Endometriosis is commonly associated with pelvic pain or infertility in human females. Although the diagnosis can be strongly suspected by history and physical findings, correct diagnosis requires surgery. Laparoscopy is currently the most common method of surgical diagnosis. Accurate laparoscopy depends on specific technical and cognitive factors. Safe and proper patient positioning, trocar sites, and knowledge of the common locations and the protean visual manifestations of the disease are all important. Distinction between superficial and more deeply invasive disease is critical in applying the proper surgical therapy.
The patient should be positioned far enough down the operating table for adequate uterine manipulation (Figure 1). If the patient's hips are not slightly off the edge of the table, anteflexion of the uterus may be inadequate during surgery and may lead to problems with diagnosis and surgical treatment. The patient's legs must be safely supported by stirrups which will not allow her to slide up on the operating table when placed in steep Trendelenburg position (30 degrees). It is advisable for the surgeon personally to place the hips and legs in the proper position and to ensure adequate padding to avoid peroneal nerve damage because the length of the laparoscopic procedure may be difficult to estimate. The patient's arms should be tucked along her side to allow the surgeon full range of motion during surgery and to reduce the chance of brachial plexus injuries. Covering exposed body parts with thick blankets will help conserve body heat, and a warming blanket might be considered for long cases. The bladder is drained by a retention catheter.
Adequate visualization of the pelvis requires at least a double puncture approach, one for the viewing scope in an umbilical location, another for a manipulating probe or atraumatic graspers in the midline suprapubically (Figure 1). These trocars, combined with vigorous manipulation of uterine position, will allow every pelvic surface to be viewed. As a practical matter, most surgeons would benefit from a triple puncture technique which allows the addition of a suction-irrigator for efficient performance of laparoscopic surgery. A direct trocar insertion through the umbilicus with a reusable 10-mm trocar is safe and efficient. The trocar tip becomes slightly dull during repeated use which increases its safety. Direct trocar insertion avoids the blind insertion of a small, sharp insufflating needle. The abdominal wall must be elevated with the hands or towel clips, and the trocar must be directed toward the hollow of the pelvis, otherwise damage to the great vessels may occur.
After the laparoscope is inserted and intra-abdominal placement confirmed, pneumoperitoneum is established. The anterior abdominal wall is next inspected for the location of the inferior epigastric vessels. These vessels course superiorly and somewhat medially from a point just lateral to the internal inguinal ring and are retroperitoneal structures best visualized directly. Transillumination of the abdominal wall is unreliable for identification of these vessels. For the triple puncture laparoscopy, the two lower ports are placed lateral to the inferior epigastric vessels. Adhesions in the area must be lysed before insertion of accessory trocars. For safer insertion of these lower ports, the laparoscope can be used to elevate the lower abdominal wall adjacent to the selected insertion site. The trocar is passed horizontally beneath the laparoscope into the pneumoperitoneum.
If video laparoscopy is to be performed, a fourth port is often necessary. For surgeons perfuming surgery looking directly through an operating laparoscope, the three ports described above suffice for most advanced operative laparoscopy procedures (Figure 1). An intrauterine manipulator is necessary for proper visualization of the entire pelvis (Figure 2).
Pathophysiology of the visual appearances of endometriosis
Surgical diagnosis of endometriosis depends heavily on the surgeon's awareness of the multiple visual appearances possible with endometriosis, as well as what constitutes visually normal peritoneum. Close examination of the peritoneum by near-contact laparoscopy (Figure 3) can help identify subtle lesions of endometriosis. Surgeons looking only for hemorrhagic lesions will under diagnose most patients and miss the diagnosis completely in others. Microscopy of endometriosis reveals rather empty glandular elements and stroma which is largely devoid of capillaries (Figure 4). Therefore, endometriosis itself can be rather bland or colorless visually (Figures 5 and 6). Many of the visual manifestations of endometriosis are actually sequelae of the local effects of the disease rather than the actual disease itself. For example, hemorrhage in association with endometriosis is not a direct visual manifestation of the disease itself, but merely destabilization of capillaries adjacent to the disease. Endometriosis exists as glands and stroma. Glands secrete while blood vessels bleed. The blood may pool in an area remote from the actual disease, leading to biopsy specimens which seem mysteriously negative for endometriosis. Similarly, white (Figure 7) or yellow fibrosis and scarring are results of endometriosis in the vicinity presumably secreting a paracrine substance which results in stimulation of fibroblasts, leading to "burned-in" rather than "burned-out" disease.
