83686 P1130055

13.4.4 Endometritis

[    AocumulsDons of fluid imkte the uterine lumen are

I »ery typical of marcs suflering from chronię endorrastri-I sjł The amount of fluid in cases of uterine infectioos i v*ńcs front matę to marę (Fig. 1.105 to 1.107). The ! amount of the secnetions in the same mare can also vary i &om day to day. This js dependent on the stage of the | cyde. Fluid accumulanons found during estrus may be phyuokigK. but may also be an earły indication of en-dometritK hi many cases (Adams et al. 1987). When-| ever fluid secretions are found in the uterus during di-estru* they sbouki be regarded as abnormal. Sometimes che secretions are concentrated in a partkrular area of the uterus and at other times they can be detected along tbe entire uterine lumen.

The outime of the fluid accumulations in endometri-tts cases k typically stellate shaped (Lhidl and Kahn 19M) in a transverse section of a fluid filled uterine hom in which the endometrial folds bulge into the uter-ine lumen (Fig. 1.106). The interface between the seeretion and the surrounding uterine wali Ls wavy. Ouite frequentiy the 6 to 8 endometrial folds that are i normalfy present in the uterus of a mare can be seen. The fluid distentkm of tbe uterus causes fluid to also penetrate in between the longitudinal folds, separating them from one another whereas in the absence of any fluid they normally He in tight apposition.

The stellate shaped appearance of the sonographic cross section of a free intra-uterine fluid accumulation in cases of endometritis cannot be seen in fluid accumu-iations of other origśns sucb as in intact pregnancies or with endometrial cysts. Due to the inner tension of the płacenia] membranes or endometrial cysts these form relatńeiy tightiy filled vesicles which stretch the folds of the endometrium to form smooth lines. The interface between the uterine contents and the endometrium thus forms a smooth linę. In rare indhśdual cases a stel-latc shaped proirusion of the endometrial fokk into the piacental membranę* can be found evcn in intact preg-nancics. The cases thus far identified al! occurred in oł-der, multiparous mares. The irregular interface between the embryonic fluid and the surrounding uterine wali appears to be a conststent finding in ali cases of embryonic death.

A typical feature of the uterine seeretion in the case of endometritis is the inereased eehogenicity of the fluid. Clear fluids usually produce an aneehoic, black image on ultrasonography. In contrast, the secretions of endometritis mares ałways contain echoes of yarying in-tensity. Oepending on the degree of change these can vaty from occasional floccular echoic spots to echo pat-tems that can be morę echoic than the surrounding uterine wali. Smali air bubbles inside fluid accumulations can also produce floccular reflections. These are particu-Iarfyevidentafteruterineinfuskmsorflushes(Fig.l. 108).

From a differential diagnosis point of view it should be pointed out that amniotic fluid can also be echoic during the 2nd and 3rd trimesters of gestation. Due to the inerease in cellular components it is first floccular and later the amniotic fluid will have snowy reflections. This also applies to the allantoic fluid during the last trimester of pregnancy. The sonographic differentiation between the seeretion of an endometritis and other fluid types in the uterus such as piacental fluid or that contained in endometrial cysts, must be undertaken in conjunction with the assessment of other criteria. Im-portant criteria in this regard are the eehogenicity of the fluid, its intra-uterine position and its shape. The most suitable time for the ultrasonic diagnosis of an endometritis appears to be during the mid to late diestrous period (Adams et al. 1987). At this stage of the cyde, pathologic fluid secretions seem to be most prominent and can still be differentiated from the possibly physio-logic secretions that may appear during estrus.