Abstract
Ovarian remnant syndrome occurs in patients who have had attempted oophorectomy and part of the ovary was left behind. It often happens in patients who are undergoing total abdominal hysterectomy with bilateral salpingo-oophorectomy in the setting of severe pelvic adhesions. In those cases, the surgeon, to avoid injury to the ureter, which is not well visible, clamps gonadal vessels too close to the ovary and some ovarian tissue remains in the patient. The patient often experience severe, sharp unilateral pelvic pain that is cyclical in nature. On ultrasound there is often a cystic adnexal mass but lack of a mass does not rule out an ovarian remnant. Hormonal assays may also be helpful. Treatment is surgical but surgery for this condition may be overly difficult because the original surgery to remove the ovary was most likley difficult in the first place. Procedures to remove ovarian remnants should be performed only by highly qualified providers who are experienced in operating in the setting of severe adhesions. On a positive note, patients in whom ovarian remnant was successfully removed are almost always cured of their pain.
Editor’s Introduction
Ovarian remnant syndrome occurs in patients who have had attempted oophorectomy and part of the ovary was inadvertently left behind. It often happens in patients who are undergoing total abdominal hysterectomy with bilateral salpingo-oophorectomy in the setting of severe pelvic adhesions. In those cases, the surgeon, to avoid injury to the ureter, which is not well visible, clamps gonadal vessels too close to the ovary and some ovarian tissue remains in the patient. The patient often experience severe, sharp unilateral pelvic pain that is cyclical in nature. On the ultrasound there is often a cystic adnexal mass but lack of a mass does not rule out an ovarian remnant. Hormonal assays may also be helpful. Treatment is surgical but surgery for this condition may be overly difficult because the original surgery to remove the ovary was most likley difficult in the first place. Procedures to remove ovarian remnants should be performed only by highly qualified providers who are experienced in operating in the setting of severe adhesions. On a positive note, patients in whom ovarian remnant was successfully removed are almost always cured of their pain.
Introduction/Definition
Ovarian remnant syndrome (ORS) is defined as the presence of ovarian tissue after oophorectomy [1]. It typically presents with pelvic pain and/or a pelvic cystic lesion. Traditionally, ORS only included patients with a history of bilateral salpingo-oophorectomy (BSO). However, the definition has since been expanded to include patients with unilateral oophorectomy with residual ovarian tissue on the side of the previous resection [2]. It is also possible to have ectopic implantation of excised ovarian tissue, especially if the specimen is cut into pieces and removed uncontained at the time of extraction through laparoscopic trocar sites. There are reports of patients developing ovarian tissue at trocar sites from the removal of uncontained fragmented ovaries [3].
ORS was described in a study conducted in 1970 in which felines, after surgical excision of the ovaries, had portions of the ovarian cortex intentionally left in the abdominal cavity. These portions were able to reimplant and demonstrate ovarian function [4].
ORS should not be confused with supernumerary ovary syndrome or residual ovarian syndrome (ROS). Supernumerary ovary syndrome is a rare condition that refers to the development of extraovarian tissue during embryogenesis [5]. ROS, or retained ovary, refers to subsequent pelvic pain or pathology caused by an ovary that is intentionally left in place during surgery.
Incidence
The available data on the incidence of ORS is difficult to determine and limited to case reports and retrospective case series [4, 6]. A small cohort study looked at 119 symptomatic women who underwent operative laparoscopy after total hysterectomy and BSO. Five of the women were already diagnosed with ovarian remnant with at least one prior laparoscopic attempt at removal of tissue. Of the remaining 114 patients, 21 (18%) had ovarian remnant [7]. It is believed that the incidence may be increasing [8].
Risk Factors
Incomplete removal of ovarian tissue at the time of oophorectomy, regardless of route (vaginal, laparoscopy, or laparotomy), is the main risk factor for ORS, and typically is due to deficient surgical technique in a patient with adhesions. Factors that prevent complete removal of ovarian tissue include limited visualization due to adhesive disease, distorted anatomy, anatomical variations, and intraoperative bleeding [8]. Previous abdominal surgeries, history of appendicitis, and inflammatory pelvic (including endometriosis) or bowel disease increase the risk of adhesive disease and distorted anatomy. Endometriosis can increase the risk of functional ovarian tissue on nearby structures (i.e., pelvic peritoneum), thus making identification and complete ovarian removal challenging [9]. Interestingly, the majority of case reports since 2006 demonstrate that endometriosis is the most common reason for oophorectomy in those diagnosed with ORS [10].
