UterineNCT06633692
Female Pelvic Blood Flow Under Simulated Microgravity
A study testing Head down tilt (HDT) in people with Uterine and Ovary, run by Ceren UNAL at 1 site in Turkey (Türkiye).
Trial summary
Spaceflight is characterized by unique physiological adaptations. Cardiovascular system response to the microgravity includes major changes. During spaceflight, body fluids are displaced in the cephalad direction due to changes in gravity, resulting in altered vascular dynamics and the redistribution of the blood… Read more about this study
- Who is it for?
- Ages 18 to 44 years, women onlyHealthy volunteers can take part
- Conditions the study is for
- Uterine, Ovary, Microgravity
- What is being tested?
- Head down tilt (HDT)
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 20 participants
- Where
- 1 siteTurkey (Türkiye)
- Study dates
- 1 Dec 2024to 1 Aug 2025
- Phase
- Interventional
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 44 years
- Women only
- Healthy volunteers accepted
- Adult
Who may be able to join
- 18-44 years old healthy female individuals
Who cannot join
- History of hysterectomy and/or oophorectomy
- Pregnancy
- Premature ovarian insufficiency
- Women with reproductive tract pathologies
- Cardiovascular diseases
Trial locations and contacts
1 site in 1 country.
About this study
Spaceflight is characterized by unique physiological adaptations. Cardiovascular system response to the microgravity includes major changes. During spaceflight, body fluids are displaced in the cephalad direction due to changes in gravity, resulting in altered vascular dynamics and the redistribution of the blood circulation.
As the investigators approach crewed Moon and Mars missions and commercial spaceflights become more frequent, understanding the impact of space travel on women's health is crucial. Despite the known importance of these vascular dynamics in both clinical and research settings, there is limited information on the pelvic blood flow under microgravity. The aim of this project is to fill this gap by analyzing the impact of simulated microgravity on the perfusion of female reproductive organs using Doppler velocimetry. Head-down tilt (HDT) position is an established model in literature for simulated microgravity on Earth.
This prospective study will assess pelvic organ blood flow in the supine position after a period of acclimation as a control. After completing Doppler measurements in the supine position, the participant will be placed in the HDT position. Following a period of acclimation, Doppler measurements will be repeated on the same vessels.During both supine and simulated microgravity conditions, vital signs (i.e., blood pressure, heart rate, oxygen saturation) will be collected.
Read the detailed description
Cardiovascular system response to the microgravity includes major changes. During spaceflight, body fluids are displaced in the cephalad direction due to changes in gravity, resulting in altered vascular dynamics and the redistribution of the blood circulation. Redistribution of fluids triggers baroreceptor reflex and autonomic response initiates. Cardiovascular response to the microgravity environment is affected by gender. Women tend to lose more plasma volume and have less peripheral vascular resistance in response to microgravity analogue situations like bed rest.
Simulated microgravity leads to increased stiffness and remodeling of the aorta, a major vessel supplying blood to the abdomen, pelvis, and lower extremities. Pelvic organs are located in the lower abdomen and have rich blood supply through these major blood vessels and anastomosis. Mathematical modeling for microgravity showed a 6% mean flow rate variation in the last part of abdominal aorta. Furthermore, mean flow rate variations and resistance changed based on the branching arteries, such as internal iliac arteries. The uterine and ovarian arteries branch from the internal iliac arteries and abdominal aorta, respectively. Blood supply to an organ and tissue perfusion are vital for the proper functioning of the organs and tissues.
As the investigators approach crewed Moon and Mars missions and commercial spaceflights become more frequent, understanding the impact of space travel on women's health is crucial. Despite the known importance of these vascular dynamics in both clinical and research settings, there is limited information on the pelvic blood flow under microgravity. Our aim is to fill this gap by analyzing the impact of simulated microgravity on the perfusion of female reproductive organs using Doppler velocimetry. Head-down tilt (HDT) position is an established model in literature for simulated microgravity on Earth.
This prospective study will be conducted at Koç University Hospital. Adult women of reproductive age (18-44 years) undergoing abdominal ultrasound will be recruited. Participants will be selected from a cohort presenting for their well-woman visit; there will be no additional visits. Ultrasound and Doppler spectrometry evaluations will be carried out with convex and linear probes of the GE Loqic S8 device. The researchers will assess pelvic organ blood flow in the supine position after a period of acclimation as a control. After completing Doppler measurements in the supine position, the participant will be placed in the HDT position. Following a period of acclimation, Doppler measurements will be repeated on the same vessels. During both supine and simulated microgravity conditions, vital signs (i.e., blood pressure, heart rate, oxygen saturation) will be collected. Pre- and post-HDT Doppler measurements will be compared and analyzed.
