CHRONIC pelvic pain is defined as non-menstrual pain of at least six months’ duration. Most doctors are familiar with patients talking about long-standing ‘belly bottom’ pain and the radiologist is no different. In our practice, this is a common indication for pelvic ultrasound.

The figures for Jamaica are not readily available, but chronic pelvic pain is a common condition occurring in about 15 per cent of women between the ages of 18 and 50 years in the United States of America. It is responsible for 10 to 40 per cent of all outpatient gynaecologic visits.

Thirty-five per cent of diagnostic laparoscopies and 15 per cent of hysterectomies are performed because of chronic pelvic pain. The economic impact of chronic pelvic pain in the USA is thought to be responsible for US$14 billion of lost productivity per year. Interestingly, it is thought that black women and women over the age of 35 have a lower risk of developing this condition.

Many conditions can produce chronic pelvic pain in women. These conditions range from problems in the gastrointestinal tract to gynaecological diseases and urological abnormalities.

Many conditions are easy to diagnose but some go unrecognised or misdiagnosed. Patients are often left feeling frustrated when their imaging findings do not seem to match up with the severity of their symptoms.

The purpose of this article is to describe the imaging findings of endometriosis, adenomyosis, pelvic congestion, and less common congenital and acquired abnormalities, which are often under or misdiagnosed, but account for many cases of chronic pelvic pain.

ENDOMETRIOSIS

Endometriosis is defined as functional endometrial tissue outside the boundaries of the uterine musculature that is implanted on the surface of other organs, and that respond to hormonal stimuli. In other words, bits of the lining of the womb are deposited on other organs and swell up and bleed during the period just like normal endometrial tissue.

This predisposes to pain and scarring. The most frequent sites of endometriotic deposits are the ovary, uterine ligament, pouch of Douglas, pelvic peritoneum, fallopian tube, and uterus. Endometriosis has been found everywhere in the body, however.

Endometriosis occurs in women during the reproductive years (primarily 25-29 years) and is present in seven to 10 per cent of the general population of women.

Endometriosis can be associated with infertility, dysmenorrhea (painful periods), dyspareunia (painful sexual intercourse), and abnormal menstrual bleeding. There are many other symptoms, depending on the location of the deposit. For example dysuria (painful urination) or diarrhoea can result from bladder or intestinal deposits.

Women are often frustrated by the limited imaging findings in endometriosis. Small implants and adhesions are usually not detectable with transvaginal ultrasound. Some small deposits and adhesions are also difficult to detect with MR imaging. Laparoscopy is often performed to diagnose and treat these small lesions.

Transvaginal ultrasound is used for the initial evaluation of endometriosis. Ultrasound is useful for the detection of endometriotic cysts or endometriomas. They appear as cystic masses with low level, internal echoes. They can have thick, vascular septations. When detected, a follow-up ultrasound in six weeks will be useful to differentiate endometriomas from cystic malignancies, because the blood in endometriomas will change over time.

MR imaging is useful in cases where the ultrasound findings are uncertain or in diagnosis of peritoneal implants in other organs. MR imaging-featured diagnostics of endometriomas are a cystic mass with high-signal intensity on T1-weighted images and loss of signal intensity on T2-weighted sequences.

Treatment of endometriosis can be medical or surgical. Medical treatment involves use of anti-inflammatory painkillers as well as oral contraceptive pills, which cause an anovulatory state (stops the menstrual cycle).

Surgical treatment includes laparoscopic ablation (burning) of implants, lysis (breaking up) of adhesions or removal of endometriomas implants. Removing the womb and ovaries is definitive treatment, but obviously this is not acceptable in young women.

ADENOMYOSIS

Adenomyosis is a condition in which glands from the endometrium migrate into the uterine walls. There are two types: diffuse and focal.

The disease is frequently misdiagnosed clinically and radiologically as fibroids. Uterine adenomyosis is a common disease. It most commonly affects women between the ages of 40 and 50 years who have had children. Seventy per cent of women with adenomyosis have symptoms including painful, heavy periods, pelvic tenderness, or infertility. There is also a greater risk of abnormal pregnancy within the uterine walls (intramural ectopic).

Symptoms are rarely seen in nulliparous (never been pregnant) or postmenopausal patients.

The goals of transvaginal ultrasound and MR imaging are as follows:

1. Establish the correct diagnosis for potential treatment;

2. Determine the extent and depth of myometrial penetration;

3. Monitor the evolution of the disease during conservative therapy.

Transvaginal ultrasound reveals a heterogenous, bulky uterus with subendometrial cysts or nodules, or an echogenic vascular mass with ill-defined borders in the case of diffuse or focal disease, respectively.

MR imaging is more sensitive and specific for identifying adenomyosis. Widening of the junctional zone (zone just below the endometrium) between eight and 12mm is suggestive of focal adenomyosis, whereas widening above 12mm is diagnostic of diffuse adenomyosis.

Adenomyomas present as low-signal, ill-defined masses on T2W sequences. Haemorrhage or dilated endometrial glands may produce high signal on T1- and T2-weighted sequences, respectively.

Treatment usually begins with hormones and painkillers. Surgical treatment includes endometrial ablation or lesion excision. Uterine artery embolisation is now an accepted treatment. The only definitive treatment however is hysterectomy.

PELVIC CONGESTION SYNDROME

Patients with pelvic congestion syndrome complain of a deep, dull ache associated with movement, posture and activities that increase intra-abdominal pressure. The pain is long-standing and may affect one or both sides of the pelvis to different degrees

It may be associated with painful sex or painful periods. Rectal discomfort and increased frequency of urination may also result. On physical examination, there may be varicose veins in the vulva, buttocks or legs.

Many factors may cause pelvic congestion syndrome, including compression of the renal or pelvic veins by masses or anatomical abnormalities or conditions such as portal hypertension.

Transvaginal pelvic ultrasound with colour Doppler and Doppler spectral analysis, identifies multiple tubular structures around the uterus and ovary with venous blood flow signal. The ovaries of women with pelvic congestion tend to have cystic components ranging from a few cysts to polycystic ovaries.

MR and CT imaging show pelvic varices as dilated, tortuous, enhanced structures around the uterus and ovary, with possible extension into the broad ligament and pelvic sidewall. They can also involve the paravaginal venous plexus.

Treatment for pelvic congestion syndrome includes medical management of hormonal issues and invasive procedures such as laparoscopic, transperitoneal ligation of ovarian veins and percutaneous coil embolisation of the gonadal vein. Venous stent placement may be used for anatomic abnormalities.

RARE CONDITIONS

High-resolution transvaginal MR imaging is best suited for imaging abnormalities of the female genito-urinary tract. Congenital abnormalities, such as Gartner cysts, periurethral cysts, and urethral diverticula are best imaged by this method.

Imaging of patients with chronic pelvic pain is difficult because of the many pathologies which can cause pain and the absence of imaging findings in many of these pathologies. Nonetheless, use of the appropriate imaging modality as well as knowledge of the imaging features of common pelvic problems can ensure timely, appropriate treatment is started.

Dr Duane Chambers is a consultant radiologist and founding partner of Imaging and Intervention Associates located at shops 58 and 59 Kingston Mall, 8 Ocean Boulevard. He may be contacted through the office numbers 618-4346 or 967-7748.