Imaging findings in inflammatory disease of the genital organs

Cervicitis is characterized by cervical inflammation. Cervicitis is primarily diagnosed based on clinical findings, and no specific imaging findings are associated with this condition. However, imaging findings of cervicitis have been reported, including an enlarged and abnormally enhancing or hyperemic endocervical canal, with or without parametrial fat stranding visible on CT or MRI (Fig. 2a); free fluid may also be observed in the cul-de-sac [6]. Cystic cervicitis is a distinct form of cervical inflammation, and its symptoms may include jelly-like vaginal discharge. On imaging, cystic cervicitis typically presents as round, multicystic lesions located centrally within the cervix (Fig. 2b). Due to the presence of hemorrhage and infected material, the signal intensity on pre-contrast T1-weighted images may vary from low to high [7].

Endometritis refers to the inflammation or infection of the endometrium, the lining of the uterus. The diagnosis of endometritis is primarily based on clinical findings. In contrast, uterine empyema is a condition in which the uterine cavity is filled with purulent content [6]. It is often a consequence of endometritis and can be caused by various factors, such as benign conditions, including endometrial polyps, senile endometritis, idiopathic conditions leading to cervical stenosis, or postoperative infections. Uterine empyema is commonly observed in postmenopausal women and is typically asymptomatic; its incidence increases with age and decreased activity, with incontinence being a significant risk factor [6]. CT findings of endometritis are non-specific and may include a normal-appearing endometrium, an enlarged uterus, and fluid accumulation in the endometrial canal. Abnormal enhancement of the endometrium was also observed [6] (Figs. 3a and 5a). Uterine empyema is characterized by the distention of the uterine cavity with complex fluid, and imaging findings may include gas bubbles and air-fluid levels [6] (Fig. 5b).

Salpingitis is the most common early acute form of PID and refers to the inflammation of the fallopian tubes. It is primarily caused by STIs, and if left untreated, can progress to tubal empyema, a condition characterized by the accumulation of pus in the fallopian tubes. Salpingitis can be categorized as acute or chronic. Acute salpingitis is an infection of the fallopian tubes, in which pus may accumulate in one or both tubes. Chronic salpingitis refers to persistent inflammation of the fallopian tubes that results in adhesions within the tubal lumen. This can lead to tubal damage, pelvic pain, and infertility. Women with chronic salpingitis are at an increased risk of ectopic pregnancies (30–40%) and infertility (40–50%) [6]. The diagnosis of salpingitis relies primarily on clinical findings. Imaging findings of salpingitis are non-specific and may include a normal appearance to thickening of the fallopian tubes (usually ≥ 5 mm), pelvic fat infiltration or haziness, and pelvic edema [6, 8, 9] (Fig. 3b). Tubal empyema is characterized by fluid-filled fallopian tubes, with thickening and enhancement of the tubal wall (Fig. 4). Hydrosalpinx refers to fimbrial obstruction and distention of the fallopian tubes with non-purulent fluid. Although often asymptomatic, it can cause chronic pelvic pain, dyspareunia, and infertility [6, 10].

Oophoritis is a condition characterized by the extension of infection from the fallopian tubes to the ovaries. Inflammatory exudates spread to the ovary or periovarian region, leading to swelling of the ovarian stroma, surrounding edema, hyperemia, and a polycystic appearance on imaging. Oophoritis is often represented by polycystic ovaries with multiple small follicles measuring 2–10 mm and an ovarian short-axis diameter > 3 cm (Figs. 3b and 7a). However, there is an overlap with a normal ovarian appearance, making it challenging to diagnose oophoritis based solely on ovarian findings [8].

Tubo-ovarian abscess (TOA) is a severe and complex complication of PID, occurring in approximately 15–34% of patients with PID [11, 12]. TOA is characterized by the accumulation of pus in the fallopian tubes and ovaries. Risk factors for TOA include STIs, ovarian endometriosis, and other conditions that cause inflammation of the reproductive organs. Imaging findings of TOA typically reveal a multilocular septate cystic mass in the adnexa with a thick, uniformly enhancing wall. There is often a loss of fat planes between the mass and adjacent pelvic organs. In addition, thickening of the uterosacral ligaments and presence of fluid in the cul-de-sac may be observed [6] (Figs. 5, 6a, b).

Pyometra, pyosalpinx, and TOA can cause peritonitis when an abscess ruptures or pus leaks from an infected organ. Peritonitis is a serious condition that requires urgent medical attention and typically involves antibiotics, and if necessary, surgical intervention. Delayed diagnosis and treatment can result in severe complications including sepsis and even death [2, 13]. Contrast-enhanced CT is a valuable tool for diagnosing peritonitis and determining its underlying cause. Findings associated with peritonitis include enhancement of the peritoneum with thickening, enhanced fascial planes, inflammatory changes in the mesentery and bowel wall, and intraperitoneal abscesses [13] (Fig. 6c, d).

Fitz-Hugh–Curtis syndrome is a rare complication of PID characterized by inflammation of the liver capsule and the formation of adhesions. The condition was named after the two physicians who first reported it in the 1930s [14]. The primary symptom of Fitz-Hugh–Curtis syndrome is sudden onset of abdominal pain in the right upper quadrant, which may be accompanied by right shoulder pain. The diagnosis of this syndrome can be challenging, as pelvic pain, vaginal discharge, and cervical tenderness are frequently absent or minimal, if present. This condition occurs when infectious bacteria travel from the pelvis to the liver capsule, bypassing pelvic structures. Contrast-enhanced CT findings associated with Fitz-Hugh-Curtis syndrome may include marked enhancement in arterial-phase, thickening of the liver capsule, fluid and fat stranding extending from the pelvis into the right upper quadrant through the paracolic gutter, loculated fluid around the liver, and gallbladder wall thickening [9, 15] (Fig. 7b). Fitz-Hugh–Curtis syndrome can also occur in men [14, 15].

