Endometriosis is a common condition where tissue similar to the lining of the uterus, called the endometrium, grows outside the uterine cavity. A C-section is a surgical procedure for delivering a baby through incisions in the mother’s abdomen and uterus. While a C-section is not generally considered a primary cause of widespread pelvic endometriosis, it is strongly linked to a specific, localized form known as scar endometriosis. This condition develops when endometrial cells are inadvertently transferred to the surgical incision site during the delivery procedure. The resulting growth is confined to the abdominal wall, near the surgical scar, and is distinct from the generalized disease found in the pelvis.
C-Section Scar Endometriosis Definition and Cause
C-Section Scar Endometriosis (CSSE) is a rare occurrence where endometrial glands and stromal cells implant and grow within the tissue of a previous Cesarean incision. This ectopic tissue, though outside the uterus, remains hormonally responsive, meaning it attempts to shed or bleed during the menstrual cycle. The resulting buildup of tissue and blood within the confined space of the scar causes symptoms.
The primary mechanism for CSSE is mechanical transplantation, often termed iatrogenic seeding. During a C-section, the surgeon opens the uterus, exposing the uterine lining and its cells. Endometrial cells can be accidentally transferred to the surrounding abdominal wall tissue via surgical instruments or direct contact as the wound is being closed. These cells then take root and begin to grow outside their normal location.
This condition occurs in a small percentage of patients, with the reported incidence ranging from 0.03% to 0.8% following a C-section. The tissue most commonly implants in the subcutaneous fat and fascia immediately beneath the skin incision. Over time, the implanted cells form a palpable mass or nodule near or within the scar itself.
The classic presentation of CSSE involves a palpable lump or swelling at the scar site. This mass is often accompanied by localized pain that typically worsens during menstruation, known as cyclical pain. The cyclical flare-up is a strong indicator, as the ectopic endometrial tissue swells and bleeds in response to hormonal changes.
Distinguishing Scar Endometriosis from Pelvic Endometriosis
Scar endometriosis differs from the more common chronic, widespread pelvic endometriosis (PE). The most significant difference is the location of the disease; CSSE is an extrapelvic condition, localized to the abdominal wall incision. Conversely, PE involves the growth of endometrial-like tissue on organs within the pelvic cavity, such as the ovaries, fallopian tubes, and the outer surface of the uterus.
The presumed causes of the two conditions also differ. CSSE is thought to be a direct result of iatrogenic transplantation, a mechanical accident during surgery. In contrast, the cause of PE is complex and thought to involve multiple theories, including retrograde menstruation, where menstrual blood flows backward through the fallopian tubes, or coelomic metaplasia, where cells outside the uterus transform into endometrial-like cells.
CSSE is typically an isolated occurrence, meaning a patient with scar endometriosis may not have the chronic, widespread pelvic form of the disease. While the two can coexist, the localized nature of the scar lesion means it does not cause the widespread inflammation and adhesion formation that characterize PE. Because the lesions are outside the pelvic cavity, CSSE does not typically contribute to the chronic pelvic pain or fertility issues associated with PE.
The treatment approaches also highlight the distinction between the two forms. Pelvic endometriosis is often managed with hormonal therapy to suppress the cyclical growth of the tissue and pain medication. CSSE, being an isolated mass, does not respond well to hormonal treatments alone, requiring a different, more localized intervention.
Diagnosis and Treatment Options
The diagnosis of C-section scar endometriosis begins with a thorough medical history, looking for the classic triad of symptoms: a history of C-section, a palpable mass at the scar site, and pain that correlates with the menstrual cycle. A physical examination can often confirm the presence of a firm, tender nodule within or immediately adjacent to the surgical scar.
Imaging studies are often used to confirm the presence and extent of the mass and to rule out other potential causes, such as hernias, suture granulomas, or tumors. Ultrasound is typically the first line of imaging, revealing a solid or cystic mass in the subcutaneous tissue. Magnetic Resonance Imaging (MRI) is considered superior for determining the precise depth and size of the lesion, which is essential for surgical planning.
The definitive treatment for C-Section Scar Endometriosis is wide local surgical excision. This procedure involves removing the entire endometriotic nodule along with a margin of healthy surrounding tissue to ensure complete removal. Complete excision is necessary because leaving even small amounts of the ectopic tissue behind significantly increases the risk of recurrence.
The removed tissue is then sent for histopathological examination, which provides the final confirmation of the diagnosis by identifying the characteristic endometrial glands and stroma. Unlike pelvic endometriosis, hormonal therapies are generally not effective as a primary treatment for CSSE because they cannot shrink the established mass sufficiently. Surgical removal offers a cure for this specific, localized condition.