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ORIGINAL RESEARCH |
From the Department of Obstetrics and Gynecology, University of Rochester School of Medicine and Dentistry, Rochester, New York and the Department of Gynecology and Obstetrics, Kasr El-Aini School of Medicine, Cairo University, Cairo, Egypt
Address reprint requests to: Fred M. Howard, MS, MD, Department of Obstetrics and Gynecology, University of Rochester Medical School, Box 668, 601 Elmwood Avenue, Rochester, NY 14642, E-mail: fred_howard{at}urmc.rochester.edu
| Abstract |
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Methods: Fifty consecutive women with at least one prior procedure for chronic pelvic pain had conscious pain mapping. Operative findings and clinical outcomes were documented. Preoperative and postoperative pain levels were evaluated using visual analog scales.
Results: Conscious pain mapping was successful in 35 cases (70%). Twenty-nine patients had 42 specific positive sites, and six patients had diffuse visceroperitoneal pelvic tenderness. Adhesions and endometriosis accounted for 45% of positive lesions or sites. About half of women with endometriosis or adhesions mapped pain specifically to those lesions. For endometriosis, histologic but not visual diagnosis predicted positive mapping. Specific viscera accounted for 36% of positively mapped sites. Diagnoses of chronic visceral pain syndrome were suggested by the findings in 16 (46%) patients whose mapping was successful. Mean ± standard deviation visual analog scale pain levels were 8.7 ± 1.2 preoperatively and 5.5 ± 3.7 postoperatively. Twenty-two women (44%) had decreased pain postoperatively and eight (16%) were pain-free.
Conclusion: Conscious pain mapping can be done with reasonable success in women with prior surgical evaluations and treatments for chronic pelvic pain. Chronic visceral pain syndrome, adhesions, and endometriosis were the most common diagnoses.
Laparoscopy under local anesthesia is not new,1 but its use in diagnosis to localize areas of tenderness possibly responsible for chronic pelvic pain is relatively new. Palter and Olive2 first described this technique, usually called conscious pain mapping, in 1996. They studied 11 women with pelvic pain and found that ten had diffuse visceroperitoneal tenderness. Demco3 also published findings with it (he called it patient-assisted laparoscopy), mostly in women with endometriosis-associated pelvic pain. He found that most women localized or mapped their pain to their endometriotic lesions and the surrounding peritoneum.4
The rationale for conscious pain mapping is that it might allow specific identification of lesions that cause chronic pelvic pain and specific surgery, or it might avoid unneeded surgery in women who do not map their pain to a specific lesion. Published studies of conscious pain mapping are still limited, especially in patients who have had unsuccessful diagnoses and treatments, so we report the findings of our first 50 cases of conscious pain mapping.
| Materials and Methods |
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Procedures were done by the senior author (FMH) in the ambulatory surgery center at Rochester General Hospital with an anesthesiologist in attendance. Before sedation, the patient was placed in low lithotomy position, and an indwelling bladder catheter was inserted using topical local anesthesia at the urethra. A uterine manipulator was placed using a four-quadrant cervical block, if the patient had a uterus. If not, a lubricated sponge stick was placed in the vagina. Women were given intravenous propofol at that point to induce conscious sedation. Dosage varied based on the anesthesiologists judgment of the patients anxiety level and responsiveness. Ten milliliters of 1% lidocaine buffered 1:9 with sodium bicarbonate were injected in a fan pattern at the umbilicus, then the abdomen was elevated and a 2-mm or 5-mm disposable trocar was inserted. Two-millimeter trocars were used in 42 (84%) cases and 5-mm trocars in seven (14%). The laparoscope was introduced to confirm intraperitoneal placement. Ten milliliters of buffered 1% lidocaine were injected suprapubically while the abdomen was insufflated with up to 1 L of carbon dioxide, which allowed a view of the suprapubic lidocaine injection to the level of the peritoneum. A suprapubic 2-mm or 5-mm trocar was then inserted under direct view. A blunt probe was introduced through the suprapubic trocar to do the mapping. Pressure and traction were used as stimuli for mapping. An area of small bowel was stimulated to allow the women to establish baseline pain levels. They were instructed preoperatively to use a verbal analog scale of "0" to "10" to numerically rate their pain. They also were instructed to identify any stimuli that reproduced their usual pain. After baseline from small bowel stimulation was established, an attempt was made to map systematically the internal inguinal rings, round ligaments, bladder dome, anterior cul-de-sac, broad ligaments, fallopian tubes, ovaries, pelvic sidewalls, posterior cul-de-sac, uterus, and appendix, and any visible lesions. It was not possible to see the posterior cul-de-sac in all cases. Often, if a positive lesion was identified, the patient had difficulty continuing the evaluation because of persistent severe pain even after stimulation of the lesion was terminated. In some cases, topical lidocaine was irrigated onto the positive lesion, which generally blocked the sensitivity of the lesion and decreased pain.
