1 Isis Fertility Centre, Colchester CO4 9YA, 2 Southern General NHS Trust, Glasgow G51 4TF, 3 Information and Statistics Division, Common Services Agency, Trinity Park House, Edinburgh EH5 3SQ 4 Evicom, Twickenham TW1 2AA, and 5 Corvus, Buxted TN22 4PB, UK
6 To whom correspondence should be addressed. Email: adrian{at}lower.com
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Abstract |
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Key words: adhesions/epidemiology/gynaecology/laparoscopy/SCAR
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Introduction |
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Post-surgical adhesions form as a result of a range of insults (such as surgical trauma, infection, ischaemia, and exposure to intestinal contents and foreign materials) that disrupt the peritoneum and cause inflammation (Diamond and Freeman, 2001). Adhesion development begins during surgery and proceeds rapidly. Re-epithelialization is achieved within 57 days and adhesion formation follows if damaged surfaces remain in apposition (Holmdahl et al., 1997
; diZerega and Campeau, 2001
).
Corrective surgery is often required to resolve adhesion-related complications; however, additional surgery tends to encourage the development of additional (de-novo) adhesions and the reformation of lysed adhesions (Beck et al., 2000). As many as 93% of patients undergoing laparotomies develop adhesions attributable to earlier surgery (Menzies and Ellis, 1990
) and up to 85% of adhesions reform following adhesiolysis (Diamond and Freeman, 2001
). Furthermore, reformed adhesions tend to be denser and more severe than de-novo adhesions (van der Krabben et al., 2000
).
With the increasing use of surgery to treat gynaecological conditions (particularly infertility), adhesions now represent a growing problem for gynaecologists (Lower et al., 2000). Intra-abdominal adhesions occur in 6090% of women who have undergone major gynaecological procedures and account for 1520% of cases of secondary infertility (Mishell and Davajan, 1991
; Liakakos et al., 2001
). They are also associated with substantial morbidity, constituting one of the most common causes of pelvic pain in women (Mishell and Davajan, 1991
; Howard, 1993
; Duffy and diZerega, 1996
; Diamond and Freeman, 2001
). Furthermore, initial surgery in one region may result in adhesions in another, such that women undergoing gynaecological procedures may develop adhesive small bowel obstruction (Lower et al., 2000
).
The Surgical and Clinical Adhesions Research (SCAR) study was an epidemiological study that investigated the burden of post-surgical adhesions by analysing hospital readmissions in Scottish National Health Service (NHS) patients (n=54380) within the 10 years following initial open abdominopelvic surgery during 1986. The study included an assessment of the impact of adhesions following initial open gynaecological surgery in a cohort of 8849 women (Ellis et al., 1999; Lower et al., 2000
). The results demonstrated clearly that the clinical burden, workload and relative risk of hospital readmissions associated with post-surgical adhesions were considerable. In total, more than one in three women were readmitted on average 1.9 times during the 10-year follow-up for further surgery or for problems potentially related to adhesions (Lower et al., 2000
).
Whilst the SCAR study demonstrated clearly the burden of adhesions associated with open gynaecological surgery, data concerning the impact of adhesions following gynaecological laparoscopy are lacking. Laparoscopic surgery was in its infancy in 1986 and was used primarily as a diagnostic, rather than a therapeutic, procedure. Since then, laparoscopy has become the preferred method of access for certain gynaecological interventions, and has been claimed to be associated with lower rates of adhesion development (Garrard et al., 1999; Kavic, 2002
). The objective of this study was to compare the epidemiology of adhesion-related readmissions in the 4 years following initial open surgery with that following initial laparoscopic gynaecological surgery.
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Methods |
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Office of Population Censuses and Surveys', Fourth Edition (OPCS4) surgical procedure codes were identified in duplicate by members of the study steering group to determine open and laparoscopic gynaecological procedures (excluding Caesarean sections) that were likely to cause adhesions (Government Statistical Service, 2001). Based on these codes, two incident patient cohorts were defined within the database, comprising those undergoing initial laparoscopic gynaecological surgery (n=15 197) and those undergoing initial open gynaecological surgery (n=8849) in the financial year April 1996 to March 1997 (19961997). Adhesion-related readmissions were tracked over 4 years following initial surgery.