- Conditions
- Uterine, Ovary, Microgravity, Blood Flow
- Being tested
- Head down tilt (HDT)
- Keywords
- microgravity, female pelvic blood flow, doppler ultrasound
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Head down tilt (HDT)Other
In the head-down tilt intervention, a participant is positioned on a tilt table, initially in supine position and afterwards with their head inclined downward at a specific angle. This position causes a shift of body fluids towards the head, mimicking the fluid redistribution observed in microgravity conditions in space.
| Study group | Role | What they receive |
|---|---|---|
| Simulated microgravity | Experimental | Pre- and post-assessment of pelvic blood flow in response to simulated microgravity will be performed in the same participant. Receives: Other: Head down tilt (HDT) |
What is being measured
The primary outcome is the main question the study is designed to answer.
Internal iliac artery Doppler indices before and after HDT
Internal iliac artery Doppler flow indices will be obtained in supine and HDT positions after acclimation periods
Measured: through study completion, an average of 1 year
Secondary outcomes (1)
Ovarian artery Doppler indices before and after HDT
Ovarian artery Doppler flow indices will be obtained in supine and HDT positions after acclimation periods
Measured: through study completion, an average of 1 year
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted9 Oct 2024
- Study start1 Dec 2024
- Primary completion30 May 2025
- Study completion1 Aug 2025
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (7)Papers the sponsor has linked to this study.
- Other trials for UterineStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Other
- Allocation
- Not applicable
- Intervention model
- Single group
- Model description
- Pre- and post-assessment of the pelvic blood flow in response to simulated microgravity
- Masking
- None (open label)
- Enrolment
- 20 participants (actual)
Sponsor and investigators
- Lead sponsor
- Ceren UNAL
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor-investigator, Ceren UNAL, Koc University Hospital
- Investigators
- Afak Durur Karakaya, M.D., Principal investigator, Koç University
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06633692
- Sponsor's protocol ID
- 2024.238.IRB1.028
- Status last verified
- Nov 2025
- First submitted
- 7 Oct 2024
- Last updated
- 28 Nov 2025
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
Publications
Perhonen MA, Franco F, Lane LD, Buckey JC, Blomqvist CG, Zerwekh JE, Peshock RM, Weatherall PT, Levine BD; New Collective Author. Cardiac atrophy after bed rest and spaceflight. J Appl Physiol (1985). 2001 Aug;91(2):645-53. doi: 10.1152/jappl.2001.91.2.645.
PubMed 11457776Waters WW, Ziegler MG, Meck JV; New Collective Author. Postspaceflight orthostatic hypotension occurs mostly in women and is predicted by low vascular resistance. J Appl Physiol (1985). 2002 Feb;92(2):586-94. doi: 10.1152/japplphysiol.00544.2001.
PubMed 11796668Herault S, Fomina G, Alferova I, Kotovskaya A, Poliakov V, Arbeille P. Cardiac, arterial and venous adaptation to weightlessness during 6-month MIR spaceflights with and without thigh cuffs (bracelets). Eur J Appl Physiol. 2000 Mar;81(5):384-90. doi: 10.1007/s004210050058.
PubMed 10751099Shen M, Frishman WH. Effects of Spaceflight on Cardiovascular Physiology and Health. Cardiol Rev. 2019 May/Jun;27(3):122-126. doi: 10.1097/CRD.0000000000000236.
PubMed 30365406Gallo C, Ridolfi L, Scarsoglio S. Cardiovascular deconditioning during long-term spaceflight through multiscale modeling. NPJ Microgravity. 2020 Oct 1;6:27. doi: 10.1038/s41526-020-00117-5. eCollection 2020.
PubMed 33083524Tuday EC, Meck JV, Nyhan D, Shoukas AA, Berkowitz DE. Microgravity-induced changes in aortic stiffness and their role in orthostatic intolerance. J Appl Physiol (1985). 2007 Mar;102(3):853-8. doi: 10.1152/japplphysiol.00950.2006. Epub 2006 Nov 2.
