Image Presentation Sonographic Spectrum of Hemorrhagic Ovarian Cysts Kiran A. Jain, MD Objective. To present the spectrum of sonographic findings associated with hemorrhagic ovarian cysts. Methods. Experience with making specific and correct diagnosis of hemorrhagic cysts with the use of sonography was reviewed, and the spectrum of sonographic findings was identified. Results. Endovaginal sonography facilitated excellent visualization of internal architectural details of an adnexal mass, which enabled specific diagnosis of hemorrhagic cysts instead of other adnexal masses. Conclusions. A hemorrhagic cyst is a common and important entity to recognize and diagnose correctly, and because it can be confused with more ominous conditions, it is important to recognize its specific diagnostic patterns. Key words: cystic mass; hemorrhagic cysts; reticular pattern; sonogram. Abbreviations hCG, human chorionic gonadotropin; HOC, hemorrhagic ovarian cyst Received March 1, 2002, from the Department of Radiology, University of California Davis Medical Center, Sacramento, California. Revision requested March 28, 2002. Revised manuscript accepted for publication April 10, 2002. Address correspondence and reprint requests to Kiran A. Jain, MD, Department of Radiology, University of California Davis Medical Center, 4860 Y St, Suite 3100, Sacramento, CA 95817. A hemorrhagic ovarian cyst (HOC), although frequently encountered during routine pelvic sonography, is a great imitator.1 Hemorrhagic cysts have a variety of imaging appearances, which can be confused with various adnexal masses in the female pelvis. This complex cystic adnexal mass can generate a long list of differential diagnoses, including ovarian cancer, if its characteristic sonographic features are not recognized. Confident diagnosis of an HOC on the basis of transvaginal sonography, however, is possible if the characteristic imaging findings are correlated with the appropriate clinical setting. The correct diagnosis allows conservative treatment, avoiding unnecessary invasive or additional diagnostic procedures and unnecessary surgery. The intent of this presentation is to familiarize readers with the most commonly encountered characteristic imaging findings and the imaging spectrum of hemorrhagic cysts and their differentiation from other adnexal masses. © 2002 by the American Institute of Ultrasound in Medicine • J Ultrasound Med 21:879–886, 2002 • 0278-4297/02/$3.50 Sonographic Spectrum of Hemorrhagic Ovarian Cysts Pathophysiologic Process The mechanism of development of a hemorrhagic cyst is as follows. The granulosa layer of the ovary is avascular until ovulation. At the time of ovulation, as the maturing graafian follicle enlarges, the immediately surrounding stromal cells also enlarge and become round and plump. This change in a stromal cell is called luteinization. The luteinized theca cells become noticeably more vascular than the adjacent stroma. In response to the midcycle peak of pituitary luteinizing hormone, the graafian follicle ruptures, expels the oocyte, and rapidly becomes a corpus luteum. The granulosa layer becomes vascularized. These vessels within the wall on the cyst are very fragile and rupture easily, giving rise to a hemorrhagic cyst. Cytopathologic examination of an HOC shows the presence of luteinized granulosa cells, fibroblasts, hemosiderin-laden macrophages, fresh blood, and abundant fibrin.2 There is no malignant potential in these functional cysts despite the occurrence of the hemorrhage. Natural History In patients with HOCs, the apparent clinical features include pelvic pain and a pelvic mass. Hemorrhagic ovarian cysts are also found in asymptomatic patients. The classic history of hemorrhage into an ovarian cyst is the abrupt onset of pelvic or lower abdominal pain,3 which can wake the woman from her sleep. Hemorrhagic ovarian cysts occur almost exclusively in premenopausal women and in postmenopausal women receiving hormonal treatment. Although HOCs are not common in early adolescence, they are occasionally seen in childhood.4 Hemorrhagic cysts tend to evolve slowly into various stages of acute hemorrhage, clot formation, and clot retraction, thus giving rise to changing sonographic appearances until they completely resolve. Classically, fresh blood is anechoic. In subacute stages when the clot forms, it becomes echogenic. The echogenicity of the HOC diminishes with time as the