"It can be a useful sign to confirm renal agenesis when the kidney is not visualised during antenatal ultrasound 5,6, as well as during postnatal imaging of patients to distinguish from post-nephrectomy state."
Line 2:200·Only use medical adjectival hyphens where the letters at the end and start of the compound word are the same, e.g. post-transplant. In this case, don't use the hyphen: 'post-nephrectomy'.