One of the most frequent patient reports encountered by a gynecologist is pelvic pain, either acute (hours duration) or chronic (weeks, months, years duration). Transvaginal sonography (TVS) alone and with color Doppler sonography (CDS) is an effective means to detect the location and source of pelvic pain. Imaging is most helpful when there is a structural, as opposed to functional, cause of pelvic pain such as an ovarian cyst, fibroid, or congested pelvic vasculature.

There are many causes of pelvic pain, some of which can be detected with imaging techniques; in other cases, the cause of pain remains uncertain even after laparoscopy. One of the most common causes of acute and/or recurrent pelvic pain is associated with hemorrhage into functional ovarian cysts or endometriomas. In one study, only 63% of women undergoing laparoscopy for pelvic pain had abnormal findings using direct inspection.¹ Conversely, 18% of women with pain and abnormal pelvic examinations had no abnormalities at laparoscopy. In this correlative study of women with pelvic pain who underwent laparoscopy, ovarian abnormalities accounted for approximately 10%, 27% had pelvic adhesions, 22% had pelvic inflammatory disease, and 3% had unsuspected endometriomas. Thus, functional or dynamic disorders may be the cause of pelvic pain; there is not always correlation between the presence of pelvic pain and an anatomic abnormality of the pelvic organs.

Patients with acute pelvic pain most often present in an emergency department setting. Because several causes of acute pain can be life-threatening (eg, ectopic pregnancy, hemorrhagic cyst), prompt diagnosis is critical. Part of this diagnosis is dependent on accurate imaging assessment. Additionally, TVS and/or transabdominal sonography (TAS) have a pivotal role in distinguishing gynecologic from nongynecologic causes such as appendicitis or distal ureteral obstruction due to a renal calculus.²

Chronic pelvic pain is defined as intermittent or constant pain in the pelvic region of at least 6 months’ duration that does not occur exclusively with menstruation or intercourse and not accounted for by a pregnancy-related condition. It is conceptually important to realize that chronic pelvic pain is a symptom and not a diagnostic entity. This is because it can be the result of gynecologic or nongynecologic conditions, such as fibromyalgia, adhesions, and ischemic and/or inflamed bowel. Globally, patients with chronic pelvic pain present to the primary care health worker as frequently as that of migraine or low back pain.

As is true for acute pelvic pain, TVS has an important role in the assessment of the gynecologic and nongynecologic organs in the pelvis in patients with chronic pelvic pain, but it is best suited to diagnose gynecologic-related disorders. Those disorders associated with acute and/or chronic pelvic pain that are discussed and illustrated in this chapter include:

1. 
   

   adnexal torsion

   
   
2. 
   

   ureteral calculi

   
   
3. 
   

   appendicitis and other bowel-related disorders such as inflammatory bowel disease (IBD)

   
   
4. 
   

   tubo-ovarian abscess (TOA), in the setting of pelvic inflammatory disease

1. 
   

   endometriosis/adenomyosis

   
   
2. 
   

   ovarian remnant syndrome

   
   
3. 
   

   pelvic inflammatory disease

   
   
4. 
   

   pelvic “congestion”

Other disorders that may be associated with pelvic pain, such as ectopic pregnancy, are covered in Chapters 4, 32, and 38.

Adnexal Torsion

Adnexal torsion, either ovarian or tubal in origin, is the rotation of the organ around its support structure, resulting in complete or partial obstruction of blood flow to that organ. Typically, there is an associated enlargement of the tube or ovary, usually a cyst, that causes it to be imbalanced.⁶ Ovarian torsion can occur along the infundibulopelvic ligament and utero-ovarian ligament; the fallopian tube can torse with the ovary, or have an isolated torsion along the mesosalpinx or the tube itself. Usually, adnexal torsion involves both the tube and ovary. Torsion of the tube can be encountered in patients who have had tubal ligation where the fimbriated end of the tube agglutinates and the other end is the ligated tube.⁷ Tubal torsion can also be associated with a tubal cyst.

Adnexal torsion is one of the most common gynecologic emergencies, and patients with adnexal torsion may present several times to the emergency department for urgent evaluation.⁸

Transabdominal and/or transvaginal color Doppler sonography (TA or TV-CDS) has an important role in the evaluation of those women presenting with lower abdominal and pelvic pain. In particular, sonography provides a primary means to assess the possible adnexal torsion. Confident and early diagnosis of this entity, which can result in ovarian rescue and preservation, relies on attention to scan technique, specifically, optimization of scanning parameters such as grayscale or color-write priority settings. If the color or grayscale priority is not optimized, the absence of flow may be the result of technical error. In addition, it is always important to assess the opposite ovary for flow because torsion is usually unilateral and flow is usually detectable by TV-CDS in the unaffected ovary and the larger pelvic side wall vessels such as the internal iliac vein. The importance of recognition of certain flow patterns is also clinically important because these patterns relate to the viability of the ovary once it is torsed and subsequent attempt to detorse the adnexa.

