Caesarean section greatly increases risk of scar endometriosis

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Abstract

Objective

To estimate the incidence of scar endometriosis after different surgical procedures.

Study design

A retrospective study of 72 patients diagnosed with scar endometriosis between 1978 and 2003 was performed. Patient age, site of endometriosis, previous operations, time-gap between last surgery and onset of symptoms, nodule characteristics, and recurrence were evaluated.

Results

Age ranged from 16 to 48 years. Location varied according to the previous surgery: 46 caesarean section, one hysterectomy, one in abdominal surgery, 19 episiotomy, one was a relapse and two pelvic floor procedures, two women with no previous surgery. The incidence of scar endometriosis after caesarean section was significantly higher than after episiotomy (0.2 and 0.06%, respectively: p < 0.00001) with a relative risk of 3.3. Pain was the most frequent symptom. The mean time between surgery and onset of symptoms was 3.7 years.

Conclusion

Our findings confirm that scar endometriosis is a rare condition and indicate, probably for the first time, that caesarean section greatly increases the risk of developing scar endometriosis.

Introduction

Endometriosis is characterized by the presence endometrial tissue implants outside the uterine cavity. These implants can be found in all areas surrounding the uterus such as the fallopian tubes, ovaries, and pelvic peritoneum (pelvic endometriosis). More rarely, endometriosis can be found in unusual places such as in the central nervous system, thorax, urinary tract, gastrointestinal tract, lower limbs, and in cutaneous cellular tissues. These uncommon implants are referred to as extrapelvic endometriotic implants [1].

Extrapelvic implants can occur in subcutaneous cellular tissues of surgical scars, or in the surrounding areas, following obstetric and gynecological procedures. These implants are more likely to occur as a consequence of procedures performed during gestation. Endometriosis has been reported in scars originated after caesarean section [2], in episiotomy scar after delivery [3], and in consequence of procedures that had contact with endometrial tissue, such as hysterectomy [4], ectopic pregnancies [2], salpingostomies [5], and those performed during the first half of the pregnancy [6].

Additionally, endometriosis has also been reported as umbilical endometriosis after puerperal sterilization [7] or after laparoscopy [4], amniocentesis [8], appendectomy [9] and surgery for inguinal hernia [10]. Reports on the occurrence of primary endometriosis in umbilical scar, vulva, perineum, and groin, and which are not related to any surgical procedure have been documented [10]. Scar endometriosis is a rare occurrence, with reported incidences that vary around 3.5% [11]. It is more commonly found after obstetric procedures such as interruption of pregnancy in the second trimester by hysterotomy [12]. Some authors have reported incidences of 1.08–3.5% when pregnancy is interrupted in the second quarter and of 0.03–0.4% after caesarean section [6]. Additional reports [13] suggested that the risk of endometriosis increases when caesarean section is performed before labor has truly initiated. The occurrence of endometriosis in episiotomy scar is less frequent than in scars of the abdominal wall [14]. Recent studies indicate that the incidence of perineal endometriosis following episiotomy is higher than previously thought [14].

The pathophysiology of the scar endometriosis may be due to the direct implantation of the endometrial tissue in scars originated at operation [10]. During surgery, the endometrial tissue is inoculated directly in the surgical wound, keeping the endometrial cells viable. These cells proliferate under appropriate hormonal stimulus (cellular transport theory) or induce the surrounding tissue to undergo metaplasia, which leads to scar endometriosis (coelomic metaplasia theory). Alternatively, the endometrial tissue may reach the surgical scar through the lymphatic or vascular pathways and later develop into scar endometriosis.

In this study we aimed to estimate the incidence of scar endometriosis within a large period of time and to compare the impact of the different surgical procedures on its frequency.

Section snippets

Material and methods

A retrospective observational cohort study was performed through analysis of the medical reports of patients presenting a histopathological diagnosis of scar endometriosis, in Hospital das Clínicas of the Federal University of Minas Gerais, Brazil, between May 1978 and December 2003.

Endometriosis was considered when endometrial tissue was found in fibrous connective or skeletal muscle tissue in areas of focal hemorrhage or in areas of active chronic endometriosis with fibrosis in which

Results

A total of 72 cases were analyzed in this study. The site of the scar endometriosis varied according to the surgery performed. Of the 72 women, 48 (66.6%) had lesions in the abdominal wall, 22 (30.5%) presented lesions in the perineum, one had a lesion in the posterior vaginal wall (1.38%) and one patient (1.38%) had an umbilical scar lesion (Table 1). Patient ages ranged from 16 to 48 years old, with an average of 30.8 ± 5.87.

The surgical procedures performed prior to the appearance of the scar

Comments

This study reported the occurrence of scar endometriosis cases that happened during a period of 25 years, providing important data that might contribute to a better understanding of this rare condition and its incidence. The average age observed in this group of patients (30.8) is similar to that described by other authors and indicates that scar endometriosis is a disease that affects mostly young women of reproductive age [2], [4], [6], [9], [15], [16]. Our findings strongly support the

Conclusion

The findings of our study may help to determine the real incidence of scar endometriosis after gynecological and obstetrical surgical procedures, as to our knowledge this study has identified the occurrence of scar endometriosis during the longest period (25 years) ever analyzed. Our findings also indicate that caesarean section greatly increases the risk of developing scar endometriosis when compared to episiotomy.

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