Testicular Torsion

The testis and epididymis attach to the inner scrotal wall by a broad attachment. When this attachment is too narrow, it may function as a pedicle around which the testis may twist. This twisting, or torsion, compromises the blood supply to the testis, which may lead to infarction of the testis. Acute scrotal pain is often the presenting complaint in males with testicular torsion, a condition that requires emergent treatment to maintain viability of the affected testis. Testicular salvage rates are greatest when surgery is performed within 6 hours of the onset of symptoms. After 24 hours the testis is usually no longer salvageable. Patients with the “bell clapper” deformity, where the tunica vaginalis joins high on the spermatic cord, are more prone to testicular torsion than the general population.

Sonography is the preferred imaging examination for the diagnosis of testicular torsion because of its high sensitivity and specificity. Gray-scale ultrasound findings are often completely normal when torsion is present, and the testes may appear symmetric with respect to both size and echogenicity. A small hydrocele may be present on the affected side. Within a few hours of the onset of symptoms, the scrotal wall will appear thickened, and the testis and epididymis will appear enlarged and hypoechoic secondary to inflammation and/or hemorrhage. Color Doppler is crucial for the diagnosis of torsion. The lack of demonstrable blood flow to the affected testis, assuming appropriate ultrasound settings are used, is virtually pathognomonic for torsion (Fig. 10-1). In prepubertal patients it is often difficult to demonstrate the presence of blood flow even in normal testes. Two potential false negative scenarios need to be considered when evaluating for torsion. First, a torsed testis may untwist spontaneously with resultant hyperemia on color Doppler, thus mistaking testicular torsion for epididymo-orchitis; and second, incomplete torsion may result in venous occlusion without arterial occlusion, which may result in arterial flow being detected in the testis despite torsion being present.

Figure 10-1 Sonographic image of a 19-year-old patient with testicular torsion. No flow is identified in the left testis.

Testicular scintigraphy is often used as an adjunct to ultrasound when a diagnosis of torsion cannot be made with certainty. Given the added delay of scintigraphic examinations, however, some surgeons operate on the basis of an equivocal ultrasound. The treatment for testicular torsion is de-torsion of the affected testicle, and orchiopexy, where the testis is affixed to the scrotal wall to prevent torsion from recurring in the future.

Torsion of the Testicular Appendages

While there are four testicular appendages, only two are commonly visible at ultrasound: the appendix testis and appendix epididymis. These appendages are remnants of embryonic ducts and serve no real function. Because they are attached by a small pedicle, they are prone to torsion. Torsion of these appendages is one of the most common causes of acute scrotal pain in children. The appendix testis is more commonly affected than the appendix epididymis, although it is often difficult to identify the offending appendage. Patients are usually young, prepubertal males who complain of acute onset scrotal pain. On clinical examination there may be a bluish discoloration of the skin at the site of pain, which is called the “blue dot” sign and is pathognomonic. At ultrasound the torsed appendix is often identified as a round, extratesticular, extra-epididymal mass lacking color Doppler flow (Fig. 10-2). A reactive hydrocele may be present, as well as scrotal wall skin thickening.

Figure 10-2 Sonographic image of the testis of a 9-year-old patient showing torsion of the testicular appendix. The arrows show an enlarged swollen appendix testis.

Epididymitis and Orchitis

Epididymitis or epididymo-orchitis is an infection of the epididymis and/or testis and is a common cause of acute onset scrotal pain. Typically, scrotal pain associated with epididymitis or epididymo-orchitis is relieved when the testes are elevated over the symphysis pubis, a maneuver called the Prehn sign. In contradistinction, the pain associated with testicular torsion is not relieved by this maneuver. While the causative agent in epididymitis is usually not identified in young children, the infection usually originates in the prostate gland or bladder and spreads to the epididymis and testis via the vas deferens and spermatic cord lymphatics. A congenital anomaly of the urinary tract may be present. In adolescents the cause is most often a sexually transmitted infection.