Clinical Features

There are a variety of disorders that result in lower abdominal and pelvic pain. TVS and/or TAS have a pivotal role in distinguishing adnexal causes from nongynecologic causes such as appendicitis or distal ureteral obstruction due to a renal calculus.² Patients with adnexal torsion may present several times to the emergency department for urgent evaluation.³ Their symptoms may be attributed to appendicitis, urinary tract infection, IBD, endometriosis, or functional ovulatory pain. It is not uncommon for patients who have the final diagnosis of adnexal torsion to initially be treated for urinary tract infection or other nonrelated disorders. The pain associated with adnexal torsion is usually intense and localized to either adnexal region. It may be come and go; this can be attributed to intermittent episodes of incomplete torsion. Expeditious and confident identification of adnexal torsion by CDS can result in salvage of the ovaries and affected fallopian tubes (Figure 37-1).

The pathophysiology of adnexal torsion differs according to its cause. In some cases, there is massive edema of the ovary, probably related vasodilatation with leakage of blood into the ovarian interstitium combined with hindered venous outflow.⁴ In these patients, the massively edematous ovary appears as a spongiform ovarian mass with small (2-3 mm), peripherally located immature follicles.⁵ In some cases, thrombus within the ovarian vein may contribute to venous engorgement of the ovary, further precipitating torsion. Under microscopic inspection, our group has documented the presence of thrombi within the smaller intraovarian veins in some cases of torsion.⁵ In other cases, torsion is associated with a mass or hemorrhage within the ovary.⁶ Some cases of torsion can be attributed to relatively lax ligamentous support of the ovary, particularly in children. Tubal torsion should be suspected in women who have undergone tubal ligation. The ligated tubal segment may become filled with fluid and be predisposed to torsion. Ovarian stimulation for ovulation induction may be associated with enlarged ovaries that contain numerous follicles. These enlarged and engorged ovaries are at risk for torsion, and quick recognition of torsion may lead to fertility preservation. Adnexal torsion may also be encountered in pregnant patients possibly related to corpus luteum cysts that may persist during pregnancy. Thus, it is emphasized that adnexal torsion is typically associated with:

1. 
   

   massive edema and/or hemorrhage within the ovary

   
   
2. 
   

   multiple follicles or corpora lutea associated with ovulation induction or pregnancy

   
   
3. 
   

   adnexal masses such as ovarian or paraovarian tumors

Accordingly, torsion is typically seen in either younger patients who are more susceptible to cyst formation related to intraovarian hemorrhage or conditions that increase the “weight” of the affected ovary or older women elated to the presence of ovarian or adnexal masses (Figure 37-2). A third group of patients in which torsion is seen is in women undergoing ovulation induction associated with ovarian hyperstimulation.

Usually, adnexal torsion involves both the tube and ovary. Torsion of the tube only can be encountered in patients who have had tubal ligation where the fimbriated end of the tube agglutinates and the other end is the ligated tube.⁷

Sonographic Findings

The pathophysiology of adnexal torsion differs according to its cause. In some cases, there is massive edema of the ovary, probably related vasodilatation with leakage of blood into the ovarian interstitium combined with hindered venous outflow.⁴ In these patients, the massively edematous ovary appears as a spongiform ovarian mass with small (2-3 mm), peripherally located immature follicles.⁵ In some cases, thrombus within the ovarian vein may contribute to venous engorgement of the ovary, further precipitating torsion. Under microscopic inspection, our group has documented the presence of thrombi within the smaller intraovarian veins in some cases of torsion.⁵

Before discussing the CDS findings in ovarian torsion, one should be aware of the spectrum of CDS findings in normal ovaries. The arterial flow to and within the ovary is dependent on the presence of maturing follicles and functioning corpora lutea. Doppler signals arising from the larger feeding vessels (adnexal branch of uterine arteries and main ovarian artery) should be apparent throughout the cycle and in most postmenopausal women. Intraovarian arteries and arterioles can be seen around corpus luteum due to the extensive vascularity in their wall. Venous signals are also seen within the ovary in most patients.

The ovarian blood supply may differ in its predominate flow from either ovarian or uterine circulations. From the larger feeding vessels, usually five to six branches or two large branches with multiple twigs penetrate the capsule to supply the ovarian parenchyma. The intraovarian branches are coiled in areas devoid of significant follicular development but are circumferential in areas of maturing follicles. A vascular “wreath” is seen around functioning corpora lutea.

It has been our observation that torsion associated with venous obstruction results in an enlarged but morphologically recognizable ovary.³ The sonographic findings most likely correlate with the presence or absence of intraovarian hemorrhage and chronicity and completeness of the torsion (Figures 37-2, 37-3, 37-4, 37-5, 37-6, 37-7). It is possible that, because the ovary has a dual arterial blood supply, torsion in one arterial system may be compensated by increased flow from blood in the other arterial system. Chronic or intermittent torsion may be associated with the establishment of collateral arterial and venous flow. As in testicular torsion, repeated episodes may even be associated with a reactive hyperemia.

Torsion is rarely encountered in normal-sized ovaries.⁹ Ovarian and adnexal torsion often produces ovarian enlargement. This may be either diffuse or focal enlargement, related to areas of hemorrhage or the presence of an intraovarian mass.^10-13 When central edema is present, the ovaries may be enlarged with central increased echogenicity. Multiple immature follicles may be present along the periphery of the ovary, the result of central ovarian edema.³ Hemorrhage within the ovary usually produces hypoechoic areas that are either homogeneous or contain delicate linear and punctate echogenicities arising from fibrin strands. Rarely, intraovarian hemorrhage produces irregular echogenic areas within the ovary. The echogenicity of the hemorrhagic area probably depends on the presence and extent of organized clot or interstitial bleed.