Fertility Treatment: Impact on Symptoms of Irritable Bowel Syndrome
Phase: NA
Conditions: PCOS (Polycystic Ovary Syndrome)
Sponsor: Universitair Ziekenhuis Brussel

 
 
 
 
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Study Protocol – FIBS 
 
Study Title: Fertility treatment: Impact on symptoms of Irritable Bowel syndrome   
Study Acronym: FIBS   
Protocol Version and Date: 3
rd version, 03/02/2026 
Sponsor: VUB  
Principal Investigator: Prof. Dr. Sébastien Kindt  
Study Start Date: 1 December 2025  
Expected Study End Date*: 31 July 2028  
 
 
 
 
The information contained in this document is the property of the Sponsor/Coordinating 
Investigator and may not be reproduced, published or disclosed to others without written 
authorization of the Sponsor/Coordinating Investigator. 
 
 
PROTOCOL SIGNATURE PAGE 
 
Protocol version and date: Version 3, 03/02/2026 
 
Protocol title: Fertility treatment: Impact on symptoms of Irritable Bowel Syndrome (FIBS) 
 
Sponsor: VUB  
 
Principal Investigator: Prof. Dr. Kindt  
 
 
I agree: 
- 
to assume responsibility for the proper conduct of this study 
- 
to conduct the study in compliance with this protocol  
- 
not to implement any deviations from or changes to the protocol without prior review 
and written approval from the Ethics Committee, or for administrative aspects of the 
study (where permitted by all applicable regulatory requirements) 
- 
to ensure that all persons assisting me with the study are adequately informed about 
their study-related duties and functions as described in the protocol 
- 
that I am aware of and will comply with the current good clinical practice (GCP) guidelines 
and ethical principles outlined in the Declaration of Helsinki 
- 
to conduct the study in accordance with all applicable laws and regulations 
 
 
 
Prof. dr. S. Kindt 
 
 
 
Signature 
 
 
 
Date 
 
 
 

 
 
 
 
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Table of Contents 
1 
Sponsor/Coordinating Investigator Information.................................................................... 4 
2 
List of Abbreviations ........................................................................................................... 4 
3 
Protocol Version History ...................................................................................................... 4 
4 
Trial Registration/Protocol Summary ................................................................................... 4 
5 
Background and Rationale ................................................................................................... 6 
5.1 
Pathogenenis & diagnosis of PCOS ................................................................................................. 6 
5.2 
Types of PCOS ................................................................................................................................. 7 
5.3 
Social freezing ................................................................................................................................... 7 
5.4 
Irritable bowel syndrome pathogenesis ............................................................................................ 7 
5.5 
IBS and psychosocial factors ............................................................................................................ 7 
5.6 
IBS prevalence .................................................................................................................................. 7 
5.7 
IBS subtypes ..................................................................................................................................... 8 
5.8 
IBS symptoms during fertility treatments .......................................................................................... 8 
5.9 
Rationale for this study ..................................................................................................................... 8 
5.10 
Rationale for study design ................................................................................................................ 8 
6 
Study Objectives and Endpoints ........................................................................................... 9 
6.1 
Primary Objective .............................................................................................................................. 9 
6.2 
Secondary Objectives ....................................................................................................................... 9 
6.3 
Endpoints ........................................................................................................................................ 10 
7 
Study Design .................................................................................................................... 10 
7.1 
Study Design ................................................................................................................................... 10 
7.2 
Date Range for collected study data ............................................................................................... 11 
8 
Study Population ............................................................................................................... 11 
8.1 
Population of interest ...................................................................................................................... 11 
8.2 
Inclusion & exclusion criteria........................................................................................................... 11 
9 
Study Assessments and Procedures ................................................................................... 11 
9.1 
Schedule of Activities ...................................................................................................................... 11 
9.2 
Detailed Study Assessments .......................................................................................................... 12 

 
 
 
 
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9.2.1 
Screening .................................................................................................................................... 12 
9.2.2 
Visit before fertility treatment ...................................................................................................... 12 
9.2.3 
Visit after fertility treatment ......................................................................................................... 12 
9.3 
Assessment types ........................................................................................................................... 12 
9.3.1 
IBS symptoms ............................................................................................................................. 12 
9.3.2 
Gastrointestinal symptoms ......................................................................................................... 13 
9.3.3 
Depression levels ....................................................................................................................... 13 
9.3.4 
Anxiety levels .............................................................................................................................. 13 
10 
Data Collection and Management................................................................................... 14 
10.1 
Monitoring ....................................................................................................................................... 14 
10.2 
Data Collection ................................................................................................................................ 14 
10.3 
Data collection from patient file ....................................................................................................... 14 
10.4 
Database Management and Quality Control................................................................................... 14 
10.5 
Statistical Considerations and Data Analysis ................................................................................. 15 
11 
Ethical Considerations ................................................................................................... 16 
11.1 
Ethical Conduct of the Study........................................................................................................... 16 
11.1.1 
Declaration of Helsinki............................................................................................................ 16 
11.1.2 
Ethics Committee ................................................................................................................... 16 
11.2 
Recruitment and Informed Consent ................................................................................................ 16 
11.3 
Study Data Protection ..................................................................................................................... 16 
11.4 
Subject Identification ....................................................................................................................... 16 
12 
Insurance...................................................................................................................... 16 
14 
Finance and Conflict of Interest Statement ..................................................................... 17 
15 
References .................................................................................................................... 18 
16 
Appendices ................................................................................................................... 20 
 

 
 
 
 
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1 Sponsor/Coordinating Investigator Information 
 
Sponsor:  
 
 
VUB 
 
Principal Investigator:   
Prof. Dr. Sébastien Kindt  
 
Sub-investigator(s):  
 
Prof Dr S Mackens, Prof Dr. M De Vos , Myrthe Van Baele 
 
Statistician:  
 
 
Wilfried Cools   
 
Study Coordinator: 
 
Elsie Nulens 
  
Study site(s) :  
 
 
BIVF , UZ Brussel 
 
2 List of Abbreviations 
 
IBS  
 
Irritable Bowel Syndrome  
IBS-SSS  
Irritable Bowel Syndrome- Symptom Severity Scale  
COC  
 
Cumulus-oocyte complex  
COS  
 
Controlled ovarian stimulation  
GAD-7  
Generalized Anxiety Disorder 7-item  
GI  
 
Gastrointestinal  
GPA  
 
Gravida, para and abortus   
GSRS 
 
Gastrointestinal Symptom Rating Scale  
ICF  
 
Informed Consent Form  
IVF  
 
In Vitro Fertilization  
PCOS   
Polycystic Ovarian Syndrome  
PHQ-9  
Patient Health Questionnaire 9  
PPOS   
Progestin-Primed Ovarian Stimulation  
US  
 
Ultrasound  
VUB  
 
Vrije Universiteit Brussel  
 
3 Protocol Version History 
 
Version N
O 
Version Date 
Summary of changes 
1 
01/10/2025  
 
2 
10/11/2025 
Response to questions EC 
3 
03/02/2026 
Response to questions EC 
 
4 Trial Registration/Protocol Summary 
 
Information 
Objectives: 
The objective is to study IBS (Irritable bowel syndrome) symptoms in women 
who undergo controlled ovarian stimulation and oocyte retrieval, which are 
the cornerstones of fertility treatment. Two groups will be studied: women 
with PCOS (Polycystic Ovarian syndrome) and women who undergo elective 
oocyte cryopreservation (social freezing).  
 
