Standardised Registration of Surgical Complications in Laparoscopic-Gynaecological Therapeutic Procedures Using the Clavien-Dindo Classification.

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The registration of complications represents an important component in the evalu- ation of surgical therapeutic procedures. The aim of the present study was to examine the fre- quency of occurrence as well as the severity of surgical complications after laparoscopic-gynae- cological operations in a standardised manner us- ing the Clavien-Dindo system.

Altogether 7438 treat- ment courses after laparoscopic-gynaecological interventions by 9 working groups were eval- uated. Covariates recorded were the technical complexity of the operation, type of study cohort, study size, data acquisition as well as study centre. Target variables recorded were the surgi- cal morbidity rate, subdivided into mild (Clavien- Dindo grade I –II) and severe complications (Cla- vien-Dindo grade III –V). In addition, a binary lo- gistic regression analysis for the mentioned cova- riates and the occurrence of surgical complication was carried out.

946 complications were recorded (over- all complication rate: 13 %). These included 664 mild complications (8.9 %) and 305 severe compli- cations (4.1 %). A correlation was found between the covariates technical complexity (relative risk [rR] 1.37; p < 0.01), study size (rR: 0.35; p < 0.01) and study centre (rR 0.19; p < 0.01) and the occur- rence of surgical complications.

By means of a standardised registra- tion of complications using the Clavien-Dindo classification it appears to be possible to limit the methodologically caused underestimation of sur- gical morbidity in the retrospective evaluation of gynaecological-endoscopic therapeutic proce- dures. Factors decisively influencing the surgical morbidity of gynaecological-laparoscopic thera- peutic procedures are the respective operative ex- perience of the treating facility as well as the tech- nical complexity of the intervention. Zusammenfassung ! Einführung: Die Erfassung von Komplikationen stellt einen wichtigen Bestandteil bei der Evalua- tion operativer Therapieverfahren dar. Ziel der vorliegenden Arbeit war es, die Häufigkeit des Auftretens sowie die Schwere von chirurgischen Komplikationen nach laparoskopisch-gynäkolo- gischen Operationen standardisiert mithilfe des Clavien-Dindo-Systems zu untersuchen.

und Methodik: Insgesamt 7438 Behand- lungsverläufe nach laparoskopisch-gynäkologi- schen Eingriffen, erhoben von 9 Arbeitsgruppen, wurden ausgewertet. Als Kovariaten wurden technischer Schwierigkeitsgrad des Eingriffs, Art der Studienkohorte, Studiengröße, Datenakquise sowie Studienzentrum erfasst. Als Zielvariable wurde die chirurgische Morbiditätsrate, unter- teilt in leichte (Clavien-Dindo Grad I –II) und schwere Komplikationen (Clavien-Dindo Grad III–V) erhoben. Ferner erfolgte eine binär logisti- sche Regressionsanalyse für die aufgeführten Ko- variaten und dem Auftreten von chirurgischen Komplikationen. Resultate: 946 Komplikationen wurden erfasst (Gesamtkomplikationsrate: 13 %). Hierbei handel- te es sich um 664 leichte Komplikationen (8,9 %) und 305 schwere Komplikationen (4,1 %). Es zeig- te sich eine Korrelation zwischen den Kovariaten technischer Schwierigkeitsgrad (relatives Risiko [rR] 1,37; p < 0,01), Studiengröße (rR: 0,35; p < 0,01) und Studienzentrum (rR 0,19; p < 0,01) und dem Auftreten chirurgischer Komplikatio- nen. Schlussfolgerungen: Durch eine standardisierte Komplikationserfassung mithilfe der Clavien-Din- do-Klassifikation erscheint es möglich, die me- thodisch bedingte Unterschätzung der chirurgi- schen Morbidität bei der retrospektiven Auswer- tung von gynäkologisch-endoskopischen Thera- pieverfahren zu begrenzen. Als die chirurgische Morbidität gynäkologisch-laparoskopischer The- Standardised Registration of Surgical Complications in Laparoscopic-Gynaecological Therapeutic Procedures Using the Clavien-Dindo Classification Standardisierte Erhebung chirurgischer Komplikationen bei laparoskopisch-gynäkologischen Therapieverfahren unter Anwendung der Clavien-Dindo-Klassifikation Authors M. P. Radosa1, G. Meyberg-Solomayer 2, J. Radosa 2, J. Vorwergk 1, K. Oettler 1, A. Mothes 1, S. Baum 2, I. Juhasz-Boess 2, E. Petri 3, E. F. Solomayer 2, I. B. Runnebaum 1 Affiliations 1 Department of Gynecology and Obstetrics, Jena University Hospital, Jena 2 Department of Obstetrics and Gynecology, University of Saarland, Homburg/Saar 3 Department of Obstetrics and Gynecology, University Greifswald, Greifswald Key words l" laparoscopy l" gynaecological surgery l" complications Schlüsselwörter l" Laparoskopie l" gynäkologische Chirurgie l" Komplikationen received 7. 4. 2014 revised 18. 6. 2014 accepted 30. 6. 2014

