| − | In the early stages of simple obstruction of the small and large intestine, the peritoneal fluid will look normal. A cloudy fluid is suggestive of an increased number of white blood cells, which indicates the disease is relatively advanced. The protein level of abdominal fluid can be analysed, and may also give information as to the integrity of intestinal blood vessels. Elevated lactate levels in the sample can also give an indication of the degree of compromise to bowel, particularly as a peritoneal:peripheral lactate ratio. A sanguinous fluid can be caused by an infarction, which indicates surgery is necessary. The peritoneal fluid of a case of infarction will also have an increased total protein concentration and nucleated cell count. However, sanguinous fluid can also be caused by external trauma (e.g. rib fractures), middle uterine artery rupture in post-foaling mares, intra-abdominal hemorrhage, intestinal necrosis, splenic puncture or by inadvertent bleeding caused by the veterinarian. If the spleen has accidentally be punctured then the fluid will have a greater PCV than the blood and will contain lots of small lymphocytes. Intra-abdominal hemorrhage will have a fluid with a PCV lower than the blood, few if any platelets and evidence of erythrocytophagia. Peritoneal fluid that contains food material can indicate rupture of the gastro-intestinal tract, although care should be taken that intestine has not been punctured inadvertently. The peritoneal fluid of a case with bowel rupture will be dark, turbid and smell of ingesta. It will have an increased total protein concentration due to intestinal necrosis and an increased nucleated cell count with intracellular bacteria and plant material evident grossly and microscopically.
| |
| − | A normal peritoneal fluid sample does not rule out a strangulating lesion. For example, in the case of a diaphragmatic hernia, the strangulating gut is contained within the thoracic cavity, so will not affect fluid within the abdominal cavity. A similar situation is true of intussuception, where the strangulating gut is contained with another piece of non-strangulating gut.
| |