Original Scientific Article

Incisional Endometriosis: An Underappreciated Diagnosis in General Surgery

Raminder Nirula, MD, Gregory C Greaney, MD, FACS

Background: Incisional endometriosis is a described clinical entity in the gynecologic literature, but it is not well recognized among general surgeons; only 32 cases have been reported in the general surgery literature. The preoperative diagnosis is often mistaken for a suture granuloma, lipoma, abscess, cyst, or incisional hernia.

Study Design: We performed a retrospective review of 10 cases of incisional endometriosis at our institution to determine which, if any, clinical factors would suggest the diagnosis preoperatively. All general surgery patients who had the diagnosis of endometriosis in their pathology specimens from January 1990 to December 1998 were reviewed.

Results: All 10 patients had previous cesarean sections through either a Pfannenstiel (n=8) or a lower midline (n=2) incision. Ages ranged from 27 to 41 years (mean 33.4 years). The most common presenting symptom was a slow-growing, painful lump in the lateral aspect of the Pfannenstiel incision. Two of the patients had a change in symptoms with their menstrual cycle. The duration of symptoms ranged from 2 months to 3 years. All patients underwent surgical excision. The size of the excised endometriomas ranged from 1.5cm to 4.8cm (mean 3.1cm).

Conclusions: Incisional endometriosis may be more common than previously recognized. In all cases it was found to occur in women with a history of cesarean section. Most patients presented with a painful, slow-growing lump at the lateral edge of their incision. Cyclic changes in pain and size of the mass with menses was elicited in only two of these patients, but this may be from a lack of awareness and questioning on the part of the physician. If the diagnosis is made preoperatively, additional diagnostic studies may be avoided. An awareness of this disease process on the part of general surgeons is necessary to guide preoperative evaluation and therapy appropriately.

The presence of functional endometrial tissue outside the uterine cavity has been well described since the early 1900s.1 This ectopic tissue, referred to as endometriosis, is most often found in the pelvis, ovaries, pouch of Douglas, and peritoneum.2 Unusual extrapelvic sites have been well documented in the gynecologic literature.3 Similarly, the presence of endometrioma within cesarean section scars have been documented in the gynecologic literature since 1956.4

The first case of a cesarean section endometrioma in the general surgical literature was reported in 1975.5 Since then, there have been a total of 32 cases described anecdotally. Most surgical reports indicate that preoperatively, the condition is often confused with other pathologic conditions such as incisional hernia, suture granuloma, abscess, or lipoma.2,6,7

This retrospective study of 10 patients reviews their presentation, assessment, and the therapeutic interventions undertaken by general surgeons at our community hospital. It is the largest series in the general surgery literature to date, which underscores our underappreciation of this disease.

METHODS

From January 1990 to December 1998 the charts of 10 patients with the diagnosis of cesarean section scar endometrioma were reviewed. Data regarding age, type of incision, presentation, preoperative diagnosis, workup, and management were collected.

RESULTS

Duration of symptoms ranged from 3 months to 10 years. Patient ages ranged from 27 to 41 years (mean 33.4 years). Eight patients had Pfannenstiel incisions and two had lower midline incisions. The most common presentation was that of a slow-growing, painful mass at the incision site. The onset of symptoms from the time of cesarean section ranged from 1 year to 7 years. The preoperative diagnosis was correctly made in only two patients and was documented with CT scan. All patients were treated with surgical excision (Table 1).

