572
August 1992 Am J Obstet Gynecol
Letters
ternity ward in Paris in 1969. Other French surveys conducted later on national samples or on regional samples' outside of Paris did not report any clear relationship between daily travels and the preterm birth rate. Long daily travels are a consequence of the development of very large cities, which depend on urban policy and the labor market. Even if it is important that women be aware of the risks, it is probably unnecessary to recommend that they change their commuting habits. The mode of transportation they have chosen is the result of a compromise between several personal factors, and for them it is the only feasible solution. Doctors have to keep in mind that long commuting may be a risk factor for preterm birth, and all decisionmakers must be aware of the health consequences of their economic choices. Morie-josephe Saurel-Cubixolles Institut National de la Sante et de La Recherche Medical, 16 Av. P. Vaillant-Couturier, 94807 j!illejuif Cedex, France
REFERENCES 1. Mamelle N, Laumon B, Lazar P. Prematurity and occu-
pational activity during pregnancy. Am j Epidemiol 1984; 119:309-22.
2. McDonald AD, McDonald jC, Armstrong B, Cherry NM, Nolin AD, Robert D. Prematurity and work in pregnancy. Br J Ind Med 1988;45:56-62. 3. Saurel-Cubizolles M], Subtil D, Kaminski M. Is preterm delivery rate still related to physical working conditions during pregnancy? j Epiderniol Community Health 1991;45:29-34.
4. Kaminski M, Papiernik E. Multifactorial study of the risk of prematurity at 32 weeks of ges~ation. II. A comparison between an empirical prediction and a discriminant analysis. J Perinat Med 1974;2:37-44.
Imaging of the levonorgestrel implantable contraceptive device To the Editors: The availability of the levonorgestrel implantable contraceptive device in the United States has led to its frequent use and predictions that many users of oral contraceptives will switch to the levonorgestrel implant device (Norplant, WyethAyerst, Philadelphia). 1 The routine removal of such a device should pose no problem in the vast majority of cases because the subcutaneous implants are palpable. However, in cases in which infection develops or the implant migrates to a deeper non palpable location, the identification and removal of implants may be a problem. Prompted by such a case, we attempted to identify the levonorgestrel implantable contraceptive device in a normal location with roentgenography and ultrasonography of the arm. The implant was easily identified on an anterior-posterior projection film of the distal humerus with softtissue film and filming technique (55 kvp, 10 rnA sec). The six fanlike projections of the levonorgestrel device are radiopaque (Fig. 1). Nonpalpable implants could be easily localized with radiopaque skin markers similar to those techniques used in mammography. With a 10 MHz transducer and 1 em gel pad the six arms of the levonorgestrel implant device can be identified in the transverse plane on the basis of their posterior acoustic shadowing, a characteristic often seen with high-attenuation foreign bodies (Fig. 2). The longitudinal axis can also be identified because of the posterior shadowing. Plain film roentgenography of the arm for localiza-
Fig. 1. Soft-tissue x-ray film of the forearm shows the levonorgestrel implantable device with the fan-like configuration of its six radiopaque arms (arrows).
Volume 16i Number 2
Letters 573
Fig. 2. Ultrasonogram of the levonorgestrel implantable device with the six arms in their axial planes shows the posterior shadowing from the high attenuation of the implant (arrowheads).
tion in our case was faster, easier, less expensive; it also provided better resolution than ultrasonography. Localization for nonpalpable implants can be easily done with skin markers. In summary, a single anterioposterior soft-tissue roentgenography of the arm can localize the radiopaque levonorgestrel implant device easily and with
favorable resolution. This is recommended when palpable localization of the levonorgestrel implant device is not possible. Diane M. Tunckler, MD, and Barry E. Schwarz, MD Department of Obstetrics and Gynecology and Radiology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75235-7786
August 1992 Am J Obstet Gynecol
Letters
ternity ward in Paris in 1969. Other French surveys conducted later on national samples or on regional samples' outside of Paris did not report any clear relationship between daily travels and the preterm birth rate. Long daily travels are a consequence of the development of very large cities, which depend on urban policy and the labor market. Even if it is important that women be aware of the risks, it is probably unnecessary to recommend that they change their commuting habits. The mode of transportation they have chosen is the result of a compromise between several personal factors, and for them it is the only feasible solution. Doctors have to keep in mind that long commuting may be a risk factor for preterm birth, and all decisionmakers must be aware of the health consequences of their economic choices. Morie-josephe Saurel-Cubixolles Institut National de la Sante et de La Recherche Medical, 16 Av. P. Vaillant-Couturier, 94807 j!illejuif Cedex, France
REFERENCES 1. Mamelle N, Laumon B, Lazar P. Prematurity and occu-
pational activity during pregnancy. Am j Epidemiol 1984; 119:309-22.
2. McDonald AD, McDonald jC, Armstrong B, Cherry NM, Nolin AD, Robert D. Prematurity and work in pregnancy. Br J Ind Med 1988;45:56-62. 3. Saurel-Cubizolles M], Subtil D, Kaminski M. Is preterm delivery rate still related to physical working conditions during pregnancy? j Epiderniol Community Health 1991;45:29-34.
4. Kaminski M, Papiernik E. Multifactorial study of the risk of prematurity at 32 weeks of ges~ation. II. A comparison between an empirical prediction and a discriminant analysis. J Perinat Med 1974;2:37-44.
Imaging of the levonorgestrel implantable contraceptive device To the Editors: The availability of the levonorgestrel implantable contraceptive device in the United States has led to its frequent use and predictions that many users of oral contraceptives will switch to the levonorgestrel implant device (Norplant, WyethAyerst, Philadelphia). 1 The routine removal of such a device should pose no problem in the vast majority of cases because the subcutaneous implants are palpable. However, in cases in which infection develops or the implant migrates to a deeper non palpable location, the identification and removal of implants may be a problem. Prompted by such a case, we attempted to identify the levonorgestrel implantable contraceptive device in a normal location with roentgenography and ultrasonography of the arm. The implant was easily identified on an anterior-posterior projection film of the distal humerus with softtissue film and filming technique (55 kvp, 10 rnA sec). The six fanlike projections of the levonorgestrel device are radiopaque (Fig. 1). Nonpalpable implants could be easily localized with radiopaque skin markers similar to those techniques used in mammography. With a 10 MHz transducer and 1 em gel pad the six arms of the levonorgestrel implant device can be identified in the transverse plane on the basis of their posterior acoustic shadowing, a characteristic often seen with high-attenuation foreign bodies (Fig. 2). The longitudinal axis can also be identified because of the posterior shadowing. Plain film roentgenography of the arm for localiza-
Fig. 1. Soft-tissue x-ray film of the forearm shows the levonorgestrel implantable device with the fan-like configuration of its six radiopaque arms (arrows).
Volume 16i Number 2
Letters 573
Fig. 2. Ultrasonogram of the levonorgestrel implantable device with the six arms in their axial planes shows the posterior shadowing from the high attenuation of the implant (arrowheads).
tion in our case was faster, easier, less expensive; it also provided better resolution than ultrasonography. Localization for nonpalpable implants can be easily done with skin markers. In summary, a single anterioposterior soft-tissue roentgenography of the arm can localize the radiopaque levonorgestrel implant device easily and with
favorable resolution. This is recommended when palpable localization of the levonorgestrel implant device is not possible. Diane M. Tunckler, MD, and Barry E. Schwarz, MD Department of Obstetrics and Gynecology and Radiology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75235-7786