Study population: 
Nulliparous women with a diagnosis of PCOS who are eligible for IVF (in vitro 
fertilization) treatment with freeze-only strategy (i.e. deferred embryo 
transfer). 
Nulliparous 
women 
who 
embark 
on 
elective 
oocyte 

 
 
 
 
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cryopreservation. Both groups will receive PPOS (progestin-primed ovarian 
stimulation).  
 
In- 
and 
exclusion 
criteria: 
 
 
Inclusion criteria PCOS group :  
- 
Diagnosis of PCOS according to the 2004 Rotterdam criteria  
- 
Initiating their first cycle of IVF treatment (PPOS and freeze only 
protocol)  
- 
Nulliparous  
- 
≥  18 years 
- 
Willing to participate in the study  
- 
Understanding Dutch, French or English  
 
Exclusion criteria PCOS group :  
- 
Known inflammatory bowel disorder  
- 
Known major intestinal bowel disorder  
- 
Known systemic or auto-immune disorder with implication for the 
GI system  
- 
History of abdominal surgery (appendectomy and cholecystectomy 
allowed if >6 months earlier)  
- 
History of gastro-enteritis in the past 6 weeks  
- 
Previous IVF treatment cycles   
 
Inclusion criteria social freezing group:  
- 
Initiating their first ovarian stimulation protocol for elective oocyte 
cryopreservation (PPOS and freeze only protocol)  
- 
Nulliparous  
- 
≥ 18 years  
- 
Willing to participate in the study  
- 
Understanding Dutch, French or English  
 
Exclusion criteria social freezing group:  
- 
Diagnosis of PCOS  
- 
Known inflammatory bowel disorder  
- 
Known major intestinal bowel disorder  
- 
Known systemic or auto-immune disorder with implication for the 
GI system 
- 
History of abdominal surgery (appendectomy and cholecystectomy 
allowed if >6 months earlier)  
- 
History of gastro-enteritis in the past 6 weeks  
 
 
Factors of interest / 
Data to be collected: 
IBS diagnosis and symptom severity  
Gastrointestinal symptom severity  
Depression levels  
Anxiety levels  
 
Factors to be collected before ovarian stimulation:  
• 
Demographics (length, weight)  
• 
The duration of infertility  
• 
Obstetrical history: GPA (Gravida, Para and abortus)  
• 
The ethnicity  
• 
For the study group: the type of PCOS  
 
Factors to be collected after oocyte pick-up:  
• 
The hormonal profile at start and end of ovarian stimulation  
• 
The number of follicles on the last ultrasound before pickup  
• 
The number of COC (Cumulus-oocyte complex) collected during 
pick-up  

 
 
 
 
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Endpoints: 
The primary endpoint is to explore whether there is a difference between 
the IBS prevalence before and after ovarian stimulation.  
The score on the Rome Criteria for IBS before and after ovarian stimulation 
will be compared.  
The severity of IBS symptoms before and after the fertility treatment will 
be compared using the IBS-SSS (IBS- Symptom Severity Scale) questionnaire. 
The prevalence of gastrointestinal symptoms before and after the fertility 
treatment will be compared using the GSRS (Gastrointestinal symptom 
rating scale) questionnaire.  
The prevalence of anxiety levels before and after the fertility treatment will 
be compared using the GAD-7 (Generalized Anxiety Disorder 7-item) 
questionnaire.  
The depression levels before and after the fertility treatment will be 
compared using the PHQ-9 (Patient Health Questionnaire 9). 
 
The PCOS and social freezing group will each be divided in different 
subgroups based on the type of stimulation.  
The IBS prevalence (with the Rome Criteria) and the IBS symptom severity 
(with the IBS-SSS) will be compared in these subgroups before and after 
ovarian stimulation.    
The same will be done based on the number of treatments that were 
received before this treatment, the duration of -infertility, the number of 
previous pregnancies, the number of children, the ethnicity, the hormonal 
profile during COS (continuous ovarian stimulation).  
The PCOS group will be divided in different subgroups based on the type 
of PCOS. . The IBS prevalence (with the Rome Criteria) and the IBS 
symptom severity (with the IBS-SSS) will be compared in these subgroups 
before and after the fertility treatment. 
 
 
Target sample size: 
Since there is no study that has explored the prevalence of IBS during a 
fertility treatment, there is not enough data to do a power analysis before 
starting this study. This study will be an explorative study with a PCOS group 
of 60 and social freezing group of 60. After the data has been collected, a 
power analysis will be done and the option of including more participants 
will be explored. In this case, we will submit an amendment to the ethical 
committee.  
 
There are multiple studies that found a connection between IBS and 
infertility. Most of these studies are retrospective studies and are focused 
on male infertility. (1).  A study in 2013 analyzed gastro-intestinal symptoms 
during IVF in infertile women. This study had 124 participants. (2) Since this 
study from 2013 is the most like our study, the aim for our target sample 
size is going to be similar, namely 120 participants.  
 
 
5 Background and Rationale 
5.1 
Pathogenenis & diagnosis of PCOS  
Polycystic Ovarian Syndrome (PCOS) affects the endocrine system resulting in excessive androgen 
levels and the metabolic system which can lead to, for example, hyperinsulinemia. The disease is 
linked to a higher risk of preeclampsia, endometrial cancer, gestational diabetes and preterm 
birth. (3) Obesity, anovulation, polycystic ovaries and infertility can be seen in PCOS patients. (4) 
Due to these risks, women with PCOS are more likely to have to receive a fertility treatment to get 
pregnant and to prevent losing the pregnancy prematurely. PCOS affects up to 10% of women 

 
 
 
 
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(prevalence changes based on the use of different criteria). (5) The Rotterdam criteria are mostly 
used for diagnosis. Other diagnoses should be excluded and two out of three criteria need to be 
met. The three criteria are irregular cycles (criteria 1), high antimüllarian hormone or polycystic 
ovarian morphology on transvaginal ultrasound (criteria 2) and/or biochemical or clinical 
hyperandrogenism (criteria 3). (6) 
5.2 
Types of PCOS  
There are four types of PCOS. Phenotype A PCOS has ovulatory dysfunction, hyperandrogenism 
and polycystic ovarian morphology. Phenotype B PCOS has the same characteristics but without 
the polycystic ovarian morphology. These two phenotypes are considered the “classic PCOS”. 
Phenotype C is characterized by hyperandrogenism and polycystic ovarian morphology. It is also 
called the ovulatory PCOS. Phenotype D PCOS is also called non hyperandrogenic PCOS, it is 
characterized by ovulatory dysfunction and polycystic ovarian morphology. (7) 
5.3 
Social freezing  
The process of freezing your oocytes to preserve the ability to fertilize your own oocytes is called 
social (egg) freezing. The women receive ovarian stimulation (hormones) to grow as many follicles 
as possible before the pick-up of the oocytes. The oocytes are preserved using cryopreservation. 
The main reason for social freezing is the lack of an appropriate partner to start a family. (8) 
5.4 
Irritable bowel syndrome pathogenesis  
The pathogenesis of irritable bowel syndrome has not been fully discovered. Patients experience 
gastro-intestinal motor problems and visceral hypersensitivity. IBS is associated with a modified 
gut microbiota which has an influence on immunity and the gut-brain axis. Genetic factors such as 
single nucleotide polymorphisms and epigenetic factors such as DNA methylation have been 
linked to IBS. (9) IBS patients are more likely to experience infertility. Most studies have focused on 
male infertility and IBS. A possible explanation for this link could be higher reactive oxygen 
species (ROS). However, more research is needed to explore this topic. (1) Serotonin dysregulation 
has been observed in patients with IBS. Patients with constipation showed a reduced level of 
serotonin concentrations and patients with diarrhea showed a higher level of serotonin 
concentrations. The serotonin concentration influences the secretion, sensation and motility of the 
gastrointestinal tract. More factors are possibly involved in the pathogenesis of IBS such as 
bacterial overgrowth, psychosocial factors, central dysregulation,… (10) 
5.5 
IBS and psychosocial factors  
Patients with IBS have a higher risk of suffering from anxiety or depression, up to threefold higher 
than healthy subjects. (11) IBS symptoms exacerbate during stressful times. (12) A study 
investigated the stress levels during first and repeat IVF cycles and found higher stress levels in all 
IVF cycles. Women with lower stress levels had a higher pregnancy rate. Stress management can be 
beneficial for pregnancy rates and for IBS symptom severity. (13)  
 
