If you have had years of abdominal pain workups — endoscopy negative, colonoscopy negative, CT negative, transvaginal ultrasound negative, IBS protocols that changed nothing — and the pain lives in one spot you can press to reproduce it, you are probably reading the right post. The condition is anterior cutaneous nerve entrapment syndrome (ACNES). The pain comes from a nerve in the abdominal wall, not from anything inside the abdomen. A 30-second bedside test and a short injection at the tender spot usually confirm it. When the pain keeps coming back, a small operation that removes the trapped nerve endings has the best long-term results.
Read the film's transcript
Stomach pain in one spot, and every scan comes back normal? The cause may be a trapped nerve in the belly wall, not in your gut.
Nerves from your lower ribs wrap around to the front of your belly. At the edge of the long stomach muscle, each one turns sharply and passes through a tight ring of tissue on its way to the skin.
That ring is where a nerve can get caught, sometimes after surgery or near a laparoscopy scar, and often with no clear trigger at all. The pain is sharp or burning, in a spot you can cover with a fingertip.
A thirty-second test helps sort it out. Lying flat, you press on the spot, then lift your head to tighten your stomach muscles. If the pain stays the same or gets worse, the belly wall is the likely source. If it eases, the cause is more likely inside.
A numbing injection at the spot confirms it. If the pain drops by at least half within twenty minutes, it points to that nerve. Repeat injections alone give lasting relief to about one in five people.
When the test confirms the nerve and the pain keeps coming back, a small operation removes the trapped nerve endings. It has the best long-term results of any treatment studied, and about six in ten people stay pain-free for years.
Pain that comes on suddenly and severely, vomiting blood, black or bloody stools, or a belly that turns hard and rigid point to a problem inside the abdomen. Those need the nearest emergency room, or call 911.
Pain you can cover with a fingertip deserves a closer look.
Why this gets missed
First, chronic abdominal pain in a working-age adult runs through gastroenterology. The workup — endoscopy, colonoscopy, CT, sometimes MRI enterography, sometimes diagnostic laparoscopy — is built to find Crohn’s disease, ulcers, cancer, motility disorders and adhesions. It is not built to examine the abdominal wall. A negative workup usually ends in a label of IBS or functional abdominal pain, and neither label addresses a trapped nerve.
Second, the bedside test is rarely done. Carnett described it in 1926. The Dutch ACNES group at Máxima Medical Center built its whole diagnostic workup around it (Boelens 2011), and a 2025 randomized comparison found that lifting the head and lifting the legs pick it up equally well (Otero Regino 2025). Most internists and gastroenterologists were never taught to use it, so the patient who most needs the test is the one least likely to get it.
Third, the numbers work against the patient. Abdominal wall pain makes up only 2–3% of chronic abdominal pain overall, but up to about 30% of the patients whose workup comes back clean (Koop 2016), and 10–30% of chronic abdominal pain patients are eventually diagnosed with it after expensive testing (Glissen Brown 2016). Rare enough that nobody thinks of it first. Common enough that a lot of people are stuck in a multi-year loop of normal scans.
The fix is the 30-second test. If Carnett’s is positive, the next step is not another scope or scan. It is a local anesthetic injection at the spot.
The anatomy that matters
The anterior cutaneous branches are the end branches of the lower intercostal nerves, T7 to T12. Each runs forward between the internal oblique and transversus abdominis muscles, reaches the outer edge of the rectus abdominis, turns sharply, and passes through a tight fibrous ring to travel through the muscle toward the skin (Scheltinga 2018). That turn and that ring are where the nerve is thought to be trapped.
What can trap it:
- Scar or mesh from prior open or laparoscopic abdominal surgery, including port sites placed through or beside the rectus
- Nothing identifiable at all, which is the case for many patients who have never had surgery
Who gets it: about four in five patients in the Dutch series are women, with an average age of 47 (Boelens 2011, van Assen 2015). Children and teenagers get it too, and respond to the same step-up approach (Markus 2021).
The clinical clue is the spot. ACNES pain sits at one fingertip-sized point, usually near the outer edge of the rectus, and pressing it reproduces the pain. The quality is sharp, burning or stabbing, unlike the dull, deep, crampy pain that comes from the bowel.