DOI http://dx.doi.org/ 10.1055/s-0034-1382925 Geburtsh Frauenheilk 2014; 74: 752–758 © Georg Thieme Verlag KG Stuttgart · New York · ISSN 0016‑5751 Correspondence Prof. Ingo B. Runnebaum Jena University Hospital Department of Gynecology and Obstetrics Bachstraße 18 07743 Jena [email protected] 752 Radosa MP et al. Standardised Registration of … Geburtsh Frauenheilk 2014; 74: 752 –758 GebFra Science Deutschsprachige Zusatzinformationen online abrufbar unter: www.thieme-connect.de/ ejournals/toc/gebfra

! The registration of postoperative complications represents an es- sential component in the evaluation of surgical treatment proce- dures [1]. Currently the registration of surgical morbidity in clin- ical case series is, however, difficult due to the lack of a widely ac- cepted definition of the term “complication” [2]. Standardised classification systems for recording the surgical morbidity of sur- gical interventions provide uniform definitions for the existence of a complication as well as for its degree of severity. They are thus helpful in the recording of the surgical morbidity of a surgi- cal technique, in the categorisation of the severity of the ob- served event and thus improve the comparability of individual studies on surgical procedures [3]. In the daily clinical routine, standardised systems for recording complications contribute to a structured quality assurance in gynaecological endoscopy and thus to a higher quality of care [4, 5]. The Clavien-Dindo classifi- cation is one such standardised system for the registration of sur- gical complications. It defines the occurrence of a complication as any deviation from the ideal postoperative course that is not in- herent to the operation and that cannot be considered as a ther- apeutic failure of the operation. In concept, the classification is made according to the degree of severity on the basis of the re- spective therapeutic intervention that led to treatment of the ob- served deviation ( l " Table 1 ) [6]. In its current revised form, the Clavien-Dindo classification has experienced an exponential use in visceral and urological clinical research in the course of the past two decades; its use to record surgical complications in the course of scientific evaluations is recommended in the two spe- cialties [7, 8]. In contrast, the use of standardised systems to register surgical complications in general and the use of the Cla- vien-Dindo classification in particular has yet not found regular usage in the published gynaecological research literature. The current evaluation of our own laparoscopic-gynaecological ther- apeutic interventions as well as those of treatment courses from other institutions identified in a selective search of the literature in which the occurrence and degree of severity of surgical com- plications were primarily recorded with the help of the Clavien- Dindo classification was carried out with the objective to exam- ine the frequency of occurrence as well as the degree of severity of surgical complications after endoscopic gynaecological proce- dures by means of a standardised registration method.

