4 yr, 7mo old, 15 lb, Female, Spayed, Shih Tzu


Presenting complaint of difficulty urinating.  There is a history of bladder urolith. The patient is eating a dissolution diet. At a recheck examination yesterday a smaller stone was found in the opening of the urethra. The stone could be visualized with endoscopy (air used) and with rectal palpation the stone could be felt moving through the urethra. It was possible to visualize the stone and extraction- was attempted The stone fractured but could could not be retrieved. It was difficult to pass a Foley cathter past the stone. The patient is able to urinate- There is hematuria and stranguria but the patient is producing and voiding urine past the stone. The patient appears normal. There is concern for the air in the bladder, vaginal vault, and colon but this is presumed secondary to endoscopy. Further attempts at retrieval vs. surgical intervention (retropulse into bladder and/or void with flush thru bladder) are being considered.  The patient is currently being treated with midazolam, Meloxicam, prazosin, and buprenorphine.



Large bilobed gas opacities are present within the caudal ventral abdomen, in the region of the urinary bladder, extending cranially to the level of L4-5 in the right abdomen, appreciable in the VD projection.  Small multifocal gas opacities are present caudal and ventral to this in the lateral projections and extending into the pelvic inlet resulting in mild heterogeneity in these regions.  The urinary bladder itself is not definitively identified.  There is no overt evidence of mineralization in the caudal ventral abdomen.  There is a vaguely rounded mineral opacity, approximately 1.4 cm in diameter, superimposed with the caudal pubic symphysis and ischium in the VD projections of the pelvis, and caudal to the coxofemoral joints in the lateral projections.   Gas is present throughout the retroperitoneal space, appreciable bilaterally in the VD projection.  Gas dissects along the fascial planes of the cranial retroperitoneal space and is superimposed dorsal to the cardiac silhouette within the visible thorax, suspected to be mediastinal in location.  The stomach is mildly distended with gas and fluid.  The small intestines are unremarkable in diameter and content.  The colon is suspected to be minimally distended with heterogeneous poorly formed fecal material.  There is equivocal microhepatia.  The visible margins of the spleen are normal.  No abnormalities of the kidneys are evident.  Aside from suspected pneumomediastinum, the visible caudal thorax is unremarkable.  The included skeletal structures are normal.


The rounded mineral opacity superimposed with the pubic symphysis likely represents the reported urethral stone.  As described above, the urinary bladder itself is not definitively identified; it is possible that the urinary bladder is small or empty, though the integrity of the urinary bladder is not confirmed.  There is gas within the caudal ventral abdomen, which may be peritoneal in location.  Additionally, there is pneumoretroperitoneum and pneumomediastinum, which may have been introduced with insufflation during endoscopy. The impression of microhepatia may be the result of a normal variation though a degenerative hepatic process (fibrosis, cirrhosis, or degenerative changes secondary to a congenital vascular anomaly such as a portosystemic shunt) is also possible. An underlying endocrinopathy (hypoadrenocorticism) can result in microhepatica.


If further assessment is desired, an excretory urogram (ideally CT) could be considered if the patient is adequately hydrated.  Consultation with a surgeon may be of benefit for potential treatment and management recommendations of the suspected urethral stone. If the inciting cause is removed, pneumoretroperitoneum and pneumomediastinum will likely resolve; if the volume of gas persists and/or progresses, additional evaluation may be necessary.

One comment

  1. Findings: There is a large amount of free air within the retroperitoneal space , extending all the way from the diaphragm through the pelvic inlet. I suspect some air has entered the caudal mediastinum as well. A large gas pocket is seen outlining the margins of the kidneys, particularly the left kidney. On the VD view, these gas pockets give the impression of two gas-filled urinary bladders. There is gas stippling within the soft tissues all through the pelvic inlet and extending into the soft tissues around the hips. There is adequate serosal detail within the peritoneal cavity. The reported urinary stone is difficult to identify within the caudal abdomen/pelvic inlet due to the severe soft tissue heterogeneity.

    Interpretation: Iatrogenic pnuemoretroperitoneum (and likely pneumomediastinum) and soft tissue injury of the intrapelvic structures secondary to urethral tear/rupture (either during the endoscopy procedure or placement of the urinary catheter).

    Recommendations: A positive contrast vaginocystourethrogram would be very helpful in this patient to locate the source of the rupture. Ultimately, surgical intervention will be necessary to repair the tear and guide placement of a urinary catheter for healing.

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