When the same nerve hurts at the flank or beside the spine
Each lower thoracic spinal nerve sends branches to the skin at three points: beside the spine, at the side of the trunk, and at the edge of the rectus. ACNES is the front one. The same Dutch group has described the other two. Lateral cutaneous nerve entrapment syndrome (LACNES) puts the fingertip-sized spot on the flank. Posterior cutaneous nerve entrapment syndrome (POCNES) puts it 3–5 cm from the spine, somewhere between the tip of the shoulder blade and the lowest rib. Six of the 14 patients in the POCNES series had already had an ACNES neurectomy on the same side (Maatman, J Pain Res 2019), so a new spot on the back after ACNES treatment deserves an exam, not a shrug.
We treat both the way we treat ACNES. The injection is lidocaine alone, and we don’t use pulsed radiofrequency. For LACNES it goes in the plane between the internal oblique and transversus abdominis, a little back from the tender spot along the nerve’s path. For POCNES it goes just under the thoracolumbar fascia at the spot. When the relief keeps fading, the referral goes to the same surgeon we use for ACNES, one who focuses exclusively on peripheral nerve entrapment. The evidence is thinner here. The LACNES series had 30 patients, and more than half did well long-term on injections alone (Maatman 2017). The largest POCNES series had 14, and only one did well without surgery (Maatman, J Pain Res 2019).
How we diagnose
The visit starts with the history and an exam aimed at the wall: the fingertip test, Carnett’s test, and a check for a hernia or other lump at the spot. Signs of a problem inside the abdomen — fever, vomiting, blood in the stool, weight loss — come first, and those go back to GI before anything else.
Then the confirming injection, done in our procedure suite at 369 Lexington Avenue. Using ultrasound, we look at the layers of the abdominal wall, confirm there is no hernia or other lesion at the spot (Shian 2018), and inject lidocaine just under the front layer of the rectus sheath at the Carnett-positive spot, the same placement used in the double-blind diagnostic trial (Boelens 2013). A drop of at least 50% in pain within 15–20 minutes counts as a positive response, the threshold used in the trials (Boelens 2013). You keep a short pain diary over the next few hours and days.
Ultrasound shows us the anatomy, but it is not what makes the injection work. In a randomized trial of 391 injections, ultrasound-guided and freehand injections relieved pain equally often (Jacobs 2021). We don’t add a steroid. In the one randomized trial that tested it, adding methylprednisolone to lidocaine did not raise the success rate at 6 or 12 weeks (Mol 2018), so a steroid would add side effects without adding relief.
Treatment: confirm the nerve, then remove the trapped ending
Step 1 — the lidocaine test injection. The injection that confirms the diagnosis is also the first treatment, and it can be repeated. In the Dutch cohort of 139 patients, 81% had at least half their pain gone after the first injection (Boelens 2011). The relief often fades. In the randomized trial of repeat lidocaine injections, three injections two weeks apart helped 38% at six weeks, and about one in five still had at least half their pain gone at 12 weeks (Mol 2018). Gabapentin, pregabalin or a lidocaine patch over the spot are reasonable to try alongside, but none has been tested in an ACNES trial.
Step 2 — anterior neurectomy. When the test confirms the nerve and the pain keeps coming back, the trapped nerve endings are removed through a small incision. Of every ACNES treatment studied, this one has the best long-term results (De Troyer 2026). In a double-blind trial, 16 of 22 patients had a successful result six weeks after neurectomy versus 4 of 22 after sham surgery (Boelens 2013). Success held in 61% at an average of 32 months (van Assen 2015), and 62% of a randomized surgery group were still pain-free with no further treatment at a median of almost six years (Ten Have 2023). When an anterior neurectomy fails, a posterior neurectomy helps about half of patients over the long term (Ten Have 2024). A surgeon who focuses exclusively on peripheral nerve entrapment performs it. Modal Pain coordinates the referral and sends the documented injection response that surgical programs ask for.
Why we skip pulsed radiofrequency. Some centers put pulsed radiofrequency between the injections and surgery. We don’t. In the one randomized trial that compared the two, pain fell further after neurectomy, and 61% met the success threshold at eight weeks against 38% after pulsed radiofrequency (Maatman 2019). The gap widened with time: one patient in 23 stayed pain-free after a single pulsed radiofrequency session, against 62% after surgery (Ten Have 2023). A 2026 review of 18 studies put its success near one in five, with relief lasting a median of four months (De Troyer 2026). For a nerve that is mechanically caught, a treatment that wears off adds procedures and months before the one most likely to work. Peripheral nerve stimulation, which requires referral to an implanting specialist, has only case-level reports in ACNES (Chrona 2017).