PubMed 17082368Mathyk B, Imudia A, Quaas A, Halicigil C, Karouia F, Avci P, Nelson N, Guzeloglu-Kayisli O, Denbo M, Sanders L, Scott R, Basar M, Guevara-Cerdan A, Strug M, Monseur B, Kayisli U, Szewczyk N, Mason CE, Young SL, Tasoglu S, Costes S, Beheshti A.Understanding how space travel affects the female reproductive system to the Moon and beyond. npj Womens Health 2, 20 (2024). https://doi.org/10.1038/s44294-024-00009-z
Study at a glance
From the registry record, last updated by the sponsor on 28 Nov 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Female Pelvic Blood Flow Under Simulated Microgravity
- ClinicalTrials.gov ID
- NCT06633692
- Acronym / sponsor ID
- 2024.238.IRB1.028
- Conditions
- Uterine, Ovary, Microgravity, Blood Flow
- Keywords
- microgravity, female pelvic blood flow, doppler ultrasound
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 20 participants (actual)
- Lead sponsor
- Ceren UNALUniversity, hospital or other
- Study start
- 1 Dec 2024 (actual)
- Primary completion
- 30 May 2025 (actual)
- Study completion
- 1 Aug 2025 (actual)
- First posted
- 9 Oct 2024 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
Spaceflight is characterized by unique physiological adaptations. Cardiovascular system response to the microgravity includes major changes. During spaceflight, body fluids are displaced in the cephalad direction due to changes in gravity, resulting in altered vascular dynamics and the redistribution of the blood circulation.
As the investigators approach crewed Moon and Mars missions and commercial spaceflights become more frequent, understanding the impact of space travel on women's health is crucial. Despite the known importance of these vascular dynamics in both clinical and research settings, there is limited information on the pelvic blood flow under microgravity. The aim of this project is to fill this gap by analyzing the impact of simulated microgravity on the perfusion of female reproductive organs using Doppler velocimetry. Head-down tilt (HDT) position is an established model in literature for simulated microgravity on Earth.
This prospective study will assess pelvic organ blood flow in the supine position after a period of acclimation as a control. After completing Doppler measurements in the supine position, the participant will be placed in the HDT position. Following a period of acclimation, Doppler measurements will be repeated on the same vessels.During both supine and simulated microgravity conditions, vital signs (i.e., blood pressure, heart rate, oxygen saturation) will be collected.
Detailed description
Cardiovascular system response to the microgravity includes major changes. During spaceflight, body fluids are displaced in the cephalad direction due to changes in gravity, resulting in altered vascular dynamics and the redistribution of the blood circulation. Redistribution of fluids triggers baroreceptor reflex and autonomic response initiates. Cardiovascular response to the microgravity environment is affected by gender. Women tend to lose more plasma volume and have less peripheral vascular resistance in response to microgravity analogue situations like bed rest.
Simulated microgravity leads to increased stiffness and remodeling of the aorta, a major vessel supplying blood to the abdomen, pelvis, and lower extremities. Pelvic organs are located in the lower abdomen and have rich blood supply through these major blood vessels and anastomosis. Mathematical modeling for microgravity showed a 6% mean flow rate variation in the last part of abdominal aorta. Furthermore, mean flow rate variations and resistance changed based on the branching arteries, such as internal iliac arteries. The uterine and ovarian arteries branch from the internal iliac arteries and abdominal aorta, respectively. Blood supply to an organ and tissue perfusion are vital for the proper functioning of the organs and tissues.
As the investigators approach crewed Moon and Mars missions and commercial spaceflights become more frequent, understanding the impact of space travel on women's health is crucial. Despite the known importance of these vascular dynamics in both clinical and research settings, there is limited information on the pelvic blood flow under microgravity. Our aim is to fill this gap by analyzing the impact of simulated microgravity on the perfusion of female reproductive organs using Doppler velocimetry. Head-down tilt (HDT) position is an established model in literature for simulated microgravity on Earth.
This prospective study will be conducted at Koç University Hospital. Adult women of reproductive age (18-44 years) undergoing abdominal ultrasound will be recruited. Participants will be selected from a cohort presenting for their well-woman visit; there will be no additional visits. Ultrasound and Doppler spectrometry evaluations will be carried out with convex and linear probes of the GE Loqic S8 device. The researchers will assess pelvic organ blood flow in the supine position after a period of acclimation as a control. After completing Doppler measurements in the supine position, the participant will be placed in the HDT position. Following a period of acclimation, Doppler measurements will be repeated on the same vessels. During both supine and simulated microgravity conditions, vital signs (i.e., blood pressure, heart rate, oxygen saturation) will be collected. Pre- and post-HDT Doppler measurements will be compared and analyzed.
