (1998) 155]165

161

Fig. 5. Monolocular cyst without internal echoes representing a follicle.

important as the internal echoes and, in general, it allows the distinction of a cystic from a solid structure, where dorsal extinction phenomena are more likely to be found. The rare cases, where no dorsal sonar amplification can be proved with cystic formations may be caused by structures in the immediate neighborhood of the cyst, which

absorb the ultrasound, e.g. by adherent inflammatory intestinal twistings w12x. In the vaginal-sonographic assessment of ovarian findings concerning endometriotic cysts, Guerriero et al. w7x found a specificity of 89% and a sensitivity of 83%. They defined the typical endometriotic cyst as ‘round-shaped homoge-

Fig. 6. Monolocular smooth-walled endometriotic cyst with homogeneous internal echoes.

162

A. Suren et al. r International Journal of Gynecology & Obstetrics 62 (1998) 155]165

Fig. 7. Monolocular cyst with homogeneous internal echoes representing a mucinous cystoma.

neous hypoechoic tissue of low-level echoes within the ovary’. In a differential diagnosis of hemorrhagic cysts functional findings like follicle or corpus luteum cysts have to be distinguished. In general, such hemorrhagic cysts recede spontaneously. The risk of a second occurrence is 26% w12x, their average size is 5 " 2.2 cm Ž2.5]14 cm..

There may be secondary wall thickenings up to 4]10 mm, but also up to 22 mm. Septations may arise. A layer of hemorrhagic cell material may accumulate at the bottom of the cyst. Correspondingly, in ultrasonic examinations with functional findings a picture of heterogeneous echogeneity is found in 83% of the cases. In an

Fig. 8. Monolocular endometriotic cyst with mixed echogeneity.

A. Suren et al. r International Journal of Gynecology & Obstetrics 62 (1998) 155]165

163

Fig. 9. Monolocular cyst with dense echoes at the bottom representing a tubo-ovarian abscess.

analysis by Juhnke et al. w13x, out of 43 histologically confirmed endometriotic cysts of more than 1 cm cross-section 30% were found to be purely cystic and smooth and 47% purely cystic but partially smoothly limited. When internal echoes occurred these were usually homogeneous Ž61%., while sparse echoes were found less frequently

Ž37%. and hardly any inhomogeneous ones were observed Ž2%.. Fig. 3 shows the sonomorphological distribution of our analysis, which resulted in complex cystic-solid findings in approx. 16%, cystic findings without any internal echoes in approx. 38% and with internal echoes in 60% of the cases. However, the sonomorphological feature

Fig. 10. Bilocular endometrioma with internal echoes, thickened septa Ž­., solid structures at the bottom Žr. and unsharp borders.

164

A. Suren et al. r International Journal of Gynecology & Obstetrics 62 (1998) 155]165

Fig. 11. Komplex cyst with homogenous and partially inhomogenous echoes representing an endometriotic cyst Ž­. and a corpus luteum Ž­­..

can change according to cyclic influences. The incidence peak between 31 and 35 years of our analysis corresponds to an average age of 37 years in the literature w13x. However, while Juhnke et al. w13x observed an average cyst-size of 5 cm with a dispersion of 1.5]11 cm, in our clients most cysts Ž34%. were found to be in the range between 3 and 4 cm. This may be due to the increasing use of vaginal sonography in routine screening, so that today smaller findings can be treated. In summary, one can say that the so-called ‘typically’ monolocular smooth-walled endometriotic cyst with internal echoes ŽFig. 6. was only found in 43% of the cases in our collective. More than half of the findings were observed to be multilocular, partially without any internal echoes, partially even with solid parts or purely solid. But even in classifying the monolocular cysts with homogeneous internal echoes, one must not assume this sonomorphology to almost certainly represent endometriomas. In a prospective study by Osmers et al. w14x on 240 monolocular smooth-walled cysts with internal echoes, the classical sonographic feature of an endometriosis, 63.8% were found to be functional cysts, 28.3% retention cysts including endometriosis, 7.5% benign neoplasia and 0.4% malignant neoplasia.

Figs. 4 and 5; 6 and 7; 8 and 9 demonstrate impressively that the same sonographic feature can mean completely different histological diagnoses. Thus, a premature operative dissection in the case of a suspected endometriosis would, on the one hand, be performed in more than half of the cases on functional incidences that may recede spontaneously and, on the other hand, endanger the patient due to an inadequate operation technique and a non-calculable residual risk of malignancy. References w1x Beard RW, Belsey EM, Lieberman BA, Wilkinson JCM. Pelvic pain in women. Am J Obstet Gynecol 1977; 128:566. w2x Lundberg WI, Wall Je, Mathers JE. Laparoscopy in evaluation of pelvic pain. Obstet Gynecol 1973;42:872. w3x Martin DC, Hubert GD, Vander Zwaag R, El-Zeky FA. Laparoscopic appearances of peritoneal endometriosis. Fertil Steril 1989;51:63. w4x Stripling MC, Martin DC, Chatman DL. Subtle appearance of pelvic endometriosis. Fertil Steril 1988;49:427. w5x Stout AL, Steege JF, Dodson WC, Hughes CL. Relationship of laparoscopic findings to self-report of pelvic pain. Am J Obstet Gynecol 1991;164:73. w6x Vercellini P, Fedele L, Moteni P. Laparoscopy in the diagnosis of gynecologic chronic pelvic pain. Gynecol Obstet 1990;32:261.

A. Suren et al. r International Journal of Gynecology & Obstetrics 62 (1998) 155]165 w7x Guerriero S, Mais V, Ajossa S et al. The role of endovaginal ultrasound in differentiating endometriomas from other ovarian cysts. Clin Exp Obstet Gynecol 1995;22:20]22. w8x Hughesdon PE. The structure of endometrial cysts of the ovary. J Obstet Gynaecol Br Cwlth 1957;44:481]487. w9x Martin DC, Berry JD. Histology of chocolate cysts. J Gynecol Surg 1990;6:43]46. w10x Schweppe KW. Aetiology, histology and pathophysiology of endometriosis. In: Schindler AE, Schweppe KW, editors. Endometriosis-Buserilin, a new therapeutic concept. Hrsg. Berlin, New York: Walter de Gruyter, 1989;3:23. w11x Damario MA, Rock JA. Pain recurrence: a quality of

165

life issue in endometriosis. Int J Gynecol Obstet 1995;50:S27]42. w12x Baltarowich OH, Kurtz AB, Pasto ME, Rifkin MD, Goldberg BB, Needleman L. The spectrum of sonographic findings in hemorrhagic ovarian cysts. Am J Roentgenology 1987;148:901]905. w13x Juhnke I, Duda V, Waldschmidt I, Rode G, Schulz KO. Will a standardisation of ovarian sonomorphology establish a better diagnosis? Ber Gynakol Geburtshilfe 1990;127:625. w14x Osmers RGW, Osmers M, von Maydell B, Wagner B, Kuhn W. Preoperative evaluation of ovarian tumors in the premenopause by transvaginosonography. Am J Obstet Gynecol 1996;175:428.