Intuitive Surgical Inc. ISRG -0.58% shares fell 6% on Thursday in extended trading after the health care company reported earnings that were below analysts’ expectations. Intuitive Surgical’s fiscal second-quarter earnings were $426 million or $1.18 per share. This compares to net income of $307,8 million or 85 cents a piece in the previous quarter. Earnings adjusted to $1.20 per share. The revenue jumped from $1.5 billion to $1.76billion, a jump of 45%. FactSet surveyed analysts who expected an average net profit of $1.33 per share on revenue of $1.7 billion. Intuitive Surgical shares have risen 31% this year while the S&P 500 SPX -0.68% index has risen 18%.