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Balloon tamponade in atonic bleeding induces uterine contraction: attempt to quantify uterine stiffness using acoustic radiation force impulse elastography before and after balloon tamponade

2011; Informa; Volume: 90; Issue: 10 Linguagem: Inglês

10.1111/j.1600-0412.2011.01169.x

1600-0412

Takashi Yorifuji, Toshitaka Tanaka, Shintaro Makino, Taro Koshiishi, Motoi Sugimura, Satoru Takeda,

Ultrasound and Hyperthermia Applications

Sir, Balloon tamponade can be performed rapidly and easily, and is highly effective for achieving hemostasis in atonic bleeding, as recently reported (1,2,3). However, the mechanisms underlying hemostasis have not been elucidated. We have performed balloon tamponade in six women with atonic bleeding after normal vaginal delivery, and complete hemostasis was achieved with the balloon alone. A metreurynter was inserted into the uterine cervix as a balloon catheter and inflated with enough saline both to prevent the device falling into the vagina and to stop the bleeding from the uterine os. In each of the six women, the placenta was located in the uterine corpus, or its separation surface covered the uterine corpus. We presumed that the mechanism of hemostasis by balloon tamponade involved factors other than direct compression of the bleeding site. Although the balloon was placed in the uterine cervix, we could palpate good uterine contractions after inserting the balloon, suggesting a hemostatic mechanism whereby balloon insertion into the uterine cervix induces contraction of the uterine corpus. To investigate the mechanisms by which intrauterine balloons achieve the tamponade effect of inducing uterine contraction, we estimated the stiffness of the uterine corpus and cervix by acoustic radiation force impulse elastography before and after balloon tamponade in one patient. In acoustic radiation force impulse imaging, an initial ultrasonic pulse is transmitted at diagnostic intensity levels to obtain a baseline signal for later comparison. A short-duration (approximately 0.3s), high-intensity acoustic 'pushing pulse' is then transmitted by the same transducer, followed by a series of diagnostic intensity pulses that are used to track displacement of the tissue caused by the pushing pulse (4,5). Velocity of the shear wave depends on tissue stiffness, so acoustic radiation force impulse technology can be applied to elastography. We used a Siemens ACUSON S2000 US system (Mochida Siemens Medical Systems Co., Ltd, Tokyo, Japan) with convex probe (4C1), tissue harmonic imaging (4MHz) and a mechanical index of 1.7. An acoustic push pulse was transmitted to the uterine corpus and cervix at a depth of approximately 15mm from the uterine surface, where the shear-wave velocity was calculated and expressed with a numerical value (in meters per second). Measured values are given as the mean value of three measurements at the same site. Measurements of myometrial stiffness were performed before, immediately after, and 1, 2 and 24hours after balloon insertion (Figure 1). Shear wave velocity in the uterine corpus and cervix. Stiffness of the uterine corpus (continuous line) increased just after inserting the balloon into the uterine cervix, but stiffness of the uterine cervix (dotted line) was unchanged. Uterine corpus stiffness was 2.79m/s before balloon insertion, 4.09m/s immediately after balloon insertion, 2.60m/s after one hour, 2.35m/s after two hours and 3.34m/s after 24hours. Uterine cervical stiffness was 1.31m/s before balloon insertion, 1.66m/s immediately after balloon insertion, 1.50m/s after one hour, 1.43m/s after two hours and 1.56m/s after 24hours. Our findings suggest that the hemostatic mechanisms underlying balloon tamponade in atonic bleeding involve not only direct compression, but also induction of contraction of the uterine corpus by insertion of the balloon into the uterine cervix, leading to hemostasis.