Prevention
Incomplete ovarian tissue removal is almost always a result of deficient surgical technique. This includes improper dissection to gain adequate access to the infundibulopelvic ligament. The most commonly affected side for ORS is the left, where the sigmoid colon is frequently attached at the pelvic brim [10, 11]. A common technique for oophorectomy is placing traction on the ovary medially and ligating the infundibulopelvic ligament without opening the retroperitoneum. Ligating and excising too close to the ovary may leave ovarian tissue behind (Figure 14.1). Microscopic ovarian stroma has been noticed in the infundibulopelvic ligament within 0.2–1.4 centimeters of the proximal pole of the ovary in 14% of patients [12]. It is also believed that blunt dissection of ovarian adhesions instead of sharp dissection can risk tearing the ovarian cortex, leaving fragments in surrounding structures [8]. Failure to adequately remove ovarian tissue in this manner may increase the risk of ORS as well as ureteral injury. All ovarian adhesions and tissue must be removed with the ovary to prevent ORS (Figure 14.2).
Clinical Presentation
The most common complaints of ORS include chronic pelvic pain (84%), dyspareunia (26%), cyclic pelvic pain (9%), dysuria (7%), and tenesmus (6%). ORS may also present as a pelvic mass after oophorectomy, which may be accompanied by pain or be asymptomatic. In a study of 186 patients who had a history of BSO and were treated surgically for pathologically confirmed residual ovarian tissue, 56% presented with a pelvic cystic lesion. Symptoms will typically present within 5 years of oophorectomy; however, it has also been noted 20 years later [13, 14].
Pain can be cyclic or chronic, and can range from dull and achy to severe, sharp, and stabbing [15, 16]. The mechanism of pelvic pain for patients with endometriosis may include hormonal stimulation of endometriotic implants by remnant ovarian tissue, infiltration of nerves, or local inflammatory processes. In addition, in women without endometriosis, pain can be elicited due to cystic enlargement with compression of surrounding pelvic structures (i.e., ureteral compression) or the inability for expansion of ovarian volume within a fixed space due to adhesive disease (ovarian tissue entrapment) [15, 17, 18].
One should suspect ORS when there is an absence of menopausal symptoms after BSO in a premenopausal woman who has not received estrogen replacement therapy (ERT). These symptoms include lack of vasomotor symptoms, mood changes, and/or vaginal dryness. In women who are on ERT immediately following menopause, discontinuation and subsequent lack of menopausal symptoms may be helpful in diagnosing ORS [8].
Diagnosis
Clinical Suspicion
Usually there is a history of a difficult unilateral or bilateral oophorectomy. It is helpful to obtain operative and pathology reports to identify risk factors (i.e., dense ovarian adhesions from prior surgeries, other pathology such as endometriosis, poor surgical technique, etc.).
One should also ask about indicators, including the presence or absence of menopausal symptoms, in women with bilateral oophorectomy. In addition, asking about menstrual molimina or cyclical bleeding is helpful in determining if ovarian function is intact. Cyclic vaginal bleeding in a patient post-hysterectomy and post-BSO is indicative of ORS and endometriosis infiltrating the vaginal wall [19].
Laboratory Evaluation
In premenopausal women with a history of BSO, the use of serum follicle-stimulating hormone (FSH) levels (<30 UI/dL) and/or serum estradiol levels (>20 pg/mL) is useful but unreliable. Even then, these levels are not used to confirm menopausal status, but rather to test for any evidence of ovarian function. Pathologically confirmed ovarian remnants have been found in patients with menopausal hormone levels [8].
Unfortunately, a single test may be of little use, as women with ORS can have fluctuating FSH and estradiol levels, ranging from postmenopausal levels (high FSH, low estradiol) to premenopausal levels (low FSH, high estradiol).
Serum levels are also affected by women who are on ERT. Therefore, one should consider discontinuation of ERT for at least 10 days prior to obtaining serum FSH and estradiol [10].
Imaging
Imaging is necessary when suspecting ORS. A pelvic ultrasound is the imaging modality of choice and should be first in line for testing, as it appears to adequately identify the presence of cystic pelvic masses. In one study on excision of pathologically confirmed ovarian remnants, 89.6% had an adnexal mass detected by preoperative ultrasound [2]. Computed tomography (CT) and magnetic resonance imaging (MRI) are other options that can provide higher-resolution images (though they are more costly). In a series of 186 patients, complex pelvic masses related to ORS were seen in 93 of 100 (93%) patients by ultrasound, in 67 of 73 (92%) patients by CT, and in 7 of 9 (78%) patients by MRI [13].
Clomiphene Stimulation Test
In patients with negative imaging but high clinical suspicion, a stimulation test is mandatory. This entails the use of clomiphene citrate aimed to stimulate ovarian follicular development. Administering clomiphene citrate (100 mg daily for 10 days) followed by a pelvic ultrasound is highly effective to diagnose ORS. A study examined six patients with pelvic pain, a history of BSO, and a negative ultrasound. These patients received clomiphene citrate followed by repeat ultrasound. Four of the six patients developed cystic structures consistent with ovarian follicles [20]. Therefore, a positive provocation test with clomiphene citrate may potentially identify ORS and allow for a definite location of the remnant for surgical planning to expedite surgical removal. On the other hand, a negative provocation test does not necessarily exclude ORS, as some women may have a very small amount of unresponsive remnant tissue [10].
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