! Study design In the present analysis we included 1050 laparoscopic-gynaeco- logical treatment courses from our own groups that were eval- uated in a standardised manner using the Clavien-Dindo classifi- cation as well as 6388 published treatment course from other working groups. The Clavien-Dindo classification as a tool for the standardised registration of surgical morbidity has been in use in the frame- work of clinical research projects in our working group at the De- partment of Gynaecology and Obstetrics, Jena University Hospital since 2009 and since 2011 at the Department of Gynaecology and Obstetrics, University Hospital of the Saarland. For the present analysis all standardised treatment courses after laparoscopic in- terventions that were recorded in the course of scientific clinical evaluations by our group in both treatment centres up to July 2013 were collected in anonymised form in a complication regis- ter by means of an electronic data base (SPSS Statistics, Version 22, IBM, Armonk, USA). For the identification of previously published treatment courses evaluated by means of the Clavien-Dindo classification after lap- aroscopic-gynaecological interventions, we performed a litera- ture search in July 2013 with the help of the databank ISI Web of Science. All original papers and meta-analyses from the field of gynaecology which contained references to the Clavien-Dindo classification among the citations were selected [6, 9]. 57 publica- tions were primarily identified and, in a subsequent step, sub- jected to abstract text analysis in order to select articles concern- ing laparoscopic-gynaecological treatment procedures. Ten con- tributions published by nine working groups were finally chosen (l " Table 2 ) [10 –19] and the described treatment courses were entered into our complication register for further analysis.

of evaluation For the included treatment courses consisting of study cohorts from our own group as well as study cohorts identified by means of a literature search the covariates degree of technical difficulty of the laparoscopic intervention, study size, data acquisition as well as study centre were recorded. For those treatment courses iden- tified by means of the literature search, registration of these co- variates was achieved by a full text analysis of the respective pub- rapieverfahren maßgeblich beeinflussende Faktoren wurden die jeweilige operative Erfahrung der durchführenden Behandlungs- einrichtung sowie der technische Schwierigkeitsgrad des Ein- griffs identifiziert. Table 1 Classification for recording postoperative complications in its revised version according to Clavien and Dindo [6]. Degree Definition I Every deviation from normal postoperative course without the necessity for drug treatment or a surgical, endoscopic or radio- logical intervention. Permissible therapeutic measures: drugs from the substance classes antiemetics, antipyretics, analgesics, diuretics; electro- lyte substitution and physiotherapy. Surgical treatment of wound infections at the bedside. II Drug treatment in excess of the pharmacological measures listed under degree I. Blood transfusions and parenteral nutri- tion. III Necessity for surgical, endoscopic or radiological intervention. III a Intervention without general anaesthesia. III b Intervention with general anaesthesia. IV Life-threatening complications leading to transfer to an inter- mediate care or intensive care unit. IV a Dysfunction of an organ system (including the necessity for temporary dialysis). IV b Multiorgan dysfunction. V Death of the patient. Suffix d The complication degree is given the suffix “d” if the complica- tion needs further treatment after release of the patient from hospital. 753 Radosa MP et al. Standardised Registration of … Geburtsh Frauenheilk 2014; 74: 752 –758 Original Article lication. For an assignment according to degree of technical diffi- culty of the respective laparoscopic procedure, we used the clas- sification suggestion by the group of Barakat and Abu-Rustum in- to interventions with low or medium degrees of technical diffi- culty (Levels I –II) and those with enhanced or higher degrees of difficulty (Levels III –IV) (l " Table 3) [10]. For the type of study co- hort we distinguished between mixed study cohorts and study cohorts in which exclusively the treatment courses of gynaeco- logical-oncological patients were assessed. For the covariate study size treatment courses from research projects with patient cohorts containing less than 500 patients and analyses with co- horts of 500 or more patients were compared. For the covariate data acquisition a distinction was made as to whether the post- operative complications arising in the included treatment courses were recorded retrospectively or prospectively. With re- gard to the covariate study centre , a comparison was made be- tween treatment courses evaluated by our own group and the treatment courses from other working groups. For the included treatment courses the postoperative complications recorded as target variables by means of the Clavien-Dindo classification were subdivided into mild (Clavien-Dindo grade I –II) and severe complications (grade III –V). Complications of severity degree V according to Clavien-Dindo were used for calculation of the mor- tality rate in the evaluated treatment courses. Statistics After a descriptive analysis of the data, further investigations with regard to a relationship between the above-mentioned co- variates and the occurrence of postoperative complications were undertaken. For this we performed a binary logistic regression analysis for the covariates degree of technical difficulty, cohort size, data acquisition, study cohort and study centre and the occur- rence of postoperative complications overall , the occurrence of mild postoperative complications and the occurrence of severe postoperative complications. For each covariate we also calculated the Wald statistics, the relative risk, the significance level p, and the 95 % confidence interval.