Chronic inflammation can lead to the formation of scar tissue and adhesions within the affected organ as well as with surrounding organs. Adhesions within the bowel can cause bowel obstruction, whereas those within the ureter can result in hydronephrosis. Furthermore, chronic inflammation can give rise to thrombophlebitis, which involves the formation of blood clots within the ovarian veins. The combination of inflammation, impaired blood flow, increased blood coagulation, and vein compression contributes to the development of ovarian vein thrombophlebitis. If left untreated, this condition can pose a risk of pulmonary embolism, in which the blood clot travels to the lungs and blocks the pulmonary arteries [6].

The vas deferens, also known as the ductus deferens, is a component of the spermatic cord. It originates at the caudal end of the epididymis and transports sperm from the epididymis to the ejaculatory duct. Vasitis, also referred to as deferentitis or funiculitis, is an acute inflammation that causes painful swelling of the groin. It is commonly observed in patients who have undergone procedures involving the manipulation of the vas deferens, such as vasectomy, prostatectomy, or herniorrhaphy. Infectious vasitis is often associated with cystitis, epididymis, or prostatitis [21]. US is considered the gold standard for excluding conditions such as epididymitis, orchitis, and other diseases. The normal appearance of the vas deferens on US is an anechoic or hypoechoic tubular structure with no detectable internal blood flow [22]. In contrast, vasitis shows a heterogeneously hypoechoic mass within the inguinal canal with increased vascularity on color Doppler US. However, US is less sensitive for distinguishing vasitis from incarcerated inguinal hernias. CT is more effective in differentiating between these two conditions and can reveal unilateral edema and abnormal enhancement of the spermatic cord [23] (Fig. 11). Some have reported that MRI is a preferred modality over CT because it detects abnormal signals in and around the vas that indicate edema and inflammation [24].

Epididymitis, orchitis, and epididymo-orchitis are the most common causes of acute scrotal pain and involve inflammation of the epididymis, testes, or both. The infection typically spreads in a retrograde manner, starting from the tail of the epididymis, progressing to the head, and eventually to the testis. In some cases, orchitis can be caused by viral infections, with mumps being the most commonly associated viral cause; however, such cases are rare in developed countries owing to vaccination [25]. Recent studies have shed light on the mechanisms of mumps virus infection, interactions with host cells, and the resulting inflammatory response in testicular cells [26]. In sexually active men aged < 35 years, the most common pathogens are Chlamydia trachomatis and Neisseria gonorrhoeae. In other age ranges, organisms that typically contaminate the urinary tract, such as Escherichia coli and Pseudomonas species, are more common [20, 25]. US findings of epididymitis include an enlarged and hypoechoic epididymis due to edema. Reactive hydrocele and thickening of the scrotal wall may also be observed. Color Doppler US shows increased blood flow corresponding to hyperemia. When the infection spreads to the testis, the testicular parenchyma also exhibits heterogeneous echogenicity with increased blood flow [25]. On contrast-enhanced imaging, asymmetric enhancement of the spermatic cord vessels is indicative of ipsilateral infectious vasitis, epididymitis, or orchitis. In epididymitis, a strong enhancement of the epididymis due to hyperemia is usually observed [20, 27] (Fig. 12). Acute orchitis is indicated by asymmetry with enlargement and increased contrast enhancement of the affected testes; vasitis and epididymitis are often associated (Fig. 13). MRI has superior soft-tissue contrast resolution and can provide more valuable diagnostic information in differentiating other conditions such as testicular tumors. In addition, MRI is better at demonstrating testicular inflammation, as it shows decreased T1 signal intensity and increased T2 signal intensity compared to that in normal testes. The affected areas may exhibit intense and homogeneous enhancement or demonstrate the characteristic “tiger skin” post-contrast pattern, corresponding to preserved septa [20]. If left untreated, epididymitis, orchitis, and epididymo-orchitis can lead to complications, such as abscess formation (Fig. 13b), pyocele (collection of pus between the layers of the tunica vaginalis), and testicular ischemia. An abscess appears as a focal, complex fluid collection with no internal vascularity but with peripheral hyperemia. Pyocele is characterized by a complex collection of debris and septa. Testicular ischemia occurs when epididymal edema compresses the spermatic cord and restricts blood flow through the testicular vessels [20].

Prostatitis refers to infection or inflammation of the prostate gland. The most common route of infection is the ascending route, which is often associated with urinary tract infections, prostate biopsies, instrumentation, and in some cases, STIs. During digital rectal examination, the prostate gland is typically enlarged and tender. Approximately 10% of patients with acute prostatitis progress to chronic prostatitis, and an additional 10% develop chronic pelvic pain syndrome characterized by chronic pain in the perineum or lower abdominal regions [28]. The prostatic abscess is a rare but serious condition characterized by a collection of pus within the prostate gland. Imaging studies of prostatitis often show diffuse and asymmetric enlargement of the prostate, and contrast-enhanced images may reveal enhancement of the affected lesion and extraprostatic penetration [20] (Fig. 14a). Contrast-enhanced imaging findings of the prostatic abscess may demonstrate well-defined fluid collection with internal septations and peripheral enhancement [20].

Seminal vesiculitis refers to the infection or inflammation of seminal vesicles. Contrast-enhanced imaging often reveals diffuse wall and septal thickening with enhancement (Fig. 14b). During the acute to subacute phase, cystic dilatation of the seminal vesicles with surrounding hypervascularity or complications, such as abscess formation, may be observed. Seminal vesiculitis is commonly associated with spillage from prostatitis [20].