Not common. Per USSR statistics, wounds to low extremities were ~30%.

Of those (e.g. all wounds low extremities are 100% in further statements),

• 38% - multiple-entry wounds (e.g. shrapnel from mines, artillery shells, bombs)

• 27% - didn't require any surgical intervention (e.g. small fragments, no arteries damaged, no deep penetration, bones are intact)

• wounds to left side of low extremities were more often (as right-handed tend to keep left side closer to enemy)

• wounds to thigh were 3 times more often than to bottom and 1.5 times more often than to shins

USSR combat medics didn't track genital wounds as a separate category (AFAIK), but I could say that such wounds were rare.

In general, if one is hit near genitals with multiple fragments, there's fair chance of major artery damage ( femoral , external iliac artery ) - and then not bleeding out fast is one's overriding concern.

Abdomen penetration wounds are next on one's list of concerns - with peritonitis danger.

And only after those two major concerns are triaged out, one should take leisure to worry about family jewels. Yes, bleeding might be profuse, but dressing is usually easier than for abdomen or applying tourniquet to femoral artery

he looks at his crotch and the medic says he's fine.

---

Quite plausible - at a glance you could say that major arteries weren't hit and guts are still inside abdomen.

Sources

1. russian - Medical Portal - statistics of wounds into low extremities, Great Patriotic War

2. Combat Medicine Museum, Russia. Archive of Combat Medicine Museum, Russian Federation - Архив ВММ МО РФ resides there.

Chris Hedges provides some American statistics in his provocative book What Every Person Should Know About War (New York: 2003). The book is written in question-answer format, with each answer substantiated by archival sources or post-action reports. To the question, "Should men try to protect their genitals in combat?" Hedges writes,

"There is not much you can do. Your groin is not protected by body armor. However, genital wounds accounted for only about 1 percent of the injuries among the [US] military in Somalia, and penis wounds alone counted for a small minority of genital injuries. Most wounds are to the scrotum." (p.45)

That said, this book was published--let alone written--in 2003 before coalition troops saw major action in asymmetrical combat in Iraq and Afghanistan. I reckon suicide bombs and IEDs have raised that number substantially, since in a vehicle blasts typically come from the bottom or side and move upward to the pelvis and abdomen. With the damage IEDs can do to lower extremities, I think the statistic should be higher, but I have yet to see evidence to support this claim. That conversation, however, breaks this sub's 20-year rule, so I will leave it at that.