! Descriptive analysis Altogether 7438 treatment courses were included in the analysis. Of these 1050 treatment courses from our own working groups within the framework of four clinical evaluations on laparoscop- ic-gynaecological treatment procedures were assessed. At the Department of Gynaecology and Obstetrics, Jena University Hos- pital the surgical morbidity of 553 interventions was recorded retrospectively, of these 451 interventions were of degree of techninal difficulty II and 102 interventions were of technical dif- ficulty degree III [20, 21]. 497 treatment courses from the Depart- ment of Gynaecology and Obstetrics at the University of the Saar- land were evaluated, of these 202 treatment courses were of dif- ficulty degree II in the framework of a retrospective evaluation on quality of life after laparoscopic hysterectomy and 295 were of difficulty degree II in a prospective clinical investigation on pain reduction after laparoscopic total or subtotal hysterectomy [22]. The 6388 treatment courses identified by means of the literature search were reported by a total of nine working groups. In three original papers and one meta-analysis the perioperative morbid- ity after laparoscopic hysterectomy was recorded, three contri- butions reported surgical complications after laparoscopic, retro- Table 2 Selected publications. Study Publication type Therapeutic procedures n Degree of difficulty Study cohort Data acquisition Chi D et al., 2004 [10] original paper various surgical procedures 1 451 I/II/III/IV oncological prospective Siedhoff MT et al., 2012 [11] original paper hysterectomy 834 II mixed retrospective Alperin M et al., 2012 [12] original paper hysterectomy 446 II mixed retrospective Fagotti A et al., 2012 [13] original paper radical hysterectomy with retro- peritoneal lymphadenectomy 75 IV oncological retrospective Soudaka A et al., 2012 [14] original paper retroperitoneal lymphadenectomy 98 IV oncological retrospective Palomba S et al., 2012 [15] original paper retroperitoneal lymphadenectomy 403 IV oncological retrospective Kondo W et al., 2011 [16] original paper hysterectomy 2 092 II mixed retrospective Kondo W et al., 2011 [17] original paper resection of deeply infiltrating endometriosis 568 IV mixed retrospective Gendy R et al., 2011 [18] meta-analysis hysterectomy 332 II mixed prospective Hong JH et al., 2010 [19] original paper retroperitoneal lymphadenectomy 89 IV oncological retrospective Study: included publications; Therapeutic procedures: investigated laparoscopic therapeutic procedure; n: number of included treatment courses; Degree of difficulty: technical degree of difficulty of the analysed therapeutic procedure according to Barakat (Chi et al., 2004); Study cohort: type of investigated study collective; Data acquisition: type of data acquisition. Table 3 Classification laparoscopic interventions according to degree of technical severity after Chi et al. [10]. Degree of difficulty Type of intervention Stage I diagnostic laparoscopy Stage II " uni- or bilateral adnexectomy " uni- or bilateral cyst ablation on the ovary " hysterectomy (laparoscopic, supracervical, laparoscopy-assisted vaginal) " myomectomy " adhesiolysis/resection of superficial endometriosis lesion Stage III " second-look laparoscopy after laparotomy in gynaecological-oncological patients " reconstructive uro-gynaecological surgery " adhesiolysis after oncological, surgical interventions in abdomen or pelvis Stage IV " retroperitoneal lymphadenectomy " extended hysterectomy " resections of intestine/bladder/ureter with or without laparoscopic suture or, respectively, anastomosis 754 Radosa MP et al. Standardised Registration of … Geburtsh Frauenheilk 2014; 74: 752 –758 GebFra Science peritoneal lymphadenectomy and in one study each the surgical morbidity after laparoscopic resection of deeply infiltrating en- dometriosis and after laparoscopic radical hysterectomy with retroperitoneal