Injections settle the pain for one in five to one in three patients, depending on the series (Mol 2018, Boelens 2011). For most of the rest, a positive lidocaine test followed by neurectomy is the shortest path to lasting relief.
For referring physicians (especially GI)
When you have a chronic abdominal pain patient with negative endoscopy, negative colonoscopy, negative cross-sectional imaging, and a fingertip-sized spot that reproduces the pain, run a Carnett's test in your office — 30 seconds, no equipment. Tenderness that stays the same or gets worse with the abdominal muscles tensed makes ACNES the leading hypothesis. Send us: the prior GI workup summary, any prior surgical history (especially laparoscopic port placement records), the medication trial history, and a note on where the pain sits. We document the Carnett's response at the consultation, run the confirming injection in the room, and send notes back to your office as requested or as needed. For refractory cases, we coordinate the neurectomy referral.
Travelling to New York for an ACNES evaluation
About half of the calls and forms from this guide in the last three months came from outside New York. That makes sense. The condition is uncommon, few doctors run Carnett’s test, and the nearest one who does may be a flight away. So we plan the visit to get the answer, and the next step, in a single trip.
Where we can, the lidocaine test injection and a consultation with a surgeon who focuses exclusively on peripheral nerve entrapment fall on the same trip. You see Dr. Movshis first for the history, the exam, Carnett’s test and the injection at the spot. The pain is rated before and 15 to 20 minutes after, the window used in the trials (Boelens 2013). If it drops by at least half, that documented response is what a surgeon needs to see, and you carry it into the surgical consultation on the same trip. If it doesn’t, the surgical visit is cancelled, and the search turns back to what’s inside the abdomen.
Before you book travel:
- Send the records you have: the GI workup summary, imaging reports, operative notes from any abdominal surgery (laparoscopic port placement especially) and the medicines you have already tried.
- Check your coverage. We accept most commercial PPO plans and don’t accept Medicare, Medicaid, HMO plans or workers’ compensation. We go over what your plan covers and any expected cost by phone before your visit, so there are no surprise bills.
- Keep a short pain diary for the hours and days after the injection, even on the flight home.
Call (646) 290-6660 and say you’re travelling in for an ACNES evaluation, so the visits can be lined up together.
Ready to evaluate your chronic abdominal pain
If your abdominal pain has persisted through negative GI workups and you can press one spot to reproduce it, the next step is a Carnett’s test and a confirming injection at that spot. Same-week new-patient consultations are available at 369 Lexington Avenue in Midtown Manhattan.
Verify your insurance covers an ACNES workup Book a same-week diagnostic block
Or call (646) 290-6660.
If your pain began after abdominal surgery and you want something before the next appointment, the Post-Surgical Nerve Pain Self-Assessment takes four to six minutes and includes the DN4 neuropathic screener. Patients with ACNES often arrive having been told the workup was negative — a documented positive Carnett’s sign and a neuropathic screen change that conversation.
For the broader framework on peripheral nerve entrapments, see the peripheral nerve entrapment page.
References
This article is reviewed against the peer-reviewed literature. Citations retrieved from PubMed.
- Boelens OB, Scheltinga MR, Houterman S, Roumen RM. Management of anterior cutaneous nerve entrapment syndrome in a cohort of 139 patients. Ann Surg. 2011. doi:10.1097/SLA.0b013e31822d78b8 · PubMed
- Boelens OB, Scheltinga MR, Houterman S, Roumen RM. Randomized clinical trial of trigger point infiltration with lidocaine to diagnose anterior cutaneous nerve entrapment syndrome. Br J Surg. 2013. doi:10.1002/bjs.8958 · PubMed
- Boelens OB, van Assen T, Houterman S, Scheltinga MR, Roumen RM. A double-blind, randomized, controlled trial on surgery for chronic abdominal pain due to anterior cutaneous nerve entrapment syndrome. Ann Surg. 2013. doi:10.1097/SLA.0b013e318285f930 · PubMed