Ultrasound examination of a patient with epididymitis demonstrates enlargement of the epididymis, primarily the head, with heterogeneous echotexture. On color Doppler evaluation there is increased blood flow to the epididymis and/or testis (Fig. 10-3). A reactive hydrocele may be an associated finding. When the entire testis is involved, it is often enlarged and has altered echogenicity. On gray-scale imaging findings alone, the appearance of the testis may mimic a diffusely infiltrative disease such as leukemia or lymphoma, although the clinical presentation should suggest the correct diagnosis. Untreated epididymo-orchitis may progress to scrotal abscess formation or may result in testicular infarction, which may lead to testicular atrophy. In patients with epididymo-orchitis, a follow-up sonogram performed 4 to 6 weeks following the initial event is advised in all cases to ensure complete resolution of the imaging findings following appropriate interval therapy. This is important in order to exclude an underlying tumor as the cause for the patient’s symptoms. It is uncommon for a testicular tumor to present with acute scrotal pain; the accepted figure is less than 10% of tumors. It may occur and is usually due to acute hemorrhage or infarction of the testis that contains the tumor. Orchitis secondary to infection with mumps occurs in approximately 25% of patients that contract the disease. The sonographic findings include an enlarged hypoechoic testis, a small hydrocele, and sometimes thickening of the scrotal wall. Infertility may occasionally result following mumps orchitis. Severe scrotal infection may result in the rare condition called Fournier gangrene. This is a fulminant infectious process involving the scrotal wall and skin of the perineum that is in essence a fasciitis. The severe infection may result in gas formation along the fascial planes of the scrotal wall. Sonographic findings include the findings of epididymo-orchitis along with small echogenic ill-defined foci within the scrotal wall. These foci represent gas, and this finding requires urgent communication to the referring physician as surgical débridement may be required. In questionable cases, CT may be performed, which will clearly show the presence of any gas as hypoattenuating foci within the scrotal wall (Fig. 10-4).

Figure 10-3 Sonographic image of a 32-year-old patient with acute epididymitis of the contralateral epididymis. The epididymis is swollen and shows increased vascularity with color Doppler.

Figure 10-4 CT image of a 65-year-old male patient with Fournier gangrene. The image shows gas within the scrotum with a hydrocele and extensive subcutaneous edema.

Inguinal Scrotal Hernia

An uncommon cause of acute scrotal pain is incarceration of an inguinal hernia that extends into the scrotum. Indirect inguinal hernias are not uncommon; however, extension into the scrotal sac is rare. The clinical findings are usually obvious with a large swelling in the scrotum, although the mass may not be easily reduced. Sonographically, the appearance may be nonspecific with a heterogeneous mass identified in the scrotum. It is usually easy to identify the mass as separate from the testis, although following the mass along the inguinal canal may not be easy. The presence of bowel may be detected if the two walls and lumen are clearly visible; however, it is not always clear that the mass represents bowel, and often the mass may merely be omental fat that has herniated into the scrotum. The presence of peristalsis may confirm the diagnosis. In cases where doubt exists, a CT scan could be performed, and this would show the hernia and its contents extending into the scrotum. Signs of incarceration on sonography include the absence of color flow on color Doppler evaluation. Although this may be easy to elicit in identifiable bowel wall, if the hernia consists of omental fat alone, it may be an unreliable sign. On CT, signs of incarceration include edema of the adjacent fat around the hernia, and possibly decreased enhancement of the bowel wall of any bowel loops that may be present in the hernia.

Testicular Trauma

Trauma to the testis may be either penetrating or blunt. Penetrating trauma to the testis, like many other locations, usually requires immediate surgical exploration. Blunt trauma to the testis in a hemodynamically stable patient should be evaluated with sonography. The key diagnosis to make following testicular trauma is the presence or absence of testicular rupture. A ruptured testicle requires immediate surgical repair, and early diagnosis is required to maximize the chances of testicular salvage. A ruptured testicle that is operated on within 72 hours of the trauma has a salvage rate approaching 80%, but this drops to 30% with subsequent delay. The sonographic findings suggesting testicular rupture include loss of clarity of the margins of the testis and abnormal morphology of the testis; on occasion, testicular parenchyma may be identified protruding beyond the testicular capsule. Sonographic findings seen following trauma to the testes that does not result in testicular rupture include altered echogenicity with loss of the normal homogeneity and alternating foci of either increased or decreased echogenicity. Depending on the degree of trauma, the heterogeneity may be focal or more generalized. A focal area of heterogeneity may be mistaken for epididymo-orchitis or even tumor, so an accurate history of testicular trauma is required to help differentiate from these conditions. Despite an accurate history, when focal heterogeneity is seen resulting from trauma, a follow-up scan is advised in 4 to 6 weeks to ensure complete resolution. As with many testicular conditions, a secondary hydrocele is commonly seen following trauma to the scrotum. This appears as a hypoechoic fluid collection within the scrotum. There may be an associated scrotal hematoma, which may also appear as a hypoechoic fluid collection when hyperacute. As this resolves, more complex elements may develop within the scrotum, and the presence of complex fluid in the scrotum following trauma represents resolving hematoma. The long-term sequelae of testicular trauma include complete or incomplete infarction with a resultant smaller testicle, chronic fibrosis, and even calcification.

