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Trial registered on ANZCTR

Registration number
Ethics application status
Date submitted
Date registered
Date last updated
Type of registration
Prospectively registered

Titles & IDs
Public title
SNAP trial: Sonographic Nerve-block for Laparoscopic Appendicectomy in Children
Scientific title
SNAP trial: In paediatric laparoscopic appendicectomy does sonographically guided rectus sheath nerve block compared to standard port-site local anaesthetic infiltration reduce post-operative pain at the umbilical port site?
Secondary ID [1] 273602 0
Universal Trial Number (UTN)
Trial acronym
SNAP trial
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Appendicitis 285397 0
Condition category
Condition code
Surgery 285577 285577 0 0
Other surgery
Anaesthesiology 285578 285578 0 0
Pain management

Study type
Description of intervention(s) / exposure
After induction of anaesthesia an ultrasound-guided rectus sheath ‘nerve-block’ will be performed by the surgeon or anaesthetist.
Nerve block technique:
Guided by an axially orientated ultrasound image incorporating the lateral edge of the rectus muscle the needle will be inserted in-plane to the ultrasound beam and its tip advanced under visualisation to the posterior extent of the rectus muscle. A hypo-echogenic lentiform swelling between posterior rectus sheath and rectus muscle on injection of a small amount of solution will help confirm correct needle tip position. Half of the solution will be injected at this point. The process will be repeated on the contralateral side.
Local anaesthetic dose:
The volume of solution available for the nerve block will be calculated according to the patient’s body weight up to a maximum of 20ml, to maintain a maximum dose of bupivacaine at or below 2.5mg/kg.
Volume (ml) = Weight (kg) -10
Half the volume will be used for each side.
In addition to the nerve block, 10ml 0.25% bupivacaine with 1:400,000 adrenaline will be available for the surgeon for local infiltration of all port sites.
The nerve block is performed once intraoperatively and not repeated.
Intervention code [1] 283888 0
Treatment: Drugs
Comparator / control treatment
"Rectus sheath nerve block' with placebo - normal saline
Control group

Primary outcome [1] 286136 0
The primary endpoint will be the Pain Site Scores for the umbilicus
Timepoint [1] 286136 0
0, 4, 8, 12, 16, 20 and 24 hours after surgery
Secondary outcome [1] 295218 0
Pain on visual analogue scale
Timepoint [1] 295218 0
0, 4, 8, 12 ,16, 20 and 24 hours after surgery
Secondary outcome [2] 295219 0
Post-operative opiate consumption in morphine equivalent daily dosage (MEDD)
Timepoint [2] 295219 0
Up to 24 hours
Secondary outcome [3] 295220 0
Day 10 Post-operative Recovery Questionnaire
Timepoint [3] 295220 0
10 days post-operatively
Secondary outcome [4] 295221 0
PedsQL Pediatric Quality of Life Inventory version 4.0 Child Report, and Parent Report for Children
Timepoint [4] 295221 0
6 weeks post-opearatively

Key inclusion criteria
All children presenting to Starship Children’s Hospital, aged between 8 and 14 years, diagnosed with acute appendicitis requiring urgent laparoscopic appendectomy.
Minimum age
8 Years
Maximum age
14 Years
Both males and females
Can healthy volunteers participate?
Key exclusion criteria
Diagnosis of developmental delay, neuro-muscular impairment, attention-deficit disorder, chronic pain, or psychiatric illness.
Unable to speak and read English
Partially sighted or blind
Previous open abdominal surgery
Presence of any abdominal prostheses such as a gastrostomy or ventriculo-peritoneal shunt
Allergy to morphine
Consent not obtained from both the participating child and one parent or legal guardian

Study design
Purpose of the study
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Paediatric surgical registrars or consultants will invite children and their parents / whanau to participate in the trial.
Once recruited and consented, the allocation of each participant to the intervention or control group will be performed by an unblinded circulating theatre nurse just prior to the start of the procedure. This nurse will receive written instructions not to disclose the participant’s group allocation to anybody and will have no involvement in the post-operative care of the patient or in data collection, analysis or reporting.
Randomized study allocations will be placed into 200 totally opaque sequentially numbered envelopes by an independent research assistant who will have no subsequent involvement in this study. The envelopes will be securely sealed and kept in a central location. They will be opened strictly in sequence in the operating room just prior to the start of each procedure.
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
The generation of random numbers will be facilitated by an independent research assistant. The allocation sequence will be generated using an open source computer-based on-line random number generator, All numbers from 1 to 156 (to give 20% redundancy) will be generated in random sequence arranged in 2 columns. Study allocation will be based on these numbers.
Masking / blinding
Blinded (masking used)
Who is / are masked / blinded?