- van Assen T, Boelens OB, van Eerten PV, Perquin C, Scheltinga MR, Roumen RM. Long-term success rates after an anterior neurectomy in patients with an abdominal cutaneous nerve entrapment syndrome. Surgery. 2015. doi:10.1016/j.surg.2014.05.022 · PubMed
- Mol FMU, Heukelsfeldt Jansen C, Boelens OB, Stronks DL, van Eerten PV, Huygen FJPM, Scheltinga MR, Roumen RM. Adding steroids to lidocaine in a therapeutic injection regimen for patients with abdominal pain due to anterior cutaneous nerve entrapment syndrome (ACNES): a single blinded randomized clinical trial. Scand J Pain. 2018. doi:10.1515/sjpain-2018-0011 · PubMed
- Jacobs MLYE, van den Dungen-Roelofsen R, Heemskerk J, Scheltinga MRM, Roumen RMH. Ultrasound-guided abdominal wall infiltration versus freehand technique in anterior cutaneous nerve entrapment syndrome (ACNES): randomized clinical trial. BJS Open. 2021. doi:10.1093/bjsopen/zrab124 · PubMed
- Maatman RC, van Kuijk SMJ, Steegers MAH, Boelens OBA, Lim TC, Scheltinga MRM, Roumen RMH. A Randomized Controlled Trial to Evaluate the Effect of Pulsed Radiofrequency as a Treatment for Anterior Cutaneous Nerve Entrapment Syndrome in Comparison to Anterior Neurectomy. Pain Pract. 2019. doi:10.1111/papr.12806 · PubMed
- Ten Have T, van Geffen ST, Zwaans WAR, Maatman RC, Boelens OBA, Steegers MAH, Scheltinga MRM, Roumen RMH. Pulsed radiofrequency or surgery for anterior cutaneous nerve entrapment syndrome: Long-term results of a randomized controlled trial. Pain Pract. 2023. doi:10.1111/papr.13305 · PubMed
- Ten Have T, Jacobs MLYE, Scheltinga MRM, Zwaans WAR, Roumen RMH. Long-Term Efficacy of Posterior Neurectomy in Anterior Cutaneous Nerve Entrapment Syndrome. J Abdom Wall Surg. 2024. doi:10.3389/jaws.2024.13508 · PubMed
- De Troyer A, Allaeys M, Verelst F, Berrevoet F. Management strategies for anterior cutaneous nerve entrapment syndrome: a scoping review. Hernia. 2026. doi:10.1007/s10029-025-03576-5 · PubMed
- Shian B, Larson ST. Abdominal Wall Pain: Clinical Evaluation, Differential Diagnosis, and Treatment. Am Fam Physician. 2018. · PubMed
- Koop H, Koprdova S, Schürmann C. Chronic Abdominal Wall Pain. Dtsch Arztebl Int. 2016. doi:10.3238/arztebl.2016.0051 · PubMed
- Glissen Brown JR, Bernstein GR, Friedenberg FK, Ehrlich AC. Chronic Abdominal Wall Pain: An Under-Recognized Diagnosis Leading to Unnecessary Testing. J Clin Gastroenterol. 2016. doi:10.1097/MCG.0000000000000636 · PubMed
- Scheltinga MR, Roumen RM. Anterior cutaneous nerve entrapment syndrome (ACNES). Hernia. 2018. doi:10.1007/s10029-017-1710-z · PubMed
- Chrona E, Kostopanagiotou G, Damigos D, Batistaki C. Anterior cutaneous nerve entrapment syndrome: management challenges. J Pain Res. 2017. doi:10.2147/JPR.S99337 · PubMed
- Markus J, Sibbing IC, Ket JCF, de Jong JR, de Beer SA, Gorter RR. Treatment strategies for anterior cutaneous nerve entrapment syndrome in children: A systematic review. J Pediatr Surg. 2021. doi:10.1016/j.jpedsurg.2020.05.014 · PubMed
- Otero Regino W, Jaramillo Trujillo G, Otero Parra L, Marulanda Fernández H, Frías JS, Cardona González J, Otero Ramos E. Comparison of two maneuvers to identify Carnett's sign in patients with chronic abdominal pain. Randomized controlled clinical trial. Rev Gastroenterol Peru. 2025. · PubMed
- Carnett JB. Intercostal neuralgia as a cause of abdominal pain and tenderness. Surg Gynecol Obstet. 1926.
- Maatman RC, Papen-Botterhuis NE, Scheltinga MRM, Roumen RMH. Lateral Cutaneous Nerve Entrapment Syndrome (LACNES): A previously unrecognized cause of intractable flank pain. Scand J Pain. 2017. doi:10.1016/j.sjpain.2017.10.007 · PubMed
- Maatman RC, Boelens OB, Scheltinga MRM, Roumen RMH. Chronic localized back pain due to entrapment of cutaneous branches of posterior rami of the thoracic nerves (POCNES): a case series on diagnosis and management. J Pain Res. 2019. doi:10.2147/JPR.S178492 · PubMed
Frequently Asked Questions
Anterior cutaneous nerve entrapment syndrome is pain from a trapped end branch of one of the lower intercostal nerves (T7 to T12). Near the outer edge of the rectus abdominis, each branch turns sharply and passes through a tight fibrous ring on its way to the skin, and that is where it is thought to get caught. The result is sharp, burning or stabbing pain in one fingertip-sized spot on the front of the belly, usually on one side, often worse when sitting up, twisting or wearing a tight waistband. It is the most common cause of chronic abdominal wall pain (Shian 2018), and it is often labeled IBS or functional abdominal pain first.