Cryptorchidism

The arrest in the descent of the testis along its normal path is one of the most common disorders of the genitourinary tract. It occurs in up to 3% of term infants, although the majority of these will descend naturally over the first few months of life. Nearly four out of five maldescended testes in adults are located at or below the level of the inguinal canal. Although maldescended testes are associated with a host of congenital syndromes, this is not always the case and the condition may occur in isolation. The most damaging consequence of maldescended testes is infertility; infertility rates in unilateral maldescent are reported to be close to 20%, but this rises to 75% in cases where the maldescent is bilateral. There is a high rate of germ cell tumors in maldescended testes, and this risk extends to the contralateral descended testis as well. Maldescended testes are also at increased risk of both torsion and trauma and hence should be considered in any patient presenting with pelvic or scrotal pain in which both testes are not clearly palpable. Since the majority of maldescended testes are found in the inguinal canal, the testis may usually be identified by sonography. Maldescended testes appear as small, usually hypoechoic, rounded or oval structures along the line of the inguinal canal (Fig. 10-5). Care should be taken not to confuse the small testis with a lymph node. Any focal areas of heterogeneity within the testis could represent malignant degeneration. The sensitivity of sonography for detecting maldescended testis varies between 75% and 97% and depends on whether the testis is palpable or not. Once the maldescended testis lies higher than the inguinal canal, it becomes difficult for sonography to locate it. Other imaging modalities that may be used to locate the testis include CT and MR. With multidetector CT, the small soft tissue mass of the maldescended testis is usually identifiable, a situation that was not always the case in the era of large slice thickness CT. T2-weighted MR imaging may be useful to locate the high signal testis, which may be best identified using coronal plane imaging along the plane of the gonadal vessels.

Figure 10-5 CT image of a 22-year-old patient with bilateral maldescended testes. These are seen as bilateral oval soft tissue masses in the inguinal canals.

Prostatitis

Acute prostatitis is, in essence, a clinical diagnosis, and imaging is rarely required to make the diagnosis. It is most commonly caused by recent instrumentation or surgery; however, infection may also spread from the urinary tract. Untreated or inadequately treated prostatitis may lead to prostate abscess formation. Performing transrectal sonography in patients with acute prostatitis may help to make the diagnosis even before imaging, as the passage of the probe may be exquisitely painful. The sonographic appearance of acute prostatitis is primarily of a heterogeneous prostate gland that may show focal areas of hypoechogenicity with demonstrable increased vascularity usually within the peripheral zone. In severe cases, the hypoechogenicity may be more diffuse and the increased vascularity may be seen throughout the gland. Chronic prostatitis usually appears as bands of increased echogenicity representing areas of fibrosis. There is usually little evidence of increased vascularity. Prostatic abscess appears as a well-defined walled collection that contains hypoechoic fluid (Fig. 10-6). The fluid is usually somewhat complex with foci of increased echogenicity within it as well. Gas present in the abscess is seen as irregular foci of increased echogenicity with so-called “dirty” shadowing behind it.

Figure 10-6 A, Transrectal sonographic image of a 68-year-old patient with a prostatic abscess. This is seen as an irregular hypoechoic collection. B, Transrectal sonographic image of the prostate following transrectal drainage of the abscess. The echogenic needle may be seen.

Hemorrhagic Ovarian Cyst

Although hemorrhagic ovarian cysts are common, their imaging appearance is widely variable. Hemorrhagic cysts develop at the time of ovulation when vessels surrounding a corpus luteal cyst rupture, giving rise to hemorrhage within the corpus luteum. As the cyst evolves over time, the sonographic features change with the stage of clot retraction. Patients may present with acute onset adnexal pain, which can be severe.