Studies about the relationship between depression and IBS are scarce and results are often 
inconsistent. Most studies find a higher rate of depression in IBS patients. The impact of 
depression on IBS symptom severity and prevalence hasn’t been fully explored. Depression and IBS 
share a similar pathogenesis which makes it difficult to study these two diseases separately. Both 
IBS and depression show a dysfunction of the neuroendocrine systems and the immune system. 
(14)  
5.6 
IBS prevalence  
The Rome Foundation Global study reported an overall prevalence of 3,8% when the Rome IV 
criteria are used and an overall prevalence of 10,1% when the Rome III criteria are used. (15) The 
Rome IV criteria question the prevalence of abdominal pain while the Rome III criteria additionally 
ask for abdominal discomfort (an uncomfortable sensation and not necessary pain). (16) Women 
have a significant higher prevalence of IBS than men, up to 3-fold higher. The risk of IBS doubles 

 
 
 
 
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when the person has a biological relative with IBS. The prevalence of IBS varies greatly between 
different countries. (17) PCOS patients are more prone to experience gastrointestinal (GI) 
disturbances such as irritable bowel syndrome (IBS): a recent meta-analysis showed that the risk of 
IBS in women with PCOS is two times higher than in a control group of women with no PCOS. (18) 
The prevalence of IBS during a fertility treatment has not been studied.  
5.7 
IBS subtypes  
IBS has three subtypes. IBS-C has predominantly constipation, IBS-D has predominantly diarrhea 
and IBS-M is a mix of subtypes C and D. (19) 
5.8 
IBS symptoms during fertility treatments  
Women can experience cramping, bloating and abdominal pain during the IVF cycles. After oocyte 
retrieval, diarrhea and constipation can occur. Most research about these symptoms have been 
focused on ovarian hyperstimulation syndrome (OHSS) and only few have tried to uncover how 
many women suffer from these symptoms outside of the OHSS context. (20)  
 
This study will focus on the IBS symptoms experienced during fertility treatment. Some examples 
of drugs in fertility treatment include aromatase inhibitors, gonadotropin-releasing hormone 
(GnRH) and clomiphene. Aromatase inhibitors, for example letrozole inhibit the aromatization of 
androgen and thus reduces estrogen levels. This leads to increased GnRH release which results in 
more FSH production. (21) Aromatase inhibitors can cause headache, diarrhea and nausea. (22) 
GnRH-antagonists such as Cetrotide are used to prevent a premature rise of LH.(23) GnRH-agonists 
such as Decapeptyl are used for controlled ovarian hyperstimulation.(24) In a small study from 
2015, severe dysmotility after taking GnRH analogs was linked to a high prevalence of 
endometriosis. Further research is needed, but it does hint at the possibility that patients with 
endometriosis have a higher chance of suffering from severe gastrointestinal symptoms.  (25) 
Clomiphene citrate inhibits the negative feedback of estrogen to the pituitary and hypothalamus 
by binding estrogen receptors competitively. It stimulates the release of FSH which enhances 
follicle maturation. (26) Most common side effect of clomiphene are abdominal pain, diarrhea, 
anorexia and nausea. (27) 
5.9 
Rationale for this study  
Different fertility drugs can cause nausea, diarrhea, constipation, abdominal pain,... It is unknown 
how many women suffer from these symptoms and how large the impact of these symptoms is 
during fertility treatment. The prevalence of IBS varies between 7,9 % to 49,3% in different studies, 
while the Rome Foundation Global study found a prevalence of 3,8%. (15, 28) The prevalence of IBS 
varies greatly between different subgroups. This study aims to give an indication of the prevalence 
and severity of gastrointestinal symptoms during fertility treatment. This knowledge can lead to 
better understanding and support during fertility treatment. Moreover, women undergoing fertility 
treatment will have an idea of what to expect when it comes to IBS-symptoms.  
5.10 
Rationale for study design  
The role and significance of IBS symptoms in women who undergo fertility treatment has not yet 
been studied. Therefore, we designed this explorative study to get an overview of IBS symptoms 
during fertility treatment. There are many different subgroups of women undergoing a fertility 
treatment. This study chooses PCOS and social freezing. Women with PCOS are more at risk of 
developing gastrointestinal disturbances. (18)  Elective oocyte cryopreservation is becoming more 
popular and this subgroup is a significant proportion of the women who come to the fertility clinic 
in UZ Brussels. Since it is predicted to become even more popular in the future, it would be helpful 
to explore the IBS symptoms during this treatment.  
 

 
 
 
 
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6 Study Objectives and Endpoints 
6.1 
Primary Objective 
The primary objective of this study is to investigate whether fertility treatment is associated with 
changes in the prevalence and severity of Irritable Bowel Syndrome (IBS) symptoms. Specifically, 
the study aims to: 
1. Assess whether the proportion of participants meeting IBS diagnostic criteria (based on 
ROME III and IV) differs before and after fertility treatment. 
2. Evaluate whether there is a statistically significant change in IBS symptom severity as 
measured by the IBS Symptom Severity Score (IBS-SSS) before and after treatment. 
6.1.1 
Primary research hypotheses  
H1. 
The prevalence of participants meeting diagnostic criteria for Irritable Bowel Syndrome (IBS), as 
defined by the ROME III and ROME IV criteria, differs significantly before and after fertility 
treatment. 
H2. 
IBS symptom severity, as measured by the IBS Symptom Severity Score (IBS-SSS), changes 
significantly following fertility treatment compared with baseline. 
6.2 
Secondary Objectives 
The  secondary objective is to identify which psychological and clinical factors are 
associated with the presence or change in IBS symptoms in women undergoing fertility 
treatments, including those with Polycystic Ovary Syndrome (PCOS) and those 
undergoing social oocyte freezing.  
The secondary objectives include:  
- 
Changes in depression levels   
- 
Changes in anxiety levels  
- 
Differences in IBS symptoms based on the type of stimulation 
- 
Differences in IBS symptoms based on the number of treatments received before this 
treatment  
- 
Differences in IBS symptoms based on the duration of infertility  
- 
Differences in IBS symptoms based on ethnicity  
- 
Differences in IBS symptoms based on the type of PCOS  
- 
Differences in IBS symptoms based on the hormonal profile during COS  
- 
Differences in IBS symptoms based on the US reaction  
 
6.2.1 
Secondary research hypotheses  
H3. 
Changes in depressive symptom levels are significantly associated with changes in IBS symptom 
severity in women undergoing fertility treatment. 
H4. 
Changes in anxiety levels are significantly associated with changes in IBS symptom severity in 
women undergoing fertility treatment. 

