Images in Women's Health

Misleading Urogenital Anomaly

Alberto Farah, MD; Renate Soulen, MD

CASE HISTORY

A 42-year-old woman (gravida 3, para 2-0-1-2) presented with menorrhagia and anemia. She was referred to the hospital to undergo total abdominal hysterectomy for presumed uterine leiomyomata. Her medical history included glaucoma and mitral valve prolapse secondary to rheumatic fever. Her surgical history was significant for laparotomy for ovarian cystectomy. She reported an obstetric history of two full-term, vaginal deliveries without complication and a voluntary termination of pregnancy. There was no record of sexually transmitted infection. The patient’s family and social histories were noncontributory.

Findings from prior transabdominal/transvaginal ultrasonography reportedly demonstrated a distended urinary bladder, with no evidence of uterine abnormality. A pelvic magnetic resonance imaging (MRI) examination was performed to resolve the discrepancy between the clinical and ultrasonographic findings.

DIAGNOSIS

The MRI images demonstrated a well-defined, thin-walled, homogeneous anterior structure with low signal intensity on T1-weighted images (Figure 1) and high signal intensity on T2-weighted images (Figures 2 and 3) consistent with simple fluid. In the axial plane (Figures 1 and 2) it could easily be mistaken for the urinary bladder, but in the sagittal plane (Figure 3) it is clearly separate from and superior to the urinary bladder in the midline. These findings are most consistent with a urachal cyst. A normal uterus can be seen behind the cyst. The two structures together may have led to the clinical impression of an enlarged, myomatous uterus.

Urachal abnormalities result from a failure in obliteration of the ventral cloaca during fetal development of the urinary bladder. The most common abnormalities are a patent urachus, urachal sinuses either blind ending or communicating with the bladder and/or umbilicus, and a noncommunicating urachal cyst (the diagnosis in this case).1 Urachal anomalies usually present in childhood, with a reported 2% incidence in adults.2 There is a 2:1 male to female preponderance.2 Urachal cysts present in a variety of ways, including recurrent urinary tract infections, hematuria, suprapubic tenderness or mass, umbilical discharge, and even peritonitis.1Urachal cyst is more common in childhood, while infected urachal sinuses are seen more frequently in adults.3 In the past, diagnosis was most commonly via ultrasonography. Treatment is by excision.

Figure not available online

FIGURE 1. T1-weighted axial image of the pelvis. Homogeneous low signal mass anterior to the intermediate signal uterus and left ovary is consistent with urinary bladder. Courtesy of Alberto Farah, MD, and Renate Soulen, MD.

Figure not available online

FIGURE 2. T2-weighted axial image at the same level. The "bladder" is now homogeneously bright. The zonal anatomy of the uterus is now clear. Courtesy of Alberto Farah, MD, and Renate Soulen, MD.

Figure not available online

FIGURE 3. T2-weighted sagittal image through the midline shows the normal uterus posteriorly displaced by the mass, which is now seen to be distinct from and superior to the bladder. Both cyst and bladder contain simple fluid and have identical signal characteristics. Courtesy of Alberto Farah, MD, and Renate Soulen, MD.

back to top

DISCUSSION

Like ultrasonography, MRI can be performed without radiation exposure and in multiple planes. Unlike ultrasonography, it can provide images with a large field of view in any plane--unimpeded by bone, air, or depth from the surface. Tissue characterization is superior to both ultrasonography and computed tomography (CT). Pelvic MRI is an important adjunct to pelvic ultrasonography; it has largely replaced pelvic CT, and is the modality of choice for assessing adenomyosis and congenital genitourinary anomalies.

back to top

Alberto Farah, MD, is resident, and Renate Soulen, MD, is emeritus professor. Both are in the Department of Radiology, Wayne State University School of Medicine, Detroit, Mich.

References

1. Perry CW, Phillips BJ. Clinical management of urachal cysts. The Internet Journal of Urology. 2001;1(1).
2. Mesrobian HG, Zacharias A, Balcom AH, Cohen RD. Ten years of experience with isolated urachal anomalies in children. J Urol. 1997;158(3 pt 2):1316-1318.
3. Iuchtman M, Rahav S, Zer M, Mogilner J, Siplovich L. Management of urachal anomalies in children and adults. Urology. 1993;42(4):426-430.

back to top