red cells undergo hemolysis. In the initial 24 hours after hemorrhage, the blood is echogenic, but after this time its echogenicity decreases so that by 96 hours it may be entirely echo free.5 Bearing this pathophysiologic process in mind and having familiarity with the sonographic appearances can enable definitive diagnosis of a hemorrhagic cyst. 880 The last menstrual period should be noted in premenopausal women, because if the patient is in the luteal phase and a cyst is seen in the adnexa with the sonographic appearance of an HOC, the diagnosis can be made more reliably. Typical Sonographic Appearance The average diameter of the cyst is 3.0 to 3.5 cm (range, 2.5–8.5 cm). The cyst wall is thin (2–3 mm), well defined, and regular. Posterior enhanced through-transmission is seen, signifying the basic cystic nature of the mass. The internal echo pattern or architecture of the HOC is best visualized with transvaginal sonography. Fishnet Weave or Fine Reticular Pattern A cystic mass is shown in the adnexal region with posterior enhanced through-transmission. Within this mass there are fine interdigitating septations, which give a fishnet weave or fine reticular appearance (Figs. 1 and 2). Color Doppler sonography shows no flow in these fine septations (Fig. 3), because these are not real tissue septations but are fibrin strands, which do not contain blood vessels. This is the most common appearance of an HOC. Retracting Blood Clot Another common appearance is a retracting blood clot. The blood clot may be triangular or curvilinear and may appear slightly homogeneous or may contain a reticular pattern due to fibrin strands. The remainder of the cystic mass appears anechoic, because it contains serum separated after formation of the clot (Figs. 4 and 5). Imaging Spectrum Hemorrhagic Ovarian Cyst With a Fluid-Debris Level Occasionally the blood products can separate into layers, and an HOC can have a fluid-fluid or fluid-debris level (Fig. 6). Hemorrhagic Ovarian Cyst Simulating an Ectopic Pregnancy Occasionally a hemorrhagic cyst may appear as a thick echogenic rind surrounding a central anechoic area, an appearance remarkably similar to that of the adnexal ring, which is widely considered one of the most predictive sonographic J Ultrasound Med 21:879–886, 2002 Jain findings of ectopic pregnancy.6 Sometimes the hemorrhagic cyst may rupture, and there may be echogenic fluid in the cul-de-sac or surrounding adnexa. When the result of the pregnancy test is positive, these constellations of findings remarkably simulate a ruptured ectopic pregnancy (Fig. 7). Also, the other way to differentiate an HOC that simulates an ectopic pregnancy from a bona fide ectopic pregnancy is to note the location of the cysts. Ectopic pregnancies are extraovarian in location. Hemorrhagic Ovarian Cyst Simulating an Ovarian Neoplasm Hemorrhagic Ovarian Cyst Simulating a Papillary Cystadenoma Occasionally the retracting blood clot may become very small and may simulate a mural nodule or papilloma (Fig. 8). Color Doppler sonography would fail to show blood flow in the clot. This is in contrast to a neoplastic mural nodule, which typically is vascular. Figure 1. Transvaginal coronal sonogram from a 23-year-old woman with acute right-sided pelvic pain showing the typical sonographic appearance of an HOC. A reticular or fishnet weave pattern in a cystic adnexal mass is shown (calipers). Hemorrhagic Ovarian Cyst Simulating a Solid Mass Uncommonly the HOC may appear solid7 on sonography because of the dense internal echoes and poor through-transmission (Fig. 9). This may be seen in the subacute stage, when there is blood clot formation but the lysis of the clot has not begun. Hemorrhagic Ovarian Cyst Simulating a Malignant Ovarian Neoplasm A blood clot in a large hemorrhagic cyst may disintegrate such that the areas of a solid clot and serum together may give an appearance of a malignant ovarian neoplasm (Fig. 10). Figure 2. Transvaginal coronal sonogram from a 25-year-old woman with acute pelvic pain showing another example of a reticular pattern in an HOC. Arrow indicates a retracting blood clot; and arrowheads, fibrin strands. Ovarian Neoplasm Simulating a Hemorrhagic Ovarian Cyst Mucinous Cystadenoma Simulating a Hemorrhagic Ovarian Cyst A mucinous cystadenoma can have a reticular pattern similar in appearance to the reticular pattern of an HOC (Fig. 11). A small mucinous cystadenoma and an HOC