A bedside maneuver that separates abdominal wall pain from pain inside the abdomen. Lying flat, you point to the most tender spot and the examiner presses on it. Then you tighten your stomach muscles, by lifting your head and shoulders or by lifting both legs, while the pressure stays the same. If the tenderness stays the same or gets worse, the source is likely the abdominal wall: a positive Carnett's test. If it eases, because the tensed muscle now shields the organs underneath, the source is more likely inside the abdomen (Shian 2018). Lifting the head and lifting the legs worked equally well in a randomized comparison (Otero Regino 2025). A positive test is a strong clue, not proof. A local anesthetic injection at the spot is the confirmation.
Sometimes, but nobody has followed untreated patients closely enough to say how often. The treatment data are clearer. In the largest Dutch cohort, one in three patients stayed pain-free with injections alone (Boelens 2011). In a later randomized trial, about one in five had lasting relief from lidocaine injections without needing anything more (Mol 2018). For most of the rest, the next step is surgery.
In steps. A local anesthetic injected at the tender spot is both the test and the first treatment. In a double-blind trial, 13 of 24 patients had at least half their pain gone 15 to 20 minutes after lidocaine, against 4 of 24 after saline (Boelens 2013). A series of lidocaine injections gives lasting relief to a minority, about one in five at 12 weeks (Mol 2018). Adding a steroid did not improve results in that trial, which is why we don't add one, and ultrasound guidance did not beat a careful freehand injection (Jacobs 2021). When the test confirms the nerve but the relief keeps wearing off, the next step is an anterior neurectomy, which has the best long-term results of any ACNES treatment studied (De Troyer 2026).
For most people who need it, yes. Anterior neurectomy removes the trapped nerve endings through a small incision. In a double-blind trial, 16 of 22 patients had a successful result six weeks after neurectomy, compared with 4 of 22 after sham surgery (Boelens 2013). The benefit lasted in 61% at an average of 32 months (van Assen 2015), and 62% of the surgery group in a randomized trial were still pain-free with no further treatment at a median of almost six years (Ten Have 2023). When an anterior neurectomy fails, a posterior neurectomy helps about half of patients over the long term (Ten Have 2024). The operation is done by a surgeon who focuses exclusively on peripheral nerve entrapment, and Modal Pain coordinates that referral.
Because surgery works better and lasts longer. In the one randomized trial that compared them, pain fell further after neurectomy, and 61% met the success threshold at eight weeks against 38% after pulsed radiofrequency (Maatman 2019). At a median of almost six years, 62% of the surgery group were still pain-free with no further treatment, against one patient in 23 after a single pulsed radiofrequency session (Ten Have 2023). A 2026 review of 18 studies put its success near one in five, with relief lasting a median of four months (De Troyer 2026). Once the lidocaine test confirms the trapped nerve, we refer for the operation most likely to fix it.
Usually, yes. Modal Pain plans out-of-town visits so the lidocaine test injection and, where possible, a consultation with a surgeon who focuses exclusively on peripheral nerve entrapment happen on the same trip. The injection result is read within 15 to 20 minutes. If the pain drops by at least half, that documented response goes with you to the surgical consultation. Send your GI workup, imaging reports and any operative notes before you book travel, and check your coverage.
Yes, and this is one reason the diagnosis gets delayed. Patients can have both an intra-abdominal source of pain (IBS, endometriosis, adhesions) and a trapped abdominal-wall nerve. Carnett's test and the anesthetic injection isolate the ACNES component. Treating it can bring real relief even while the other condition stays active, because the two pain sources are separate.
Most commercial PPO plans cover ultrasound-guided rectus sheath blocks for ACNES, typically with prior authorization. We check your benefits and go over what your plan covers and any expected cost by phone before your visit, so there are no surprise bills. We accept most commercial PPO plans and do not accept Medicare, Medicaid, HMO plans or workers' compensation. Check your plan or call (646) 290-6660.
