What Causes Diarrhea, Vomitting And Tender Abdomen After Hystrectomy?

i scanned one of my pts she had hystrectomy done 12 days ago and now she presented with diarhhea vomiting and tender abdomen .. although she had no free fluid or collection her lower abdomen was very much tender and she had marked thickening of her urinary bladder wall posteriorly .. the thickening was echogenic but bladder was partially filled and not well distended as well . it was 9mm thick .which is quite significant . apart from that she had hepatomegaly .i want to know wether i shud scan her again with full bladder or advise follow up could it be due to cystitis she denies any hematuria . whats causign the tenderness . n is it all due to gastroentritis ?