 
 
 
 
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H5. 
Changes in IBS symptoms differ significantly according to the type of ovarian stimulation used 
during fertility treatment. 
H6. 
Changes in IBS symptoms differ significantly based on the number of fertility treatments received 
prior to the current treatment. 
H7. 
Changes in IBS symptoms differ significantly according to the duration of infertility. 
H8. 
The prevalence and/or change in IBS symptoms differ significantly across ethnic groups. 
H9. 
Among women with Polycystic Ovary Syndrome (PCOS), changes in IBS symptoms differ 
significantly according to PCOS phenotype. 
H10. 
Changes in IBS symptoms are significantly associated with the hormonal profile during controlled 
ovarian stimulation (COS). 
H11. 
Changes in IBS symptoms differ significantly according to the ovarian response assessed by 
ultrasound during COS. 
 
6.3 
Endpoints 
The IBS prevalence before and after the fertility treatment will be compared using the Rome 
Criteria for IBS. The severity of IBS symptoms before and after the fertility treatment will be 
compared using the IBS-SSS questionnaire. The difference in gastrointestinal symptoms before and 
after the fertility treatment will be compared using the GSRS questionnaire.  The prevalence of 
anxiety levels before and after the fertility treatment will be compared using the GAD-7 
questionnaire. The depression levels before and after the fertility treatment will be compared 
using the PHQ-9. 
 
The PCOS and social freezing group will each be divided in different subgroups based on the type 
of stimulation. The IBS prevalence (with the Rome Criteria) and the IBS symptom severity (with the 
IBS-SSS) will be compared in these subgroups before and after the fertility treatment. The same will 
be done based the duration of infertility, the ethnicity, the hormonal profile during COS and the US 
reaction. The PCOS group will be divided in different subgroups based on the type of PCOS. . The 
IBS prevalence (with the Rome Criteria) and the IBS symptom severity (with the IBS-SSS) will be 
compared in these subgroups before and after the fertility treatment. 
 
7 Study Design 
7.1 
Study Design 
This study is an explorative non-interventional prospective study. Questionnaires will be used as 
form of intervention. The intervention will take place before and after hormonal stimulation (on 
the day of pick-up). The aim of this study is to get a view on the prevalence of IBS symptoms in the 
PCOS and social freezing group.  

 
 
 
 
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7.2 
Date Range for collected study data 
The first inclusions will be done in December 2025 and the last inclusions will be in July 2026.  
This means that study data will be collected till February 2027. 
 
8 Study Population 
8.1 
Population of interest 
Women with PCOS who are nulliparous and initiate IVF treatment.  
Woman who are nulliparous and initiate ovarian stimulation for social freezing.  
Both groups will receive PPOS (progestin-primed ovarian stimulation) and will get the freeze-all 
procedure after pick-up of oocytes.  
Patients will be recruited at the fertility clinic of the UZ Brussels.  
8.2 
Inclusion & exclusion criteria  
Inclusion criteria PCOS group :  
- 
Diagnosis of PCOS according to the 2004 Rotterdam criteria  
- 
Initiating  their first cycle of IVF treatment (PPOS and freeze only protocol)  
- 
Nulliparous  
- 
≥ 18 years  
- 
Willing to participate in the study  
- 
Understanding Dutch, French or English  
 
Exclusion criteria PCOS group :  
- 
Known inflammatory bowel disorder  
- 
Known major intestinal bowel disorder  
- 
Known systemic or auto-immune disorder with implication for the GI system  
- 
History of abdominal surgery (appendectomy and cholecystectomy allowed if >6 months 
earlier)  
- 
History of gastro-enteritis in the past 6 weeks  
 
Inclusion criteria social freezing group:  
- 
Initiating their first ovarian stimulation protocol for elective oocyte cryopreservation (PPOS 
and freeze only protocol)  
- 
Nulliparous  
- 
≥ 18 years   
- 
Willing to participate in the study  
- 
Understanding Dutch, French or English  
 
Exclusion criteria social freezing group:  
- 
Diagnosis of PCOS  
- 
Known inflammatory bowel disorder  
- 
Known major intestinal bowel disorder  
- 
Known systemic or auto-immune disorder with implication for the GI system 
- 
History of abdominal surgery (appendectomy and cholecystectomy allowed if >6 months 
earlier)  
- 
History of gastro-enteritis in the past 6 weeks  
 
9 Study Assessments and Procedures 
9.1 
Schedule of Activities 
 

 
 
 
 
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9.2 
Detailed Study Assessments 
9.2.1 
Screening  
When a patient visits the fertility clinic and is considered a possible participant for the study, they 
will be informed about the study. Inclusion and exclusion criteria will be checked. The doctor will 
go over the informed consent form (ICF) and the patient will get enough time to ask questions. If 
the patient is eligible and wants to participate in the study, they will sign the ICF.  
9.2.2 
Visit before fertility treatment  
Informed consent will be obtained. The IBS-SSS (IBS Symptom Severity Scale) (appendix 2) and 
Rome IV Criteria (appendix 1) are used to determine resp. IBS symptom severity and presence. The 
GSRS (appendix 3) is used to get a more general insight in gastrointestinal symptoms. The Patient 
Health Questionnaire-9 (PHQ-9) (appendix 5) will be used to determine the depression level of the 
patient. the Generalized anxiety Disorder 7-item (GAD-7) (appendix 4) examines the anxiety levels. 
These questionnaires will be available in three languages: Dutch, French and English. The 
questionnaires will be filled out on paper. In total, it will take about 15 minutes to fill out all the 
forms.  
9.2.3 
Visit after fertility treatment  
After the fertility treatment (ovarian stimulation) the patient will come to the fertility clinic for pick-
up of the oocytes. During this visit the following questionnaires will be filled-out: IBS-SSS 
(appendix 2) , Rome IV criteria (appendix 1) , GSRS (appendix 3) , PHQ-9 (appendix 5) and the 
GAD-7 (appendix 4) .   
9.3 
Assessment types  
9.3.1 
IBS symptoms  
The IBS-SSS (IBS Symptom Severity Scale) (appendix 2)  and Rome IV Criteria (appendix 1) are used 
to determine IBS symptoms. The result of the IBS-SSS is a score of 0 to 500. Each of the five topics 
is rated from 0 to 100. The topics are number of days with abdominal pain, satisfaction with bowel 
habits, abdominal pain, bloating/distention and IBS-related quality of life. A 15% change in the score 

 
 
 
 
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is considered clinically significant. (29) A score of 75-175 is considered mild, a score of 175 to 300 
is considered moderate and a score of >300 is considered severe. (30) The Rome IV Criteria for IBS 
describe recurrent abdominal pain on average at least 1day per week in the last 3 months, associated 
with two or more of the following criteria: associated with a change in the frequency of stool, 
associated with a change in the form of stool and/or related to defecation. The criteria should be 
present for the last 3 months and symptoms should be present at least 6 months before the 
diagnosis is made. (16)  
 
IBS prevalence differs greatly based on if the Rome IV or Rome III criteria are used. The Rome 
Foundation Global study reported an overall prevalence of 3,8% when the Rome IV criteria are used 
and an overall prevalence of 10,1% when the Rome III criteria are used. (15) The Rome IV criteria ask 
for abdominal pain while the Rome III criteria ask for abdominal discomfort (an uncomfortable 
sensation and not necessary pain). (16) Because of this big difference in prevalence, this study will 
first ask for abdominal pain (Rome IV criteria) and afterwards ask for abdominal discomfort (Rome 
III Criteria). This gives us a more complete picture of the IBS symptoms.  
9.3.2 
Gastrointestinal symptoms  
The Gastrointestinal Symptom Rating Scale (appendix 3) contains 15 questions divided over five 
domains: abdominal pain, reflux syndrome, indigestion syndrome, constipation syndrome and 
diarrhea syndrome. Each question is scored from 1-7 depending on the inconvenience that the 
person experienced in the previous week. A higher score correlates with more inconvenient 
symptoms. (31) This questionnaire is used to get a more general overview of gastrointestinal 
symptoms.  
9.3.3 
Depression levels  
The Patient Health Questionnaire-9 (PHQ-9) (appendix 5) will be used to determine the depression 
level of the patient. The questionnaire contains the nine DSM-V criteria for depression. Each question 
can be scored from “0” (not at all) to “3” (nearly every day). A score of “0-4” is considered minimal 
depression, “5-9” is mild depression, “10-14” is moderate depression, “15-19” is moderately severe 
and “20-27” is severe. (32)  
9.3.4 
Anxiety levels  
Thirdly, the Generalized anxiety Disorder 7-item (GAD-7) (appendix 4) examines the anxiety levels. 
The questionnaire consists of seven questions with each time four response options (not at all = 0, 
several days = 1, more than half the days = 2 and nearly every day = 3). A total scores determine the 
severity of anxiety: 0-4 = minimal anxiety, 5-9= mild anxiety, 10-14 = moderate anxiety and  15 or 
more = severe anxiety. (33) 
 
