Sacral Dimples: Advice for Referrers

RHC for Health Professionals
NHS GGC

A sacral dimple is an indentation in the lower back, present at birth, but sometimes not noticed until the infant’s 6 week check. Most are blind ending, just above or within the crease of the buttocks, and do not require investigation or treatment.

However, if the following are present the infant should be referred for investigation. Please refer as soon as possible. Ultrasound is the initial investigation of choice, but after around 8 weeks of age (after ossification of the vertebral arches) an MRI is performed (either a feed-and-sleep, or with a general anaesthetic).

Refer if

  1. the dimple is >2.5cm above the anal margin
  2. there are associated cutaneous marking, hairy patch, skin tag, or fatty lump
  3. there are associated anorectal malformations
  4. they appear in combination with other lesions

The above may be associated with an underlying neurological problem, for example spinal dysraphism.

Please note: As per updated guidance not being able to see the base of the dimple is not (on its own) an indication for referral.

Please include the following points from history in the referral letter

Is the child otherwise well, thriving and developing normally?

Please include the following points from the clinical examination in the referral letter

  1. Is the dimple greater than 5mm in size?
  2. How far above the anal margin is the dimple?
  3. Are there associated skin changes, hairy patch, skin tag or fatty lump?
  4. Are there associated anorectal malformations?
  5. Do they appear in combination with other lesions?
  6. Can the infant move their legs normally?
  7. Are there any problems with urination or stooling?
  8. If you are sending in a photograph, please ask the parents to place a tape measure next to the dimple/lesion to the position of the anus, so that the reader can estimate the distance from the anal margin.

Please state the concerning features leading to the referral.

Suggestions for management whilst waiting for outpatient appointment

Nothing specific.  Please refer as soon as possible so that an ultrasound may be requested before 8 weeks of age.

Useful resources for Parents

Nil.

Useful resources for Health Professionals

Zywicke HA, Rozzelle CJ. Sacral Dimples. Pediatrics in Review 2011;32;109.

The Royal College of Radiologists. iRefer [Website]. Available from: https://www.rcr.ac.uk/our-services/irefer/

Guidelines l iRefer [website]. Available from: https://www.irefer.org.uk/guidelines

Editorial Information

Last reviewed: 07/04/2025

Next review date: 30/11/2029

Author(s): Ruth M Bland, Consultant Medical Paediatrics, Ruth Allen, Consultant Paediatric Radiologist, Grace Ong, FY2.