Physiologic ovarian follicles measure less than 3.0 cm in diameter. Most hemorrhagic cysts measure 3.0 to 3.5 cm in diameter, have a thin outer wall, and demonstrate posterior acoustic through-transmission. Fine, reticular septations resembling a fishnet pattern are a common finding at ultrasound. These septations represent fibrin strands, which contain no blood flow. In some patients the hemorrhagic cyst contains retracting clot. While a large portion of the cyst appears anechoic, the retracting clot appears as an adherent, echogenic structure within the cyst that contains no blood flow. In rare cases, when the clot becomes very small it can simulate a mural nodule and raise concern for ovarian neoplasm. Fluid–fluid or fluid–debris levels can also be demonstrated within a hemorrhagic cyst. Hemorrhagic cysts can be complicated by rupture, with free spill of hemorrhagic contents into the pelvis. When this occurs, echogenic fluid will be demonstrated within the pelvis surrounding the uterus and adnexa. In some cases, the hemoperitoneum may be massive. Although the sonographic features are well described, given that many patients with a ruptured hemorrhagic cyst present with pelvic pain, in the emergency room setting this is often interpreted as abdominal pain, and CT imaging may be the first modality used. We are seeing CT imaging of ovarian cysts, hemorrhagic cysts (Fig. 10-7), and ruptured cysts (Fig. 10-8) with increasing frequency. The normal ovaries may be difficult to identify on CT imaging, and identification often depends on hormonal status. When the ovaries are larger, as in younger women of childbearing age, they are more likely to be identified. Similarly, in patients with little pelvic fat, the ovaries may be difficult to distinguish from loops of unopacified bowel in the pelvis. Often the position of the ovaries is assumed and the usual location is either side of the uterus along the margin of the round ligament. In young patients with malignancy that requires pelvic radiation therapy, the ovaries are frequently surgically sutured to the superolateral aspect of the pelvic wall. This is done to move the ovaries out of the path of the treating radiotherapy beam. In these cases, the ovaries appear as solid masses with cystic components located superiorly and laterally to their usual position. These masses should not be mistaken for pathology, particularly tumor, and knowledge of the prior pexy procedure is useful to avoid confusion. The findings of a simple ovarian cyst are similar to those of a cyst elsewhere, namely, a well-defined round or oval mass in the location of the ovary with an imperceptible wall and containing simple fluid with Hounsfield unit (HU) values of 10 or less. A hemorrhagic cyst might be identified as a mass similar to a simple cyst, but there may be an irregular enhancing ring seen within the cyst, which represents the enhancing involuting wall of the cyst. The CT findings of a ruptured cyst are more variable. Often the cyst itself can no longer be identified because the contents have spilled into the peritoneal cavity. What may be seen is free fluid in the cul-de-sac or even in the location of one of the adnexa. This fluid is frequently of slightly higher attenuation than simple fluid and may have an HU value of 60 to 80. This represents the blood from the ruptured cyst. Active extravasation may occasionally be seen as a line of high density representing administered intravenous contrast being lost into the peritoneal cavity.

Figure 10-7 CT image of a 32-year-old patient with a hemorrhagic ovarian cyst. The linear high-attenuation foci in the right adnexa represents the blood.

Figure 10-8 CT image of a 27-year-old patient with a ruptured hemorrhagic cyst. The active bleeding into the peritoneum is seen as an irregular focus of high attenuation in the left adnexa.

Ovarian Torsion

Acute onset of adnexal pain in a female is concerning for ovarian torsion. The Fallopian tubes are relatively long in children and the ovaries are hypermobile, which increases their susceptibility to torsion. Although normal ovaries may torse, most often there is an ovarian or paraovarian cyst or mass that predisposes the ovary to torsion by functioning as a fulcrum around which the ovary can twist. The ovary becomes twisted around its pedicle, leading to various degrees of hemorrhagic infarction. If surgery is not performed expeditiously, future fertility and hormonal regulation may be compromised. There is a slight predilection for torsion to involve the right ovary. When the right ovary is affected, the diagnosis is more difficult to establish given the number of other conditions that present with right lower quadrant or pelvic pain such as appendicitis, Meckel’s diverticulitis, and inflammatory bowel disease. The median age of patients with ovarian torsion is 11 years old.