9.3.5 
Results on the GAD7 and/or PHQ9 questionnaires  
The GAD and PHQ-9 both are screening tools meant for preliminary assessment of anxiety and 
depression in patients. No specific training is required, and the questionnaires are meant for self-
administration to the patient. Scoring is only indicative of possible underlying disorders, 
requiring a more comprehensive clinical assessment for confirmation. Therefore, for higher 
scores, the decision to refer for further specialised assessments relies on the clinical evaluation by 
the attending physician of the fertility clinic. The scoring will be performed by the student.  Scores 
> 10 for the GAD and PHQ-9 will be communicated to the attending physician. 
 
Both questionnaires will be scored according to the scoring sheet: 
 
Scoring sheet: 
GAD-7: 
    5-9: mild symptom severity 
    10-14: moderate 
    > 15: severe 

 
 
 
 
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PHQ-9: 
    0-4: none 
    5-9: mild depression 
    10-14: moderate depression 
    15-19: moderate to severe depression 
    20-27: severe depression 
 
10 Data Collection and Management 
10.1 
Monitoring  
The investigator must make all trial documentation and related records available in case a 
monitoring visit or audit by the Sponsor is requested. Also in case of regulatory inspections all 
trial documentation should be made available to the inspector(s). All participant data must be 
handled and treated confidentially. 
The Sponsor’s monitoring frequency will be determined prior to the start of the trial. A monitoring 
plan will be generated detailing the frequency and scope of monitoring for the trial. Throughout 
the course of the trial the monitoring plan can be adjusted as necessary. 
10.2 
Data Collection 
All questionnaires will initially be collected on paper. Each paper questionnaire will be assigned a 
unique study code and will not contain any identifiable participant information. The linkage between 
study codes and participant identities will be securely stored and accessible only to the study 
investigators. Completed paper questionnaires will subsequently be entered into the REDCap system 
in a timely manner.  
 
An Electronic Data Capture system “REDCap” will be used for data collection. The system is validated 
and access to all levels will be granted/revoked by the Sponsor representative. Trial data should be 
entered within reasonable time after the subject attended the visit. Corrections/modifications will 
be automatically tracked by an audit trail detailing date and time of the correction and the name of 
person performing the correction. 
10.3 
Data collection from patient file  
The patient file will be utilized to collect specific data for the purpose of this study. The following 
information will be gathered: age, the type of medication administered for ovarian stimulation, the 
hormonal profile, the number of follicles observed on the final ultrasound, and the number of 
oocytes retrieved during oocyte pick-up (OPU). This data will be obtained post-OPU. 
10.4 
Database Management and Quality Control  
The investigator should ensure the accuracy, completeness, legibility, and timeliness of the data 
reported to the sponsor in the eCRF and in all required reports. 
The investigator must keep source documents for each subject in the study. All information on the 
eCRF must be traceable to these source documents, which are generally stored in the subject's 
medical file. The source documents should contain all demographic and medical information, 
including laboratory data, ultrasound data, etc., and the original signed informed consent forms. 
Data reported on the eCRF that derive from source documents should be consistent with the 
source documents or the discrepancies should be explained. 
 
The investigator and the sponsor should maintain the study documents as specified in the 
“Essential Documents for the Conduct of a Clinical Trial” chapter 8 of ICH-GCP and as required by 
the applicable regulatory requirement(s). 
These are documents which individually and collectively permit evaluation of a study and the 
quality of the data produced and include groups of documents, generated before the study 

 
 
 
 
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commences, during the clinical study, and after termination of the study and include but are not 
limited to: study protocol, amendments, submission and approval of EC, raw data of subjects 
including lab tests, insurance contracts, signed informed consent forms, confidential subjects 
identification code, eCRF, curricula vitae of the investigator and other participants in the study, 
study staff lists and responsibilities, monitoring reports and final study report. 
The investigator and the sponsor should take measures to prevent accidental or premature 
destruction of these documents. 
The investigator and the sponsor must retain study documents as long as needed to comply with 
ICH-GCP, national and international regulations. By signing the protocol, the investigator and the 
sponsor agree to adhere to these requirements. 
 
10.5 
Statistical Considerations and Data Analysis 
The primary objective of this study is to investigate whether fertility treatment is associated with 
changes in the prevalence and severity of Irritable Bowel Syndrome (IBS) symptoms. Specifically, 
the study aims to: 
3. Assess whether the proportion of participants meeting IBS diagnostic criteria (based on 
ROME III and IV) differs before and after fertility treatment. 
4. Evaluate whether there is a statistically significant change in IBS symptom severity as 
measured by the IBS Symptom Severity Score (IBS-SSS) before and after treatment. 
5. Identify which psychological and clinical factors are associated with the presence or 
change in IBS symptoms in women undergoing fertility treatments, including those 
with Polycystic Ovary Syndrome (PCOS) and those undergoing social oocyte freezing. 
Participants will either meet the criteria for IBS or not meet the criteria for IBS (based on the ROME 
III and IV criteria). This will correlate to a binary outcome: yes (1) or no (0) answer. This answer will 
be defined before and after the fertility treatment. A logistic regression model will be used to 
determine the chance of P(1) which is the chance of meeting the IBS criteria (yes answer). This 
regression model will be used for the PCOS group and the social freezing group. This model 
estimates the probability of an event occurring (meeting the IBS criteria) based on a given set of 
independent variables . The independent variables include GAD-7 score, PHQ-9 score, ethnicity, 
duration of the desire to have children, the number of follicles found on the US,…  
 
These independent variables will be evaluated with the AIC (Akaike information criterion). AIC is 
used to compare different possible regression models and define which model is the best fit for 
the given data. If the AIC is lower, the data is a better fit. The regression model will be made with 
different independent variables and each time the AIC will be calculated. The model with the 
lowest AIC will be the final model.  
 
Participants will fill in the IBS-SSS and obtain a score between 0 and 500 . The difference in score 
before and after the fertility treatment will be calculated. This score difference, which is a 
continuous outcome, will be used in a multiple linear regression model. This model estimates how 
several independent variables influence a single outcome. The regression analysis will show which 
independent variables (such as ethnicity, anxiety scores, duration of the desire to have children,…) 
have an influence on the score difference of IBS-SSS questionnaire. AIC will be used to evaluate the 
different possible models which will include different independent variables. The model with the 
lowest AIC will be used.  
 
All analyses will be performed with SPSS. 
 

