A Classical Case of Cesarean Scar Endometriosis in a 35-Year-Old Woman Presenting with Cyclical Abdominal Pain: A Case Report

Background

Endometriosis is defined as the presence of endometrial glands and stroma outside the uterus, usually occurring in reproductive-age women, with a prevalence of 10–15% [1]. It can occur in both pelvic and extrapelvic sites, most commonly in the ovaries, posterior cul-de-sac, uterine ligaments, pelvic peritoneum, rectovaginal septum, and abdominal wall [2]. Diagnosis is based on history and imaging, with the criterion standard being laparoscopy and biopsy. However, laparoscopy cannot always be done due to its impracticability and unsuitability for certain women [3]. The management of endometriosis can be medical (hormonal or non-hormonal) or surgical, with the latter usually reserved for resistant or recurrent cases [4].

Iatrogenic endometriosis is defined as the presence of endometrial glands and stroma outside the uterus following a surgical procedure involving the uterus. Cesarean sections, total or supracervical hysterectomies, and myomectomies are some examples of surgical interventions that can lead to iatrogenic endometriosis [5].

Surgical scar endometriosis is a rare complication of cesare-an sections that accounts for 0.03–0.4% of all endometriosis cases. The incidence of scar endometriosis after hysterectomies is estimated to be 1.08–2% [6]. After episiotomy, its incidence is 0.06–0.7% [7].

Because it is so rare, scar endometriosis is commonly misdiagnosed as hematomas, hernias, granulomas, abscesses, neuromas, or even neoplastic tissues [8]. A high index of suspicion is needed to diagnose iatrogenic scar endometriosis in women who present with abdominal pain and have a history of any abdominal surgeries [9].

Ping Zhang et al, Rohit Nepali et al, and Fatimah Alnafisah et al all described cases of cesarean section endometriosis that followed the classic presentation of cesarean scar endometriosis and closely mirror the presentation of this case [6,10,11].

This report presents a case of iatrogenic cesarean scar endometriosis in a 35-year-old woman presenting with cyclical abdominal pain occurring 4.5 years after a cesarean section.

Case Report

A 35-year-old medically free, multiparous Saudi woman presented to the Obstetrics and Gynecology (OB/GYN) clinic reporting abdominal pain and spontaneous bleeding over her previous cesarean section scar. She also noticed a lump that had developed over the scar that was associated with hyper-pigmentation. Her symptoms began 1 year ago and had been increasing in intensity over the last 6 months, with a cyclical pattern. She was not known to have endometriosis previously and her menstrual history was unremarkable. Her surgical history was positive for 1 cesarean section that occurred 4.5 years ago.

She sought help at a different hospital when her symptoms began, during which she was treated medically, but did not respond.

On examination we found a non-mobile, hyperpigmented mass, approximately 3×2 cm in size, protruding at the left corner of the Pfannenstiel incision scar, that was tender on palpation, with a 5-cm indurated area surrounding the mass (Figure 1). Clinically, our differential diagnoses were surgical scar endometriosis, abscess, and complicated surgical scar hernia.

A magnetic resonance imaging (MRI) scan of the pelvis with contrast was performed and the findings were a 3×3×3.5 cm left lower abdominal wall soft-tissue mass with dark T2 and T1 signal and homogenous post-contrast enhancement. There were minor cystic changes in the mass. There was invasion to the skin but not to the rectus muscle. There also was a 1×1.5 cm mass with similar appearance inseparable from the left rectus sheath laterally. There were no signs of deep pelvic endometriosis (Figure 2A–2D).

A clinical diagnosis of cesarean scar endometriosis was made based on the classical cesarean section endometriosis history (positive cesarean section, cyclical abdominal pain, and mass at the scar site), physical examination that revealed a bulging mass at the corner of the Pfannenstiel incision scar, and positive MRI finding. We then opted for surgical excision. The endometriomas were found to be implanted in the subcutaneous tissues and in the skin; the mass was not invading the rectus sheath. We excised, dissected, and removed all of the implants along with the indurated fibrous tissues surrounding it (Figure 3). The whole subcutaneous area was thoroughly cleaned and then closed. Histopathology was not done on request of the patient as she was not covered by insurance and would have had to pay out of pocket for it. The patient remained stable and recovered well. She was discharged the day after and was followed in the clinic postoperatively for 4 months with complete recovery (Figure 4).

Discussion

This report shows a typical case of cesarean scar endometriosis. We demonstrate how to recognize the classic presentation of this disease as well as how to go about making a clinical diagnosis and discuss the most effective treatment.

Endometriosis is a gynecological disease characterized by growth of endometrial tissue outside the uterus. This growth can be classified by location as either endopelvic or extra-pelvic. Pelvic sites include the ovaries, uterosacral ligaments, ovarian fossa, and pouch of Douglas [12]. Extrapelvic sites include the abdominal wall, groin, perineum, kidneys, liver, lungs, and pleura [13].

Cutaneous endometriosis is defined as the presence of endometrial glands and stroma in the skin and can be divided into both primary and secondary cutaneous endometriosis [14]. Primary cutaneous endometriosis occurs spontaneously, and its etiology is unclear [15]. Secondary cutaneous endometriosis is caused iatrogenically by surgical procedures of the abdomen or pelvis that result in endometrial tissue implantation into the skin [14,15].