can sometimes be confused with each other. Dermoid Simulating a Hemorrhagic Ovarian Cyst Occasionally an HOC can have an appearance similar to that of a benign cystic teratoma. J Ultrasound Med 21:879–886, 2002 881 Sonographic Spectrum of Hemorrhagic Ovarian Cysts A B Figure 3. Images from a 29-year-old woman with acute pelvic pain. A, Transvaginal right adnexal sonogram showing fine fibrin mesh. The color flow box shows no evidence of flow in these fibrin strands. B, Septate cyst in the left ovary. Pulsed Doppler sonography shows flow within the septation, indicating that this is not a fibrin strand. Figure 4. Sagittal transvaginal sonogram from a 21-year-old woman with an adnexal mass found on bimanual pelvic examination. A typical retracting clot with a curvilinear surface (c) is shown, with no evidence of color flow within the mass. Especially, the echogenic lines produced by the hair in the dermoid can resemble fibrin strands (Fig. 12). This can be differentiated by the fact that the benign cystic teratoma will not change its echo pattern over a period of days. Complications of Hemorrhagic Cysts Rupture of a Hemorrhagic Ovarian Cyst When a simple ovarian cyst ruptures, anechoic fluid is seen in the pelvis. However when a hemorrhagic cyst ruptures, echogenic fluid is seen in the pelvis or may even result in massive hemoperitoneum.8 A ruptured HOC with hemoperitoneum can have imaging features similar to those of hemoperitoneum from other causes.8 Echogenic blood may surround the uterus and adnexa, and sonographic findings of a ruptured HOC can very closely mimic a ruptured ectopic pregnancy when a woman of childbearing age has acute pelvic pain and hemoperitoneum (Fig. 7). This can become particularly challenging in the setting of positive pregnancy test results in a very early intrauterine pregnancy when no intrauterine pregnancy is visualized. The assertion that a positive β-human chorionic gonadotropin 882 J Ultrasound Med 21:879–886, 2002 Jain (β-hCG) finding indicates ectopic pregnancy and a negative β-hCG finding suggests a ruptured hemorrhagic cyst becomes very limiting in such a situation.8 Coincidental occurrence of a corpus luteal cyst rupture and an ectopic pregnancy has been reported.9 Torsion of a Hemorrhagic Ovarian Cyst Adnexal torsion due to a hemorrhagic cyst is rarely encountered but has been occasionally reported.10 Differential Diagnosis of a Hemorrhagic Ovarian Cyst Acute onset of pain in the pelvis or lower abdomen due to an HOC in women closely mimics other gynecologic conditions such as ovarian torsion, ectopic pregnancy, and pelvic inflammatory disease. It can also mimic gastrointestinal disorders such as appendicitis, mesenteric adenitis, Crohn’s disease, and other gastrointestinal conditions. Clinical correlation is crucial, because an HOC is unlikely in the presence of fever and leukocytosis. In summary, the definitive diagnosis of an HOC can be made in most cases with the use of transvaginal sonography in light of an appropriate history and characteristic sonographic findings. Such patients have abrupt onset of acute pelvic pain, usually in the midcycle, negative pregnancy test results, and absence of fever and leukocytosis. Sonography reveals a cystic mass with good through-transmission and a fine reticular pattern of fibrin strands, which do not show blood flow, and it shows a change in echo pattern with time, which is related to the temporal sequence of clot formation and lysis. Hemorrhagic ovarian cysts can be followed to spontaneous resolution sonographically in 6 to 8 weeks; most completely resolve in 6 weeks or decrease considerably in size and change in morphologic appearance. Figure 5. Sagittal transvaginal sonogram from a 19-year-old woman with an adnexal mass showing another example of a retracting clot with a fine reticular appearance and no color flow. recognized. In cases in which the diagnosis of an HOC cannot be easily made, having the patient return for follow-up sonography after 1 or 2 cycles between days 5 and 11 in most cases will clearly facilitate the diagnosis of an HOC. Figure 6. Transvaginal oblique coronal sonogram from a 31-year-old woman with pelvic pain showing a retracting clot with a horizontal level and clear serum component, which can be mistaken for a fluid-debris level (arrowheads). Conclusions Hemorrhagic ovarian cysts are essentially “nonsurgical” lesions, and in most cases with correct sonographic