Unfortunately, salpingitis is something that many hen get eventually. It is not rare. I have lost quite a few hens to internal laying, egg yolk peritonitis, and ascites which are all related, and I have only seen one lash egg inside a hen on necropsy. I assume there were lash eggs that may have been laid, but disappeared when a chicken scarfed them up. Broken or soft shelled eggs will certainly disappear that way if I don't see them first. Infectious bronchitis, one of the milder respiratory diseases, can cause thin or shell-less eggs.
	
		
			
		
		
	
				
			
	
			
			
			
			
			