Positive mapping cases were defined as those in which one or more lesions were found that correlated with some or all of patients pain. A primary positive site was defined as a site or lesion that correlated with some or all of the patients pain and had the highest verbal analog scale severity rating. A secondary positive site was defined as a site or lesion that correlated with the patients pain, but had a lower verbal analog scale rating than the primary site.
A conscious pain mapping procedure was defined as successful if the patient tolerated the procedure and consistently identified the source(s) of her pain, or stated that no sources could be identified. Complete view of the entire pelvis was not considered essential for the procedure to be successful, but all areas had to be accessible to laparoscopic probing, including the posterior cul-de-sac.
Pain levels were measured using a 10-cm visual analog scale with endpoint labels "no pain" and "worst pain ever." Preoperative pain levels were measured in the month before conscious pain mapping and postoperative pain levels were measured at regular intervals postoperatively. Visual analog scale pain levels at last follow-up visit were those reported in this study as postoperative pain levels.
Data were analyzed with SPSS for Windows 10.0 (SPSS Inc., Chicago, IL). Dichotomous variables were compared by
2 and Fischer exact testing. Nonparametric data were compared using the Wilcoxon rank sum test.
| Results |
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Before referral to the Rochester Endometriosis and Pelvic Pain Center, 46 (92%) women had laparoscopies, 22 (44%) had laparotomies, and 13 (26%) had hysterectomies. All women had at least one prior procedure for pelvic pain. Preoperative visual analog scale pain levels ranged from 6 to 10, with a mean ± standard deviation (SD) of 8.7 ± 1.2, and 45 (90%) women had pain levels of 8 or more.
Conscious pain mapping was successful in 35 cases (70%) (Table 1
). Twenty-nine women had positive sites mapped; 18 had one positive site, ten had two positive sites, and one had four positive sites, for a total of 42 positive sites. In six other women, conscious pain mapping was successful, but they had diffuse visceroperitoneal tenderness that appeared to reproduce their chronic pelvic pain and did not have any specific, discrete positive lesions or sites. Primary and secondary positive lesions or sites are summarized in Table 2
. Of the 42 lesions or sites mapped, adhesions and endometriosis accounted for almost half (19 or 45% of sites mapped). Specific viscera (bladder, ovary, vaginal apex, uterus, round ligament, and fallopian tube) also accounted for a significant portion of positively mapped sites (15 or 36% of positive sites in ten of 35 successfully mapped women). Combined with six women with diffuse visceroperitoneal tenderness, these data suggest that 16 women, 45% of those successfully mapped, may have had chronic visceral pain syndrome.
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Adhesions accounted for 11 of 42 positively mapped sites (Table 2
), more than any other specific lesion or site and were present in 27 of 50 women (54%). In six women, adhesions directly caused failed conscious pain mapping. Among 21 remaining cases, 15 were mapped successfully and one or more adhesions mapped as painful in seven (47%) cases.
Several miscellaneous sites appeared to correlate with and reproduce patient pain at conscious pain mapping. Fifteen women mapped pain specifically to visceral structures, with bladder, ovary, and vaginal apex the most common (Table 2
). Other uncommon sites included a sciatic hernia, leiomyoma, hernia repair site, and postoperative peritoneal cyst.
In 13 cases with positive lesions it was necessary to apply lidocaine solution topically to primary and secondary positive sites to continue the procedure. In 12 of 13 primary sites and in all six secondary sites, lesions became nontender. No other positive sites were located in these cases.
Forty women had operative laparoscopy under general anesthesia immediately after conscious pain mapping (Table 3
). The only complication of conscious pain mapping was omental perforation with the umbilical trocar in eight cases, but there were no further sequelae caused by those perforations.
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Preoperative visual analog scale pain levels correlated with the duration of pelvic pain (Pearson correlation coefficient .302, P = .03), but postoperative visual analog scale pain levels did not significantly correlate with preoperative duration of pain (Pearson correlation coefficient .127, P = .53).
| Discussion |
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Palter and Olive2 compared their cases to 16 women with infertility who had microlaparoscopy. They noted that mean pain levels with conscious pain mapping in women with chronic pelvic pain were two points higher (on a ten-point scale) than pain levels in infertility patients who had diagnostic microlaparoscopy.
Demco3 published findings for 100 women who had conscious pain mapping with positive pain mapping in all but two of the successful cases. Our technique for conscious pain mapping was similar, although Demco did paracervical blocks before mapping and we did not. Our avoidance of anesthetizing the uterus might account for our finding uterine visceral pain in several cases.