Intervention assignment
Other design features
Not Applicable
Type of endpoint(s)
Statistical methods / analysis

Recruitment status
Date of first participant enrolment
Date of last participant enrolment
Date of last data collection
Sample size
Accrual to date
Recruitment outside Australia
Country [1] 4017 0
New Zealand
State/province [1] 4017 0

Funding & Sponsors
Funding source category [1] 284371 0
Name [1] 284371 0
Auckland District Health Board
Address [1] 284371 0
Private Bag 92024
Auckland 1142
Country [1] 284371 0
New Zealand
Primary sponsor type
Auckland District Health Board
Private Bag 92024
Auckland 1142
New Zealand
Secondary sponsor category [1] 283309 0
Name [1] 283309 0
Address [1] 283309 0
Country [1] 283309 0
Other collaborator category [1] 260396 0
Name [1] 260396 0
University of Auckland Department of Surgery
Address [1] 260396 0
Auckland Clinical School
Level 12
Auckland City Hospital Support Building
Park Road
Auckland 1142
Country [1] 260396 0
New Zealand

Ethics approval
Ethics application status
Ethics committee name [1] 286333 0
Multi-region Ethics Committee
Ethics committee address [1] 286333 0
C/- Ministry of Health, PO Box 5013, 1 the Terrace, Wellington.
Ethics committee country [1] 286333 0
New Zealand
Date submitted for ethics approval [1] 286333 0
Approval date [1] 286333 0
Ethics approval number [1] 286333 0

Brief summary
When performing a laparoscopic appendicectomy the surgeon injects local anaesthetic to numb the sites where “keyhole” ports, used for the surgical instruments, are placed through the abdominal wall. For the first port, placed at the belly button (umbilicus) local anaesthetic is placed under the skin, but much of the pain after the operation may come from the deeper tissue layer at the level of “abs” muscles (rectus abdominis). The rectus sheath nerve block, in which local anaesthetic is injected just behind the rectus muscle to numb the nerves that supply the umbilicus, has been shown to be safe and effective in paediatric umbilical operations. Rectus sheath nerve blocks have not been previously studied in paediatric laparoscopic appendicectomy to our knowledge, although a similar block called the TAP (transversus abdominis plane) has been shown to be effective. The possible advantage of the rectus sheath block is that the anaesthetic is placed closer to the umbilicus, and it is easy to perform. Needle placement during a rectus sheath nerve block is more accurate, and possibly safer, when ultrasound is used to ‘see’ where the needle is going. We propose to investigate how an ultrasound guided rectus sheath nerve block can reduce pain after laparoscopic appendicectomy for acute appendicitis.
Trial website
Trial related presentations / publications
Hamill JK, Liley A, Hill AG. Rectus sheath block for laparoscopic appendicectomy: a randomized clinical trial. ANZ journal of surgery. 2015 Dec 1;85(12):951-6.
Public notes
Attachments [1] 627 627 0 0

Principal investigator
Name 33532 0
Dr James Hamill
Address 33532 0
Starship Hospital
Private Bag 92024
Auckland 1142
New Zealand
Country 33532 0
New Zealand
Phone 33532 0
Fax 33532 0
Email 33532 0
Contact person for public queries
Name 16779 0
Dr James Hamill
Address 16779 0
Paediatric Surgery & Urology Services
Starship Children's Hospital
Private Bag 92024
Auckland 1142
Country 16779 0
New Zealand
Phone 16779 0
+64 21 753081
Fax 16779 0
Email 16779 0
Contact person for scientific queries
Name 7707 0
Dr James Hamill
Address 7707 0
Paediatric Surgery & Urology Services
Starship Children's Hospital
Private Bag 92024
Auckland 1142
Country 7707 0
New Zealand
Phone 7707 0
+64 21 753081
Fax 7707 0
Email 7707 0

No information has been provided regarding IPD availability
Summary results
Have study results been published in a peer-reviewed journal?
Other publications
Have study results been made publicly available in another format?
Results – basic reporting
Results – plain English summary