Initial open surgical procedures were classified by operation site, according to OPCS4 codes, as procedures performed on the Fallopian tubes, ovaries, uterus and vagina. Since OPCS4 codes for the classification of laparoscopic procedures are less specific than those describing open surgery, the laparoscopic cohort was subdivided into procedures associated with high, medium and low risks of adhesion-related readmissions. Laparoscopic adhesiolysis and cyst drainage operations constituted high-risk procedures, Fallopian tube sterilizations were categorized as low-risk procedures, and medium-risk procedures were represented by all other therapeutic and diagnostic laparoscopies (including other tubal procedures) (Table I). Most interventions in the medium-risk group (99%) were categorized under code T439: unspecified diagnostic endoscopic examination of the peritoneum.
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Data were also collected for patients undergoing initial open and laparoscopic surgery in the financial years April 1997 to March 1998 (19971998) and April 1998 to March 1999 (19981999). Patients were followed up for 2 years and data were compared with the 19961997 cohort to identify any variation in readmissions between years and to determine time to first directly/possibly adhesion-related readmission. Where patients had a directly and a possibly related readmission within the same year, only the first event was counted when they were combined, as this was thought to best reflect the time lapse between initial surgery and the first requirement for further treatment. It should be noted that, because only the first event was counted, addition of the directly related and possibly related readmission data does not equal the sum of the directly/possibly related readmission data. The incidences of readmissions in the 3-yearly cohorts were compared using Peto's log-rank test (Peto et al., 1977).
A final objective was to assess the impact of previous surgery on adhesion-related readmissions by identifying patient subgroups within the 19961997 open and laparoscopic cohorts who had had no abdominopelvic surgery within the previous 5 years. To identify these patients, all OPCS4 readmission codes were matched, where possible, to the earlier OPCS3 codes, as coding had changed in 1989 (Ellis et al., 1999; Lower et al., 2000
).
Adhesion-related readmissions in all cohorts are expressed as rates of patient readmission and rates of readmission episodes. Readmission episode rates are presented because some patients were readmitted more than once, and are expressed as a percentage of the total number of initial surgical procedures; the risk of a readmission was calculated from these percentages.
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Results |
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Freeing of adhesions of the peritoneum represented the most common directly adhesion-related surgical cause of readmission in patients undergoing initial open surgery on the Fallopian tubes, ovaries and uterus (Table III). The most common non-operative reason for a directly adhesion-related readmission was intestinal adhesions with obstruction. None of the patients undergoing initial open surgery on the vagina required readmission for directly adhesion-related operative or non-operative causes (Table III).
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Discussion |
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Some caution is required when interpreting data concerning medium-risk interventions, since these comprised a range of diagnostic procedures that may have identified pre-existing adhesions, adhesion-related problems or conditions associated with the formation of adhesions (such as endometriosis) rather than representing causes of adhesion formation or re-formation. Furthermore, because coding for laparoscopic surgery has lagged behind the rapid advancements in this field, appropriate codes were not available to describe certain therapeutic laparoscopic procedures, resulting in the possible inclusion of therapeutic interventions in this risk group. For these reasons, this category was associated with greater risks of adhesion-related readmissions than might be expected. Further work is required to complete development of appropriate codes for the description of laparoscopic procedures.
OPCS4 surgical codes do not enable direct comparisons to be made between specific open and laparoscopic procedures, because laparoscopic surgical procedures have advanced beyond the limits of the OPCS4 coding system. However, evaluation of the readmission rates associated with high-risk laparoscopy (including many ovarian procedures) compared with ovarian (high-risk) laparotomy provides some indication that laparoscopy is less adhesiogenic. After 4 years, 33.0% of patients undergoing initial high-risk laparoscopy had been readmitted as a result of possibly adhesion-related events, compared with 43.6% of those undergoing initial ovarian laparotomy. However, the higher frequency with which gynaecological laparoscopies are performed may result in a higher overall burden of adhesion-related readmissions, and consequently a greater surgical workload, compared with laparotomy.
