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A Randomized Controlled Trial Evaluating the Requirement for Post-operative Packing of Perianal Abscesses

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Perianal Abscess

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Trial Information

A Randomized Controlled Trial Evaluating the Requirement for Post-operative Packing of Perianal Abscesses



Perianal abscesses are common with an incidence of 0.5-1%. Some present as emergencies
and all require surgery, placing a significant burden on health resources.

The mainstay of management is incision and drainage. Traditionally the residual cavity
is then packed. On discharge, the cavity packing requires frequent changing. This uses
considerable community nursing resource. Perianal abscesses can alternatively be
treated by primary closure or without packing the cavity. Benefits of treating without
packing include greater patient comfort and acceptance and reduced nursing requirement.
However treating without packing is not yet widely accepted, in the absence of
sufficient evidence that it is as safe and effective. This study aims to address this


- Question: In patients with perianal abscesses, does incision and drainage without
packing the subsequent cavity reduce patient discomfort without increasing healing
time or recurrence compared with management involving cavity packing?

- Hypothesis: Perianal abscess can be managed without cavity packing, with no
increase in healing time or recurrence.

- Note this was partly addressed by Tonkin et al (2004) but their study was
underpowered. We intend to have a sufficiently powered study to definitively
answer the question.


- Assess whether there is any statistically significant difference in patients with
perianal abscesses managed with and without cavity packing in terms of:

- Length of hospital stay

- Time to cavity healing

- Recurrent abscess or fistula formation

- Pain score

- Analgesia usage


- This is a randomised controlled trial.

- Due to the nature of the intervention (packing), it is impossible for either the
subjects or the research team to be blinded.

- Duration: recruitment into the study will remain open until the target number of
subjects has been reached.

- Number and type of subjects: power calculations from a published pilot study show
that to demonstrate a difference of 10% vs 20% in e.g. fistula and recurrent
abscess formation, 316 patients need to be recruited. We will perform a pilot
study of 20 patients in each group and at this time calculate the number of
subjects to be recruited


- Length of hospital stay

- Time to cavity healing

- Recurrent abscess or fistula formation

- Pain score

- Analgesia usage



- Documentation of the duration of symptoms before presentation.

- Examination and documentation of abscess characteristics (can be done at the time
of the operation): size, site and type.

- Co-morbidities


- Perianal abscess.

- Over 18 years of age.


- Under 18 years of age.

- Those unable to give informed consent.

- Abscesses associated with Crohn's disease or other underlying causes.

- Abscesses in which initial drainage is considered inadequate (if the skin is not
open sufficiently to allow drainage of the abscess cavity).


- If the patient wants to withdraw from the study at any point they can do so and
resume standardised treatment pathways


5.1 DEFINITIONS Adverse Event (AE): any untoward medical occurrence in a patient or
clinical study subject.

Serious Adverse Event (SAE): any untoward and unexpected medical occurrence or effect

• Results in death

- Is life-threatening - refers to an event in which the subject was at risk of death
at the time of the event; it does not refer to an event which hypothetically might
have caused death if it were more severe

- Requires hospitalisation, or prolongation of existing inpatients' hospitalisation

- Results in persistent or significant disability or incapacity

- Is a congenital anomaly or birth defect

Medical judgement should be exercised in deciding whether an AE is serious in other
situations. Important AEs that are not immediately life-threatening or do not result
in death or hospitalisation but may jeopardise the subject or may require intervention
to prevent one of the other outcomes listed in the definition above, should also be
considered serious.

5.3 REPORTING PROCEDURES All adverse events should be reported. Depending on the
nature of the event the reporting procedures below should be followed. Any questions
concerning adverse event reporting should be directed to the Chief Investigator in the
first instance.


- Patients in the packing group will have their dressing changed day 1
post-operatively. On discharge they will have their care transferred to the District
Nurses for daily dressing care in their own home.

- Patients in the non-packing group will have the initial haemostatic dressing
removed day 1 post-operatively and be discharged with a superficial protective
dressing to absorb any discharge and protect the wound.

