PDS (Polydiaxonene Suture) Versus Prolene (Polypropylene Suture) as Suture Material for Vaginal Sacrospinous Hysteropexy - a Randomised Controlled Study
Phase: NA
Conditions: Pelvic Organ Prolapse, Prolapse
Sponsor: Medical University of Vienna

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Study Protocol and Statistical Analysis Plan 
 
PDS (polydiaxonene suture) versus prolene (polypropylene 
suture) as suture material for vaginal sacrospinous 
hysteropexy – a randomised controlled study 
 
 
10.05.23 
 
2079/2022 
Medical University of Vienna 
 

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1. Introduction 
Lifetime risk for pelvic organ prolapse (POP) is high and around 3-6% of symptomatic 
POP are associated with  symptoms connected to a decisive lower quality of life, 
including bladder and bowel issues as well as sexual dysfunction [1,2]. Therefore, 
these women should be offered feasible, safe, and functional treatment options. 
Individual treatment plans based on patient's expectations wishes and necessities 
should be chosen. Treatment options can range from conservative pessary 
application to various surgical repair methods [3,4], with 11-19% in women reported 
to be undergoing surgery for prolapse or incontinence [5] . As women have 
expressed more and more the desire to keep their uterus, uterine-preserving 
procedures such as vaginal sacrospinous hysteropexy (SSH) have become an 
increasingly utilized surgical option for the primary treatment of POP [3]. 
Sacrospinous hysteropexy is an uterine-preserving, well established surgical 
procedure that gained popularity after the publication of the SAFE U trail conducted 
by the Dutch research group of Detollenaere and Schulten et al. about its successful 
use [6,7]. Furthermore, several studies investigated the surgical outcomes after the 
different types of surgery and concluded that compared with vaginal hysterectomy 
with apical fixation, SSH has similar or possibly even better outcomes [8–10].   As 
such it has also become the most commonly performed uterine-preserving surgical 
technique at our institution.  
However, it is crucial also to identify surgical variables that may have an impact on 
the outcomes of prolapse surgery: especially as the scientific evidence guiding the 
choice of suture material in sacrospinous hysteropexy is scant. In their SAFE U trail 
Detollenaere et al. used prolene as suture material, however patients reported 
buttock pain for some time after the intervention [6]. At our institution we mainly use 

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PDS sutures as a late resorbable suture material and noticed no such claims from 
patients. 
The aim of this RCT is to investigate the effects of resorbable (PDS) versus non-
resorbable (prolene) suture material in patients with symptomatic POP undergoing 
vaginal sacrospinous hysteropexy.  
 
2. 
Experimental Plan 
 
2.1 Study hypothesis 
Primary study hypothesis is that patients receiving a sacrospinous hysteropexy with 
non-resorbable Prolene sutures (study group) experience a better subjective 
symptom improvement (evaluated by the prolapse domain score of the Deutscher 
Beckenboden Fragebogen [11]) assessed at 12 months after surgery, than patients 
with  resorbable PDS sutures (control group).  
The secondary hypotheses are, that the study group will have: 
- 
better anatomical outcomes (better rate anatomical outcome in each 
compartment (change in POP-Q values from baseline) [12]),  
- 
better condition-specific quality of life scores (changes in questionnaire from 
baseline), 
- 
less postoperative complications (haematoma, vesico-vaginal fistula, ureteral 
obstruction, urinary tract infection, incomplete bladder emptying, overactive 

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bladder or stress incontinence symptoms, suture erosion, vaginal wound 
dehiscence, infection or granulation tissue, etc),  
- 
lower use of pain killers for buttock pain during the hospital stay and in the 12 
months postoperative period 
- 
lower pain levels (assessed through the standardised Visual Analog Scale 
(VAS) and Numeric Rating Scale (NRS) [13]) at postoperative day 1, at 
discharge, at 4 to 6 weeks, 6 and 12 months. 
 
