Fetal sheep’s health during labor is assessed using cardiotocography. Umbilical cord occlusion or UCO can identify hypotension. This fetal indicator can predict hypoxic-ischemic injuries too. But the clinical algorithms are not reliable. This study aims to relate the deceleration area and capacity during UCO with arterial hypotension and subsequent injuries.
A prospective study with control parameters was designed in a laboratory set-up. 18 fetal sheep who were near term were selected for sample measurements. They were divided into two groups of 6 and 12. The first group was provided 1 minute UCO every 5 minutes or 1:5, while the second group had 1:2.5 min. The study went on for 4 hours or until the mean arterial blood pressure of the fetus fell less than 20 mmHg.
The 1:5 min group had mild metabolic acidaemia without any hypotension. But in the second group, 10 to 12 fetuses had hypotension and severe acidaemia. Their peak value was 16.8±0.9mmHg after 71.2±6.7 UCOs. In the 1:5 group, deceleration capacity and area were unchanged. They progressively increased in the second group. Their hypotension median predictions before final occlusion were also 103 min and 123 min, respectively. The severity also correlated with these two key measures.
Deceleration area and capacity in the UCO series showed a strong relation to fetal hypotension. These measurements have the potential to identify the risks of hypoxic-ischemic injury during labor.