- All patients will be reviewed at 2 weekly intervals in the outpatient clinic until
the cavity is closed and the skin completely re-epithlialised. At outpatient
appointments, patients will be asked to score their pain over the previous two
weeks on a standard 10cm Visual Analogue Scale for pain.

- Patients who do not attend clinic will be interviewed by telephone to gather the
information listed above.

- The end point is patient discharge from the outpatient clinic with complete
healing (as described above) or the development of a fistula or recurrent abscess.


- Data and all appropriate documentation will be stored for a minimum of 5 years
after the completion of the study, including the follow-up period.

- The data will be tested for normal distribution and analysed accordingly:

o If it is normally distributed, an unpaired T-test will be performed on the
continuous data (time to healing, length of stay, pain score, morphine dose) and a
Fischer test will be performed on the categorical data (fistula rates, recurrence,
delayed healing).

- If it is not normally distributed, a Mann-Whitney U test will be performed in
place of the T-test.

- The tests will be two-tailed with a significance level of 0.05.

- Following a pilot study of 40 patients we will perform a power calculation however
a similar pilot study already published indicates the need for 316 subjects to be

8.1 CONSENT Consent to enter the study must be sought from each participant only after a
full explanation has been given, an information leaflet offered and time allowed for
consideration. Signed participant consent should be obtained. The right of the participant
to refuse to participate without giving reasons must be respected. After the participant
has entered the study the clinician remains free to give alternative treatment to that
specified in the protocol at any stage if he/she feels it is in the participant's best
interest, but the reasons for doing so should be recorded. In these cases the participants
remain within the study for the purposes of follow-up and data analysis. All participants
are free to withdraw at any time from the protocol treatment without giving reasons and
without prejudicing further treatment.

8.2 CONFIDENTIALITY The Chief Investigator will preserve the confidentiality of participants
taking part in the study and is registered under the Data Protection Act.

8.3 AUDITS The study may be subject to inspection and audit by Imperial College London under
their remit as sponsor and other regulatory bodies to ensure adherence to GCP and the NHS
Research Governance Framework for Health and Social Care (2nd edition).


The day-to-day management of the study will be co-ordinated through Mr Mikael Sodergren.


All publications and presentations relating to the study will be authorised by the Trial
Management Group (TMG). The first publication of the trial results will be in the name of
the Trial Management Group, or appropriately names authors. If there are named authors,
these will include at least the trial's Chief Investigator, and Trial Coordinator. Members
of the TMG will be listed and contributors will be cited by name if published in a Joint
Research Office journal where this does not conflict with the journal's policy. Authorship
of parallel studies initiated outside of the Trial Management Group will be according to the
individuals involved in the project but must acknowledge the contribution of the Trial
Management Group and the Study Coordination Centre.

Inclusion Criteria:

- Adults aged 18

- Clinical diagnosis of perianal abscess.

Exclusion Criteria:

- Patients who are unable or unwilling to consent.

- Known fistulae

- Crohn's Disease

- Immune-suppression or malignancy

- Recurrent abscess (where initial drainage insufficient).

Type of Study:


Study Design:

Allocation: Randomized, Endpoint Classification: Safety/Efficacy Study, Intervention Model: Parallel Assignment, Masking: Single Blind (Caregiver), Primary Purpose: Treatment

Outcome Measure:

Time to abscess healing

Outcome Description:

When abscess cavity has re-epitheliased. Assessed at two weeks and then weekly until healing occurs. Followed up for one year to assess recurrence

Outcome Time Frame:

Two weeks post operative

Safety Issue:


Principal Investigator

Paraskevas Paraskevas, MBBS

Investigator Role:

Principal Investigator

Investigator Affiliation:

Department of Surgery and Cancer, Imperial College London


United Kingdom: Research Ethics Committee

Study ID:




Start Date:

May 2011

Completion Date:

April 2016

Related Keywords:

  • Perianal Abscess
  • Colorectal
  • Surgery
  • Perianal
  • Abscess
  • Abscess