Pelvic ultrasound is the study of choice for evaluation of ovarian torsion. Normal ovaries often appear hypoechoic relative to the adjacent pelvic tissue and have an ovoid or ellipsoid shape. Microcystic follicles are routinely identified in normal ovaries. When the ovaries demonstrate normal gray-scale imaging characteristics and have a normal size and shape, color Doppler evaluation is usually not necessary. If, however, one ovary appears abnormally large relative to the other side, torsion may be present. In nearly all cases of ovarian torsion, the affected ovary is massively enlarged and has a round or globular configuration. In neonates and young girls ovarian torsion is commonly seen as a large cystic mass with fluid–debris levels. In young or adolescent girls the more classic imaging appearance is an enlarged, echogenic ovary with multiple enlarged peripheral follicles. In other cases, the ovary may appear as a complex cystic mass secondary to the presence of an underlying cyst or tumor (Fig. 10-9). Color Doppler evaluation of the ovary often reveals an absence of blood flow, a finding classically associated with ovarian torsion. However, torsion may be present even if arterial waveforms are demonstrated because the ovary has a dual blood supply (from both the uterine and ovarian arteries). The presence of arterial waveforms within the ovary should not sway the diagnosis away from ovarian torsion if the gray-scale imaging findings and physical examination are consistent with torsion.

Figure 10-9 Sonographic image of a 48-year-old patient with a cystic ovarian mass that underwent torsion. The solid mural nodule is identified by the white arrow.

Endometriosis

Endometriosis is a condition defined as the presence of endometrial tissue outside of the uterus. The condition may be localized or widespread. Widespread endometriosis may result in extensive endometrial implants throughout the abdomen and pelvis and the diagnosis may be extremely difficult to make. Sonography is of limited value in making this diagnosis, and CT and MR too have both poor sensitivity and poor specificity for making the diagnosis. All three imaging modalities, however, are useful in identifying localized disease. The most frequently encountered presentation of endometriosis is a single or multiple small adnexal masses called endometriomas. These have been referred to as “chocolate cysts” in the past. Patients may present with acute pelvic pain. Sonography is the normal first-line imaging modality, and the sonographic findings are usually diagnostic. On sonography, an endometrioma appears as a complex cystic mass in the adnexa that lies outside of the ovary. The mass is well defined and contains homogeneous low-level echoes throughout the mass. Endometriomas range in size from 1 cm to more than 15 cm, although the vast majority lie in the 3 to 6 cm range. Rarely, a thin septation may be identified within the endometrioma. The sonographic features are classic, although the potential differential diagnosis includes a hemorrhagic cyst and, rarely, an ovarian neoplasm in cases in which the classic features are not easily identified. On CT imaging, an endometrioma appears as a well-defined cystic mass that has a uniform HU value greater than that of a simple cyst, usually lying in the range of 30 to 60 HU. On MR imaging, endometriomas show high signal on T1-weighted imaging with classic “shading” appearance on T2-weighted imaging. The “shading” appearance is a progressive change from high signal at one side of the mass to low signal on the opposite side with varying levels of intermediate signal between them. This pattern of signal intensity is caused by the high level of iron within the endometrioma. Both CT and MR may show evidence of the complications of long-standing endometriosis, which include obstruction to either the ureter or bowel. Endometriosis should be considered in unusual cases of ureteric or bowel obstruction of unknown etiology in females of childbearing age presenting through the emergency room.