lymphadenectomy was evaluated. One last pub- lication reported a standardised investigation of the complica- tion rates in oncological patients after laparoscopic gynaecolog- ical interventions of various types ( l " Table 4 ). Altogether 146 laparoscopic interventions of difficulty degree I, 5654 interventions of difficulty degree II, 326 interventions of difficulty degree III and 1312 interventions of difficulty degree IV were evaluated. The registration of the occurring postoperative complications was retrospective in 5360 treatment courses and in the frame- work of prospective clinical evaluations in 2078 treatment courses. 5220 treatment courses were recorded in investigations in which exclusively patients with a malignant underlying disease were included; 2218 treatment courses were from mixed patient col- lectives. 2493 of all included treatment courses were from clinical investi- gations involving cohorts of 500 or fewer patients, 4945 treat- ment courses were recorded in studies on cohorts of 500 or more patients. Logistic regression analysis In the entire investigated collective, 969 complications occurred (overall complication rate: 13 %). Of these 664 were mild compli- cations (Clavien-Dindo grade I –II; 8.9 %) and 305 were severe complications (grade III –V; 4.1 %). The mortality rate in the ob- served collective amounted to 0.1 % ( l " Table 4). The binary logistic regression analysis revealed a significant de- pendence between the covariates degree of technical difficulty, study size ,a n d study centre and the occurrence of surgical com- plications overall. The covariates data acquisition and study col- lective did not have a significant influence on the overall rate of observed complications. After interventions with enhanced and higher degrees of diffi- culty complications occurred significantly more frequently (rR: 1.37; p < 0.01). The reason for the increased rate of surgical mor- bidity was the increased occurrence of severe complications after interventions with enhanced and higher degrees of difficulty (grade III–V; rR: 2.37; p < 0.01). In contrast, for the occurrence of mild complications (grade I –II) there was no significant differ- ence between interventions with enhanced and higher degrees of difficulty and those with low or moderate degrees of difficulty. In clinical investigations of cohorts with 500 and more patients a significantly lower rate of complications was observed compared to those with less than 500 patients (rR: 0.35; p < 0.01). This ap- plied not only to the frequency of occurrence of mild complica- tions (rR: 0.33; p < 0.01) but also to the occurrence of severe com- plications (rR: 0.41; p < 0.01). Furthermore in treatment courses from the studies of our own working group a significantly lower rate of complications was ob- served (rR: 0.19; p < 0.01). This lower risk could be observed not only for the occurrence of mild complications (rR: 0.2; p < 0.01) but also for the occurrence of severe complications (rR: 0.23; p < 0.01) (l " Table 5). Table 4 Survey – evaluated study collectives. Study cohort Cohort size (n) Degree of technical difficulty after Barakat Complications according to Clavien-Dindo degree of severity (n) Complications overall n I II III IV V (n) (%) Our own working group 1 050 65 6.19 II 948 26 13 14 0 0 53 III 102 6 5 1 0 0 12 Chi et al. 1 451 129 8.89 I 146 14 1 4 0 3 22 II 1 002 42 24 20 0 0 86 III 224 5 5 6 1 0 17 IV 79 1 1 2 0 0 4 Siedhoff et al. 834 130 15.59 II 834 10 78 38 4 0 Alperin et al. 446 82 18.39 II 446 30 27 23 2 0 Fagotti et al. 75 34 IV 75 0 2 1 0 0 Soudaka et al. 98 8 8.16 IV 98 0 0 7 1 0 Palomba et al. 403 166 41.21 IV 403 44 28 52 40 2 Kondo et al. 2 660 264 9.92 II 2 092 100 55 31 0 0 186 IV 568 38 12 28 0 0 78 Gendy et al. 332 113 34.04 II 332 30 64 19 0 0 Hong et al. 89 8 8.98 IV 89 4 2 2 0 0 755 Radosa MP et al. Standardised Registration of … Geburtsh Frauenheilk 2014; 74: 752 –758 Original Article

