Background and Aim: Ultrasonography (USG) is useful for non-invasively identifying changes that occur in soft tissue architecture. The objective of this research was to demonstrate postpartum (PP) uterine involution through the changes of perineal muscle intensity and thickness in Madura beef cow by ultrasonography.

Materials and Methods: Madura's breed cows used in the research consist of eight non-pregnant (NP) cows and three PP cow. The transrectal and transperineal USG imaging of NP cows was performed on days 1, 33, and 65. USG imaging of PP cows was performed every day starting from day 1 (24 h after parturition) until day 21 PP. Transrectal USG of the reproductive tract was performed for the cervix, corpus uteri, and cornua uteri. USG was performed transcutaneously over the perineal area for coccygeus and levator ani muscles at the longitudinal and transverse angles. Reproductive tract diameter and perineal muscle intensity and thickness were measured with ultrasound imaging.

Results: The analysis of the sonogram of PP cows showed that the diameter of the cervix, corpus uteri, and cornua uteri decreased within 21 days PP. The transverse view of the coccygeus muscle of PP cows showed decreased muscle intensity and thickness. On the other hand, the longitudinal view showed increased coccygeus muscle intensity and thickness. The transverse view of the coccygeus muscle of NP cows showed increased muscle intensity, while muscle thickness was reduced. Sonogram analysis of the levator ani muscle of PP cows showed decreased muscle intensity with increasing muscle thickness. However, imaging of the levator ani muscle of NP cows showed a decrease in both intensity and muscle thickness. There was a significant difference in the mean value intensity of the scanning view analysis results of the levator ani muscle of the PP cow (523.6 AU increased to 672.1 AU) and the NP cow (515.9 AU decreased to 465.4 AU). Furthermore, there was a significant difference (p<0.05) in the mean value thickness of both scanning view analyses of the coccygeus and levator ani muscles of PP cows (5.8 mm increased to 6.5 mm and 3.8 mm increased to 4.8 mm, respectively) and NP cows (8.8 mm increased to 9.1 mm and 5.9 mm decreased to 4.9 mm, respectively).

Conclusion: We found that the perineal muscles, namely, the levator ani muscle and coccygeus muscle, change in size, and intensity during uterine involution as demonstrated on Madura beef cow.

Keywords: coccygeus, levator ani, Madura beef cow, postpartum, ultrasonography.