In the 21st century in the United States, the plethora of imaging studies has made the incidental finding of a pelvic mass common. Abdominal and pelvic computerized tomograms (CT scans), sonograms, magnetic resonance imaging (MRI), and positron emission test (PET) scans are being performed with much more frequency than in the past. In 2006, it was estimated that over 60 million CT scans were performed in the United States (1). Sometimes these procedures are performed for nonspecific abdominal complaints or to evaluate urologic, intestinal, or orthopedic problems. Sometimes these tests are performed to further evaluate a known problem such as cancer. There is an increase in the performance of these imaging studies in asymptomatic women as part of a general executive health screening (2). Small asymptomatic cystic ovarian masses assessed on vaginal ultrasound to be <5 cm diameter without septae or nodularity within (simple cysts) may be followed with repeat vaginal sonography in several months time (3). Generally, asymptomatic masses that do not grow are considered benign. In reproductive age women not using hormonal contraception, a functional ovarian cyst (including hemorrhagic corpora lutea and dominant follicles) would be a common finding. Such cystic masses can sometimes be associated with uterine changes indicating an early pregnancy. In such cases, a pregnancy test is indicated. An adnexal mass imaged in a reproductive age woman with a positive pregnancy test and absence of an intrauterine gestational sac could be the first evidence of an early ectopic pregnancy. Management of ectopic pregnancy is covered in Chapter 3 of this book.

For the premenarchal female, an asymptomatic pelvic mass could represent a congenital anomaly involving the upper genital tract, urinary tract, vagina, or colon and rectum. Prior to the availability of sophisticated imaging studies such as sonography and CT scans, a pelvic kidney was commonly misdiagnosed as an ovarian mass. Although the finding of an asymptomatic pelvic mass in a premenarchal girl is not a medical emergency, further evaluation is appropriate. Some of the more common premenarchal conditions that could present as a pelvic mass in an infant or adolescent are as follows: hematocolpos from an imperforate hymen, uterine anomalies, ovarian germ cell or stromal neoplasia, and rarely, endometriomas or abscesses (4,5). Other information obtained by history and general physical examination will be helpful in determining an appropriate differential diagnosis. For example, the presence of
precocious puberty with premature breast and pubic hair development or premature menarche may lead to the discovery of an ovarian stromal neoplasm. It is always prudent to consider simple problems such as urinary retention with a full bladder or constipation with a dilated colon or rectum as the cause of a so-called “asymptomatic pelvic mass” in a female child. Further elucidation is beyond the scope of this chapter. The reader is referred to well-documented previous works (6,7,8).

In reproductive-age women with an intact uterus, the most common asymptomatic pelvic mass after a functional ovarian cyst or early pregnancy is uterine leiomyoma. This occurs in 20% to 30% of women over 30 years of age (9) and is found in up to 75% of hysterectomy specimen (10). Leiomyoma is often discovered on routine screening pelvic examinations. Women with leiomyoma may have unrecognized symptoms of heavy menstrual periods and pelvic fullness with urinary frequency and/or constipation. The presence of uterine leiomyoma does not represent a medical emergency unless it is causing severe symptoms such as pain or uterine bleeding significant enough to cause acute anemia with decreased intravascular volume. A very large or rapidly growing leiomyoma may cause ureteral obstruction or hydronephrosis. The development of uterine leiomyosarcoma is a feared sequela of uterine leiomyoma. Fortunately, this is a rare condition that occurs in <1% of women with suspected leiomyoma (11). Occasionally, a pelvic mass that is thought to represent a leiomyoma is later determined to be an ovarian mass. If normal ovaries cannot be clearly identified in a women with a pelvic mass suspected to represent leiomyoma, additional studies including combined abdominal/vaginal ultrasound or MR of the pelvis should be considered.

The most feared pelvic mass is ovarian cancer. This is an insidious condition with a peak incidence among women in their mid 50s. Like uterine leiomyoma, women with ovarian cancer may experience abdominal fullness, swelling, or early satiety. As women go through menopause and stop menstruating, uterine leiomyoma tend to get smaller, but ovarian masses may continue to grow. Fortunately, most ovarian neoplasms are benign with cystic teratomas being the most common (12). Like leiomyoma, benign ovarian tumors may reach great size, distorting the abdominal contour while causing little in the way of symptoms.

Ovarian masses that are detected during routine prenatal sonograms are particularly challenging. Ovarian masses are detected in approximately 6% of pregnancies during routine obstetrical sonography (13,14). Most of these resolve representing physiologic cysts of pregnancy. Those that persist may cause the same complications seen in nonpregnant women (e.g., torsion, rupture, or hemorrhage), but these events are uncommon. Approximately 2% of ovarian masses detected during pregnancy will prove to be malignant and most of these are stage 1 (15). In the past, persistent adnexal masses in pregnancy were managed surgically in the second trimester between 14 and 20 weeks’ gestation. Masses detected later were managed by elective cesarean delivery at term followed by surgical management of the ovarian mass. Within the past decade, there has been a trend toward a more conservative management with careful sonographic monitoring allowing vaginal delivery and then management of the mass weeks to months after delivery (15,16,17,18).