Abdominal Cutaneous Nerve Entrapment (ACNES) Injection

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Please use your clinical judgement and note that this is not necessarily standard practice in NZ.

Abdominal Cutaneous Nerve Entrapment (ACNES) Injection
Indication ACNES
Syringe 10mL
Needle 25G 38mm
Steroid optional 10mg triamcinolone
Local Clinician choice
Volume 10mL

Various authors have described a technique for performing a block for anterior cutaneous nerve entrapment (ACNE) [1][2]


Ultrasound Guided

  • First locate the point of maximal tenderness using the Carnett Sign
  • Position: Supine
  • Ultrasound Anatomy
    • Transverse plane in the midline at first to identify the rectus abdominis muscle and linea alba (the medial border of the rectus abdominis).
    • Move the transducer laterally to view the lateral border of the rectus abdominis and the linea semilunaris
    • The target abdominal cutaneous nerve normally exits between the rectus abdominis and linea semilunaris.
  • Advance the needle lateral to medial in plane
  • Aspirate to ensure needle not penetrated a blood vessel.
  • Inject local anaesthetic +/- steroid around the nerve


Anterior Cutaneous Nerve Entrapment Syndrome


Infection, subcutaneous injection, allergic reaction, intravascular injection ADR from steroids

This procedure cannot be used to exclude a visceral cause of pain such as appendicitis. In recent one study of 100 patients with appendicitis, 39 had abdominal wall somatosensory disturbances in the right lower quadrant such as discriminative sensibility changes with a swab, vital sensibility with alcohol gauze, skin fold squeezing sensitivity, and/or positive Carnett's test. They reported cases of appendicitis where there was temporary improvement in pain following local anaesthetic injection, only for the patient's underlying appendicitis to later worsen.[3]


Advised to keep active within pain limits, and is reassessed about 10 days later. Repeated injections may be performed

Further Reading


  1. โ†‘ Hong MJ, Kim YD, Seo DH. Successful treatment of abdominal cutaneous entrapment syndrome using ultrasound guided injection. Korean J Pain. 2013;26(3):291-294. doi:10.3344/kjp.2013.26.3.291
  2. โ†‘ Misoon Lee, Yong-Ik Kim, Woobin Kang. Diagnosis and Treatment of Abdominal Cutaneous Nerve Entrapment Syndrome Using Ultrasonography. Soonchunhyang Medical Science (SMS) 2016; 22(2): 147-150
  3. โ†‘ Roumen RMH, Vening W, Wouda R, Scheltinga MM. Acute Appendicitis, Somatosensory Disturbances ("Head Zones"), and the Differential Diagnosis of Anterior Cutaneous Nerve Entrapment Syndrome (ACNES). J Gastrointest Surg. 2017 Jun;21(6):1055-1061. doi: 10.1007/s11605-017-3417-y. Epub 2017 Apr 14. PMID: 28411350.

Literature Review