Almeida and Val-Gallas8 reported that all but two of their 50 patients who had conscious pain mapping had positive findings. Seventeen women had prior laparoscopies for chronic pelvic pain, but none had prior laparotomies. Thirty-three had no prior surgical evaluations or treatments for chronic pelvic pain, distinctly different from our study. All our patients had prior surgical evaluations or treatments for chronic pelvic pain. We suspect that the marked differences between our results and those of Almeida and Val-Gallas and of Demco are most likely because of significant differences in populations studied. The only visceral pain reported by Almeida and Val-Gallas was from the appendix. We did not observe appendiceal tenderness in any of our initial 50 cases. Our results with conscious pain mapping and those reported show that in some patients with endometriosis or adhesions, the lesions are tender to direct palpation or stretching, which reproduces patients pain. Although it is generally accepted that endometriotic lesions can cause pain, conscious pain mapping results were consistent with the clinical observation that not all endometriotic lesions produce pain and tenderness. Demco tried to correlate the appearance of endometriotic lesions with tenderness at conscious pain mapping and found that 84% of red lesions, 76% of clear lesions, 44% of white-scar lesions, and 22% of black lesions were painful.9 Our series of patients with tender endometriotic lesions was too small for any reliable comparative data; however, our data confirm that a visual-only diagnosis of endometriosis is unreliable10 and that histologically confirmed endometriotic lesions are much more likely to positively map at conscious pain mapping than lesions visually consistent with endometriosis but without histologic confirmation.
Whether adhesions can produce pain is more controversial. The findings in all published series of conscious pain mapping that adhesions can be tender and that stimulation can reproduce patients pain strongly support the conclusion that some adhesions cause abdominopelvic pain. As with endometriosis, those data also suggest that adhesions are not always a source of pain in women with chronic pelvic pain and adhesions.
From our data it appears that conscious pain mapping is worthwhile even in complex patients who have had surgical evaluation and treatment for pain. In such women, as in other series of patients with chronic pelvic pain, adhesions and endometriosis are still common diagnoses, but conscious pain mapping findings suggest that visceral pain syndrome is also a frequent diagnosis.
Chronic pelvic pain is a multifaceted and complicated problem, and it is not appropriate to assume that findings with conscious pain mapping directly translate into cause and cure. In a series from our center that evaluated laparoscopic diagnosis and treatment of 65 patients, before the introduction of conscious pain mapping, we found that endometriosis and adhesive disease were the most common diagnoses, with prevalences of 38% and 34%, respectively.11 Those data are similar to gross visual diagnoses in the current series of 40% and 54%, respectively, for endometriosis and adhesions, but conscious pain mapping only confirmed that those lesions were associated with patients pain in 14% and 16%, respectively. In our previous series, after laparoscopic evaluation and treatment without conscious pain mapping, 78% of women had decreased pain and 45% were pain-free, compared with the current series with conscious pain mapping, in which 44% had decreased pain and 16% were pain-free. A significant difference between the populations in the two studies is that only half of the women in the previous series had prior evaluations and treatments for chronic pelvic pain.
The clinical value of conscious pain mapping diagnostically and therapeutically cannot be stated based on this or other observational series. We believe our series allowed us to avoid unnecessary operative laparoscopies in seven of 35 successfully mapped cases. Whether it improves outcomes in women with chronic pelvic pain, by decreasing unnecessary surgical interventions or improving pain relief by more specific medical and surgical treatments, probably will require a randomized trial.
| Footnotes |
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Received April 3, 2000. Received in revised form June 26, 2000. Accepted August 17, 2000.
| References |
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2. Palter SF, Olive DL. Office microlaparoscopy under local anesthesia for chronic pelvic pain. J Am Assoc Gynecol Laparosc 1996;3: 35964.[Medline]
3. Demco LA. Effect on negative laparoscopy rate in chronic pelvic pain patients using patient assisted laparoscopy. J Soc Laparoen-dosc Surg 1997;1:31921.
4. Demco L. Mapping the source and character of pain due to endometriosis by patient-assisted laparoscopy. J Am Assoc Gynecol Laparosc 1998;5:2415.[Medline]
5. Sharp JR, Pierson WP, Brady CE III. Comparison of CO2- and N2O-induced discomfort during peritoneoscopy under local anesthesia. Gastroenterology 1982;82:4536.[Medline]
6. Lipscomb GH, Summitt RL Jr, McCord ML, Ling FW. The effect of nitrous oxide and carbon dioxide pneumoperitoneum on operative and postoperative pain during laparoscopic sterilization under local anesthesia. J Am Assoc Gynecol Laparoscop 1994;2:5760.[Medline]
7. Wesselman U. A call for recognizing, legitimizing, and treating chronic visceral pain syndromes. Pain Forum 1999;8:14650.
8. Almeida OD Jr, Val-Gallas JM. Conscious pain mapping. J Am Assoc Gynecol Laparosc 1997;4:58790.[Medline]
9. Demco L. Mapping the source and character of pain due to endometriosis by patient-assisted laparoscopy. J Am Assoc Gynecol Laparosc 1998;5:2415.
10. Martin DC, Hubert GD, VanderZwaag R, el-Zeky FA. Laparoscopic appearances of peritoneal endometriosis. Fertil Steril 1989; 51:637.[Medline]
11. Howard FM. Laparoscopic evaluation and treatment of women with chronic pelvic pain. J Am Assoc Gynecol Laparosc 1994;1: 32531.[Medline]
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