Which flow pattern is typical for the superior mesenteric artery before meals?

Which flow pattern is typical for the superior mesenteric artery before meals?

• A. Low resistance
• B. High resistance
• C. Pulsatile
• D. Turbulent

Answer: (B)

The key idea is that the blood flow pattern in visceral arteries mirrors the organ’s metabolic needs. Before a meal, the small intestine isn’t actively digesting, so the splanchnic arterioles constrict enough to raise downstream resistance. On a Doppler waveform, that shows up as a high-resistance pattern: a sharp systolic forward flow with little or even reversed flow during diastole, meaning diastolic flow is reduced. After eating, the gut requires more blood for digestion, so the splanchnic circulation vasodilates and resistance drops. The waveform shifts to a low-resistance pattern, with more continuous forward flow through diastole. So, before meals, the superior mesenteric artery typically displays a high-resistance Doppler pattern. The other descriptors aren’t as characteristic here: pulsatile flow is common to arteries but doesn’t distinguish fasting from fed states; a turbulent pattern would suggest an abnormality; low-resistance flow is more typical after a meal.

The key idea is that the blood flow pattern in visceral arteries mirrors the organ’s metabolic needs. Before a meal, the small intestine isn’t actively digesting, so the splanchnic arterioles constrict enough to raise downstream resistance. On a Doppler waveform, that shows up as a high-resistance pattern: a sharp systolic forward flow with little or even reversed flow during diastole, meaning diastolic flow is reduced.

After eating, the gut requires more blood for digestion, so the splanchnic circulation vasodilates and resistance drops. The waveform shifts to a low-resistance pattern, with more continuous forward flow through diastole.

So, before meals, the superior mesenteric artery typically displays a high-resistance Doppler pattern. The other descriptors aren’t as characteristic here: pulsatile flow is common to arteries but doesn’t distinguish fasting from fed states; a turbulent pattern would suggest an abnormality; low-resistance flow is more typical after a meal.