Overview and Imaging: The two ovaries are ovoid structures generally located posterior or lateral to the uterus within the mesovarium of the broad ligament. Ovaries may be located anywhere along their embryologic course from the inferior border of the kidney to the broad ligament. Ovaries may be involved in indirect inguinal hernias, 15% of which occur in females. Herniated ovaries can extend as low as the labia (e-Fig. 127-1), the female equivalent of the scrotum.^1–5

Adnexal volume is determined by ultrasound using the formula for a modified prolate ellipse: (0.523) × L × W × D. Length (L) and depth (D) usually are measured on a longitudinal (parasagittal) image, and width (W) is measured on a transverse view (Fig. 127-2). In the first 3 months of life, when gonadotropin levels are highest in children, ovarian volumes average 1.06 cm³ but have a range of normal as high as 3.6 cm³. The high end of the range of normal is 2.7 cm³ for 4- to 12-month-olds and 1.7 cm³ for 13- to 24-month-olds. The mean ovarian volume reported for children older than 2 years who have not undergone puberty is 1 cm³. For menstruating females, the mean ovarian volume typically is 6 to 9.8 cm³.^1,6–10

Ultrasound routinely identifies follicles or cysts in most children of all ages. Cysts were noted in 80% of the imaged ovaries of a group of healthy children who were newborn to 2 years old, 72% of a 2- to 6-year-old group, and 68% of a 7- to 10-year-old group (Fig. 127-3). Macrocysts occasionally are seen in all age groups. The ovary is not a quiescent organ in childhood but rather is a dynamic organ undergoing constant internal change.^1,11

Overview and Imaging: The uterus of the newborn has a mean length of 3.5 cm, which decreases to 2.6 to 3 cm by the fourth month of life as gonadotropin levels decrease. On ultrasound examination of a newborn’s uterus, it is not uncommon to find either a hypoechoic halo around an echogenic endometrial cavity stripe or endometrial cavity fluid.1,3,12 The typical newborn’s uterus is shaped like a spade, with the anteroposterior diameter of the cervix as much as twice that of its fundus (Fig. 127-4). The newborn’s cervix is also longer than the fundus. After the first year of life, the typical uterus is tube shaped and remains that way for several years (e-Fig. 127-5).^1,3,13

Uterine length increases gradually between 3 and 8 years of age. The mean perimenarchal measurement is 4.3 cm. After puberty, the typical pear-shaped (Fig. 127-6) uterus measures 5 to 8 cm in length. It is said to descend deeper in the pelvis and no longer maintains the typical neutral position of premenarchal life but instead may be anteverted or retroverted.^1,14

Overview: The müllerian duct system (MDS) develops into the fallopian tubes, uterus, and upper two thirds of the vagina, and the wolffian system degenerates. External genital development proceeds along female lines except in the presence of androgens. By 11 weeks, a Y-shaped uterovaginal primordium has developed into the two fallopian tubes and, with fusion of a large portion of the MDS of both sides, a single uterus and upper two thirds of the vagina. Nonfusion or variably incomplete fusion of the MDS can lead to a wide spectrum of anomalies (Fig. 127-7). The association of uterine and renal abnormalities is quite common, and when a gynecologic anomaly is present, one should evaluate for renal anomalies or agenesis (e-Fig. 127-8) and vice versa.^1,15

Overview: In a person with a transverse vaginal septum, the vagina is obliterated by fibrous connective tissue with vascular and muscular elements lined by squamous epithelium. The area of obliteration may be a thin membrane, but more commonly it involves a segment of the vagina (segmental vaginal atresia). The imperforate hymen is a thin membrane, which forms at the junction of the caudal end of the MDS and the cranial end of the urogenital sinus. Both a transverse vaginal septum and imperforate hymen may present with an obstructed uterus and vagina.1,12,16–19

A distended vagina (colpos) or uterus (metros) is filled with secretions (muco), fluid (hydro), or blood (hemato). For example, hematometrocolpos is defined as hemorrhagic material filling a distended vagina and uterus. It is suggested on physical examination by either seeing an interlabial mass or palpating a pelvic mass. Clinical presentation in the teenage years includes amenorrhea (despite normal development of secondary sex characteristics) and cyclic crampy abdominal pains, or a pelvic mass resulting from accumulation of menstrual blood in the proximal vagina (and uterus and tubes). Complete or partial obstructions may occur in association with various MDS anomalies.1,15,20–22