 
 
 
 
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11 Ethical Considerations 
11.1 
Ethical Conduct of the Study 
11.1.1 
Declaration of Helsinki 
The trial will be performed in accordance with the Declaration of Helsinki, the conditions and 
principles of Good Clinical Practice, the protocol and applicable local regulatory requirements and 
laws. 
11.1.2 
Ethics Committee 
Before the start of the trial or implementation of any amendment, approval of the trial protocol and 
amendments, informed consent forms and other relevant documents will be obtained from the 
applicable ethical committee(s). 
11.2 
Recruitment and Informed Consent 
Each participant shall provide a signed and dated Informed Consent Form before performance of 
any study-related activities. The IC form that is used will be approved by reviewing EC and will be in 
a language that the participant can read and understand. The ICF will be in accordance with current 
ICH and GCP guidelines and with applicable local regulations. 
11.3 
Study Data Protection  
The collection and processing of personal data from participants enrolled in the study will be limited 
to those data that are necessary to fulfill the objectives of this study.  
These data must be collected and processed with adequate precautions to ensure confidentiality 
and compliance with applicable data protection laws and regulations. 
11.4 
Subject Identification  
The participant identification will be treated as confidential and will be filed by the investigator in 
an identification log. This log is kept at the participating site and shall not be copied. In all reports 
and communication between the site and the Sponsor the participant shall be identified with a 
participant study number. 
 
12 Insurance 
VUB is, as Sponsor of the trial, responsible for ensuring appropriate general/product liability 
insurance and as required in accordance with applicable laws and regulations, country-specific 
liability insurance coverage for claims made by a trial subjects for injury arising from the subject’s 
participation in the trial. 
 
13 Reporting and Dissemination 
The data and information collected during this trial will be reported in a publication in a 
scientific/medical journal. Reporting of trial results will be performed according to local regulations. 
 
For the correct authorship rules we refer to the International Committee of Medical Journal Editors: 
https://www.icmje.org/recommendations/browse/roles-and-responsibilities/defining-the-role-of-authors-and-
contributors.html 
 
 

 
 
 
 
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14 Finance and Conflict of Interest Statement 
Investigators and study team members will provide the Sponsor with sufficient, accurate financial 
information in accordance with local regulations to allow the Sponsor to submit complete and 
accurate financial certification or disclosure statements to the appropriate regulatory 
authorities/ethics committee. Any update of information on financial interests should be disclosed 
during the course of the study. 
 
 

 
 
 
 
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15 References 
1. 
Anton C, Ciobica A, Doroftei B, Maftei R, Ilea C, Darii Plopa N, et al. A Review of the 
Complex Relationship between Irritable Bowel Syndrome and Infertility. Medicina (Kaunas). 
2020;56(11). 
2. 
Hammar O, Roth B, Bengtsson M, Mandl T, Ohlsson B. Autoantibodies and gastrointestinal 
symptoms in infertile women in relation to in vitro fertilization. BMC Pregnancy Childbirth. 
2013;13:201. 
3. 
Atiomo W, Rizwan MNH, Bajwa MH, Furniturewala HJ, Hazari KS, Harab D, et al. Prevalence 
and Diagnosis of PCOS Using Electronic Health Records: A Scoping Review and a Database 
Analysis. Int J Environ Res Public Health. 2024;21(3). 
4. 
Singh S, Pal N, Shubham S, Sarma DK, Verma V, Marotta F, et al. Polycystic Ovary Syndrome: 
Etiology, Current Management, and Future Therapeutics. J Clin Med. 2023;12(4). 
5. 
Salari N, Nankali A, Ghanbari A, Jafarpour S, Ghasemi H, Dokaneheifard S, et al. Global 
prevalence of polycystic ovary syndrome in women worldwide: a comprehensive systematic review 
and meta-analysis. Arch Gynecol Obstet. 2024;310(3):1303-14. 
6. 
Dason ES, Koshkina O, Chan C, Sobel M. Diagnosis and management of polycystic ovarian 
syndrome. CMAJ. 2024;196(3):E85-E94. 
7. 
Azziz R. Introduction: Determinants of polycystic ovary syndrome. Fertil Steril. 
2016;106(1):4-5. 
8. 
Katsani D, Paraschou N, Panagouli E, Tsarna E, Sergentanis TN, Vlahos N, et al. Social Egg 
Freezing-A Trend or Modern Reality? J Clin Med. 2024;13(2). 
9. 
Tang HY, Jiang AJ, Wang XY, Wang H, Guan YY, Li F, et al. Uncovering the pathophysiology 
of irritable bowel syndrome by exploring the gut-brain axis: a narrative review. Ann Transl Med. 
2021;9(14):1187. 
10. 
Saha L. Irritable bowel syndrome: pathogenesis, diagnosis, treatment, and evidence-based 
medicine. World J Gastroenterol. 2014;20(22):6759-73. 
11. 
Zamani M, Alizadeh-Tabari S, Zamani V. Systematic review with meta-analysis: the 
prevalence of anxiety and depression in patients with irritable bowel syndrome. Aliment Pharmacol 
Ther. 2019;50(2):132-43. 
12. 
Myers B, Greenwood-Van Meerveld B. Role of anxiety in the pathophysiology of irritable 
bowel syndrome: importance of the amygdala. Front Neurosci. 2009;3:47. 
13. 
Turner K, Reynolds-May MF, Zitek EM, Tisdale RL, Carlisle AB, Westphal LM. Stress and 
anxiety scores in first and repeat IVF cycles: a pilot study. PLoS One. 2013;8(5):e63743. 
14. 
Mudyanadzo TA, Hauzaree C, Yerokhina O, Architha NN, Ashqar HM. Irritable Bowel 
Syndrome and Depression: A Shared Pathogenesis. Cureus. 2018;10(8):e3178. 
15. 
Huang KY, Wang FY, Lv M, Ma XX, Tang XD, Lv L. Irritable bowel syndrome: Epidemiology, 
overlap disorders, pathophysiology and treatment. World J Gastroenterol. 2023;29(26):4120-35. 
16. 
Lacy BE, Patel NK. Rome Criteria and a Diagnostic Approach to Irritable Bowel Syndrome. J 
Clin Med. 2017;6(11). 
17. 
Canavan C, West J, Card T. The epidemiology of irritable bowel syndrome. Clin Epidemiol. 
2014;6:71-80. 
18. 
Saei Ghare Naz M, Ghasemi V, Amirshekari S, Ramezani Tehrani F. Polycystic Ovary 
Syndrome and Irritable Bowel Syndrome: Is There a Common Pathway? Endocrinol Diabetes Metab. 
2024;7(2):e00477. 
19. 
Kibune Nagasako C, Garcia Montes C, Silva Lorena SL, Mesquita MA. Irritable bowel 
syndrome subtypes: Clinical and psychological features, body mass index and comorbidities. Rev 
Esp Enferm Dig. 2016;108(2):59-64. 
20. 
Suthersan D, Kennedy S, Chapman M. Physical symptoms throughout IVF cycles. Hum Fertil 
(Camb). 2011;14(2):122-8. 
21. 
Bülow N, Macklon N. The role of letrozole in in vitro fertilization treatment: new remedy or 
old mirage? Fertil Steril. 2025;123(1):41-9. 
22. 
Files JA, Ko MG, Pruthi S. Managing aromatase inhibitors in breast cancer survivors: not just 
for oncologists. Mayo Clin Proc. 2010;85(6):560-6; quiz 6. 
23. 
Findeklee S, Diedrich PK. Cetrorelix in reproductive medicine. F S Rep. 2023;4(2 Suppl):62-
4. 
24. 
Lai Q, Zhang H, Zhu G, Li Y, Jin L, He L, et al. Comparison of the GnRH agonist and 
antagonist protocol on the same patients in assisted reproduction during controlled ovarian 
stimulation cycles. Int J Clin Exp Pathol. 2013;6(9):1903-10. 