Disorders of the Fallopian Tubes

Disorders of the Fallopian tubes include hydrosalpinx, pyosalpinx, and tubo-ovarian abscess. Hydrosalpinx is seldom an acute condition and is most frequently an incidental finding. It results from occlusion of the Fallopian tube and is often bilateral. The most common etiology, infection, often follows instrumentation. The obstruction leads to dilatation of the Fallopian tube, which becomes filled with serous fluid. Although hydrosalpinx can present with acute pelvic pain, the condition may remain asymptomatic; however, long-term consequences include infertility. Sonographic findings are usually characteristic, and a dilated tubular cystic structure with anechoic fluid within is usually found. When a hydrosalpinx becomes secondarily infected the condition is known as pyosalpinx. This presents as acute pelvic pain with the signs and symptoms of acute infection including elevated fever and white cell count. The fluid within the Fallopian tube will no longer be anechoic on sonography, indicating the presence of pus within the tube (Fig. 10-10). Aggressive antibiotic therapy is indicated, but when the tube is extremely distended, percutaneous or transvaginal drainage may be required. A condition that overlaps pyosalpinx and one that occurs more frequently is tubo-ovarian abscess formation. This in essence has a similar etiology to pyosalpinx in that the most common cause is a sexually transmitted disease. The infection travels along the Fallopian tube and results in an abscess forming in the adnexa. The clinical presentation usually leads to the diagnosis being suspected. Sonography is again the imaging modality of choice. A complex mass may be identified in the adnexa, and the mass may be shown to lie outside of the ovary. On transvaginal sonography, gentle pressure placed directly over this mass will be exquisitely painful. This may help to confirm the diagnosis, as other causes of complex adnexal masses tend not to cause such discomfort. As with other pelvic pathologies, the presentation may be interpreted as abdominal pain, rather than pelvic pain, and CT may be the first-line imaging modality used. In this case, a tubo-ovarian abscess may be seen as a pelvic abscess with thick walls and may contain fluid and/or solid components (Fig. 10-11). The presence of a dilated tubular structure on the ipsilateral side representing a hydro- or pyosalpinx may help to distinguish this abscess as a TOA rather than an appendiceal or diverticular abscess.

Figure 10-10 Sonographic image of a 38-year-old patient with pyosalpynx. The tubular nature of the hypoechoic lesion may be appreciated. The hypoechoic fluid contains multiple low-level echoes indicating that this is not a hydrosalpynx.

Figure 10-11 A, CT image of a 27-year-old patient with a pyosalpynx. The tubular nature of the lesion in the right adnexa may be appreciated. B, Another CT image of the same patient. There are some inflammatory changes in the fat adjacent to the Fallopian tube. This pyosalpynx has progressed to form a tubo-ovarian abscess.

Endometritis

Endometritis is defined as inflammation of the endometrium and may be acute or chronic. Endometritis may extend to involve the myometrium or even the parametrium. The most common cause is infection. Most causative agents are Staphylococcus or Streptococcus, and it usually occurs following instrumentation such as delivery or abortion. The clinical presentation is typically with fever and purulent vaginal discharge and may be associated with vague lower abdominal pain. Chronic endometritis is usually the result of Chlamydia, tuberculosis, or chronic pelvic inflammatory disease, and this usually presents as a bloody discharge. The presence of pus within the endometrial canal is called pyometra.

From an imaging perspective, given that lower abdominal pain or pelvic pain is a frequent cause for presenting to the emergency room, sonography is usually the imaging modality first used. The sonographic appearance of acute endometritis may be normal in the early stages. The endometrium may also appear as thickened and heterogeneous, and hypoechoic fluid may be identified in the endometrial canal. Gas is occasionally present and can be identified on sonography as hyperechoic foci with “dirty” posterior shadowing. Given that endometritis is frequently seen in the presence of retained products of conception, signs of this may also be present. These include the presence of a hematoma seen as a heterogeneous intrauterine mass with debris and fluid. Increased vascularity may occasionally be seen with endometritis, although this is an inconsistent finding.

CT may also be the first-line imaging modality used depending on what symptoms the patient presents with. If the gynecologic symptoms of discharge and pelvic pain predominate, sonography will likely be initially requested. If the pain predominates as a symptom and there is a suggestion of abdominal pain rather than pelvic pain, then CT may be requested first. The findings of endometritis on CT are somewhat nonspecific. These include the presence of fluid within the endometrial canal. The canal may be widened due to the presence of fluid, hematoma, and debris. This might be less easy to appreciate on conventional axial imaging but easier when reviewing the images in the sagittal plane. Gas is also identified on occasion, seen on the CT as tiny black bubbles within the endometrial canal. When endometritis is diagnosed on imaging, care should be taken to exclude further foci of inflammation or infection such as salpingitis or oophritis, as these are common associations of endometritis.

