TABLE 1.

Troubleshooting table.

Step	Problem	Possible reason	Solution
9	Air bubbles	Solution not prewarmed	Ensure solution is prewarmed to at least 40–50 °C
		Air pockets in catheters	Agitate the catheters as they are flushed to ensure all air is purged.
17	Arterial leak	Pierced or punctured wall	An arterial leak can be fixed by suturing the vascular wall to the catheter downstream of the leak (Supplementary Fig. 2 and Supplementary Video 2)
21	Arterial rigor	Excessive delay	Surgical processes improve over time, decreasing the delay, but as a short-term solution the umbilical vein and artery can be separated after the uterine artery has been cannulated, reducing umbilical contraction and stiffening
24	Venous collapse	Elevated negative pressure	Lowering negative pressure and removing the complete vascular seal can improve perfusion efficiency, but it does lead to reduced collection rate
		Vascular wall suction	Use of a larger-diameter catheter can prevent possible wall suction, as the larger diameter is more difficult to obstruct