! Gynaecological-laparoscopic interventions are in general associ- ated with a low surgical morbidity [23 –25]. This estimation has been decisively influenced by two investigations on the postop- erative morbidity after minimally invasive gynaecological inter- ventions from the last decade of the last century. Chapron and coworkers retrospectively determined the surgical complication rate after gynaecological-laparoscopic operations in seven uni- versity endoscopic centres in the period from 1985 to 1995, with inclusion of altogether 29 966 patients. The overall complication rate in the investigated collective was given as 0.46 %. According to a free-text analysis of the complications listed in the publica- tion there were 96 adverse events that could be assigned to Cla- vien-Dindo severity stage III and higher. This corresponds to a rate of severe complications of 0.32 % [26]. In a second study in 1997 Harkki-Siren evaluated the data of the Finnish statutory health insurance with regard to claims for reimbursement due to surgical complications after gynaecological-laparoscopic in- terventions. In the observation period, the statutory insurance funds reimbursed the costs for 70 607 gynaecological-laparo- scopic operations whereby 0.36 % reimbursement claims due to surgical complications were recorded; in the total of 10 pro- cessed claims, the responsible health insurance authorities re- ported just one case due to a “severe complication”. The defini- tion of the term “severe complication” used here essentially cor- responds to the severity degree III –V according to Clavien-Dindo [27]. Thereafter appreciably higher complication rates for gynaecolog- ical-laparoscopic interventions were reported in prospectively collected monocentric studies. Mirhashemi determined the sur- gical morbidity rates after gynaecological-laparoscopic interven- tions in an academic teaching hospital; the overall complication rate in this study amounted to 19.6 % and the rate of severe com- plications with an indication for surgical revision to 4.7 % [28]. Saidi reported on a similar complication rate (10.4 % overall; 5.1 % severe complications) after gynaecological-laparoscopic in- terventions of various degrees of difficulty [29]. A French report evaluated 1033 gynaecological-laparoscopic procedures of mod- erate and enhanced degrees of difficulty (stages III and IV accord- ing to Barakat) at a single treatment centre and stated a compli- cation rate of 3 %, the complications mentioned in the publication can be assigned to severity stages III to V according to Clavien- Dindo [30]. In our own analysis of the data from 10 treatment centres on gy- naecological-laparoscopic interventions the determined compli- cation rate was in a comparable order of magnitude with the re- sults of the prospective monocentric studies mentioned above. In comparison with the retrospective evaluations of Chapron and Hakki-Siren, not only the overall complication rate but also the rate of severe complications were, in contrast, about 10-fold higher. The reason for such a widely different evaluation of the postoperative morbidity risk of gynaecological-laparoscopic op- erations seems to be inherent to the methodology: Hakki-Siren did not determine the complication rate by evaluation of individ- ual treatment courses but rather from the ratio of reimburse- ment claims due to surgical complications to the number of all gynaecological-laparoscopic operations reimbursed by the Fin- nish statutory health insurances in the observation period. The use of such a surrogate parameter for surgical morbidity after op- erative interventions could represent a bias in the sense of an underestimation of the actually occurring complication rates. In the investigation of Chapron it is not clear which definition of the term “complication” was used in the evaluation of the study collective; a standardised procedure for the registration of the complications occurring in the investigated patient collective was not described in the publication. A free-text analysis of the complications listed by the authors could place them in the se- verity grades III and higher according to the Clavien-Dindo classi- fication. The occurrence of complications of the severity grades I and II was not reported, this could be indicative of a systematic underestimation in the registration of complications. On the whole, the differing evaluations of the morbidity of gy- naecological-laparoscopic operations by the individual working groups suggests that the use of a laparoscopic approach as such should not a priori be set as being equal to a low complication rate. Instead, it seems that the risks for complications in gynaeco- logical-laparoscopic operations is influenced to an appreciable extent by covariates. Table 5 Binary logistic regression analysis, risk factors for the occurrence of complications. Covariate Wald Relative risk p 95 % Confidence interval lower value upper value Complications overall Enhanced technical difficulty 16.32 2.04 < 0.01 1.44 2.89 Large study cohort (≥ 500) 59.98 0.35 < 0.01 0.26 0.45 Own working group 34.87 0.19 < 0.01 0.11 0.34 Oncological study cohort 0.84 1.18 0.36 0.82 1.69 Retrospective data acquisition 2.81 0.74 0.09 0.52 1.05 Mild complications (Clavien-Dindo I–II) Enhanced technical difficulty 7.45 0.75 0.06 0.62 1.02 Large study cohort (≥ 500) 91.41 0.41 < 0.01 0.34 0.49 Own working group 76.51 0.23 < 0.01 0.17 0.32 Severe complications (Clavien-Dindo III–V) Enhanced technical difficulty 46.47 2.37 < 0.01 1.85 3.03 Large study cohort (≥ 500) 75.38 0.33 < 0.01 0.26 0.42 Own working group 37.15 0.19 < 0.01 0.11 0.32 Enhanced technical difficulty: laparoscopic intervention with degrees of difficulty stages III and IV according to Barakat; large study cohort ( ≥ 500): analysed treatment courses from study collectives of 500 and more patients; own working group: analysed treatment courses from our own working group; oncological study cohort: analysed treatment courses from oncological study collectives; retrospective data acquisition: retrospective analysis of treatment courses. 