Imaging: Ultrasound images are similar in appearance whether seen in a neonate or a menarchal teenager. The distended vagina appears as a tubular mass that usually is midline, often with contained echogenicities either from accumulated cervical mucus secretions or hemorrhage from sloughing of a hormonally stimulated endometrial lining. The uterus can be identified separately from the vagina by the thick muscular uterine wall, whereas the vaginal wall is thin (Fig. 127-9). Pelvic MRI in the sagittal or coronal plane can show the dilated vagina as well (Fig. 127-10).^{1,15,16,23,24}

Treatment: The vaginal obstruction in patients with congenital hydrocolpos is corrected in the newborn period. In patients presenting with hematometrocolpos at puberty, the obstruction should be corrected as promptly as possible to avoid endometriosis as a result of distal obstruction and repeated reverse spillage of menstrual blood into the peritoneal cavity through the fallopian tubes. Hysterectomy is indicated in patients with vaginal agenesis with a rudimentary uterus and a functional endometrium and in patients with cervical atresia occurring as an isolated lesion or in association with vaginal agenesis (Mayer-Rokitansky-Küster-Hauser syndrome).1,3,22–25

Overview and Imaging: The differential diagnosis of interlabial masses is usually made on visual inspection based on the location and external appearance of the mass. Masses associated with the urethral orifice include prolapse of an ectopic ureterocele—identified as a small, reddened, doughnutlike mass with its central opening being the urethral meatus itself—and cystic dilatation of an obstructed paraurethral (Skene) gland, presenting as a mass located on either side of a displaced urethral meatus. Masses associated with the vaginal introitus include prolapse of a vaginal cyst; a remnant of the wolffian or müllerian duct systems or epithelial inclusions originating from elements of the urogenital sinus; an imperforate hymen (e-Fig. 127-11); cystic dilatation of an obstructed Bartholin gland; and prolapse of a sarcoma botryoides or rhabdomyosarcoma of the vagina.^1,3,7

A cystogram or vaginogram, as well as ultrasound of the bladder and upper genitourinary tract, may be necessary to further define the lesion. CT or MRI may help if continued anatomic questions remain. At times, only surgery is conclusive.1,7,22

Overview: Pelvic inflammatory disease (PID) is the most serious complication of sexually transmitted diseases. PID includes a spectrum of abnormality that ranges from isolated endometritis to extension of infection into the tubes (salpingitis) and ovaries (oophoritis), potentially resulting in a tuboovarian abscess (TOA), and even extension into the peritoneum as disseminated peritonitis. Neisseria gonorrhoeae and Chlamydia trachomatis are the most common etiologic agents.1,26,27

Clinical presentation includes lower abdominal/pelvic pain, purulent vaginal discharge, fever, leukocytosis, and an elevated erythrocyte sedimentation rate. Adnexal tenderness, generally bilateral, and cervical motion tenderness are hallmarks for the clinical diagnosis on bimanual examination.1,26,27

Imaging and Treatment: Early in the course of PID or salpingitis, no abnormal ultrasound findings may be present, and the diagnosis will be based solely on clinical and laboratory evaluation. A helpful ultrasound finding in cases of salpingo-oophoritis is prominent ovaries that may be adherent to the uterus (e-Fig. 127-12). More advanced cases of acute or, more often, chronic PID may demonstrate evidence of hydrosalpinx, pyosalpinx, or TOA. The affected tubal walls may be thickened with intraluminal linear echoes. The echogenicity of the fluid within the fallopian tube is not a reliable indicator of the presence or absence of infection (Fig. 127-13). TOA appears on ultrasound as partial or complete replacement of the normal ovarian tissue by a heterogeneous mass or an echopenic region with contained debris (Fig. 127-14). The contents (debris filled) of the echopenic areas of a TOA often can be better seen by transvaginal ultrasound examination. TOA usually is treated aggressively with intravenous antibiotic regimens and, if necessary, percutaneous drainage or surgery.^1,27,28