Photomicrograph of endometriosis at the center of obliteration of the cul-de-sac. A vigorous fibromuscular reaction surrounds the glands and stroma of endometriosis. Notice the relative absence of capillaries. The absence of capillaries results in a nonhemorrhagic appearance of even deeply invasive endometriosis.
Two small, clear papules of endometriosis. Notice that the disease itself is colorless, visible as bullous blebs with overlying neovascularity. Because the size of endometriosis gland/stroma complexes ranges from about 100 to 800µm in dimension, the majority will be visible with near-contact laparoscopy, and the incidence of unseen microscopic disease will approach zero.
The subtle lesions of endometriosis show whitish-yellow scarring associated with peritoneal disease. Notice that underlying capillaries are obscured by the reactive process.
Surgical photograph of the left uterosacral ligament showing "burned-in" endometriosis. Notice that the ligament is covered by white fibrosis, which represents scarring associated with active underlying endometriosis. Surgeons should resist the temptation to classify such disease as "burned-out" or inactive. Notice small islands of white plaques of endometriosis adjacent to the ligament.
Any location in the body where endometriosis is found may have a visual appearance ranging from subtle and innocuous  (Figures 5 and 6) to invasive, hemorrahgic, and inflammatory (Figure 8). The visual appearance of lesions can change over time, with adjacent hemorrhage and scarring accumulating and becoming more obvious with time . Even significantly obstructing nodules of the intestinal tract may have no discoloration whatsoever, displaying mainly white fibrotic modularity with resultant distortion of the bowel wall (Figure 9). Variations in the appearance of endometriosis depend in part on the quota of hormone receptors imparted to the disease in each pelvic area at the moment of conception. Because of the low and varying levels of estrogen and progesterone receptors of endometriosis compared with the native endometrium, endometriosis bleeds noncyclically, unpredictably, or not at all . Identification of the subtle endometriosis depends heavily on knowledge of what constitutes visually normal peritoneum. Close inspection of the peritoneum by near-contact laparoscopy is necessary to discern normal from abnormal peritoneum (Figure 10).
Invasive endometriosis of the cul-de-sac and uterosacral ligaments. Black hemorrhagic "powderburn" lesions occur in a field of yellowish scarring resulting from deeply invasive endometriosis. Such black powderburn lesions are a relatively common manifestation of the disease.
Significant endometriosis of the sigmoid colon. Notice the distortion of the bowel wall with rare punctate hemorrhage.
Microscopic endometriosis is a subject which has received more attention than it deserves. Microscopic endometriosis implies the existence of disease which cannot be seen and which is located on visually normal peritoneum, allegedly in up to 25% of patients . The criteria for visually normal peritoneum have been established and verified. Basic scientific knowledge should serve to dispel the notion of microscopic endometriosis. First, the unaided human eye has the ability to easily resolve details as small as 100µm, which is the thickness of a human hair (figure 11). Second, it has been found that unrecognized or "microscopic" deposits of endometriosis ranged from about 100 up to 800µm in diameter, with the average unseen lesion being about 300µm . Third, endometriosis is a disease of the mesothelium, beginning on the surface with varying degrees of invasion dependent on inborn differences in metabolic activity. Thus, it should be possible to see virtually all endometriosis if the observer uses modest magnification to distinguish normal from abnormal peritoneum. Criteria for the visual appearance of the normal peritoneum have been established and validated [6, 7]. If magnification is used, it is clear that as the distance between the observer's eye and the peritoneum decreases, the frequency of unseen "microscopic" endometriosis plunges almost to zero [5, 6, 7, 8]. Microscopic endometriosis is often used as a lame explanation for pain which continues after surgical therapy, as a reason to justify medical therapy, or as an explanation for persistent disease after incomplete surgical therapy. There is no evidence that sporadic tiny lesions of endometriosis which may be missed at surgery will ever develop into more significant invasive disease which will cause future pain or infertility. While there is no question that endometriosis can exist in extremely subtle forms, invisible microscopic disease does not appear to be one of them.
