Investigation of bowels adjacent to the uterus using MRI. For relief of bowel complications following intracavitary brachytherapy for cervical cancer

Intracavitary brachytherapy occasionally causes bowel injuries other than rectum. To relieve these adverse events, we investigated the relationships between uterine bodies and surrounding bowels using MRI. A hundred and ten of serial 252 pelvic MRI of women, excluding the following, were reviewed. The excluded items were large intrapelvic extrauterine masses over 3.5 cm in greater diameter, large uterine corpus masses over 2 cm, three or more uterine corpus masses, past history of hysterectomy or rectocolonic resection, and massive ascites. We investigated the fundus-bowel distance (FBD), site of the nearest bowel to the uterine body, flexion type and deviation of uterus, uterine wall thickness, subcutaneous fat thickness and age. FBD ranged from 8 to 42 mm (20.2±8.2 mm). In 66 cases (60%), FBD was 20 mm or less. The sites of the nearest bowel were 67 sigmoid colons, 27 rectums, 8 small intestines, and 7 descending colons. Eighty-three uteri (75.5%) were anteflexion and 27 uteri (24.5%) were retroflexion. Of the anteflexion group, 78.3% were adjacent to the sigmoid colon, and 92.6% of the retroflexion group were adjacent to rectum. Right-deviation uteri represented 33 cases (30%); mid-position 33, (30%); and left-deviation uteri, 44 (40%). Uterine wall thickness was 5 to 33 mm (17.8±5.2). Subcutaneous fat thickness was 10 to 47 mm (20.2±9.3). The age of patients ranged from 21 to 83 years (39.9±14.4). FBD showed statistical good correlation to uterine wall thickness and subcutaneous fat thickness. In anteflexion group, correlation of uterine wall thickness with FBD was significant. In retroflexion group, however, it was not significant. The site of bowels, flexion type, and deviation type did not correlate with FBD. FBD, uterine wall thickness and subcutaneous fat thickness showed regression of quadric curves with age; these peaked at ages 50.4, 46.0 and 46.2, respectively. It is presumed that predictive factors of bowel complication are thin uterine wall, young and aged, thin patients and retroflexion uterus. Uterine deviation does not shorten FBD. To relieve a radiation injury to bowels adjacent to the uterine fundus, the isodose curve must be decrease the irradiation dose of the tandem tip. At this time we conformed so as to recommend refering to MRI, CT and ultrasonography to detect the uterine wall thickness and the involved area of primary carcinoma. Retroflexion uterus as should be reformed to anteflexion by hard tandem applicator. Laterally-deviated uteruses should be adjusted such that they lie within the central shielding zone of the external beam. (author)