Diagnosis of Endometriosis

Robert Z. Spaczynski, MD, PhD, Antoni J. Duleba, MD


Semin Reprod Med. 2003;21(2) 

In This Article

Surgical Procedures

Laparoscopic assessment in combination with histological examination of the excised lesions remains the gold standard for diagnosis of endometriosis. Knowledge of the most common locations of endometriosis is required for accurate visual inspection of the pelvic and abdominal cavities. Three different forms of endometriosis must be considered during laparoscopic visualization: peritoneal implants, endometriomas, and deep infiltrating lesions of the rectovaginal septum. An increased awareness of the variations in the appearance of endometriotic lesions has resulted in an almost twofold increase in the diagnosis of endometriosis at laparoscopy.[151]

Peritoneal Implants

Peritoneal implants are most commonly localized in the uterosacral ligaments, cul-de-sac, ovarian fossa, and adjacent pelvic sidewalls. Less frequently, implants can also be found in the upper abdomen as well as on the surface of the bladder and the bowel (predominantly rectum, sigmoid colon, appendix, and cecum).[64,71] Hence careful and close inspection of the entire peritoneal cavity should be performed. Magnification obtained during laparoscopy depends on the distance between the laparoscope and the area inspected; for example, the magnification rate is approximately 3.2 and 1.7 from a distance of 10 and 20 mm, respectively.[152] Magnification allows the recognition of lesions as small as 400 µm for red and 180 µm for clear lesions.[151,153]

The classic peritoneal implant appears as a bluish-black "powder burn" lesion with variable degrees of pigmentation and surrounding fibrosis. Typical dark coloration is the result of hemosiderin deposits from entrapped menstrual debris. However, the majority of peritoneal implants appear as nonpigmented, atypical (subtle) lesions, usually red or white. Jansen and Russell[154] have described the relationship between morphological and histological features of various endometriotic lesions. Lesions that were commonly endometriotic included areas of white opacification (81%), red flame-like lesions (81%), and glandular lesions (67%). Less frequently, histological confirmation of endometriosis was obtained in subovarian adhesions (50%), yellow-brown peritoneal patches (47%), and circular peritoneal defects (45%).[154]

As demonstrated by Nisolle and Donnez,[155] red lesions are highly vascularized and proliferative, usually representing an early stage of endometriosis. In contrast, white lesions contain fibrous tissue and are poorly vascularized. They are metabolically inactive and probably represent healed or latent lesions. Black, pigmented foci represent an advanced stage of the disease and the diagnosis of endometriosis has been histologically confirmed in 76 to 93% of these specimens.[156,157] Biochemical activity and clinical features of various lesions from infertile patients with minimal or mild endometriosis were assessed in a prospective study. White peritoneal implants were associated with less pain than black or red lesions, and both black and red lesions showed similar activity expressed in terms of prostaglandin F2 production.[54] In a prospective study, changing patterns in activity of the peritoneal lesions were observed with no change in the stage of the disease when evaluated at laparoscopy before and 6 months after medical therapy.[158]

Redwine[159] proposed that endometrial peritoneal implants undergo a process of "natural evolution." This concept is supported by the observation that the frequency of red lesions and clear papules declines with patients' age and these implants appear to be replaced by black, and ultimately white, scarred lesions over a period of 7 to 10 years.[159] There is a significant overlap in the time course of the presentation of these defects, and all types of lesions may coexist in the same patient.

Endometriosis may also be detected in the lesions visible only under the microscope or scanning electron microscope.[152,160] The prevalence of endometriosis (including microscopic forms) in asymptomatic patients undergoing laparoscopy was estimated to be as high as 45 to 50%.[161] Novel techniques such as "peritoneal blood painting" and infusion of crystalloid into the cul-de-sac ("bubble test") were developed to improve the detection of subtle lesions.[162,163] However, the clinical significance of microscopic endometriosis remains uncertain. It is conceivable that microscopic endometriosis may be present in the majority of women and that a symptomatic disease may develop only in some.[161]

Because endometriotic implants vary in appearance, the experience and the expertise of the surgeon may greatly influence the selection of the biopsy area and hence the likelihood of a diagnosis of endometriosis. In a prospective study, Walter et al[164] correlated visual diagnosis of endometriosis at laparoscopy with final histological confirmation in 44 patients evaluated for chronic pelvic pain. Use of strict histological criteria resulted in lower rates of confirmed endometriosis because visually detected endometriosis was observed in 36% of cases but confirmed histologically in only 18% of cases.

Peritoneal endometriosis can be associated with other pathological changes such as general hypervascularization and adhesion formation. Adhesions should be evaluated for density (filmy, vascular, dense/fibrotic) and for the extent to which they limit mobility of pelvic organs. Assessment of the severity of periadnexal adhesions is of particular importance in infertile patients because the extent of adhesions is related to the prognosis.[165]


At the time of laparoscopy, endometriomas may be identified as smooth-walled, dark, brownish cysts, usually strongly associated with the presence of adhesions.[56] Upon incision, dense, brown, chocolate-like fluid is released. As reported by Vercellini et al,[166] careful visual inspection of the ovaries is usually highly reliable in identification of endometriomas, with 97% sensitivity and 95% specificity. Endometriomas larger than 3 cm are frequently multilocular, and in 8% a combination with communicating or noncommunicating luteal cysts has been described.[167]

In patients with enlarged ovaries and at high risk for endometriosis, ovarian punctures may aid in the detection of small and deep endometriomas. Candiani et al[168] found endometriotic material in 48% of aspirates collected from infertile patients who had enlarged ovaries with smooth whitish surfaces and no obvious dominant cysts.

Superficial or deep ovarian endometriosis is a marker for the presence of more extensive disease. Using a computerized pelvic mapping system in 1785 patients with endometriosis Redwine[169] demonstrated that patients with ovarian endometriosis have more pelvic and intestinal areas affected than subjects with no ovarian involvement.

Deep nodular endometriosis is usually localized in the rectovaginal and uterovesical septum, in other fibromuscular pelvic structures (e.g., uterosacral ligaments), and in the muscular wall of pelvic structures.[170] Rectovaginal nodules are histologically similar to an adenomyoma, being composed of smooth muscle, endometrial glands, and stroma. They probably constitute an entity distinct from peritoneal and ovarian endometriosis and are thought to originate from the müllerian rests present in the rectovaginal septum.[155,171]

Deep endometriotic lesions may be predominantly retroperitoneal with little or no superficial peritoneal involvement. These lesions, associated with pain and infertility, have been classified as deep when infiltrating more than 5 mm beneath the peritoneal surface.[172,173] Evaluation of the size and the depth of the nodule may be difficult at laparoscopic examination; however, meticulous palpation using a probe may identify these lesions. A subtle retraction of the bowel may also be suggestive of deep implants. Identification of deep endometriosis is greatly improved by a careful preoperative examination, preferably during menstruation, of the posterior vagina, cul-de-sac, and uterosacral ligaments.[84]

When endometrioma in a surgical scar is suspected, histopathological diagnosis can be obtained by a fine-needle aspiration biopsy.[174]

Transvaginal hydrolaparoscopy, using a needle-cannula system inserted into the posterior fornix and injection of saline for peritoneal distention, was recently introduced as an office screening technique for infertile women. Interestingly, it was reportedly more accurate than traditional laparoscopy in diagnosis of early endometriotic lesions.[175,176]


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