The unaided human eye has the ability to easily resolve details as small as 100Ám, which is the thickness of a human hair. "Microscopic" endometriosis can be seen from arm's length.
The guiding principle for the surgeon must be that any visual abnormality must be considered to be endometriosis until proven otherwise by biopsy. Video systems differ greatly in quality, and no one has validated any video system as being superior to the unaided eye. Surgeons using video cameras and monitors to identify endometriosis must be willing to accept an unquantified degree of inaccuracy in the diagnosis of their patients, which may contribute to the repetitive cycles of incomplete and ineffective surgery which are the hallmarks of modern endometriosis treatment.
Inspection of the upper abdomen
The upper abdomen should be inspected first because it is easy to forget about it later during laparoscopy. The liver edge and surface should be visualized. The diaphragm represents the upper abdominal site most likely to have disease. Both leaves of the diaphragm should be investigated for any evidence of endometriosis. Because the liver will obscure the right diaphragm in steep Trendelenburg position, it is helpful to examine the upper abdomen with the operating table flat, or even in reverse Trendelenburg as this will allow the liver to drop away from the diaphragm. Proper inspection of the diaphragm is particularly important in patients with chest or shoulder pain occurring before or during menses. Some patients with diaphragmatic endometriosis may have innocuous-appearing sentinel lesions visible on the mid-diaphragm with significant invasive lesions hidden along the posterior edge of the diaphragm (Figure 12). If only the sentinel lesions are found, the surgeon may trivialize the disease and miss an opportunity to make a full and complete diagnosis. Brown deposits of old blood can be found on the diaphragm (Figure 13), although these are not endometriosis. Such deposits of old, brown blood are caused by the repeated rupture of ovarian endometrioma cysts. When the surgeon finds such deposits on the diaphragm or elsewhere in the pelvis or abdomen, significant endometrioma cysts will be found in one or both ovaries. The gallbladder and spleen are occasionally visible without the need for upper abdominal manipulation. Viewing these structures is optional when searching for endometriosis.
Diaphgramtic endometriosis. The diaphragm is only about 0.5cm thick. Symptomatic endometriosis of the diaphragm always penetrates through the entire thickness of the diaphragm, making laparoscopic treatment problematic.
Hemosiderin deposits on the diaphragm. These deposits are not endometriosis, but are due to repeated ruptures and leakage of ovarian endometrioma cysts. When diaphragmatic staining such as this is present, the omentum and pelvis frequently have similar deposits of brownish hemosiderin.
Inspection of the cecum, appendix, and ileum
The laparoscope now sweeps down the right abdominal wall, viewing the transverse and ascending colon. The cecum is visualized, as is the appendix. Endometriosis of the cecum may appear as superficial reddish discoloration with underlying whitish nodularity of the bowel wall. Endometriosis of the appendix is usually represented by localized tortuosity without significant hemorrhagic discoloration (Figure 14). Atraumatic graspers can be used to run the terminal ileum. Endometriosis of the ileum is most commonly found on the antimesenteric border, frequently in a nonrandom linear distribution (Figure 15). Occasionally, the peritoneum of the mesentery will be involved in a fan-like distribution of superficial lesions which correlate with the affected segment of ileum. Nodular endometriosis of the ileum can result in serial retraction which can lead to kinking of the bowel wall (Figure 16), sometimes with overlying fleshy red lesions of endometriosis.
Endometriosis of the appendix is frequently asymptomatic because it is usually confined to the peritoneal surface. The area of involvement may have only a slightly hemorrhagic appearance, with resultant retraction and fibrosis producing curling of the tip of the appendix or kinking of the shaft.
Ileal endometriosis does not exhibit a random pattern of involvement because it usually occurs in a linear distribution on the antimesenteric border of the bowel wall. These lesions are fairly superficial and can usually be removed by delicate partial thickness resection.
Ileal endometriosis. Scarring and retraction associated with invasion of the bowel wall have resulted in distortion and partial bowel obstruction. Because the wall of the ileum is thin, full-thickness penetration will usually accompany surgical treatment of these lesions. Frequently, a segmental resection will be necessary to treat such a process.