Ectopic Pregnancy

Ectopic pregnancy is a common condition that may result in death if not adequately diagnosed and treated; as such, missing the diagnosis is a far greater sin than making a false positive diagnosis. Ectopic pregnancy is responsible for up to 15% of maternal deaths. By definition, any female patient with a positive pregnancy test and an empty uterus should be regarded as having an ectopic pregnancy until otherwise proven. It is not always possible to identify the ectopic pregnancy directly, and not identifying this should never be taken as evidence that the patient does not have an ectopic pregnancy. Ectopic pregnancy usually presents with pelvic pain and may well be associated with bleeding. On imaging, the best way to determine that an ectopic pregnancy is not present is to identify an appropriately positioned gestational sac. In cases with ectopic pregnancy, the sloughing of the decidua may result in the appearance of a pseudogestational sac. This can be differentiated from a gestational sac as a fluid collection within the endometrial canal surrounded by a single decidual layer, unlike the gestational sac, which appears as a fluid collection within the decidua that abuts the endometrium or as concentric rings, the so-called “double decidual” sign. The most specific sonographic sign confirming ectopic pregnancy is the identification of a live embryo that lies outside the uterus, usually in the adnexa (Fig. 10-12). This sign is positively identified in only approximately 20% to 25% of cases of ectopic pregnancy and therefore cannot be relied on to make the diagnosis. A nonspecific complex adnexal mass in a patient with a positive pregnancy test is strong evidence to support the presence of an ectopic pregnancy. Complex free fluid in the pelvis is also a good indicator in the correct clinical setting (Fig. 10-13). The presence of an adnexal mass in association with complex free fluid has a sensitivity of close to 40% but a specificity of 99% for the detection of an ectopic pregnancy. It is important to remember that up to one third of patients with an ectopic pregnancy may have a completely normal sonogram. Hence the importance of the mantra “positive pregnancy test with an empty uterus equals ectopic pregnancy until proven otherwise.”

Figure 10-12 Sonographic image of a 23-year-old patient with a ruptured ectopic pregnancy. The free fluid containing echogenic debris representing blood is seen in the cul-de-sac (arrows).

Figure 10-13 A, Sonographic image of a 27-year-old patient showing an ectopic pregnancy located in the left adnexa. The classic “ring of fire” is well shown. B, Further image of the same patient shows an ectopic pregnancy with a clearly identifiable yolk sac. C, Another image from the same patient showing a documented fetal heartbeat with the ectopic pregnancy.

Another condition that may present with pelvic pain associated with bleeding is early pregnancy failure. This may be characterized by a positive pregnancy test with no demonstrable intrauterine pregnancy and hence may have an appearance similar to ectopic pregnancy. There will usually be fluid within the endometrial canal with perhaps a gestational sac present. The gestational sac will be abnormal and may be enlarged, with no evidence of a developing fetus within it. In cases in which it is not easy to distinguish between early loss of pregnancy and ectopic pregnancy, the key is to monitor the level of HCG. This will continue to rise in patients with an ectopic pregnancy but will start to fall if the pregnancy fails.

Postpartum Bleeding

Patients with postpartum bleeding often first present to the emergency room. The most common cause of postpartum bleeding is retained products of conception (RPOC). It is important to differentiate RPOC from the presence of a simple hematoma within the endometrial canal. Both conditions have similar sonographic appearances, characterized by the presence of a heterogeneous, predominantly echogenic mass located within the endometrial cavity. The most specific sonographic sign that may distinguish these two entities is the presence of vascularity in the RPOC with demonstrable blood flow when using color Doppler. Simple hematoma will not have any blood flow within it. It may not be possible to separate these entities using CT imaging alone, as the hematoma will be of high attenuation in the acute setting just as RPOC will appear as a high-density focus within the uterus. CT is unlikely to be sensitive enough to detect the attenuation difference with the small degree of vascular enhancement that is present with RPOC. It is important to attempt to differentiate these entities when the patient presents to the emergency room, as the management is considerably different. The presence of a hematoma within the endometrial cavity may often be treated conservatively and will frequently resolve spontaneously. RPOC, on the other hand, usually requires evacuation of the endometrial cavity to arrest the bleeding and permit normal uterine contraction.