 
 
 
 
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25. 
Cordeddu L, Bergvall M, Sand E, Roth B, Papadaki E, Li L, et al. Severe gastrointestinal 
dysmotility developed after treatment with gonadotropin-releasing hormone analogs. Scand J 
Gastroenterol. 2015;50(3):291-9. 
26. 
Liang Y, Guo Q, Wu XH, Zhang LN, Ge J, Xu ML, et al. Does the additional use of clomiphene 
citrate or letrozole for in vitro fertilization deserve more attention? BMC Pregnancy Childbirth. 
2021;21(1):275. 
27. 
LiverTox: Clinical and Research Information on Drug-Induced Liver Injury. 2012. 
28. 
Makkawy EA, Abdulaal IE, Kalaji FR, Makkawi M, Alsindi N. Prevalence, Risk Factors, and 
Management of Irritable Bowel Syndrome in Saudi Arabia: A Systematic Review. Cureus. 
2023;15(10):e47440. 
29. 
Lyra A, Hillilä M, Huttunen T, Männikkö S, Taalikka M, Tennilä J, et al. Irritable bowel 
syndrome symptom severity improves equally with probiotic and placebo. World J Gastroenterol. 
2016;22(48):10631-42. 
30. 
Francis CY, Morris J, Whorwell PJ. The irritable bowel severity scoring system: a simple 
method of monitoring irritable bowel syndrome and its progress. Aliment Pharmacol Ther. 
1997;11(2):395-402. 
31. 
Hori K, Matsumoto T, Miwa H. Analysis of the gastrointestinal symptoms of uninvestigated 
dyspepsia and irritable bowel syndrome. Gut Liver. 2009;3(3):192-6. 
32. 
Kroenke K, Spitzer RL, Williams JB. The PHQ-9: validity of a brief depression severity 
measure. J Gen Intern Med. 2001;16(9):606-13. 
33. 
Sapra A, Bhandari P, Sharma S, Chanpura T, Lopp L. Using Generalized Anxiety Disorder-2 
(GAD-2) and GAD-7 in a Primary Care Setting. Cureus. 2020;12(5):e8224. 
 
 
 
 
 

 
 
 
 
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16 Appendices 
 
APPENDIX 1: ROME IV IBS QUESTIONNAIRE (English version) (Rome Foundation)  
 
 
Question 
Answer 
40. In the last 3 months, how often did you have 
pain anywhere in your abdomen? 
 
 
 
 
 
 
 
 
 
 
40b. In the last 3 months, how often did you have 
discomfort anywhere in your abdomen ?  
 
 
 
 
 
  Never  
  Less than one day a month 
  One day a month 
  Two to three days a month 
  Once a week 
  Two to three days a week 
  Most days 
  Every day 
  Multiple times per day or all the time 
 
 
  Never →  If you answered “Never” on 
question 40 and 40b: Skip question 41 
  Less than one day a month 
  One day a month 
  Two to three days a month 
  Once a week 
  Two to three days a week 
  Most days 
  Every day 
  Multiple times per day or all the time 
 
41. How often did this pain in your abdomen 
happen close in time to a bowel movement -- just 
before, during, or soon after? (Percent of times 
with pain) 
 
  0%  Never  
  10% 
  20% 
  30% 
  40% 
  50% 
  60% 
  70% 
  80% 
  90% 
  100%  Always 

 
 
 
 
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42. How often did your stools become either 
softer than usual or harder than usual when you 
had this pain? (Percent of times with pain) 
 
  0%  Never  
  10% 
  20% 
  30% 
  40% 
  50% 
  60% 
  70% 
  80% 
  90% 
  100%  Always 
43. How often did your stools become either more 
frequent than usual or less frequent than usual 
when you had this pain? (Percent of times with 
pain) 
 
  0%  Never  
  10% 
  20% 
  30% 
  40% 
  50% 
  60% 
  70% 
  80% 
  90% 
  100%  Always 
48. Has it been 6 months or longer since you 
started having this pain? 
  No 
  Yes 
 
 

 
 
 
 
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Bowel movements of Type 1 or 2 and also of Type 6 or 7 in the picture above can be considered to be 
abnormal.  Type 1 or 2 means you are constipated, and Type 6 or 7 means you have diarrhea. 
 
64. In the last 3 months, when you had 
abnormal stools, what were they usually 
like? 
 
 Usually constipation (like Type 1 or 2 in the 
picture)  
  Usually diarrhea (like Type 6 or 7) 
  Both diarrhea and constipation  - that is, more 
      than 1/4 of all the abnormal bowel movements 
      were constipation and more than ¼ 
      were diarrhea 
  Not applicable, because I never or rarely  
      had abnormal bowel movements 
 
 
 
 

 
 
 
 
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APPENDIX 2: IBS Symptom Severity Scale (IBS-SSS) (English version) (Rome 
Foundation)  
 
1a. Do you currently (in the past 10 days) suffer from abdominal (stomach) pain? 
No Skip to question 3a 
Yes 
 
1b. How severe was your abdominal (stomach) pain in the past 10 days? (Please indicate a 
number from 0 to 100, with 0 meaning “no pain” and 100 meaning “very severe pain”) 
0 -- No pain 
10 
20 
30 
40 
50 
60 
70 
80 
90 
100 -- Very severe pain 
 
2. Please enter the number of days you had the abdominal pain in the past 10 days. (For 
example, if you enter 4 it means that you had pain 4 out of 10 days. If you have pain every 
day, enter 10.) 
0 days 
1 
2 
3 
4 
5 
6 
7 
8 
9 
10 days 
 
3a. Do you currently (in the past 10 days) suffer from abdominal distention (bloating, 
swollen or tight stomach)? 
Women: Please ignore distention related to your period when answering this question. 
No Skip to question 4 
Yes 
 
3b. How severe was your abdominal distention/tightness in the past 10 days? (Please 
indicate a number from 0 to 100, with 0 meaning “no distention” and 100 meaning “very 
severe 
distention”) 
0 -- No distention 
10 
20 
30 
40 
50 
60 
70 
80 
90 
100 -- Very severe distention 
 
 

 
 
 
 
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4. How dissatisfied are you with your bowel functioning in the past 10 days? (Please indicate 
a number from 0 to 100, with 0 meaning “Not dissatisfied” and 100 meaning “very 
dissatisfied”) 
0 -- Not dissatisfied 
10 
20 
30 
40 
50 
60 
70 
80 
90 
100 -- Very dissatisfied 
 
5. How much did abdominal pain or discomfort or altered bowel functioning affect or 
interfere with your life in general in the past 10 days? (Please indicate a number from 0 to 
100, with 0 meaning “Not at all” and 100 meaning “completely”) 
0 -- Not at all 
10 
20 
30 
40 
50 
60 
70 
80 
90 
100 -- Completely 

 
 
 
 
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Appendix 3: Gastrointestinal Symptom Rating Scale (GSRS) (Astrazeneca, 
1995) (English version)  
THE GASTROINTESTINAL SYMPTOM RATING SCALE 
(GSRS) 
 
Please read this first: 
This survey contains questions about how you have been feeling and whatit has been like DURING THE 
PAST WEEK. Mark the choice that best applies to you and your situation with an “X” in the box. 
 
1. Have you been bothered by PAIN OR DISCOMFORT IN YOUR UPPER ABDOMEN OR THE PIT 
OF YOUR STOMACH during the past week? 
 
 No discomfort at all 
 Minor discomfort 
 Mild discomfort 
 Moderate discomfort 
 Moderately severe discomfort 
 Severe discomfort 
 Very severe discomfort 
 
2. Have you been bothered by HEARTBURN during the past week? (By heartburn we 
mean an unpleasant stinging or burning sensation in the chest.) 
 
