Case notes

A 29-year-old woman, at 40 weeks’ gestation in her first pregnancy, was admitted to the maternity ward, and labor was induced with prostaglandins. Surprisingly, a subsequent vaginal examination revealed a mass behind the posterior vaginal wall. Although the patient had undergone routine vaginal examinations during her pregnancy, this was the first time the tumor was detected. Its presence prevented progression of fetal descent, despite active pushing during the second stage of delivery. Assisted delivery was considered and then accomplished with a vacuum pump. The baby, a healthy boy, weighed 4300 g and had an Apgar score of 9/10.

Postpartum transvaginal ultrasound, computed tomography, and magnetic resonance imaging revealed a presacral ovoid tumor mass ( Figure 1 ). The patient was self-referred to our department, where she underwent surgery. She was placed in a prone position and given general anesthesia. A midline incision of approximately 4 cm was made over the distal part of her sacrum and coccyx. We carefully removed the coccyx and exposed the tumor, which contained a cheeselike material but no evidence of hair, nails, teeth, or other materials. The postoperative period was uneventful, and the patient was discharged 4 days after surgery.

On unenhanced axial T1-weighted magnetic resonance image, well-delineated presacral mass was 6 × 5 × 5 cm in size with heterogeneously low signal.

Grahovac. An unexpected obstacle. Am J Obstet Gynecol 2011.

Conclusions

A pathology examination revealed a fibrous capsule lined by keratinized, stratified, squamous epithelium without any cutaneous adnexal structures. The final diagnosis was epidermoid cyst; the presacral or retrorectal space is a rare location for a developmental cyst in an adult. As might be expected then, clinical scenarios in which presacral epidermoid cysts obstruct labor are highly unusual. While it is not known how common these particular lesions are, the reported prevalence of retrorectal tumors is 1 per 40,000 hospital admissions in large referral centers. Given the size of this patient’s tumor, 6 × 5 × 5 cm, it is remarkable that it was first diagnosed during labor.

Retrorectal tumors are classified into several subgroups: congenital, neurogenic, osseous, inflammatory, and miscellaneous lesions. Congenital lesions are further subdivided into cystic and solid lesions. Although developmental cysts of the retrorectal space are rare overall, those growths that do occur are most often epidermoid cysts, which are benign lesions derived from ectoderm.

Symptoms from retrorectal tumors are usually nonspecific, and typically, they depend on the location and size of the lesion. A benign cystic lesion, such as an epidermoid cyst, is usually asymptomatic and discovered accidentally. Extremely large masses may cause problems with normal bowel movements. Our patient did not have any signs of pelvic pain or discomfort, and her bowel movements had been normal and regular.

Few similar cases appear in the medical literature. In 1 report, the second stage of labor was impeded by a presacral epidermoid cyst in a 32-year-old woman. Other presacral tumors that can complicate labor include hemangioendotheliomas, rectal neoplasms, cystic teratomas, or low-grade myosarcomas.

Our patient’s obstetrician-gynecologist was experienced in operative delivery, and the necessary prerequisites for the procedure were evident: the cervix was fully dilated, the membranes were ruptured, the fetus was in the vertex position with a fully engaged head, fetal status was reassuring, and the tumor was soft and compressible. We do not advocate operative delivery in women with a known mass of the pelvis. In these patients, a cesarean section would be the standard of care.

Surgical excision of a presacral epidermoid cyst is advisable, due to an increased risk of malignant transformation, complications associated with pregnancy and labor, and the possibilities of rupture and infection. Four main surgical approaches are currently used, and these are the posterior approach with coccygeal excision, the transabdominal approach, the transrectal approach, and a combined transabdominal/posterior approach. The method of choice is determined by the location, size, and histological nature of the lesion. If the lesion is located below the sacral S4 level, the posterior approach is appropriate, as it was in our patient’s case. Lesions that are small, mobile, without bony invasion, and low lying are amenable to a transrectal approach.

A biopsy should only be performed when resection is contraindicated because tumor cells might be disseminated. Retrorectal tumors might go undiagnosed because they are small, their locations are not readily visualized with ultrasound, a primary focus on the uterus and fetus allows them to go unnoticed during routine sonographic examinations, or the person performing the sonogram is inexperienced in identifying the growths.

Our patient underwent magnetic resonance imaging of the pelvis 6 months after surgery. She had no evidence of tumor recurrence.