Scar endometriosis is a relatively uncommon phenomenon that can occur after many abdominal surgical interventions. However, it most frequently occurs after a cesarean section, specifically in the Pfannenstiel incision at the corners of the wound [10,11]. Similar to our report, Rohit Nepali et al and Fatimah Alnafisah et al both describe cases in which the mass was found to be on one side of the Pfannenstiel incision scar [6,11]. This agrees with Ping Zhang et al, who found that roughly 80% of patients who presented with cesarean scar endometriosis had a Pfannenstiel incision. They also discovered that regardless of the type of incision, the corners were the most common site, with 83% in Pfannenstiel incision scars and 84.2% in vertical incision scars [10].

There are multiple theories proposed about the development of scar endometriosis. Two of these theories are known as the cellular transport theory and the coelomic metaplasia theory. The former states that the pathophysiology of scar endometriosis involves endometrial tissue implanting into the incision, which later forms the surgical scar and subsequent endometrioma [16]. Under certain hormonal and nutritional conditions, the cells proliferate and grow. The latter theory states that metaplasia of the surrounding tissue is responsible. Hematogenous and lymphatic spread are other proposed ideas of the development of surgical scar endometriosis [17].

The characteristic clinical presentation is a triad of an abdominal mass at or near a surgical scar, cyclical pain, and a history of abdominal/pelvic surgery [18]. Like our case, Fatimah Alnafisah et al and Rohit Nepali et al also presented cases with this classic triad [6,11]. Fatimah Alnafisah et al also documented a brownish discharge from the mass, like ours did [11]. Ping Zhang et al found that 98.5% of patients presented with an abdominal mass and almost 87% of patients had cyclical pain [10].

Patients with scar endometriosis present on average 30 months after the surgery [19]. Ping Zhang et al found the latency period was 31.6±23.9 months, which is similar to what other studies have found [10].

These patients can present not only to obstetrics and gynecology clinics, but also to general surgery [20], plastic surgery [21], and even to orthopedic surgery [22]. Therefore, care must be taken when dealing with patients that present with abdominal masses, cyclical pain, and a positive surgical history. A good history-taking is the key to establishing the diagnosis of scar endometriosis and excluding other differential diagnoses. A clinical diagnosis can be made through detailed history-taking, physical examination, and imaging [23].

Imaging modalities to aid in the diagnosis of scar endometriosis include magnetic resonance imaging (MRI), ultrasonography (US), and computed tomography (CT), with US generally being the initial imaging modality of choice given its cost and availability. The lesions appear to be hypoechoic and heterogenous with echogenic spots [24]. Scar endometriomas on CT appear as well-circumscribed, enhancing, solid, soft-tissue masses when intravenous contrast is used [25].

MRI has a very high sensitivity and specificity for diagnosing scar endometriosis (90–92% and 91–98%, respectively) [8]. It is especially useful in determining the extent of the disease for presurgical mapping [26]. Masses appear as hyperintense heterogenous lesions on T1- and T2-weighted sequences and some spots show contrast enhancement [23].

We opted for MRI as our imaging of choice due to its high sensitivity and specificity, whereas Rohit Nepali et al and Fatimah Alnafisah et al chose US [6,8,11]. Although all can be beneficial, we believe that MRI is the clear choice when choosing an imaging modality as it can also give detailed presurgical mapping and can clearly reveal the extent of the disease [26].

Treatment of scar endometriosis can be either medical or surgical. Hormonal treatment was found to be only temporarily beneficial and symptoms recurred as soon as the medication was stopped. Surgery remains the only curative treatment [27]. Nonetheless, hormonal treatment (combined oral contraceptives, progestogens, and hormone suppression therapy with gonadotropin-releasing hormone (GnRH) analogs) still has a role in pre- and post-operative management. It can be used as an alternative in patients who do not want surgery, and can also be used as an adjunct before surgery to shrink large endometriomas. Postoperatively, it can be used to prevent recurrence [28].

Surgical excision is considered the criterion standard treatment [29]. Ping Zhang et al, Fatimah Alnafisah et al, and Rohit Nepali et al all treated their cases with surgical excision of the mass [6,10,11]. The risk of recurrence is 5–9% [29]; thus, when resecting the mass, a margin of at least 1 cm should also be excised [30]. Irrigating and flushing of the wound before closing, especially the corners, adipose tissue, and the fascia, is crucial to prevent recurrence [31]. Surgery in cases of large endometrioma removal may necessitate the usage of propylene mesh to prevent incisional hernias [30,32].

Conclusions

Iatrogenic scar endometriosis a rare complication of cesarean sections and should be considered as a differential diagnosis in women with cyclical pain and a protruding mass in a previous cesarean section scar. A clinical diagnosis can be made with a proper history-taking (the classic triad), physical examination, and imaging. MRI is a particularly helpful diagnostic assessment tool in cases of scar endometriosis. Hormonal treatment is only partially helpful. Surgical excision remains the criterion standard treatment.