756 Radosa MP et al. Standardised Registration of … Geburtsh Frauenheilk 2014; 74: 752 –758 GebFra Science Among the as yet identified factors responsible for the increased complication risks of gynaecological endoscopy are the degree of technical difficulty of the respective surgical procedure [4], the surgical experience of the operator as well as the question [31] as to whether the respective surgical method is a new or a well established process at the corresponding treatment centre [32, 33]. The influence of accompanying malignant diseases on the surgical morbidity is not evaluated uniformly. Whereas some au- thors described a significantly higher rate of complications for gynaecological-laparoscopic operations for patient collectives with malignant underlying diseases, other working groups could not detect such a correlation [34, 35]. Last but not least, some au- thors view a retrospective non-standardised registration of the surgical morbidity in the evaluation of surgical treatment proce- dures as a methodologically intrinsic reason for a systematic underestimation of the actually occurring complication rates [36]. An association of, on the one hand, the degree of technical diffi- culty of a laparoscopic intervention and, on the other hand, sur- gical complications was also observed in our studies: interven- tions with the degrees of difficulty of III and IV according to Bar- akat exhibit a significantly higher number of severe complica- tions and, in turn, a significantly higher rate of overall morbidity for this intervention group. If we compare the complication rates of gynaecological-laparoscopic treatment procedures with en- hanced and higher degrees of difficulty in our own analysis with published data from the last decade of the last century we could get the impression that nowadays such operative interventions paradoxically have a higher rate of morbidity. The averaged com- plication rate from 10 studies in the years 2004 to 2013 in our own analysis amounts to 18.07 %; in contrast Chapron in 1998 re- ported a complication rate of merely 8.9 % for laparoscopic inter- ventions with an advanced degree of difficulty [26]. A reason for this observed increase of surgical complications in gynaecologi- cal-laparoscopic interventions with enhanced and advanced de- grees of difficulty could be the ongoing development of endo- scopic techniques and the thus associated extension of the field of application of these therapeutic procedures: Chapron used a classification according to Querleu to subdivide the investigated endoscopic treatment procedures according to the respective de- gree of difficulty [37]. According to Querleu the performance of a laparoscopic hysterectomy is assigned as an intervention of cate- gory IV, the highest degree of severity in this classification. More recent classification systems such as the division according to Chi et al. used in our investigations, in contrast, assign laparoscopic hysterectomy as an intervention of the category II (medium de- gree of difficulty) [10]. On the other hand, surgical techniques, such as laparoscopic retroperitoneal lymphadenectomy, which have expanded the spectrum of endoscopic surgery in gynaecol- ogy in the past decades, are considered as interventions of a higher degree of difficulty (category IV). The results of our own investigations suggest that these interventions differ markedly with regard to their postoperative morbidity from the diagnostic and therapeutic interventions of difficulty stages I and II accord- ing to Chi. Previous reports have demonstrated a dependence of the surgical morbidity not only on the surgeon ʼs degree of experience with the respective laparoscopic operation but also on the amount of experience with endoscopic procedures of the entire treating centre [29, 38]. Here there are differing opinions about the re- quired number of completed surgical interventions in order to ensure the secure mastery of a gynaecological laparoscopic treat- ment. While in some investigations a learning curve of about 30 operations is considered to be sufficient for an experienced sur- geon to learn even technically demanding gynaecological-lapa- roscopic interventions (degree of difficulty IV according to Chi) [19], in a study collective comprising surgeons with different lev- els of training, other authors have observed an increase in expe- rience as reflected in a decline in the rate of surgical complica- tions even after the performance of 500 laparoscopic interven- tions [39]. In our own analysis we oriented ourselves on the sec- ond estimation of the endoscopic learning curve on the basis of a

