Contents

1    Introduction\

2    Gynecological Causes of Pelvic Pain\

2.1  Ovarian Cysts: Acute Cyst Events\

2.2  Pelvic Inflammatory\

2.3  Hydropyosalpinx\

2.4  Tubo-ovarian Abscess\

2.5  Ovarian Torsion\

2.6  Ectopic Pregnancy\

3    Nongynecological Causes of Pelvic Pain\

3.1  Pelvic Congestion Syndrome\

3.2  Ovarian Vein Thrombosis\

3.3  Appendicitis\

3.4  Diverticulitis\

3.5  Epiploic Appendagitis\

3.6  Crohn’s Disease\

3.7  Rectus Sheath Hematoma\

References\

A. Davis (*)

Department of Radiology, Epsom and St Helier University Hospitals NHS Trust, London, UK e-mail: adavis@doctors.org.uk

A. Rockall

Department of Radiology, The Royal Marsden Hospital, NHS Foundation Trust, London, UK e-mail: A.rockall@imperial.ac.uk

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practice is identifying the cause of pelvic pain. From a practical point of view, it is useful to classify pelvic pain as acute or chronic because these presentations differ in their differential diagnoses and therefore require different imaging strategies for their evaluation. Pelvic pain that has been present for 6 months or longer is defined as chronic pelvic pain.

The differential diagnosis of lower abdominal and pelvic pain encompasses gynecological, preg- nancy-related, gastrointestinal, urological, neurological, and abdominal wall causes. Furthermore, psychological factors have been attributed to play an important role in women, especially those suffering from chronic pelvic pain.

The single most important laboratory test in assessing pelvic pain in a woman of reproductive

age is a pregnancy test, in order to exclude a diagnosis of ectopic pregnancy. The most frequent gynecological emergencies occur in the premenopausal age group and include ectopic pregnancy, corpus luteum cyst rupture, and pelvic infection. Appendicitis accounts for most nongynecological emergencies.

Sonography is the initial imaging modality of choice in gynecologic disorders causing pelvic pain. However in the emergency setting, with uncertainty related to the underlying cause of acute severe lower abdominal pain, CT of the abdomen and pelvis is often the first imaging performed allowing assessment of the gastrointestinal tract and urologic system. MRI is usually reserved for problem-solving, although it may be used when transvaginal ultrasound is not feasible.

This chapter will review some of the more common diagnoses of acute and chronic pelvic pain that are not covered elsewhere in this book (Table 1). Gynecologic disorders highly associated with chronic pelvic pain such as endometriosis, uterine leiomyomas, and adenomyosis are discussed in different chapters.

2\ Gynecological Causes

of Pelvic Pain

2.1\ Ovarian Cysts: Acute Cyst

Events

A follicular cyst may develop when an ovarian follicle enlarges physiologically during the menstrual cycle but does not rupture for

ovulation­ . These functional simple cysts have no complex features on US, typically range from 3 to 6 cm, and usually resorb within a few menstrual cycles. In the case of a follicle that ovulates, a corpus luteum forms with wall thickening, increased wall vascularity and blood often accumulates in the central cavity. In some cases, these physiological cysts (follicular and corpus luteal) may undergo significant hemorrhage and/or there may be cyst rupture. These events may be sufficiently symptomatic to lead to an emergency presentation. Rupture of non-physiological cysts, including endometriotic cyst or mature cystic teratoma, also typically presents with acute pain.

2.1.1\ Imaging Findings

A hemorrhagic ovarian cyst is usually readily diagnosed on US (Roche et al. 2012). Rupture of an ovarian cyst is also usually confidently diagnosed on US and there is no need for additional imaging on CT or MRI. However, in the acute presentation, CT may be the initial investigation due to diagnostic uncertainty. Ovarian cyst hemorrhage on CT may be seen as mixed attenuation material within an ovarian cyst due to the ­presence of blood (Fig. 1). The differentiation between blood and enhancing soft tissue may not be possible if there is no pre-contrast CT available. MRI is occasionally used in problem-solving. In the case of cyst rupture, there is free fluid in the pelvis; there may be no evidence of the ovarian cyst in cases where the cyst collapses following

rupture­ . If the cyst rupture was related to a hemorrhagic corpus luteum, there may be a visible disrupted corpus luteum in one ovary and the free fluid may be of higher attenuation than simple fluid, due to the presence of blood. Delayed post-contrast CT may demonstrate pooling of iodinated contrast in the pelvis. On

MRI, free fluid in the pelvis may contain signs of visible hemoperitoneum (Fig. 2).

In the case of ruptured mature cystic teratoma, the presence of free globules of fat may be seen in the peritoneum and there are signs of inflammation. The original teratoma is typically seen in the adnexa (Fig. 3).

Fig. 1  CT of ruptured endometriotic cyst (arrow) showing mixed attenuation pelvic fluid consistent with blood. Uterus (star) is displaced to the right by the large complex left adnexal cyst

Fig. 2  Axial fat-saturated T1 MRI in the same patient as Fig. 1 shows a ruptured endometriotic cyst and layering of blood in the pelvis (arrow). Uterus (star) lies to the right of the large blood-filled cyst

Fig. 3  CT of a patient presented with left upper quadrant pain. Image A shows the ruptured teratoma (open arrow); image B shows thickened bowel loops (filled arrow)

secondary to chemical peritonitis. Stranding is seen in the adjacent fat and there is thickening of the left paracolic peritoneum. Courtesy of Prof. Evis Sala, New York