Study design
- Primary purpose
- Other
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Number of arms
- 1
- Model description
- Pre- and post-assessment of the pelvic blood flow in response to simulated microgravity
| Arm | Type | Receives |
|---|---|---|
| Simulated microgravity | Experimental | Other: Head down tilt (HDT)Pre- and post-assessment of pelvic blood flow in response to simulated microgravity will be performed in the same participant. |
Who may qualify
- Ages
- 18 to 44 years
- Sex
- Female only
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (1 listed)
- 18-44 years old healthy female individuals
Key exclusion criteria (5 listed)
- History of hysterectomy and/or oophorectomy
- Pregnancy
- Premature ovarian insufficiency
- Women with reproductive tract pathologies
- Cardiovascular diseases
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Head down tilt (HDT)In the head-down tilt intervention, a participant is positioned on a tilt table, initially in supine position and afterwards with their head inclined downward at a specific angle. This position causes a shift of body fluids towards the head, mimicking the fluid redistribution observed in microgravity conditions in space. | Other | Simulated microgravity |
Primary outcome
Internal iliac artery Doppler indices before and after HDT
Time frame: through study completion, an average of 1 year
Internal iliac artery Doppler flow indices will be obtained in supine and HDT positions after acclimation periods
1 secondary outcome
Ovarian artery Doppler indices before and after HDT
Time frame: through study completion, an average of 1 year
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 28 Nov 2025.
- Background: PubMed 11457776Perhonen MA, Franco F, Lane LD, Buckey JC, Blomqvist CG, Zerwekh JE, Peshock RM, Weatherall PT, Levine BD; New Collective Author. Cardiac atrophy after bed rest and spaceflight. J Appl Physiol (1985). 2001 Aug;91(2):645-53. doi: 10.1152/jappl.2001.91.2.645.
- Background: PubMed 11796668Waters WW, Ziegler MG, Meck JV; New Collective Author. Postspaceflight orthostatic hypotension occurs mostly in women and is predicted by low vascular resistance. J Appl Physiol (1985). 2002 Feb;92(2):586-94. doi: 10.1152/japplphysiol.00544.2001.
- Background: PubMed 10751099Herault S, Fomina G, Alferova I, Kotovskaya A, Poliakov V, Arbeille P. Cardiac, arterial and venous adaptation to weightlessness during 6-month MIR spaceflights with and without thigh cuffs (bracelets). Eur J Appl Physiol. 2000 Mar;81(5):384-90. doi: 10.1007/s004210050058.
- Background: PubMed 30365406Shen M, Frishman WH. Effects of Spaceflight on Cardiovascular Physiology and Health. Cardiol Rev. 2019 May/Jun;27(3):122-126. doi: 10.1097/CRD.0000000000000236.
- Background: PubMed 33083524Gallo C, Ridolfi L, Scarsoglio S. Cardiovascular deconditioning during long-term spaceflight through multiscale modeling. NPJ Microgravity. 2020 Oct 1;6:27. doi: 10.1038/s41526-020-00117-5. eCollection 2020.
- Background: PubMed 17082368Tuday EC, Meck JV, Nyhan D, Shoukas AA, Berkowitz DE. Microgravity-induced changes in aortic stiffness and their role in orthostatic intolerance. J Appl Physiol (1985). 2007 Mar;102(3):853-8. doi: 10.1152/japplphysiol.00950.2006. Epub 2006 Nov 2.
- BackgroundMathyk B, Imudia A, Quaas A, Halicigil C, Karouia F, Avci P, Nelson N, Guzeloglu-Kayisli O, Denbo M, Sanders L, Scott R, Basar M, Guevara-Cerdan A, Strug M, Monseur B, Kayisli U, Szewczyk N, Mason CE, Young SL, Tasoglu S, Costes S, Beheshti A.Understanding how space travel affects the female reproductive system to the Moon and beyond. npj Womens Health 2, 20 (2024). https://doi.org/10.1038/s44294-024-00009-z
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Afak Durur Karakaya, M.D. principal investigator
Koç University
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Head down tilt (HDT) in people with Uterine and Ovary, run by Ceren UNAL at 1 site in Turkey (Türkiye).
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 1 inclusion and 5 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 28 Nov 2025. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Turkey (Türkiye). Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Internal iliac artery Doppler indices before and after HDT (time frame: through study completion, an average of 1 year). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT06633692, which also lists 7 linked publications.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 28 Nov 2025.