value of 500 performed operations. In such an evalua- tion there are hints towards a relationship between the experi- ence with laparoscopic methods in the respective treatment centre and the occurrence of surgical complications: in the in- volved study collectives of more than 500 treatment courses a significantly lower rate of complications was observed. This re- sult can be objectively related to the fact that, in each of the six publications with study collectives of less than 500 patients in- cluded in this analysis, experience in the establishment of an up to now new operation technique for the respective study centre was evaluated. Regarding the question if and to what extent an underlying ma- lignant disease increases the risk for developing complications after gynaecological-laparoscopic interventions, only few studies are available yet: Erekson referred to a case series that analysed predominantly vaginal-operative and gynaecological-surgical in- terventions performed per laparotomy which revealed a high morbidity risk for patients with an underlying malignant disease [40]. It is not clear to what extent these results may be trans- ferred to gynaecological-laparoscopic procedures. In our own analysis the presence of an underlying malignant disease was not an independent risk factor for the occurrence of surgical complications. Instead, in the numerically largest included co- hort of oncological treatment courses, an assessment by a group at Memorial Sloan-Kettering Cancer Center, an even lower com- plication rate was seen in comparison to the averaged overall morbidity of our investigation (9 % compared to 13 %). The low complication rate of the study cohort at this specialist centre em- phasises the significance of an expertise in gynaecological-lapa- roscopic therapy procedures that is not limited to just technical aspects for the avoidance of surgical complications [10]. In our own analysis, no significant differences were found in complication rates for retrospectively and prospectively eval- uated treatment courses. This observation might suggest that the registration of surgical complication rates in retrospective co- hort studies could be improved with the help of the Clavien-Din- do system so as to approach the validity of complication rates de- termined in prospective studies. Beside the terminologically pre- formulated definition of the term “surgical complication ”,t h e conceptual structure of the Clavien-Dindo classification could al- so be of importance: the division of the degree of severity of a complication is oriented to the respective therapeutic interven- tion, which would be necessary for the correction of deviations (e.g., antibiosis, operative revision). Since these therapeutic mea- sures are regularly documented in the patient records, such a classification facilitates a valid retrospective registration of com- plications in surgical case series. 757 Radosa MP et al. Standardised Registration of … Geburtsh Frauenheilk 2014; 74: 752 –758 Original Article

for Clinical Practice ! With the use of of Clavien-Dindo classification it appears to be possible to limit the methodologically derived underestimation of surgical morbidity in the retrospective evaluation of gynaeco- logical-endoscopic therapeutic procedures. Our own analysis has identified the respective surgical experience of the treating centre as well as the degree of difficulty of the respective inter- vention to be factors decisively influencing the surgical morbid- ity of gynaecological-laparoscopic therapeutic procedures.

! The colleagues at the XXIII. Akademische Tagung Deutschspre- chender Hochschullehrer in der Gynäkologie und Geburtshilfe of September 2013 are particularly thanked for their numerous constructive suggestions that served to improve this article. Conflict of Interest ! None.

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