Scar endometriosis- post caeserean section: A diagnostic pitfall

Nervous system, thorax, urinary tract, gastrointestinal tract, or cutaneous tissues are sites for unusual extrapelvic endometriosis; abdominal wall endometriosis is a rare. Patient usually presents with painful nodule in a parous woman with a history of gynecological or obstetrical surgery. The intensity of pain and size of nodule changes with menstrual cycle. Singh and Dharwadkar reported six cases of scar endometriosis. They reviewed the case records of patients with the diagnosis of scar endometriosis seen in hospital from 2015 to 2018.

Authors found six patients of scar endometriosis. The median age of the patients was 28.5 years (range 20-31 years) and median interval from symptoms to treatment was 4 years (range 2-6 years). Four patients had first presented to either the surgery or dermatology physicians. The most common complain being cyclical pain and swelling at local site. Patients underwent wide excision of the mass with no recurrence of symptoms at a follow up ranging from 9 months to 12 years.

Most common cause of this condition is surgical procedures on the uterus and fallopian tubes. Incidence following hysterotomy being 1.08%-2% and after caesarean section 0.03%-0.4%.

When it comes to abdominal wall masses abdominal wall endometriosis should be considered. Most common compliant being cyclical pain and nodule after gynecological or obstetrical surgery. With menstruation pain and size of nodule vary.

Direct implantation theory due to seeding of the endometrial tissue during caesarean section and under estrogen influence these cells proliferate, producing endometriomas is the most acceptable theory. In this the normal menstrual effluent transplanted to the abdominal wall results in subcutaneous endometriosis. Its occurrence is seen at places like episiotomy, hysterotomy, ectopic pregnancy, laparoscopy, tubal ligation, and caesarean section where endometrial tissue came in contact.

Endometrioma is formed by metaplasia of the surrounding fascial tissue. When these endometrial tissues reach these sites via lymphatics and hematogenous routes they grow in endometrioma, hence without any surgery abdominal wall endometrioma occurs. Post-operative abdominal lump has high suspicion index.

Histology has to be performed for diagnosis of endometriosis. Only 20%- 50% of these patients have correct preoperative diagnosis. A thorough examination with imaging techniques and history with presenting complaint in an incisional mass with cesarean section make a good diagnosis.

Ultrasonography is the most common investigation which is at lower cost and findings like hypoechoic and heterogeneous mass with messy internal echoes suggest endometriosis. The endometrioma may appear as a circumscribed solid or mixed mass, enhanced by contrast, and show hemorrhages on computed tomography.

Because of its high spatial resolution, which allows better distinction of the planes between muscles and abdominal subcutaneous tissue MRI is more effective in small lesions. Better assessed feature with MRI is infiltration of abdominal wall and subcutaneous tissues. FNAC was reported in some studies for confirming the diagnosis.

The hallmark of diagnosis is histopathology. With the presence of endometrial glands, stroma, and hemosiderin pigment it is confirmed. With a microscopic examination of a standard hematoxylin and eosin-stained slide diagnosis is confirmed. Furthermore, to clarify diagnosis and exclude malignancy the cytologist's experience is most important.

Treatment of choice for scar endometriosis is wide local excision with at least 1 cm margin. Excision becomes difficult in presence of larger and deeper lesions up to the muscle or the fascia. Complete excision of the lesion may entail a synthetic mesh placement or tissue transfer for closure after resection in cases of large lesion. With the use of progestogens, oral contraceptive pills, and danazol there is partial relief of symptoms but does not ablate the lesion. The recent use of the gonadotrophin agonist (Leuprolide acetate), found to provide only prompt improvement in symptoms with no change in the lesion size

A high jet solution before closure should be used at the end of surgery to prevent its occurrence.

"In the recent past because of the increasing numbers of caesarean sections scar endometriosis incidence have increased, so one should have a high index of suspicion of scar endometriosis. To avoid confusion with other surgical conditions, imaging techniques and FNAC are indicated towards better diagnostic approach. Wide excision being treatment of choice medical treatment can be used in selected cases. Patient should be followed-up for recurrence."

Source: Singh and Dharwadkar / Indian Journal of Obstetrics and Gynecology Research 2021;8(4):454–456

https://doi.org/10.18231/j.ijogr.2021.095