AJR 2003; 180:1659-1660
© American Roentgen Ray Society
Multidetector CT Appearance of a Novel Contraceptive Device: The Vaginal Ring
Garyun B. Blackmon1 and
Erik K. Paulson
1 Both authors: Department of Radiology, Duke University Medical Center, Box
3808, Durham, NC 27710.
Received October 21, 2002;
accepted after revision November 21, 2002.
Address correspondence to E. K. Paulson.
Introduction
Anovel contraceptive device, the vaginal ring, has recently been approved
for use by the United States Food and Drug Administration
[1]. This device has a
characteristic appearance on CT that we believe has not been described.
Knowledge of this device and its expected CT appearance is important so
radiologists will not mistake it for other gynecologic devices or
diseases.
Case Report
A 28-year-old woman who was referred to our institution had a history of
recurrent pancreatitis after cholecystectomy. After failing to identify the
cause of the recurrent pancreatitis, the referring physician postulated that
the patient's only medication, oral contraceptives, might be a contributing
factor to her recurrent episodes. The oral contraceptives were discontinued
and a contraceptive vaginal ring was prescribed
(Fig. 1).
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Fig. 1. —Photograph of vaginal contraceptive ring shows 54-mm flexible
device that is to be folded on itself and inserted into vagina. Impregnated
sex steroids are absorbed into systemic circulation to prevent ovulation.
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Multidetector CT (MDCT) of the abdomen and pelvis was performed after the
administration of oral and IV contrast material. MDCT images of the abdomen
and pelvis showed no radiographic evidence of pancreatitis or its
complications. However, in the vaginal lumen, two symmetric low-attenuation
bands were identified that formed a ring-shaped configuration over five
contiguous axial images (Figs.
2A,
2B,
2C). A review of the patient's
medical record revealed that this patient had a contraceptive vaginal
ring.
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Fig. 2A. —28-year-old woman with history of chronic pancreatitis.
Sequential CT images of pelvis at level of uterus and vaginal fornix
(A), upper vagina (B), and mid vagina (C) show
low-attenuation circular ring (arrows) in vagina representing
contraceptive ring. Well-defined circular nature of structure indicates it is
implanted device rather than manifestation of disorder.
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Fig. 2B. —28-year-old woman with history of chronic pancreatitis.
Sequential CT images of pelvis at level of uterus and vaginal fornix
(A), upper vagina (B), and mid vagina (C) show
low-attenuation circular ring (arrows) in vagina representing
contraceptive ring. Well-defined circular nature of structure indicates it is
implanted device rather than manifestation of disorder.
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Fig. 2C. —28-year-old woman with history of chronic pancreatitis.
Sequential CT images of pelvis at level of uterus and vaginal fornix
(A), upper vagina (B), and mid vagina (C) show
low-attenuation circular ring (arrows) in vagina representing
contraceptive ring. Well-defined circular nature of structure indicates it is
implanted device rather than manifestation of disorder.
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Discussion
In October 2001, the United States Food and Drug Administration approved
the first hormonal contraceptive vaginal ring, which became commercially
available in 2002 [1]. The
transparent, flexible polymer (ethylene—vinyl—acetate) ring
measures 54 mm in outer diameter and 50 mm in inner diameter. Its primary
mechanism of action is similar to that of oral contraceptive pills in that the
absorbed hormones inhibit ovulation
[2]. Between the first and
fifth days of the menstrual cycle, the flexible vaginal ring is inserted into
the vagina. For 3 weeks, the ring releases a continuous low dose of hormones,
etonogestrel and ethinyl estradiol, that is absorbed through the vaginal
mucosa into the systemic circulation. The ring is then removed for 1 week
before a new ring is inserted.
Advantages of the contraceptive vaginal ring over conventional oral
contraceptive pills include the convenience of monthly rather than daily
administration; bypass of hepatic first-pass metabolism; controlled local
release of hormones not subject to varied absorption through the
gastrointestinal tract; and overall lower systemic doses of hormones with
greater bioavailability [3]. In
a 1-year, multicenter study, the ring was shown to be well tolerated and
highly acceptable to women
[4].
The use of these devices will likely increase. Knowledge of the device and
its appearance on CT is important because radiologists are likely to encounter
the devices in practice.
Unfamiliarity with the CT appearance of the contraceptive vaginal ring may
lead to an erroneous diagnosis of vaginitis emphysematosa. Vaginitis
emphysematosa is a benign, self-limited bacterial vaginitis that manifests on
CT as discrete or confluent gas-filled cysts in the vaginal wall
[5]. The cysts may range from 2
mm to 2 cm in diameter. The pattern of the gas-filled cysts may create a
low-attenuation ring in the vagina, similar in appearance to findings
associated with the contraceptive ring. Confusion can be avoided by localizing
the areas of hypoattenuation; whereas vaginitis emphysematosa occurs in the
vaginal wall itself, the contraceptive vaginal ring lies in the vaginal lumen.
Also, the cysts from vaginitis emphysematosa are gas-filled, whereas the
contraceptive vaginal ring has an attenuation similar to that of water. The
cysts from vaginitis emphysematosa have an uneven border, whereas the ring has
smooth, distinct curved inner and outer margins.
The contraceptive device resembles a ring pessary, which is also placed in
the vagina. The shape and substance of the pessary are similar to those of the
contraceptive ring; however, the pessary is larger in diameter and width and
may contain a radiodense marker or strip. Furthermore, the pessary is inserted
to support the pelvic floor and is most often encountered in older multiparous
women with pelvic laxity. The pessary presses against the internal wall of the
vagina to uplift and displace the bladder base and neck forward or to support
a prolapsed uterus or vagina
[6]. Whereas a ring pessary
should be positioned in the most posterior aspect of the vagina around the
cervix, the contraceptive vaginal ring may lie anywhere and in any orientation
in the vagina. The contraceptive vaginal ring is usually encountered in
younger women.
In summary, the vaginal contraceptive ring is a new device containing sex
steroids that diffuse through the vaginal epithelium into the systemic
circulation. Radiologists will increasingly encounter these devices on
cross-sectional imaging. Familiarity with the device and the associated CT
findings will allow accurate interpretation.
References
- Harwood B, Mishell DR. Contraceptive vaginal rings.
Semin Reprod Med
2001;19:381
–389[Medline]
- Mulders TMT, Dieben TOM. Use of the novel combined contraceptive
vaginal ring NuvaRing for ovulation inhibition. Fertil
Steril 2001;75:865
–870[Medline]
- Timmer CJ, Mulders TMT. Pharmacokinetics of etonogestrel and
ethinyl estradiol released from a combined contraceptive vaginal ring.
Clin Pharmacokinet
2000;39:233
–242[Medline]
- Dieben TOM, Roumen FJME, Apter D. Efficacy, cycle control, and user
acceptability of a novel combined contraceptive vaginal ring.
Obstet Gynecol
2002;100:585
–593[Abstract/Free Full Text]
- Leder RA, Paulson EK. Vaginitis emphysematosa: CT and review of the
literature. AJR
2001;176:623
–625[Abstract/Free Full Text]
- Maubon AJ, Boncouer-Martel MP, Juhan V, et al. Static and dynamic
MRI of a urinary control intravaginal device. Eur
Radiol 2000;10:879
–884[Medline]
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Introduction
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