Table 1. Summary of Patients with Cesarean Section Endometrioma

DISCUSSION

The presence of endometrioma has been documented in almost every organ of the body. Its occurrence has also been well documented in incisions of any type where there has been possible contact with endometrial tissue, including episiotomy, hysterotomy, ectopic pregnancy, laparoscopy, tubal ligation, and cesarean section.8-10 The true incidence of cesarean section scar endometrioma is difficult to determine, but ranges from 0.03% to 0.15%.1

The development of intrapelvic endometriosis may involve retrograde menstruation, maturation of extrauterine primordial cell remnants of embryogenesis, or hematologic or lymphatic spread of endometrial cells. Extrapelvic endometriosis in the lung, skin, and extremities not associated with surgical violation of the uterus is believed to be the result of hematogenous or lymphatic spread of endometrial tissue.11,12 Scar endometriomas are believed to be the result of direct inoculation of the abdominal fascia or subcutaneous tissue with endometrial cells. This theory is convincingly demonstrated by experiments in which normal menstrual effluent transplanted to the abdominal wall resulted in subcutaneous endometriosis.13

Review of the gynecologic literature indicates that the presentation of patients with cesarean section scar endometrioma is made easily on clinical grounds.1,4 Classically, the scenario is that of a parous woman complaining of a painful nodule, varying with menses, at the incision site. Conversely, review of the surgical literature indicates that preoperative diagnosis is often incorrect.6,7 In our own series the preoperative diagnosis was correctly made in only 2 of 10 patients (20%). These two cases were diagnosed by the same surgeon, who was alerted to the disease process by having encountered two previous patients with the same pathology. The remaining patients were diagnosed with incisional hernia, suture granuloma, neoplasm, and sebaceous cyst. In instances where the diagnosis was incorrect, the history of cyclic pain was not elicited, which may be secondary to lack of awareness. Pain may be reported as constant with little cyclic variation, but this tends to occur when symptoms have been longstanding.14 Only two of the patients in our series had symptoms that were present for more than 1 year. This suggests that the clinical clues that might have led to the diagnosis preoperatively may have been overlooked.

Both CT and ultrasonography have been used to assist in establishing the diagnosis. In this series both modalities correctly identified the mass as being associated with the abdominal wall and ruled out incisional hernia. Suspicions of hematoma, sebaceous cyst, and neoplasm were raised. In only one patient was the suggestion of endometrioma included in the radiographic diagnosis. Other series have found little value in these modalities in sufficiently characterizing the mass to distinguish it from other diagnostic possibilities, with the exception of an incisional hernia.15,16 Needle aspiration cytology has also been used and may be helpful in eliminating malignancy from the diagnosis.17 When suspicion of incisional hernia is present, this diagnostic modality should not be used. To rule out incisional hernia, ultrasonography or CT may be useful, but they do little to identify the exact cause of the subcutaneous mass.

Medical and surgical therapies have been used in the treatment of this process. Medical therapy with danazol, an antigonadotropin, has been used in the treatment of endometriosis. When used for the management of cesarean scar endometrioma it has provided temporary relief of symptoms, but does not ablate the lesion. Recurrence of symptoms is typical when there is cessation of the drug. Because the medication has androgenic properties, side effects such as amenorrhea, weight gain, hirsutism, and acne are common, making compliance unlikely.18 Surgical therapy involves total wide excision of the lesion to prevent recurrence. It is often necessary to remove a portion of the abdominal fascia to achieve complete excision. In patients in whom a large defect remains, mesh has been used for repair.17 Recurrences have been reported and have been managed successfully with reexcision.19

In conclusion, general surgeons are infrequently involved in the management of cesarean section scar lesions, so the preoperative diagnosis of endometrioma is not often entertained in this instance, predominantly because of a lack of awareness. The presence of cyclic pain in an incisional mass associated with a cesarean section scar is almost pathognomonic for the condition. When the diagnosis is made on clinical grounds, no further studies are necessary before wide surgical excision.

References

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19. Steck WD, Helwig EB. Cutaneous endometriosis. Clin Obstet Gynecol 1966;9:373-383.

No competing interests declared.

Received September 6, 1999; Revised November 17, 1999; Accepted November 17, 1999.

From Santa Barbara Cottage Hospital, Santa Barbara, CA, USA.

Correspondence address: Raminder Nirula, MD, Santa Barbara Cottage Hospital, Department of Surgery, PO Box 689, Pueblo and Bath St, Santa Barbara, CA 93105.

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