Doppler Ultrasonography for Assessing Uterine Viability and Fetal Vitality in Uterine Torsion in a Domestic Cat (Felis catus): A Case Report.

BACKGROUND: Uterine torsion is rare in domestic cats and, when diagnosis is delayed, is associated with high maternal and fetal mortality. Conventional B-mode ultrasonography cannot reliably distinguish viable from devitalised uterine tissue, and Doppler ultrasonography, despite its capacity to assess uterine, ovarian, and fetal perfusion, has not been systematically applied to feline uterine torsion. CASE DESCRIPTION: A 4-year-old queen in late gestation presented with acute abdominal pain, lethargy, abdominal distension, and tachypnoea. B-mode imaging showed an enlarged, fluid-distended uterine segment with thickened walls. Colour, spectral, and power Doppler revealed an absent to markedly reduced arterial flow distal to the torsion, elevated resistive and pulsatility indices in the uterine and ovarian arteries, and the loss of peripheral perfusion. The absence of fetal heartbeats and umbilical flow confirmed fetal nonviability. Laparotomy confirmed the torsion of a congested, devitalised uterine horn, with asymmetric fetal loading (two kittens in the torted horn, one fetal resorption in the contralateral horn) as the likely biomechanical cause. Ovariohysterectomy was performed without derotation. Histopathology confirmed haemorrhagic necrosis, and haematology showed severe regenerative anaemia and marked leucocytosis, which resolved progressively after surgery. CONCLUSIONS: Doppler ultrasonography supplied vascular and fetal viability information unavailable from B-mode imaging alone, supporting ovariohysterectomy over conservative detorsion. Based on the feline case reports identified during the preparation of this report, this appears to be among the first descriptions of a systematic, multi-vessel Doppler protocol combining colour, power, and spectral modalities with resistive and pulsatility index measurements in feline uterine torsion; as this observation derives from a single case, it should be regarded as preliminary.