Pelvic radiological imaging: a surgeon's perspective

Radiological imaging of the pelvis adds an important dimension to our understanding of rectal and perianal disease. By integrating relevant information obtained from these investigations into planning and conduct of surgical procedures, outcomes for patients may be optimised. This review focuses on three areas from a clinical viewpoint. (1) With the increased use of neoadjuvant treatments pretherapeutic staging strategies become central to the management of rectal cancer patients. At present, transrectal ultrasound (TRUS), computerised tomography and magnetic resonance imaging (MRI) serve in combination to provide the essential informations. (2) The advent of endoanal ultrasound and MRI in the diagnostic workup of patients with faecal incontinence has caused a paradigm shift both conceptionally and in the way treatments are tailored to individual patients. (3) Concerning primary perianal fistulas there is little place for endoanal ultrasound or MRI. However, when a recurrent or Crohn's fistula is present, a combination of surgical exploration with either endoanal ultrasound or MRI depending on local expertise and availability may be the optimal approach to maximise benefit for these patients.

Relationship of the fistulas to the rectum and genitourinary tract in mouse fetuses with high anorectal malformations induced by all-trans retinoic acid

Since high anorectal malformations with fistulae in human embryos and fetuses of successive developmental stages have not been reported, the embryologic relationship between the rectal fistula (RF) and the genitourinary tract (GUT) in high anorectal agenesis (ARA) remains to be elucidated. This study investigates the developmental relationship between the RF and the GUT in male and female fetuses with high ARA using our established model for high ARA with fistula in mice. Pregnant mice received all-trans retinoic acid suspended in corn oil (5 mg/ml) 100 mg/kg i.p. on day 9 of pregnancy. All fetuses were removed from the uterus on a single day from days 12 to 18 of pregnancy. The caudal regions were analyzed histologically with hematoxylin and eosin staining. All fetuses examined had high ARA with fistula. On day 12 of pregnancy, an anomalous communication was seen between the urogenital sinus (UGS) and the rectum. In the affected female fetuses, on day 14 of pregnancy the paramesonephric (müllerian) ducts and müllerian tubercle were located above the rectocloacal fistula (RCF), and on day 18 of pregnancy the uterovaginal canal was located between the cloaca and the RCF. In the male fetuses, on day 14 of pregnancy the junction between the mesonephric (wolffian) duct and the UGS was located away from the junction between the rectum and the UGS. On day 18 of pregnancy the ejaculatory duct was located between the urinary bladder and the rectourethral fistula. The results of our experiment clearly show the embryologic relationship between the RF and the GUT with high ARA. The anomalous communication between the UGS and the rectum may interfere with normal caudal migration along the dorsal wall of the UGS at the junction between the UGS and the mesonephric or paramesonephric duct.

Congenital anomalies in mice induced by etretinate

We report on the experimental induction of anorectal malformations (ARM) and other internal and external malformations in mouse fetuses induced by maternal administration of etretinate, a long-acting vitamin A analogue. The teratogen was administered to pregnant mice between the 7th and 10th gestational days (E7 and E10). The mice of the control group were given pure sesame oil on E9. We examined survival rates, crown-rump length, and the incidence of internal and external malformations, with particular attention to ARM, in each group. All mice in the E8 group exhibited rectovesical fistula, hydronephrosis, and spina bifida. All males and females in the E9 group given 60 mg/kg of etretinate developed rectoprostatic urethral fistula and rectocloacal fistula, respectively. The E10 group, given 60 mg/kg of etretinate displayed cleft palate (63.6%), forelimb malformation (68.2%), and a short club-shaped tail (100%). The fetuses had more severe types of ARM when etretinate had been administered on an earlier gestational day. The E9 group is a useful model for anorectal malformation, whereas the E8 group is a model for hydronephrosis and spina bifida.