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Trial registered on ANZCTR

Registration number
Ethics application status
Date submitted
Date registered
Date last updated
Date data sharing statement initially provided
Type of registration
Prospectively registered

Titles & IDs
Public title
Superior Hypogastric Nerve Block in Minimally-invasive Gynaecology: a Randomised Controlled Trial (Hypoplex Study)
Scientific title
Superior Hypogastric Plexus Nerve Block in Minimally-invasive Gynaecology and it's effect on Post-operative Opiate requirements: a Randomised Controlled Trial (Hypoplex Study)
Secondary ID [1] 300467 0
Nil known
Universal Trial Number (UTN)
Trial acronym
Hypoplex Study
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Post operative pain 316147 0
Condition category
Condition code
Surgery 314437 314437 0 0
Other surgery

Study type
Description of intervention(s) / exposure
10ml of 0.75% Ropivacaine (local anaesthetic) injected retroperitoneally within the presacral space targeting the superior hypogastric plexus.

Injection provided at the end of minimally invasive gynaecology surgery using laparoscopic guidance

Stratified randomisation with four patient arms
Arm 1- Laparoscopic Hysterectomy
Arm 2- Laparoscopic Myomectomy
Arm 3- Robotic-assisted Laparoscopic Hysterectomy
Arm 4- Robotic-assisted Laparoscopic Myomectomy
Intervention code [1] 316774 0
Treatment: Drugs
Comparator / control treatment
1:1 randomisation protocol (nerve block vs control)
Patient-blinded only

Control group receives no nerve-block at the end of the procedure
Control group

Primary outcome [1] 322778 0
Total opioid use in first 24 hours after surgery (from patient-controlled analgesia pump)
Timepoint [1] 322778 0
first 24 hours post surgery
Secondary outcome [1] 379707 0
Visual analogue scale (VAS) pain scores
Scale runs from 1 to 10
Timepoint [1] 379707 0
First 24 hours after surgery.
At time points 1, 2, 4, 6, 12 and 24 hours post surgery

Key inclusion criteria
Age 18 years and over
Able to give informed consent
Undergoing laparoscopic hysterectomy, laparoscopic myomectomy, robotic-assisted laparoscopic hysterectomy, robotic-assisted laparoscopic myomectomy
Minimum age
18 Years
Maximum age
No limit
Can healthy volunteers participate?
Key exclusion criteria
Known Malignancy
Liver failure or coagulopathy
Known hypersensitivity or allergy to local anaesthetic
Surgeon/ anaesthetic concerns on ability for patient to use patient-controlled opiate analgesia post-operative
Regular opioid use

Study design
Purpose of the study
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Randomisation performed by medical statistician external to trial
Randomisation outcomes provided in sealed opaque envelopes to surgeon and principal investigator
Envelope opened at the end of the surgery- determining which arm the patient will be in
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Block randomisation in groups of 16 for the four stratified groups.
Randomisation performed by computer software by medical statistician
Masking / blinding
Blinded (masking used)
Who is / are masked / blinded?
The people receiving the treatment/s

The people assessing the outcomes
The people analysing the results/data
Intervention assignment
Other design features
Not Applicable
Type of endpoint(s)
Statistical methods / analysis
Study powered to detect a 30% reduction in opioid requirements for the group randomised to receive the nerve block.
Power level set at 80%.

Prior audit of 20 patients' use of opioid medication after the same surgeries (without the nerve block) used to establish mean and standard deviation of opioid use in patients.
G-Power software used to perform power calculations.