diagnosis, conservative treatment with clinical and sonographic follow-up to resolution is indicated.1 Follow-up sonography is not necessary if the typical appearance of the HOC is J Ultrasound Med 21:879–886, 2002 883 Sonographic Spectrum of Hemorrhagic Ovarian Cysts A B Figure 7. Hemorrhagic ovarian cyst simulating a ruptured ectopic pregnancy in a 23-year-old woman with severe acute pelvic pain and a positive β-hCG finding. A, Coronal right adnexal sonogram showing a mass with an irregular thick rind (arrows). This was mistaken for a ruptured ectopic pregnancy but was identified as a ruptured hemorrhagic cyst at laparoscopy. The patient had a concurrent very early intrauterine pregnancy. B, Sagittal right adnexal sonogram showing echogenic fluid (arrows) adjacent to the ruptured hemorrhagic cyst (H). Figure 8. Hemorrhagic ovarian cyst simulating a papillary cystadenoma in a 29-year-old woman with an adnexal mass and persistent vaginal bleeding. The transvaginal coronal sonogram shows a small retracted blood clot, which can be easily mistaken for papilloma, and the lesion may be misdiagnosed as a papillary cystadenoma. 884 Figure 9. Hemorrhagic ovarian cyst simulating a solid mass in a 28-yearold woman with a pelvic mass. The transvaginal sagittal sonogram shows a left adnexal mass with dense internal echoes. This can be seen when the blood clot within the cyst is still solid and has not started retraction and lysis. This was mistaken for a solid mass (M). Normal ovarian parenchyma with a small follicular cyst is shown (arrow). J Ultrasound Med 21:879–886, 2002 Jain Figure 10. Hemorrhagic ovarian cyst simulating a malignant ovarian neoplasm in a 36-year-old woman with an adnexal mass and pelvic pain. The coronal transvaginal sonogram shows a large mass (arrows) with solid components and irregular anechoic areas. This was misdiagnosed as a malignant ovarian neoplasm. However, the solid components represent the solid portion of a blood clot, and the anechoic areas represent lysing of the clot. This lesion was completely resolved on follow-up sonography 8 weeks later. Figure 12. Dermoid cyst simulating an HOC in a 34-year-old woman with an adnexal mass. The coronal transvaginal sonogram shows an adnexal mass with poor through-transmission. Multiple echogenic lines can be mistaken for a reticular pattern of a hemorrhagic cyst; however, they represent hair in a dermoid cyst. Figure 11. Mucinous cystadenoma with an architecture similar to that of an HOC in a 32-year-old woman with abdominal and pelvic pain. The transabdominal sonogram shows a large pelvic mass with enhanced through-transmission and a reticular pattern. This was surgically removed and found to be a mucinous cystadenoma. A small mucinous cystadenoma can be mistaken for an HOC. References J Ultrasound Med 21:879–886, 2002 1. Yoffe N, Bronshtein M, Brandes J, Blumenfeld Z. Hemorrhagic ovarian cyst detection by transvaginal sonography: the great imitator. Gynecol Endocrinol 1991; 5:123–129. 2. Selvaggi SM. Cytology of nonneoplastic cysts of the ovary. Diagn Cytopathol 1990; 6:77–85. 3. Bass IS, Haller JO, Friedman AP, Twersky J, Balsam D, Gottesman R. The sonographic appearance of the hemorrhagic ovarian cyst in adolescents. J Ultrasound Med 1984; 3:509–513. 4. Kayaba H, Tamura H, Shirayama K, Murata J, Fujiwara Y. Hemorrhagic ovarian cyst in childhood: a case report. J Pediatr Surg 1996; 31:978–979. 5. Coelho JC, Sigel B, Ryva JC, Machi J, Renigers SA. B-mode sonography of blood clots. J Clin Ultrasound 1982; 10:323–327. 6. Hertzberg B, Kliewer M, Bowie J. Adnexal ring sign and hemoperitoneum caused by hemorrhagic ovarian cysts: pitfall in the sonographic diagnosis of 885 Sonographic Spectrum of Hemorrhagic Ovarian Cysts ectopic pregnancy. AJR Am J Roentgenol 1999; 173:1301–1302. 7. Reynolds T, Hill MC, Glassman LM. Sonography of hemorrhagic ovarian cysts. J Clin Ultrasound 1986; 14:449–453. 8. Hertzberg BS, Kliewer MA, Paulson EK. Ovarian cyst rupture causing hemoperitoneum: imaging features and the potential for misdiagnosis. Abdom Imaging 1999;24:304–308. 9. Hallatt JG, Steele CH, Snyder M. Ruptured corpus luteum with hemoperitoneum: a study of 173 surgical cases. Am J Obstet Gynecol 1984; 149:5–9. 10. Yilmaz E, Usal C, Kovanlikaya A, Karabay N. Sonographic and MRI finding in prepubertal adnexal hemorrhagic cyst with torsion. J Clin Ultrasound 2001; 29:200–202. 886 J Ultrasound Med 21:879–886, 2002