Inspection of the rectosigmoid colon
The laparoscope now sweeps to the left upper quadrant and down the descending colon. Intestinal endometriosis most commonly involves the rectosigmoid colon, so attention should focus on examination of the sigmoid from the pelvic brim down to the cul-de-sac. The rectosigmoid should be placed on stretch in the center of the pelvis by cephalad traction on the bowel wall near the pelvic brim. The anterior surface of the rectosigmoid is most commonly involved by endometriosis, so this traction will help expose any suspicious surface irregularities. Endometriosis of the sigmoid colon begins on the serosa and may invade the muscularis, but rarely penetrates to the lumen (Figure 17). Invasion of the muscularis results in a visual appearance which may be white and nodular with no hemorrhagic component at all. Another subtle manifestation of endometriosis of the sigmoid colon is hypertrophy of the appendix epiploica adjacent to the involved bowel wall (Figure 18), which may sometimes obscure even a bulky, nodular lesion. Hemorrhagic lesions can occur and may be pinpoint in size, fleshy and exophytic, or flat.
Cross-section through a rectal nodule of endometriosis associated with obliteration of the cul-de-sac. The surgeon would see only reddish discoloration of the pelvic floor (adjacent to the zero mark on the scalpel), whereas the invasion and fibromuscular reaction extend more than 2cm deeper.
Inspection of the cul-de-sac
The cul-de-sac is the pelvic area most commonly involved by endometriosis. The visual appearances possible here are prototypical for the visual appearances possible anywhere else in the pelvis. It is necessary to see every area of the cul-de-sac to diagnose endometriosis accurately, and the areas immediately posterior to the cervix or behind the uterosacral ligaments can be missed if the surgeon does not elevate the uterus properly (Figure 2).
The uterosacral ligaments mark the lateral boundaries of the cul-de-sac and are feequently infiltrated by invasive disease which can manifest as a palpable, whitish nodule, sometimes with a small amount of overlying hemorrhagic discoloration (Figs 7 and 8).
One clinically important variation of cul-de-sac endometriosis is obliteration of the cul-de-sac, with the rectum scarred forward to the uterosacral ligaments and posterior cervix (Figs 4, 17 and 19). This implies invasive disease of all of these areas, as well as the possibility of invasion of the bowel wall itself. Surgeons may describe this as an adhesive process only, describing "dense adhesions" behind the cervix, or the "rectum adherent to the cervix." Such descriptions imply that the surgeon has missed the clinical significance of this visual manifestation.
Obliteration of the cul-de-sac can sometimes be subtle in appearance. The patient had complete cul-de-sac obliteration without any significant hemorrhagic change. Some surgeons might think that the cul-de-sac was normal in such a case.
Inspection of the pelvic sidewalls
The ovaries are occasionally adherent to the pelvic sidewalls because of the inflammation associated with ovarian endometriomas. the ovaries can hide peritoneal endometriosis, including disease in the area of adherence itself. Such disease cannot be seen, but must be suspected. If the peritoneum is resected, the pathologist will frequently find endometriosis even if it is not obvious to the surgeon. Invasive disease of the uterosacral ligaments will sometimes involve the ipsilateral ureter with fibrosis and rarely will invade the wall of the ureter.
Inspection of the ovaries
The ovaries are not the most common site of pelvic involvement by endometriosis. If a surgeon finds in his or her patients that ovarian disease is the most common site of involvement, then that surgeon is overlooking much peritoneal disease. Chocolate cysts of the ovary are not always endometriosis, and corpus luteum cysts can mimic endometriosis . Some endometrioma cysts are not obvious on initial inspection, although an ovary may look rather plump and adherent to the pelvic sidewall. Sometimes chocolate material which has spilled from a ruptured ovarian endometrioma cyst will stain the pelvic peritoneum, diaphragm (Figure 13), or even the omentum. When the surgeon finds this, the ovaries should be dissected off the pelvic sidewall and punctured to check for a chocolate cyst. Superficial hemorrhagic adhesions are not always endometriosis (Figure 20), and it is always best to confirm clinical suspicions with biopsy.
