•We present a case of scar endometriosis with the aim to improve the awareness and diagnosis of scar endometriosis following previous abdominal obstetric surgery.

•A 44-year-old para 2 with 2 previous caesarean sections 15 and 11 years ago was referred to the Gynaecology clinic by the surgeons with a 28-month history of a left iliac lump close to her caesarean section scar. A differential of an incisional hernia by the GP warranted a referral to the surgeons. She was up-to-date with her smears and her cycles were regular. The lump was described as a left iliac lump causing discomfort, especially when bending down.

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•Ultrasound pelvis was normal, and a Computerised Tomography scan (CT) described a 16mm enhancing subcutaneous spiculated lesion within the left anterior abdominal wall with differentials as scar tissue or desmoid tumour. A sarcoma MDT referral was made as a result of this differential as well as a finding of an inflammatory lower lung nodule which was later of no concern. She subsequently had an ultrasound-guided biopsy of the hypoechoic soft tissue lesion centered within the deep subcutaneous tissue of the left lower abdominal wall measuring approximately 14 x 11 x 17 mm with mild increased internal vascularity.

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•The histology report confirmed caesarean section scar endometriosis. She is now being planned for an excision of this scar endometriosis following a failed trial of oral contraceptive pills and as she requested.

•Arriving at the diagnosis of scar endometriosis is often difficult and prolonged and women would have had to be seen by multiple specialists before this rare diagnosis is made. The most sensitive imaging modality is magnetic resonance imaging (MRI) scan. A history of cyclical pain is seen in over 60% of women which may suggest an association with the menstrual cycle. GnRH analogues may provide interim symptomatic improvement.

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•Excision of the endometriotic tissue remains the definitive treatment if symptoms persist.  The cause of scar endometriosis is thought to be due to endometrial cells being exposed and becoming implanted on the wound. It is, therefore, advisable for surgeons to take care to avoid this from occurring when operating on the uterus. 

•Pain from endometriosis is often suffered for a prolonged period of time before a diagnosis is made and it might be beneficial to empower primary care physicians on possible symptoms of endometriosis and the need to refer to the appropriate team soon.

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•The management of scar endometriosis is definitively surgical but hormone-based modalities may provide temporary relief.