Ovarian Vein Thrombosis

Ovarian vein thrombosis is a relatively uncommon condition being diagnosed in up to 0.2% of deliveries. It is unilateral in approximately 85% of cases with a right to left predominance of 12:1. It may also result from pelvic inflammatory disease, malignancy, or pelvic surgery. There is morbidity associated not only with the thrombosis but also with any superimposed infection resulting in septic thrombophlebitis. The thrombus may propagate to involve the inferior vena cava or renal veins and may result in pulmonary embolus. The clinical presentation is of pelvic pain and fever. The imaging modalities that may be used to make the diagnosis are sonography, CT, and MRI. The modality that is first used very much depends on how the patient presents and the degree of suspicion for the diagnosis. Ovarian vein thrombosis is often unsuspected at the time of diagnosis, so the onus is very much on the radiologist to suspect and make the diagnosis, particularly when imaging a postpartum patient with either fever or pain.

The diagnosis of ovarian vein thrombosis by sonography is often limited by the presence of overlying bowel gas. The characteristic finding is that of a tubular hypoechoic structure extending from the adnexa cranially. No blood flow may be identified within this structure when interrogated with color Doppler. There may be associated enlargement of the ovary on the affected side, although frequently it is difficult to be certain of this. It may be difficult to definitively discern ovarian vein thrombosis from hydronephrosis or thrombosis of the inferior mesenteric vein. CT is the most likely imaging modality to be used in the emergency room, particularly if the patient presents with fever and abdominal pain. Appendicitis is frequently the suspected diagnosis. The CT findings that make the diagnosis are the identification of an enlarged ovarian vein that contains either occlusive or nonocclusive thrombus (Fig. 10-14). This may be identified as a focus of hypoattenuation within the enhancing vein or as an abruptly occluded vessel that is dilated distally. There is usually some nonspecific stranding of the fat adjacent to the vessel resulting from the thrombosis. This may be exuberant if there is superimposed infection resulting in septic thrombophlebitis (Fig. 10-15).

Figure 10-14 A, CT image of a 34-year-old postpartum patient, showing a large mass in the right adnexa representing a dilated ovary secondary to gonadal vein thrombosis. B, CT image shows a dilated thrombosed right gonadal vein (arrow).

Figure 10-15 A and B, CT images of a 29-year-old patient showing a distended right ovarian vein. The vessel has an enhancing wall and contains thrombus. Inflammatory changes are identified around the vessel, better seen in B. This represents septic thrombophlebitis.

Dysfunctional Uterine Bleeding

There are a number of conditions that result in dysfunctional uterine bleeding (DUB). The most common entities include submucosal fibroid, endometrial polyp, endometrial hyperplasia, and endometrial carcinoma. Fibroids are a ubiquitous finding on sonographic imaging of the uterus. A small number of fibroids may be located in the submucosa with greater than 50% of their circumference projecting into the endometrial canal. These submucosal fibroids are usually asymptomatic but may cause pelvic pain or DUB. Defining a fibroid as submucosal on sonography alone is not always easy, and hysterosonography may be required. Similarly, endometrial polyps may be difficult to identify on sonography alone, and hysterosonography may also be required. On sonography, the presence of a polyp is often suspected by the presence of an abnormal-appearing endometrial stripe. The heterogeneous polyp may be indistinguishable from the endometrial stripe, and the appearances may suggest abnormal enlargement of the stripe. Instilling saline into the endometrial canal for the hysterosonogram clearly distinguishes the polyp from the endometrium. Endometrial hyperplasia and more rarely endometrial carcinoma may also present with DUB. Both of these entities will appear as irregular thickening of the endometrial stripe with carcinoma having a more aggressive and extensive appearance. Again, with hysterosonography, these entities are usually clearly distinguished and may certainly be distinguished from submucosal fibroid or polyp.

CONCLUSION

Sonography is the mainstay imaging modality for much pelvic pathology in both male and female patients and is often used to make a definitive diagnosis. In the male, sonography should be used for imaging the testes, scrotum, and prostate. In the female patient, sonography is the preferred imaging modality for gynecologic pathology. Given that many such pathologies present with abdominal pain, however, in today’s climate, CT imaging may be the modality first used. It is becoming increasingly important to be able to recognize the CT findings of many of the conditions traditionally imaged using sonography. MR has a large role to play, particularly in the imaging of gynecologic pathology; however, in the emergency room setting, this is seldom the imaging modality first used. MR is more frequently used as a further tool for more complete evaluation of the patient, either following admission or on an outpatient basis, rather than from the emergency room. The role of MR from the emergency room may well increase over time as more emergency rooms acquire magnets for the exclusive use of the emergency room.