2.2 Study design 
This trial is a single-centre, prospective, randomized trial conducted with the aim of 
determining the superiority of non-absorbable prolene over absorbable PDS suture 
material with regard to the primary outcome in POP patients undergoing 
sacrospinous hysteropexy. The study will be a single-blind study, as it is impossible 
to blind the study surgeon for the surgical procedure to which the subject is assigned. 
However, all outcome assessors and the subjects will be blinded to the assigned 
treatment. Postoperative follow-up will take place after 4-6 weeks, 6 months and 12 
months. Patients will undergo a standardized urogynaecologic examination that 
includes assessment of prolapse with POP-Q measurement [12]. Furthermore 
subjective outcome will be assessed with standardized questionnaires – our study 
participants will receive the German version of the pelvic floor questionnaire [11]. 
 
2.3 Study setting 
This study will be conducted at the urogynaecologic outpatient clinic (Division of 
General Gynaecology and Gynaecologic Oncology, Department of Obstetrics and 

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Gynaecology, Medical University of Vienna). Enrolment, treatment, and data 
collection will be standardized by all sites according to the approved study protocol. 
 
2.4 Participants and recruitment 
The study population will consist of women aged 18 years or older who are referred 
to our urogynaecologic outpatient clinic due to symptomatic POP. Women with 
anterior vaginal wall prolapse and an indication for reconstructive pelvic floor surgery 
– including sacrospinous hysteropexy – can be included in this trial.  
 
2.5 Randomization 
Randomization will be performed by the randomizer of the Medical University of 
Vienna; subjects will be stratified by parity (Primipara / Multipara) and randomized in 
blocks of four. All subjects will receive a unique study number. 
To prevent unmasking the actual procedures, the medical records will indicate the 
actual surgical procedure without stating the suture material used for anterior 
colporrhaphy. Intraoperative data collection will be conducted by the study surgeon 
rather than by other research staff. 
 
2.6 Intervention  
Sacrospinous hysteropexy will be performed in a traditional and standardized manner 
in accordance with our surgical policy. Any other concomitant procedures (e.g., 

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anterior and/or posterior colporrhaphy, cystoscopy, etc.) will be performed in 
accordance with each surgeon’s preferred technique.   
Operative management: All patients will be operated by the vaginal route. They are 
prepared under strict aseptic conditions in the dorsal lithotomy position. The bladder 
is emptied preoperatively with a thin disposable catheter and antibiotic prophylaxis 
(cefazolin) is administered before incision. A vasoconstricting solution (combination 
of vasopression and NaCl) is administered and a high posterior colpotomy is made 
towards the posterior cervix. Blunt preparation towards the right Spina ischiadica to 
visualize the right sacrospinous ligament. Once 4 cm of ligamentum sacrospinale are 
visualised, two sutures will be placed through the ligament approximately 2 cm 
medial of the spina ischiadica. Depending on preoperative randomization, patients 
will receive either PDS sutures (PDS 0) or prolene (2-0) sutures. This suture will then 
be placed through the posterior cervical wall, but not yet knotted. First, the colpotomy 
will be closed via absorbable sutures (2/0 vicryl). Should additional procedures such 
as anterior and/or posterior colporrhaphy be indicated, they will be performed at this 
stage. Only after, the pre-laid fixation sutures will be tied, whereby the portio will 
come to lie about 4-6 cm cranial of the level off the vulva towards the sacrospinous 
ligament. Participating surgeons will be defined as high volume surgeons in prolapse 
surgery and will also be part of the urogynaecologic core team.  
Perioperative management: is also standardized and includes preoperative single-
shot antibiotics as well as vaginal pack and an indwelling urinary catheter for 24 
hours after the surgical procedure. Patients will have postvoid residual volume 
measurement at the first postoperative day (when urinary catheter is removed). A 
postvoid residual volume of 2 x < 150 ml is defined as normal and no further follow- 
ups are necessary. Postvoid residual volumes of > 150 mL or greater will be 

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considered as abnormal. These patients’ volumes will continue mechanical bladder 
drainage via clean intermittent (self)-catheterisation until the postvoid residual 
volumes are consistently less than 150 ml. Patients will receive standard analgesic 
therapy in accordance with the local hospital protocol (Metamizol 1g intravenously, 3 
times a day).  
Postoperative Management: The patients are instructed to rest for 2 weeks after 
the operation (not to work, to do sport, to do the cleaning and to carry more than five 
kilos). They are allowed to return to work after 4 weeks and to take part in sport or 
have intercourse after 6 weeks. Follow-up visits are scheduled postoperative after 4-
6 weeks, 6 months and 1 year in our outpatient clinic due to our study protocol.  
 
