Figure 15b. Uterus didelphys with pyocolpos at 20 weeks gestation. The patient was referred for MR imaging because of purulent discharge from the vagina and uncertain uterine anatomy at US. (a) Sagittal T2-weighted image shows a gravid uterus containing a fetus in addition to a second uterine horn (straight arrow). Fluid fills the obstructed vagina of the nongravid uterus (arrowhead). The fluid collection communicates with the patent vagina via a small fistula (curved arrow), which was confirmed in the operating room. (b) Coronal half-Fourier RARE image shows that the nongravid uterine horn is on the left side (arrow). (c) Coronal half-Fourier RARE image obtained through the abdomen shows absence of the left kidney (arrow). The renal agenesis is on the same side as the obstructed vagina and nongravid uterine horn.