P1130015 (2)

1.2.4 Follicular and ovarian hematomas

In addition to the luteinizing. anovulatory follicles dcscribed above, therc are also anovulatory follicles which develop into hemorrhagic follicles or follicular hematomas (Squir.es et al. 1988, Leidl and Kahn 1989). In the case of the anovulatoiy, hemorrhagic fol-lides the hemorrhage takes place by diapedesls into the follicular lumen. In this type of anovulatory follicle no ultrasonically apparent luteinization occurs in the follicular wali. When only the follicle fills with blood it is referred to as a hemorrhagic follicle or a follicular hematoma. Where the surrounding ovarian tissue is largely atrophic and the hematoma encompasses vir-tually the entire ovary it is called a ovarian hematoma.

Ultrasonically, follicular hematomas do not show a widening, hyperechoic edge indicatiye of progressive lu-teinization (Fig. 135). Instead, the wali of these anovu-latory vesicle remains hyperechoic and thin and appears to remain unchanged for a long period of time, even beyond the end of a particular estrous period. The mesh of reflections that typically develops in the lumen of a luteinizing, anovulatory follicle faiłs to develop in Ihi* type of anovulatoiy follicle. In most follicular hematomas the initialły hypoechoic lumen will only develop regularly scattered floccular reflections at a later stage. These can become morę prominent as time passe*. Only rarely will a few echoic limes become evident instde the follicular lumen. They are interpreted as being fibrin strands inside the hematoma as the latter is becoming morę organized.

The diameters of anovulatory follicles which deyelop into follicular hematomas are occasionally only a łittle larger than those of maturę preovulatoiy follicles. Follicular hematomas sometimes expand considerably even after the end of estrus.

In rare cases ovarian hematomas with a diameter of 20 cm and morę and a weight of several kilograms are encountered (Fig. 1.36). On ultrasound such hematomas can appear as cystic structures with evenly scattered snow-like echoes in their lumina.