Groin strain or hernia? Adductor groin pain and hernias seen only on scans

Why is groin pain so hard to diagnose?

Groin pain has many possible causes. In young male athletes, adductor-related groin pain is the most common, and it often occurs alongside inguinal or iliopsoas pain. In older people who are not athletes, pain referred from the hip joint is the most common cause, especially when symptoms have been present for a long time.

A groin hernia is defined by a swelling, and it is usually painless or only mildly uncomfortable. When someone's main complaint is sharp, focused groin pain with no lump, a range of muscle, tendon and joint problems needs to be considered. Sports medicine uses the Doha classification to sort these into adductor-related, iliopsoas-related, inguinal-related, pubic-related and hip-related groin pain.

What is an imaging-only hernia, and why does it matter?

An imaging-only hernia is one reported by a radiologist on a scan that cannot be felt or seen on examination. Guidelines advise against routine imaging to diagnose groin hernias, yet groin ultrasound is widely used. It is highly dependent on the person doing it, can both miss hernias and over-report them, and can mistake normal anatomy for a hernia. Small hernias on imaging are also very common in people with no symptoms at all.

The growing use of groin ultrasound in Australia has been linked to rising rates of unnecessary bilateral hernia repair. When a scan finding is blamed for the pain, the muscle and tendon problems that ultrasound detects poorly can be missed, and hernia surgeons rarely receive specific training in examining the groin for them.

How is adductor-related groin pain diagnosed?

Every patient was examined for a hernia lying down and standing, and then assessed with the Groin-MAP, a structured musculoskeletal examination published by Professor Hugh's group. Adductor-related groin pain was diagnosed when the patient's own pain was reproduced by pressing on the adductor longus tendon where it attaches to the pubic bone, and by stretching and strength-testing the adductor muscles.

A clinical hernia was diagnosed only when there was a distinct swelling or a cough impulse on examination, whatever the scan said. Tenderness when pressing over the inguinal canal was recorded separately as inguinal-related groin pain.

How often did groin ultrasound agree with examination?

All 47 patients in the scan-only group had a hernia reported on imaging, nine of them on both sides, and none had a hernia on examination. Among the 29 patients with a hernia that could be felt, 26 had an ultrasound, and only 18 of those reports (69%) matched the examination.

Of 21 ultrasounds reporting a hernia on one side, four patients actually had hernias on both sides and one had the hernia on the opposite side. Of five ultrasounds reporting hernias on both sides, three patients had a hernia on one side only.

How did patients with adductor groin pain do over the long term?

Patients were surveyed by phone at a median of 29 months after diagnosis, using questions adapted from the Copenhagen Hip and Groin Outcome Score. The scan-only and clinical-hernia groups did almost equally well. Patients with pain after a previous repair carried more symptoms, yet two thirds were satisfied and 33 of 34 avoided further groin surgery.

How was adductor groin pain treated in the study?

Every patient was told that surgery for adductor pain was unnecessary, given written and verbal advice on modifying activity, and referred to a sports physiotherapist with an interest in groin pain for a multimodal program. Only 45% went on to complete a course of physiotherapy, and patients still did well overall, which partly reflects how adductor pain tends to settle with time and sensible activity changes.

Hernia advice depended on the group. Patients with a scan-only hernia were told repair was not indicated. Patients with a hernia that could be felt chose with their surgeon: 14 whose hernia was the bigger problem had a day-only open mesh repair after four to six weeks of physiotherapy, and 15 whose adductor pain was the bigger problem chose watchful waiting. Two of those 15 later had a repair, at 8 and 38 months, and both were very satisfied with no pain.

Three patients in the scan-only group later had a total hip replacement on the painful side, which shows how often the hip is part of the picture.

What about groin pain after a previous hernia repair?

The 34 patients in this group presented a median of 32 months after their repair, none had a recurrent hernia on examination, and all had adductor-related groin pain. Almost half also had tenderness over the repair site, which goes by labels such as mesh-related pain or post-herniorrhaphy inguinodynia.

They were advised against revision surgery and treated for the adductor pain. One sought another opinion and had mesh removal and removal of a testicle, and the other 33 had no further groin surgery. The authors recommend carefully excluding adductor, hip, iliopsoas and pubic causes of pain before any re-exploration, because those operations carry real risk and inconsistent benefit.

Will hernia surgery fix groin pain?

Recent studies of people booked for inguinal hernia repair report a median pain score of only 2 out of 10 before surgery, whereas people with adductor-related groin pain typically report much higher scores. When pain is the main reason for surgery, the improvement from a hernia repair can be modest, which is why identifying the true source of the pain first matters so much.

What are the limits of this study?

Patients came from one surgeon's practice, the long follow-up allows recall bias about treatments received, and the survey drew on validated questions without using the full validated questionnaire. Outcomes were measured at a single point, and pain scores at diagnosis were not recorded for comparison.