Punctate reddish discolorations on the surface of this ovary were hemorrhagic adhesions which were negative histologically for endometriosis. This ovary contained an underlying endometrioma cyst which was apparent only after puncturing the ovary, releasing chocolate colored fluid.
Inspection of the bladder
Superficial endometriosis of the bladder can be subtle or obvious. Peritoneal endometriosis of bladder peritoneum can occasionally be associated with rolling and retraction of the peritoneum near the uterovesical junction, often without any apparent hemorrhage (Figure 21). Invasive endometriosis of the bladder muscularis is rare, even when significant distortion is present (Figure 22).
Rolling and piling up of the bladder peritoneum adjacent to the uterus indicates underlying endometriosis.
Invasive bladder endometriosis frequently produces significant distortion and retraction of the peritoneal surfaces, with overlying fleshy lesions of disease. This lesion invaded the bladder muscularis but did not penetrate the entire thickness. The distinction is clear only when the disease is treated by excision.
Superficial versus deep endometriosis
The distinction between superficial and deep endometriosis is important both for staging the disease properly as well as for determination of appropriate surgical therapy. Visual inspection alone is not always sufficient for determining this distinction, and palpation during surgery is important. The peritoneum adjacent to a lesion can be grasped and pulled or elevated. If the lesion is seen to move across underlying vessels or pelvic sidewall structures, it is superficial. If not, it is deep, although the depth of invasion may not be apparent without retroperitoneal dissection during the process of excision (Figure 17). Surgeons treating endometriosis using laser vaporization or electrocoagulation without palpation may view endometriosis as a two-dimensional disease always treatable by superficial coagulation or vaporization, which would be a serious surgical error.
Medical therapy and the visual appearance of endometriosis
No medical therapy eradicates endometriosis. Evidence of efficacy of medical therapy is based on response of symptoms rather than proven response of the disease. Medical therapy can make endometriosis appear more innocuous during ovarian suppression . Therefore, the popular conventional practice of repeating a laparoscopy at the conclusion of medical therapy can induce a false sense of security in the surgeon who may or may not recognize subtle endometriosis. The apparent improvement of endometriosis after medical therapy should not be used as a reason to avoid complete surgical therapy.
All intellectual and therapeutic processes involving endometriosis begin with a surgeon identifying the disease in the pelvis. If the visual diagnosis of endometriosis is inaccurate, then our understanding of the disease will be inaccurate . Visualization, palpation, and excision are frequently necessary to distinguish superficial from deep disease.
- Stripling MC, Martin DC, Chatman DL, et al: Subtle appearance of pelvic endometriosis. Fertil Steril 49:427-431, 1988.
- Redwine DB: Age-related evolution in color appearance of endometriosis. Fertil Steril 48:1062-1063, 1987.
- Metzger DA, Olive DL Haney AF: Limited hormonal responsiveness of ectopic endometrium: Histologic correlation with intrauterine endometrium. Hum Pathol 19:1417-1424, 1988.
- Murphy AA, Green WR, Bobbie D, et al: Unsuspected endometriosis documented by scanning electron microscopy in visually normal peritoneum. Fertil Steril 46:522-524, 1986.
- Nisolle M, Paindaveine B, Bourdon A, et al: Histologic study of peritoneal endometriosis in infertile women. Fertil Steril 53:984-988, 1990.
- Redwine DB: Is "microscopic" peritoneal endometriosis invisible? Fertil Steril 50:655-666, 1988.
- Redwine DB, Yocom L: A serial section study of visually normal peritoneum in patients with endometriosis. Fertil Steril 54:648-651, 1990.
- Nezhat F, Allan CJ, Nezhat C, et al: Nonvisualized endometriosis at laparoscopy. Int J Fertil 36:340-343,1991.
- Sampson JA: Perforating hemorrhagic (chocolate) cysts of the ovary. Arch Surg 3:245-323, 1921.
- Evers JLH: The second-look laparoscopy for evaluation of the result of medical treatment of endometriosis should not be performed during ovarian suppression. Fertil Steril 47:502-504, 1987.
- Redwine DB: The visual appearance of endometriosis and its impact on our concepts of the disease. Prog Clin Biol Res 323:393-412, 1990.