2.7 Inclusion and exclusion criteria 
Inclusion criteria 
• 
Anterior vaginal wall prolapse beyond the hymen (POP-Q point Aa or Ba >0) 
with a central defect. 
• 
Apical vaginal vault prolapse beyond the hymen (POP-Q point C >0) with a 
central defect. Vaginal bulge symptoms  
• 
Uterus-preserving 
reconstructive 
surgery 
via 
vaginal 
sacrospinous 
hysteropexy is planned 
Exclusion criteria 
• 
History of hysterectomy 

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• 
Reconstructive pelvic floor surgery using mesh or obliterative surgery is 
planned 
• 
Reconstructive pelvic floor surgery with hysterectomy is planned 
• 
Prior reconstructive pelvic floor surgery with mesh 
• 
Known pelvic malignancy 
• 
Known inflammatory disease 
• 
Current systemic glucocorticoid or immunosuppressant treatment. 
• 
Subject is unable or unwilling to participate 
 
2.8 Data collection 
At baseline, the following data will be collected: demographics and medical history 
data (age, body mass index, parity, menopausal and hormone therapy status, 
nutritional status, current smoking, previous hysterectomy and previous anti-
incontinence surgery), and medical comorbidities (diabetes mellitus, connective 
tissue disorders), and data from the standardized urogynaecologic examination 
(POP-Q examination during maximal Valsalva, genital hiatus measurements and 
ultrasound of cervix, uterus, bladder, pelvic floor muscles and levator ani muscle 
hiatus).  
Urogynaecologic examination evaluations is made using the POP-Q measurement 
system on maximum Valsalva effort in the seated semi-lithotomy position (a 45° 
upright sitting position). Objective anatomical cure is defined as a Ba point < −1. 
Symptoms, quality of life and sexuality are evaluated with the Deutscher 

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Beckenboden-Fragebogen. This Pelvic Floor Questionnaire consists of four domains: 
bladder, bowel, pelvic organ prolapse and sexual function. In every domain various 
questions assess severity and condition-specific quality of life. Every question is 
scored on a scale from zero to four. The sum of each individual domain is divided by 
the maximum reachable score and multiplied by ten, giving a value between zero (0= 
no symptoms) and ten (10=maximum of symptoms) for each of the domains. 
Baessler et al. has published the results of the validation study and scoring system 
[11].  
To evaluate nutrition status, patients will receive the “Mini Nutritional Assessment”-
Fragebogen 
(https://www.dgem.de/sites/default/files/PDFs/Screening/MNA-
SF%20Deutsch-240513.pdf) and laboratory testing of albumin, electrolytes (sodium, 
potassium, magnesium, phosphate, and calcium), haematocrit, creatinine, blood urea 
nitrogen, and bilirubin.  
Patients will be asked to complete the standardised Visual Analog Scale (VAS), 
Numeric Rating Scale (NRS) [13] and answer the following questions: 
- “Do you experience a sensation of bulging or protrusion from the vagina?” and “Do 
you have a bulge or something fallen out that you can see in the vagina?” [6] 
- “Do you experience pain in the rump?” and “Do you experience pain in the lower 
back?” and “Do you experience pain while walking?” [6] 
- “What rate of postoperative recurrence would you accept and still opt for the 
surgery?” [14]. 
Furthermore, patients will answer the "Patient Global Impression of Improvement 
(PGI-I)" as it takes little effort for the patient and allows a precise result in terms of 
the rate of improvement after the operation [15]. One of the following answers can be 
given by each patient: 

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1. A lot better. 
2. Much better. 
3. A little better. 
4. no change. 
5. A little worse. 
6. Much worse. 
7. A lot worse. 
 
Scheduled in-person follow-ups will occur at 4 to 6 weeks, 6 and 12 months after the 
operation. Each check-up will include a full urogynaecologic clinical examination 
including POP-Q, ultrasound and bloodwork as well as a written questionnaire 
identical to the one at baseline. In addition, an update of current medications, an 
assessment of new or continuing pelvic floor disorders and adverse events that 
occurred since the previous evaluation will be obtained by the study coordinator at 
each visit. All data will be anonymized and collected using case report forms by 
examiners or trained research coordinators who are blinded to the treatment 
assignment.  
 
