ACNES: A Commonly Overlooked Cause of Abdominal Pain
🩺 Anterior Cutaneous Nerve Entrapment Syndrome (ACNES): A Commonly Overlooked Cause of Abdominal Pain
Anterior Cutaneous Nerve Entrapment Syndrome (ACNES) is an important — and frequently missed — cause of persistent abdominal pain.
Because routine blood tests, scans, and endoscopy are often normal, many patients are told “nothing is wrong” or are treated for visceral conditions,
when the pain is actually coming from the abdominal wall. :contentReference[oaicite:0]{index=0}
- 🎯 Localised abdominal pain (often pinpoint with one finger)
- 🩻 Normal investigations
- 🔁 Repeated referrals and testing
- ⚠️ Risk of unnecessary invasive procedures
ACNES occurs when a small sensory nerve supplying the skin of the abdomen becomes entrapped as it passes through the abdominal wall,
most commonly near the lateral edge of the rectus abdominis muscle. This produces a neuropathic abdominal wall pain syndrome.
⚠️ ACNES is very under-recognised
Despite being described for decades, ACNES remains underdiagnosed and under-recognised — including by many healthcare professionals.
As a result, patients may undergo long diagnostic journeys, repeated imaging, and sometimes non-therapeutic operations.
The literature highlights that abdominal wall pain is often wrongly attributed to intra-abdominal disease, which can lead to
unnecessary consultation, testing, and even abdominal surgery — avoidable when ACNES is considered early.
Delays can also be costly. Reports describe substantial cumulative costs from repeated investigations and procedures before the correct diagnosis is made.
🧠 Why patients get misdirected investigations (and even surgery)
Most abdominal pain pathways are rightly designed to exclude serious visceral disease — but once routine investigations are negative, it is easy to overlook the abdominal wall.
Patients with ACNES may be repeatedly evaluated for gastrointestinal, gynaecological, urinary, hernia-related, or “functional” causes, sometimes proceeding to laparoscopy or other procedures without benefit.
ACNES is a clinical diagnosis supported by examination and response to a precisely placed local anaesthetic block.
When the abdominal wall is not considered, patients can experience prolonged suffering and unnecessary interventions.
📍 Typical features of ACNES
- 🎯 Well-localised pain, often identified with one fingertip
- 🔥 Sharp, stabbing, burning, or “electric” pain
- 🤕 Worse with movement, coughing, stretching, or tightening the abdominal muscles
- 🍽️ Often not clearly linked to meals or bowel habit
A classic way to distinguish abdominal wall pain from visceral pain is Carnett’s test:
the clinician palpates the tender point, then the patient tenses the abdominal wall (e.g., lifting head/legs).
If pain stays the same or increases, the source is more likely the abdominal wall rather than internal organs.
💉 Diagnosis: the role of a diagnostic block
If clinical features suggest ACNES, a local anaesthetic injection at the point of maximal tenderness can be both diagnostic and therapeutic.
Complete or significant relief strongly supports the diagnosis. Technique matters — injections that are too deep may miss the target.
A strong reduction in pain after a properly performed local anaesthetic injection is a key confirmatory feature of ACNES.
🩻 Why ultrasound is important
Ultrasound guidance can improve both precision and safety. It allows the clinician to visualise anatomy, guide the needle accurately,
and confirm spread of injectate around the target nerve (often achieving a “hydrodissection” effect that may help release entrapment).
A published adult case series reported that ultrasound-guided abdominal cutaneous nerve infiltration served as a precision diagnostic tool with potential therapeutic benefit, with many patients reporting meaningful relief (median relief around 60% in follow-up reporting).
🔄 Treatment options: a stepwise approach
Management is typically tailored and stepwise, depending on severity, duration, and response:
- 💉 Ultrasound-guided local anaesthetic injection (± steroid)
- 🔁 Repeat injections if symptoms recur
- ⚡ Pulsed radiofrequency (PRF) neuromodulation in selected refractory cases
- 🔪 Surgical options (e.g., neurectomy) reserved for carefully selected persistent cases
PRF is a non-destructive neuromodulation technique that can reduce neuropathic pain signalling without cutting or removing the nerve.
Published literature includes PRF being used as a treatment option in ACNES.
🌟 Our experience at Pain Spa
Because ACNES is frequently overlooked, many patients arrive after long diagnostic journeys, repeated imaging, and persistent symptoms despite standard pathways.
A key part of our approach is careful clinical assessment, confirmation with a diagnostic block, and use of ultrasound guidance to maximise accuracy and safety.
For selected patients who respond to diagnostic injections but experience recurrence, pulsed radiofrequency may provide more sustained benefit as part of a broader, individualised plan.
🌱 In summary
✔ Many patients undergo unnecessary investigations and even surgery because the pain is assumed to be visceral.
✔ The pain often originates from the abdominal wall, and bedside tests (e.g., Carnett’s) can help identify this. :contentReference[oaicite:15]{index=15}
✔ A diagnostic injection is a key confirmatory step; ultrasound improves precision and safety.
✔ Specialist ultrasound-guided interventions (including PRF in selected patients) may provide meaningful relief.
If you have persistent, localised abdominal pain with normal investigations, it is worth asking:
“Could this be abdominal wall pain — could it be ACNES?”
Disclaimer: This article is for information only and does not replace medical advice. Diagnosis and treatment should be individualised.