Total sample size of 50 required to study for a 30% reduction in opioid use. At 1:1 randomisation this equates to 25 patients in each arm

Primary outcome of total opioid use over 24h will be analysed using Mann-Whitney U analysis

Recruitment status
Not yet recruiting
Date of first participant enrolment
Date of last participant enrolment
Date of last data collection
Sample size
Accrual to date
Recruitment in Australia
Recruitment state(s)
Recruitment hospital [1] 15813 0
St George Private Hospital - Kogarah
Recruitment postcode(s) [1] 29249 0
2217 - Kogarah

Funding & Sponsors
Funding source category [1] 304883 0
Self funded/Unfunded
Name [1] 304883 0
Sydney Women's Endosurgery Centre
Address [1] 304883 0
Sydney Women's Endosurgery Centre
Suite 2, Level 1
37 Gloucester Road
Hurstville 2220
Sydney, NSW
Country [1] 304883 0
Primary sponsor type
Praveen De Silva
Sydney Women's Endosurgery Centre
Suite 2, Level 1
37 Gloucester Road
Hurstville 2220
Sydney, NSW
Secondary sponsor category [1] 305222 0
Name [1] 305222 0
Address [1] 305222 0
Country [1] 305222 0

Ethics approval
Ethics application status
Ethics committee name [1] 305298 0
South Eastern Sydney Local Health District HREC
Ethics committee address [1] 305298 0
G71 East Wing Edmund Blacket Building, Prince of Wales Hospital, RANDWICK NSW 2031
Ethics committee country [1] 305298 0
Date submitted for ethics approval [1] 305298 0
Approval date [1] 305298 0
Ethics approval number [1] 305298 0

Brief summary
Minimally invasive gynaecology (MIG) requires a high level of pain medication both during the operation and after the operation. This is from the pain elicited during surgical skin incision, gas used in MIG and cutting of tissue and organs. Pain relief after surgery still has a high reliance on opioid medication. In opioid-naïve patients even small doses can lead to poor side effects including nausea and vomiting, slowing of gut transit and difficulty with breathing.

A nerve block to the superior hypogastric nerves has been studied previously through observational trials. First in patients with pelvic cancers and more recently for patients after surgery. It is not a difficult nerve block to teach to laparoscopic surgeons. Ropivacaine which is used for the nerve block is a well-studied medication and approved for use by the TGA in Australia. It is also cheap. We plan to study the effect this nerve block as it could be useful adjunct to post-operative pain relief in the future.

This is a single-centre, patient-blinded randomised controlled trial. Patients undergoing minimally invasive gynaecological surgery will be randomised to receive a superior hypogastric nerve block with Ropivacaine at the end of their surgery versus no nerve block. The primary outcome to be studied will be total opioid use in the first 24 hours after surgery. Our secondary outcome is pain scores at regular intervals in the first 24 hours. This will be performed using a visual analogue scale from 1 to 10.

Our hypothesis is that patients receiving a nerve block will use 30% less opioid over the first 24 hours compared to patients not receiving one.

We also predict patients receiving the nerve block will have lower pain scores.

Trial website
Trial related presentations / publications
Public notes

Principal investigator
Name 99902 0
Dr Praveen De Silva
Address 99902 0
Sydney Women’s Endosurgery Centre
Suite 2, Level 1
37 Gloucester Rd
Hurstville NSW 2220
Country 99902 0
Phone 99902 0
+61 2 9553 6500
Fax 99902 0
Email 99902 0
Contact person for public queries
Name 99903 0
Dr Praveen De Silva
Address 99903 0
Sydney Women’s Endosurgery Centre
Suite 2, Level 1
37 Gloucester Rd
Hurstville NSW 2220
Country 99903 0
Phone 99903 0
+61 2 9553 6500
Fax 99903 0
Email 99903 0
Contact person for scientific queries
Name 99904 0
Dr Praveen De Silva
Address 99904 0
Sydney Women’s Endosurgery Centre
Suite 2, Level 1
37 Gloucester Rd
Hurstville NSW 2220
Country 99904 0
Phone 99904 0
+61 2 9553 6500
Fax 99904 0
Email 99904 0

Data sharing statement
Will individual participant data (IPD) for this trial be available (including data dictionaries)?
No/undecided IPD sharing reason/comment
Have not requested ethics permission for this at this stage
What supporting documents are/will be available?
No other documents available
Summary results
No Results