2.8 Primary and secondary outcome measures 
The primary outcome is subjective symptom improvement (evaluated by the prolapse 
domain score of the Deutsche Beckenboden Fragebogen) assessed at 12 months 
after surgery.  
 

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The secondary outcomes are the anatomical outcomes (the rate of suboptimal 
anatomical outcome in each compartment (POP-Q point, change in POP-Q values 
from baseline), condition-specific quality of life (any changes in questionnaire 
Deutscher Beckenboden Fragebogen from baseline), postoperative complications  
(haematoma, vesico-vaginal fistula, ureteral obstruction, urinary tract infection, 
incomplete bladder emptying, overactive bladder or stress incontinence symptoms, 
suture erosion, vaginal wound dehiscence, infection or granulation tissue, etc), and 
use of pain killers during the hospital stay. In addition, patients‘ pain level will be 
assessed through the standardised Visual Analog Scale (VAS), Numeric Rating 
Scale (NRS) [13] and the earlier specified questions, patients’  improvement rate will 
be assessed through the "Patient Global Impression of Improvement (PGI-I). 
  
 
2.9 Sample size and power considerations 
Alteration of the prolapse domain score obtained from the pelvic floor questionnaire 
before and after intervention (between baseline and 12 months follow-up) will be 
compared between patients receiving continuous stitches versus simple interrupted 
stitches for anterior colporrhaphy. Schoenfeld at al. observed a mean prolapse 
domain score of 3.33 with a standard deviation of 2.2; we assume that the standard 
deviation of the pre- and post-interventional treatment will be equal, and that the 
correlation between the two values is 0.5, resulting in a standard deviation of the 
change between pre- and postinterventional value will be 2.2.; then, with 21 patients 
per group a difference of 2 between the changes in the two groups can be identified 

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with 80% power. Taking into account an expected dropout rate of 20%, 26 patients 
will be included per group. 
 
2.10 Data analysis 
Statistical analysis will be performed using SPSS and Excel software. Data will be 
calculated and graphed as mean plus minus standard error of mean (SEM). 
Metric variables will be reported by mean and standard deviation resp. median and 
IQR, categorical variables will be reported by frequencies per group and timepoint. 
The primary outcome subjective symptom improvement after 12 months in either 
group will be analyzed by a t-test or a Man-Whitney-U-test depending on the 
distribution of improvements.   
For the secondary endpoints, differences of rates of adverse events between the two 
treatment groups will be analysed by a Chi-squared test. Blood loss, use of pain 
killers and changes in condition-specific quality of life will be compared between 
groups analogously to the primary outcome. 
Changes in POP-Q values from baseline over time will be analysed by a linear mixed 
model with fixed effects group, time, POP-Q point, age and BMI and random effect 
intercept per patient. Statistical significance will be set 0.05. No correction for multiple 
testing is performed because only one main hypothesis is considered. 
 
3. Research facility 

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The patient screening will be performed at the urogynaecologic outpatient clinic of 
the Department of General Gynaecology and Gynaecologic Oncology, Medical 
University of Vienna, Austria. Infrastructure needed for this study is already present.  
 
4. Ethical and legal aspects 
4.1. Risks 
The expected risk for the subjects involved in the study can be considered as 
minimal. Sacrospinous hysteropexy will be performed as a standard procedure. This 
procedure is clinical standard of care and is not an additional study related 
procedure. It is unclear if different suture material led to different adverse effects. 
The only possible risk that patient’s data might be released to public is minimized by 
anonymization of all data that will be saved at a password secured server. Data will 
be accessible by authorized staff only. 
 
 
4.2. Publication of data 
The results of the study will be published in an adequate timeframe.  
 
4.3. Changes of the study protocol 
If changes of the study protocol should occur, they will be documented carefully. If 
significant changes should be necessary, the ethic commission will be contacted and 
asked for permission. 
 

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4.4. Protection of data privacy 
All data obtained from the subjects in this study will be handled with care and will not 
be passed to a third person. Every individual will be given a unique code to ensure 
the protection of personal data sample evaluation.  
 
4.5. Written informed consent 
Written informed consent will be obtained from every patient. Every participating 
patient will be informed thoroughly about the study. Every subject can withdraw from 
the study at any time.  
 
 
 

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