 No discomfort at all 
 Minor discomfort 
 Mild discomfort 
 Moderate discomfort 
 Moderately severe discomfort 
 Severe discomfort 
 Very severe discomfort 
 
3. Have you been bothered by ACID REFLUX during the past week? (By acid reflux we 
mean the sensation of regurgitating small quantities of acid or flow of sour or bitter 
fluid from the stomach up to the throat.) 
 
 No discomfort at all 
 Minor discomfort 
 Mild discomfort 
 Moderate discomfort 
 Moderately severe discomfort 
 Severe discomfort 
 Very severe discomfort 
 
4. Have you been bothered by HUNGER PAINS in the stomach during the past week? 
(This hollow feeling in the stomach is associated with the need to eat between 
meals.) 
 
 No discomfort at all 
 Minor discomfort 
 Mild discomfort 
 Moderate discomfort 
 Moderately severe discomfort 
 Severe discomfort 
 Very severe discomfort 
 
5. Have you been bothered by NAUSEA during the past week? (By nausea we mean a 

 
 
 
 
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feeling of sickness that may lead to retching and vomiting.) 
 
 No discomfort at all 
 Minor discomfort 
 Mild discomfort 
 Moderate discomfort 
 Moderately severe discomfort 
 Severe discomfort 
 Very severe discomfort 
 
6. Have you been bothered by RUMBLING in your stomach during the past week? 
(Rumbling refers to vibrations or noise in the stomach.) 
 
 No discomfort at all 
 Minor discomfort 
 Mild discomfort 
 Moderate discomfort 
 Moderately severe discomfort 
 Severe discomfort 
 Very severe discomfort 
 
7. Has your stomach felt BLOATED during the past week? (Feeling bloated refers to 
swelling often associated with a sensation of gas or air in the stomach.) 
 
 No discomfort at all 
 Minor discomfort 
 Mild discomfort 
 Moderate discomfort 
 Moderately severe discomfort 
 Severe discomfort 
 Very severe discomfort 
 
8. Have you been bothered by BELCHING during the past week? (Belching refers to 
the release of wind from the stomach via the mouth, often associated with easing a 
bloated feeling.) 
 
 No discomfort at all 
 Minor discomfort 
 Mild discomfort 
 Moderate discomfort 
 Moderately severe discomfort 
 Severe discomfort 
 Very severe discomfort 
 
9. Have you been bothered by BREAKING WIND during the past week? (Breaking wind 
refers to the need to release air or gas from the bowel, often associated with easing 
a bloated feeling.) 
 
 No discomfort at all 
 Minor discomfort 
 Mild discomfort 
 Moderate discomfort 
 Moderately severe discomfort 
 Severe discomfort 
 Very severe discomfort 
10. Have you been bothered by CONSTIPATION during the past week? (Constipation 
refers to a reduced ability to empty the bowels.) 

 
 
 
 
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 No discomfort at all 
 Minor discomfort 
 Mild discomfort 
 Moderate discomfort 
 Moderately severe discomfort 
 Severe discomfort 
 Very severe discomfort 
 
11. Have you been bothered by DIARRHOEA during the past week? (Diarrhoea refers to 
a too frequent emptying of the bowels.) 
 
 No discomfort at all 
 Minor discomfort 
 Mild discomfort 
 Moderate discomfort 
 Moderately severe discomfort 
 Severe discomfort 
 Very severe discomfort 
 
12. Have you been bothered by LOOSE STOOLS during the past week? (If your stools 
(motions) have been alternately hard and loose, this question only refers to the 
extent you have been bothered by the stools being loose.) 
 
 No discomfort at all 
 Minor discomfort 
 Mild discomfort 
 Moderate discomfort 
 Moderately severe discomfort 
 Severe discomfort 
 Very severe discomfort 
 
13. Have you been bothered by HARD STOOLS during the past week? (If your stools 
(motions) have been alternately hard and loose, this question only refers to the 
extent you have been bothered by the stools being hard.) 
 
 No discomfort at all 
 Minor discomfort 
 Mild discomfort 
 Moderate discomfort 
 Moderately severe discomfort 
 Severe discomfort 
 Very severe discomfort 
 
14. Have you been bothered by an URGENT NEED TO HAVE A BOWEL MOVEMENT 
during the past week? (This urgent need to go to the toilet is often associated with 
a feeling that you are not in full control.) 
 No discomfort at all 
 Minor discomfort 
 Mild discomfort 
 Moderate discomfort 
 Moderately severe discomfort 
 Severe discomfort 
 Very severe discomfort 
15. When going to the toilet during the past week, have you had the SENSATION OF 
NOT COMPLETELY EMPTYING THE BOWELS? (This feeling of incomplete 
emptying means that you still feel a need to pass your motions despite having 

 
 
 
 
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exerted yourself to do so.) 
 
 No discomfort at all 
 Minor discomfort 
 Mild discomfort 
 Moderate discomfort 
 Moderately severe discomfort 
 Severe discomfort 
 Very severe discomfort 
 
PLEASE CHECK THAT ALL QUESTIONS HAVE BEEN ANSWERED! 
THANK YOU FOR YOUR CO-OPERATION. 

 
 
 
 
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Appendix 4: General Anxiety Disorder 7 (GAD-7) (Spitzer 2006) (English 
version)  
 
Over the last 2 weeks, how often have you been 
bothered by the following problems? 
Not at 
all 
Several 
days 
Over 
half the 
days 
Nearly 
every 
day 
1. Feeling nervous, anxious, or on edge 
 
0 
1 
2 
3 
2. Not being able to stop or control worrying 
 
0 
1 
2 
3 
3. Worrying too much about different things 
 
0 
1 
2 
3 
4. Trouble relaxing 
 
0 
1 
2 
3 
5. Being so restless that it's hard to sit still 
 
0 
1 
2 
3 
6. Becoming easily annoyed or irritable 
 
0 
1 
2 
3 
7. Feeling afraid as if something awful might happen 
 
0 
1 
2 
3 
 

 
 
 
 
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Appendix 5: Patient Health Questionnaire-9 (PHQ-9) (Kroenke 2001) (English 
version)  
 
Over the last 2 weeks, how often have you been 
bothered by any of the following problems? 
Not at 
all 
Several 
days 
More 
than 
half the 
days 
Nearly 
every 
day 
1. Little interest or pleasure in doing things 
 
0 
1 
2 
3 
2. Feeling down, depressed, or hopeless 
 
0 
1 
2 
3 
3. Trouble falling or staying asleep, or sleeping too 
much 
 
0 
1 
2 
3 
4. Feeling tired or having little energy 
 
0 
1 
2 
3 
5. Poor appetite or overeating 
 
0 
1 
2 
3 
6. Feeling bad about yourself - or that you are a failure 
or have let yourself or your family down 
 
0 
1 
2 
3 
7. Trouble concentrating on things, such as reading 
the newspaper or watching television 
 
0 
1 
2 
3 
8. Moving or speaking so slowly that other people 
could have noticed? Or the opposite - being so 
fidgety or restless that you have been moving 
around a lot more than usual 
0 
1 
2 
3 
9. Thoughts that you would be better off dead or 
hurting yourself in some way 
0 
1 
2 
3 
 
If you checked off any problems, how difficult have these problems made it for you to do your 
work, take care of things at home, or get along with other people? 
 
Not difficult at all 
☐        
Somewhat difficult 
☐ 
Very difficult  
☐ 
Extremely difficult 
☐