Strong evidence is available to suggest that previous laparotomy is a major risk factor for adhesion development and adhesion-related hospital readmissions (Menzies and Ellis, 1990; Ellis et al., 1999
; Beck et al., 2000
), and the present investigation provides further evidence to support this. Rates of directly adhesion-related readmissions at 1 year following both laparotomy, and particularly high-risk laparoscopy, were reduced and maintained over the following 3 years when patients who underwent surgery within the previous 5 years were excluded. A substantial proportion of high-risk laparoscopic procedures (26.1%) comprised interventions for the endoscopic division of adhesions of the peritoneum. It is probable that previous surgery represented a major contributory factor in the development of such adhesions, so the exclusion of patients who had undergone surgery within the previous 5 years is likely to have reduced substantially the number of patients requiring this intervention, and thus the proportion of patients requiring hospital readmission for adhesion-related events.
The most common surgical cause of directly adhesion-related readmissions in patients undergoing both initial laparotomy and initial laparoscopy was freeing of adhesions of the peritoneum, whereas the most common cause in those not proceeding to surgery was intestinal adhesions with obstruction. It is recognized that surgery on the female reproductive tract can cause adhesion formation at other surgical sites, including the peritoneum and small bowel (Lower et al., 2000), and the current study supports these conclusions. It is interesting to note that the most common cause of non-operative readmissions possibly related to adhesions in all laparotomy subgroups was unspecified pain. The association between adhesions and pain is a complex one that remains a subject of debate (Diamond and Freeman, 2001
). However, numerous studies have shown a correlation between the presence of adhesions and pelvic pain, and adhesive disease is now considered to be one of the most common causes of chronic pelvic pain in women (Mishell and Davajan, 1991
; Howard, 1993
; diZerega, 1997
; Diamond and Freeman, 2001
).
In conclusion, data from the present investigation indicate that gynaecological laparoscopic and open surgical procedures are associated with comparable risks of readmission for adhesion-related problems. The current study is likely to have underestimated the number of directly adhesion-related readmissions because a substantial proportion of patients classified in the possibly adhesion-related category may have had directly adhesion-related complications. Furthermore, data from the 19971998 and 19981999 cohorts show little reduction in the rate of adhesion-related readmissions compared with the 19961997 cohort. It should be noted that, whereas the use of adhesion-prevention adjuvants has increased in recent years, their use in Scotland at the time of this study was very limited and was mainly confined to open surgical procedures. This may explain the comparable adhesion-related readmission rates associated with the yearly cohorts. Such findings indicate that gynaecological laparoscopy and laparotomy continue to exert a considerable impact on healthcare resources in terms of an adhesion-related burden, and that this burden is unlikely to decline. A cost-effectiveness model based on lower abdominal surgery cohorts from the SCAR database predicted that the cumulative year-on-year direct costs of adhesion-related readmissions for a 10-year period would be more than £569 million (Wilson et al., 2002). While similar data are, as yet, unavailable concerning gynaecological surgery, these calculations suggest that the economic costs resulting from adhesions associated with gynaecological procedures are likely to be considerable. Analyses of a similar model relating to gynaecological procedures are planned to address the issue of cost-effective interventions.
A range of strategies is available to minimize the risk of adhesion formation, including gentle tissue handling, meticulous haemostasis, minimally invasive surgery, constant irrigation and minimal foreign body contact (Holmdahl et al., 1997; Ling et al., 2002
). However, data from the present study indicate that such strategies have had little impact to date. For women undergoing gynaecological surgery, and particularly those undergoing tubal and ovarian surgery procedures, who wish to conceive, the implementation of good surgical practice, together with the widespread adoption of adhesion-reduction agents, may help to reduce readmission rates and minimize the risk of complications such as bowel obstruction, secondary infertility and chronic pain. Through such methods, it is to be hoped that we may reduce the burden of adhesive disease for both patients and health-care providers.
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Acknowledgements |
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Fellow SCAR advisers: Professor Harold Ellis, Guy's, King's and St Thomas' School of Biomedical Sciences, King's College, London; Malcolm Wilson, Christie Hospital, Manchester; Donald Menzies, Colchester Hospital, Colchester; Michael Parker, Darent Valley Hospital, Dartford; Graham Sunderland, Southern General Hospital, Glasgow; Jeremy Thompson, Chelsea and Westminster Hospital, London; Brendan Moran, North Hampshire Hospital, Basingstoke; Professor Ian Ford, Robertson Centre for Biostatistics, University of Glasgow, Glasgow, UK.
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Submitted on February 9, 2004; accepted on April 23, 2004.
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